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APPROVED STM Drainage Report Version 4.0 3-1-2021Donna Breske BLD2019-0026 & Associates Civil Engineering & Land Use Planning Drainage Report For Paradise Heights Date: March 1, 2021 - Version 4.0 Site Address: 546 Paradise Lane Edmonds WA, 98020 Parcel Number(s): 27032500302600 Prepared By: Donna L. Breske, P.E. Donna Breske & Associates, LLC 21 Ave A, Suite 4 Snohomish, WA 98290 Phone: 206-715-9582 Email: DonnaB@donnabreske.com RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Approved by Fire OaiOvzozi AW P—FLtte✓er APPLIES WITH APPLICABLE CITY STROMWA ER CODE 03/16/2021 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Table of Contents Narrative: Executive Summary.................................................................................................................Page 3 VicinityMap............................................................................................................................ Page 4 Impervious Area Exhibit.......................................................................................................... Page 5 Minimum Requirements #1 -#9........................................................................................ Pages 6-9 SWPPP Narrative & Exhibit of Land Disturbance............................................................ Pages 10-12 Disturbed Area &Topsoil Placement Exhibit........................................................................Page 13 Appendix: A: Drainage Inventory Map B: Geotech Letter and Soils C: WWHM2012 Project Report D: Water Quality E: Operations and Maintenance 2 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Executive Summary The site consists of a single tax parcel that has a gross area of 30,238 sf (0.694 acres). The site address is 546 Paradise Ln, Edmonds, WA 98020, with tax parcel number 27032500302600. This project proposes the construction of 3 residential buildings, and a paved driving surface. Each building will contain 4 dwelling units. A house and paved driving surface currently exists on site, and will be removed. A Geotechnical Engineering Study was performed by Earth Solutions NW, LLC. The analysis determined that the site's soils primarily consist of brown poorly graded sand with gravel with a calculated long term infiltration rate of 18 in/hr. This project uses 18in/hr as the design infiltration rate in the sizing of stormwater infiltration facilities. The site elevations range between 268 and 252 with most of the site mildly sloping downgradient southeast to northwest at grades between 2% and 5%. The northwest corner of the property contains slopes of approximately 31%. Along the northeastern boundary, adjacent to Paradise Ln, the site slopes northeasterly at roughly 25%. Off -site next to the cul-de-sac, are slopes of 46% and thus exceed the 40% threshold defined in the ECDC, also defined by more than 10-ft vertical difference. Existing vegetation on site include several trees shown on the site plans. The existing structures include an existing house, and detatched garage. Paved driving access to these structures is provided from Paradise Ln. The existing house, garage, and driving surface are all proposed to be removed as a part of this project. The 13 Elements of Stormwater Pollution Prevention Plan (SWPPP) are addressed on the drawing sheet titled Storm Water Prevention Plan and as well as in this report. Per the City of Edmonds' Chapter 18.30 this project must comply with the drainage requirements listed in the DOE 2014 Stormwater Management Manual for Western Washington. Since this project proposes greater than 10,000 square feet of impervious surface, Minimum Requirements 1-9 must be evaluated. Water quality treatment will also be required as this project proposes more than 5,000 sf of pollution generating hard surface. This project proposes to route proposed impervious surface stormwater runoff into infiltration trenches designed to infiltrate storm water runoff routed to them from the on -site development. For the new impervious areas of road widening, curb, gutter, and sidewalk, within the Paradise Lane right-of-way, they are effectively offset or given a trade-off for those "grandfathered-in" on -site impervious areas created prior to the date of the City's first storm water ordiance of July 6, 1977. Refer to Stormwater Compliance Overview Exhibit on following page. Water Quality treatment is designed to be achieved with the use of Contech Stormfilter catchbasins. Compliance is demonstrated via acheivement of the Low Impact Development Performance Standard as depicted within the WWHM2012 Hydrology Prinout included in Appendix C. Post construction soil in the disturbed areas, not covered by impervious surface, are to be installed in accordance to BMP T5.13. Topsoil and duff are to be stockpiled separate from other material and shall be spread at least 8" deep. 3 z Mar 02 2 CITY OF EDM( DEVELOPMENTS 14 ELM ST 04, �04 ELM 'QFF� PL C. z p�P a ,SITE n � BIRCH ST KULSHAN RD � � 131H AVE S yy q�F ALGONQUIN RD �5 226TH ST SW Sw S DOGWOOD LN � PREPARED BY.• DONNA BRESKE & ASSOCIATES, LLC 21 AVE A, SUITE 4 SNOHOMISH, WA 98290 PHONE. (425) 334-9980 DONNABRESKE©COMCAST.NET VICINITY MAP N. T. S. VICINITY MAP TAX NO. 27OJ2500302600 SITE ADDRESS: 546 PARADISE LN PROJECT PARADISE HEIGHTS EDMONDS, WA 98020 ISSUE DATE.• 11-12-18 4 1,909 SF PRE JULY 6, 19 IMPERVIOUS AREA EXISTING HOUSE ON 132 SF (.003 AC) PRE JULY 6, 1977 IMPERVIOUS AREA OF EXISTING O WALKWAYS � ja Analysis ® 0.17 p U 0.13 V 0.10 0 0.06 0.03 10E-5 Stream Protection Welland Input Volu Analyze dat—ts r 1,523 SF (035 AC) PRE JULY 6, 1977 IMPERVIOUS AREA OF DRIVEWAY. LANE WIDENING _ 847 SF NEW SIDEWALK /A 4 &WALKWAY 1,600 SF RES U B /, PAVED APRON Mar 02 2021 670 SF CITY OF EDMONDS / DEVELOPMENT SERVICES DEPARTMENT � GRANDFATHERED" 3,564 SF _ OFFSETS THE 3,117 SF OF NEW "GRAN AREA OF 7HE O IMPERVOUS AREA OF PAVEMENT, CURB, IECT. GUTTF_R, & SIDEWALK OF THE PROJECT LIMITS OF PROJECT FOR HYDROLOGY MODEL -' SOFTWARE - WWHM2012 POC, (POINT OF +, A COMPLIANCE) IS DESIGNATED AS E EXISTING CATC BASIN FOR /4 PURPOSES F i HYDROLO MODEL/ G OF 7HE This sheet not considered in project approval. 7HE INFIL77?A71ON 7RENCHES WITHIN OPROJECT FULFILL 7HE REQUIREMENT ADDRESS MR15 TO USE LID BMP" (LOW IMPACT DEVELOPMENT — B MANAGEMENT PRACTICES) / 10E-4 /E-3 10E-2 10E-1 1 P __t Time Exceeding LID Duration I Flaw Delete Selected DONNA BRESKE & ASSOCIATES 21 AVE A, SUITE 4 SIXOHOMISH, WA 98290 HONE 206-715-9582 DonnaB®DONNABRESKE. COM 501 POC 1 Predeveloped ■ 801 POC 1 Mitigated flow 10 100 Water quality Hydro developed Recharge M THE WWHM2112 HYDROLOGY SOFTWARE IS 4 USED TO DEM0NS7RA7E COMPLIANCE W17H MR17 (FLOW CONTROL) FOR SURFACE WA7ER VOLUME & QUANTITY RELEASED FROM 7HE PROJECT AT 7HE POINT OF COMPLIANCE e Facility A.SSED CONCLUSION. ox(efs) Predev it Percentage Pass INSTALLA77ON OF THE 0282 8483 08 75 Pass TWO INFILTRATION 0296 7101 53 9 75 Pass 0310 5984 440 73 Pass TRENCHES ON SITE, 0324 5019 3601 71 Pass COUPLED TOGETHER 0338 4250 2919 8 Pass WITH MODELING THE 0352 3629 2448 Pass 0366 3118 2090 67 Pass PRE-1977IMPERWOUS 0380 2697 1851 68 Pass AREAS INTO THE 0394 2338 1635 69 Pass EXIS77NG S17E COND177ON 0408 2064 1435 69 ass RESULTS IN 0422 1823 1263 69 P s 0436 1614 1099 68 Pas ACHIEVEMENT OF THE 0450 1428 977 68 Pass FLOW CONTROL 0464 1282 872 68 Pass TANDARD AS WELL AS 0477 1134 777 68 Pass 0491 998 690 69 Pass LID PERFORMANCE 0505 $91 607 68 Pass STA ARD AT THE 0519 813 550 67 Pass POIN F COMPLIANCE 0533 722 474 65 Pass 0547 656 422 64 Pass FOR PROJECT. 0561 576 370 64 Fasa STORMWATER COMPLIANCE OVERVIEW EXHIBIT TAX NO. 27032500JO2600 S17E ADDRESS. • 546 PARADISE LN PROJECT PARADISE HEIGHTS EDMONDS, WA 98020 SCALE. N.T.S. DA7E.•3-1-2021 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Paradise Heights - DATE: 3-1-2021 - Version 4.0 Edmonds Chapter 18.30 and 2014 Stormwater Management Manual for Western Washington 2.5.1 Minimum Requirement #1: Preparation of Stormwater Site Plans 3.1.1 Site Analysis: Volume 1, Section 3.1 Boundary Survey & Topography Map A survey conducted by Green Land Surveying was used to determine the site's boundary and topography. Vegetation and Utility Infrastructure • The site has a number of existing trees with locations determined by the survey conducted by Green Land Surveying. Utility locations that are shown on the plans were also provided by the survey, and the City of Edmonds GIS map. Soils Report Earth Solutions NW, LLC. Conducted a geotechnical analysis of the site's soils, and prepared a report. In the report it states that the site's soils have corrected long term infiltration rate of 18 in/hr and infiltration BMPs will be considered in the design of this project's stormwater drainage system. The soils suitable for infiltration were located at depths of at least 3' below the ground surface. Site Analysis and Summary of Existing Conditions. The site contains a single family house, garage, and paved driving surface. A number of trees exist on site. The site elevations range between 268 and 252 with most of the site mildly sloping downgradient southeast to northwest at grades between 2% and 5%. The northwest corner of the property contains slopes of approximately 31 %. Along the northeastern boundary, adjacent to Paradise Ln, the site slopes northeasterly at roughly 25%. The permeable ground surface appears to primarily consist of grass. No wetlands, or other critical areas exist on site or appear to be within the site's immediate vicinity. Off site next to the Paradise Lane cul-de-sac is a small area of slopes of 46% as determined from the topography and boundary survey provided by Guy Greene, PLS eCDC 23-80.020.4: 47WDED PER SLOPE THAT EXCEEDS HEIGHT OF 10-FEET OOOT HORIZONTAL RUN. (RISE OVER RUN. 10250.4 = 40%) — A RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT 3.1.2 Preliminary Development Layout: Vol 1, Section 3.1.2 A development layout has been prepared that shows the proposed locations of residential structures, driving surfaces, drainage facilities, and BMPs. LID techniques are used to the maximum extent feasible given the proposed layout. 3.1.3 Off -Site Upstream and Downstream Analysis: Vol 1, Section 3.1.3 • Upstream Analysis: Properties located along the most upstream section of Paradise Ln appear to discharge runoff into a 12" concrete conveyance system that expands to a 24" CMP pipe downstream of CB 12-300. This conveyance pipe then directs flows along 6ch PI S at MH 12-261. There appears to be no conveyance systems upstream of the property along Paradise Ln, between MH 12-261 and the site. Runoff from properties along Paradise Ln, downstream of MH 12-261 likely disperse runoff into their surrounding lawns, and possibly sheet flow into Paradise Ln. This project proposes to route 98.8% of runoff from impervious surface toward infiltration trenches sized to infiltrate 100% of the runoff routed to them. This project is not anticipated to have a negative impact on upstream properties or upstream conveyance systems. It is not anticipated that runoff from upstream properties to the southeast would have a significant or observable impact on the development due to soils within the project vicinity having very high infiltration rates. • Downstream Analysis: This project proposes to route runoff into proposed infiltration trenches sized with WWHM2012. An overflow conveyance system has been provided in the design that discharges to CB 12-371 located within Paradise Ln. CB 12-371 discharges to a 12" concrete pipe that connects to the conveyance system located within Edmonds Way. The conveyance system ultimately discharges flows into Willow Creek, followed by the Edmonds Marsh, and Puget Sound. A brief site visit was conducted in February 2018, and the catch basins located within Paradise Ln were observed. It is not anticipated that this project will have a negative impact on downstream properties or conveyance systems. This project intends to infiltrate 98.8% of on -site impervious surface runoff into infiltration trenches, and is not anticipated to produce any significant flows toward the downstream conveyance system. The proposed frontage improvements are also not anticipated to negatively impact downstream conveyance systems. 3.1.4 Determination of Applicable Minimum Requirements: Vol 1, Section 3.1.4 This project proposes greater than 5,000 square feet of hard surface and triggers the evaluation of minimum requirements 1-9. 3.1.5 Preparation of Permanent Stormwater Control Plan: Vol 1, Section 3.1.5 A permanent Stormwater Control Plan has been prepared with relevant elements shown on the drainage plan. Elements of the stormwater control plan include infiltration trenches, and Contech catchbasin stormfilters. 7 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT 3.1.6 Preparation of Construction Stormwater Pollution Prevention Plan (SWPPP), Vol 1, Section 3.1.6 A construction stormwater pollution prevention plan has been included in this report with elements shown on the TESC plan. 3.1.7 Completion of Stormwater Site Plan, Vol. 1, Section 3.1.7 A stormwater site plan has been prepared and is included in this project civil plans showing the locations of all proposed drainage elements. 2.5.2 Minimum Requirement #2: Construction Stormwater Pollution Prevention (SWPPP) The construction stormwater pollution prevention plan has been included in this report. Relevant elements include temporary construction entrance, tree protection, silt fences, and straw wattles. 2.5.3 Minimum Requirement #3: Source Control of Pollution Source control of pollutants will be satisfied with the implementation of appropriate stormwater pollution prevention BMPs. Elements of source control are indicated on the site plans and in the SWPPP narrative. 2.5.4 Minimum Requirement #4: Preservation of Natural Drainage Systems and Outfalls The site's topography indicates that surface flows would travel from the southeast to the northwest. This site's soils are very well draining with measured infiltration rates of 120 in/hr. This project proposes that the site's runoff will be routed to proposed infiltration trenches and it is not anticipated that the project will have a significant impact on the existing drainage patterns. 2.5.5 Minimum Requirement #5: On Site Stormwater Management This project proposes more than 5,000 sf of impervious surfaces and is required to either comply with the Low Impact Development Performance Standard, or evaluate BMPs in List #2. This Drainage Report demonstrates compliance with the LID Performance Standard and is documented in Appendix E which includes the WWHM2012 Hydrology printout. Two infiltration trenches on site are proposed. Furthermore, existing impervious areas, (house & driveway), included on site prior to the date of the City's first storm water ordinance, (July 6, 1977) are "grandfathered" and are allowed to be used as existing impervious area within the WWHM2012 model. The LID Performance Standard is achieved with the infiltration trenches on site and no other storm water management elements are required for the project. Low Impact Development Performance Standard Stormwater discharges shall match developed discharge durations to pre - developed durations for the range of pre -developed discharge rates from 8% of the 2-year peak flow to 50% of the 2-year peak flow. Refer to the Standard Flow Control Requirement section in Minimum Requirement #7 for information about the assignment of the pre -developed condition. Project sites that must also meet minimum requirement #7 — flow control - must match flow durations between 8% of the 2-year flow through the full 50-year flow. RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT 2.5.6 Minimum Requirement #6: Runoff Treatment This project proposes more than 5,000 square feet of pollution generating hard surface and requires basic water quality treatment. Water quality treatment will be provided by Contech Catchbasin Stormfilters that use ZPG media to filter runoff pollutants. The filter size selected is anticipated to adequately filter 91 % of the runoff volumes given the water quality now rates. Calculations of the water quality flow rates and Stormfilter capacity are provided in Appendix D of this report. 2.5.7 Minimum Requirement #7: Flow Control This project proposes greater than 10,000 square feet of total hard surfaces and triggers the evaluation of flow control. The effective impervious surface for this project has been reduced due to the proposed use of infiltration trenches. These trenches provide the required amount of storm water management to meet both the LID and the Flow Control Standard for the project. 2.5.8 Minimum Requirement #8: Wetlands Protection N/A- This project does not contain wetlands, and does not appear to be within the vicinity of a wetland. 2.5.9 Minimum Requirement #9: Operation and Maintenance An operations and maintenance section has been included in appendix D of this report. 9 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Stormwater Pollution Prevention Plan Narrative A Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the construction Stormwater permit requirements. The site is 0.694 acres in size and is located at 546 Paradise Ln, Edmonds, WA 98020, with tax parcel number 27032500302600. This project proposes the construction of 3 residential buildings, and a paved driving surface. Each building will contain 4 dwelling units. The limits of disturbance will be 30,238+/- SF with greater than 5,000 sf of impervious surface triggering minimum requirements #1-9. Most of the grading will consist of cut in the areas of proposed construction. The purpose of the SWPPP is to describe all temporary and permanent erosion and sediment control (TESC) measures, pollution prevention measures, inspection/monitoring activities, and recordkeeping that will be implemented during the proposed project. This narrative is to be considered a "living document." This project's Certified Erosion and Sediment Control Specialist is to amend this document as needed during construction. Applications of these elements are shown on the TESC Plan Sheet. The specific elements included in the SWPPP are: Element #1: Mark Clearing Limits Prior to the beginning of land disturbing activities, the clearing limits are defined on the TESC plan. Applicable BMP's for this project are: • BMP C 10 1 - Preserving Natural Vegetation, (includes preserving mature trees and their understory outside of the clearing limits). • BMP C103 -High Visibility Fence Element #2 — Establish Construction Access The existing asphalt driving surface is proposed as the construction entrance and is shown on the TESC plan to provide access to the site from Paradise Ln. • BMP C105 -Stabilized Construction Entrance Element #3 — Control Flow Rates Applicable BMP's are shown on the TESC Plan and include: • BMP C120-Temporary or Permanent Seeding • BMP C235: Straw Wattles Element #4 — Install Sediment Controls Specific controls include: • BMP C120 -Temporary and Permanent Seeding • BMP C233: Silt Fence 10 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Element #5 — Stabilize Soils Areas that are to remain uncovered for more than 7 days, are to be stabilized with BMPs. Specific BMP's to be implemented include Temporary and Permanent Seeding (BMP C 120), Mulching (BMP C 121), and Plastic Covering (BMP C 123). Element #6 — Protect Slopes Cut and fill slopes shall be protected as necessary through use of Temporary and Permanent Seeding (BMP C 120), Mulching (BMP C 121), and Plastic Covering (BMP C 123). Element #7 — Protect Drain Inlets Inlet protection will be utilized on catch basins down gradient and in the vicinity of the disturbed areas. The necessity to protect stormdrain inlets must be determined in the field. • BMP C220: Storm Drain Inlet Protection Element #8 — Stabilize Channels and Outlets It is not anticipated that any flows of significant velocity will leave the site or cause any negative impact to the downstream residential properties, or Edmonds Way. Straw wattles will be used as a means of controlling runoff flow rates on site. Element #9 — Control Pollutants All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well -organized, and free of debris. • BMP C 153-Material Storage, Delivery, and Containment Element #10 — Control Dewatering NA- No de -watering is anticipated for this project. Element #11— Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMP's specifications. Visual monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours of any rainfall event that causes a discharge from the site. If the site becomes inactive, and is temporarily stabilized, the inspection frequency will be reduced to once every month. All temporary erosion and sediment control BMPs shall be removed within 30 days after the final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs or vegetation shall be permanently stabilized. 11 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Element #12 — Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: • Design the project to fit the existing topography, soils, and drainage patterns. • Emphasize erosion control rather than sediment control. • Minimize the extent and duration of the area exposed. • Keep runoff velocities low. • Retain sediment on site. • Thoroughly monitor site and maintain all ESC measures. • Schedule major earthwork during the dry season. Element #13 — Protection of Lid BMP's During the life of the Paradise Heights project all proposed BMP's on -site shall fully comply with the DOE's regulations for Element #13. The subgrade soils of the proposed infiltration trenches must remain relatively undisturbed and marked off with high visibility fence until road base coarse materials are applied over them for the proposed drive aisles. Heavy equipment must not travel directly over the soil in proposed locations of the trenches. Sediments discharged to the trenches must be removed, and replacement of trench aggregates must be completed as necessary to ensure the trenches infiltrate as they were designed. 12 D = DISTURBED AREA (6,166 SF) INSTALL 8" MINIMUM DEPTH STOCKPILED SOIL Ai = PROPOSED IMPERVIOUS AREA (23,837 SF) DISTURBED AREA EXHIBIT_ SCALE. 1 "= 40' PREPARED BY. DISTURBED AREA EXHIBIT DONNA BRESKE & ASSOCIATES, LLC 21 AVE A, SUITE 4 TAX NO. 27OJ2500302600 SITE ADDRESS: 546 PARADISE LN SNOHOMISH, WA 98290 PROJECT PARADISE HEIGHTS EDMONDS, WA 98020 PHONE. (425) 334-9980 DONNABRESKE®COMCAST.NET ISSUE DATE.• 2-27-19 Mar 02 Cl OF EDI DEVELOPMENT 13 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Appendix A Drainage Inventory Map RESUB Mar 02 2021 O `� Y,I-1 CITY OF EDMONDS < N 57) N 1754 % ��.$• <'ry, `-- DEVELOPMENT SERVICES 1250 12T1 •`... _ (7•—Y - 6 O �y.. DEPARTMENT RTM ENT !1 1254 1291 1290 �P 291 '� o a �N 1257 133-1 �� 1261 1258 h 1R��F�N e� � 133 1.3Z9 Site - ns _ 7`4 - �� I H T 02 691 -13TH Wf\YSW ° O � 135� :o $ b8 _ 13TH WAY SW 777� 728 � 710 � 1351 708 720 809 o 0 1\ 710 774 -�. 776 1360 III 10876' J 6 \ PD12i7 Gp I _--- 7 PD12-38 19 Y 5 40 - btih 1 �44 405 �QY 6?p b° b i3TH WAY SW - - 740 1407 ^- Os 141�i 736 1419 / o e n 1 23 e ° r j32 , A b �1�0615 q f,,- PD12-3D bh 814 0 0 • I �II � v b� I-L' 720 ndsfd . w� J o®Dore 4sooi i ! PDn 774 _ 727 Upstream conveyance along Paradise Ln bypasses the site, and follows 6th PI S < TppHITCpw PL J J Z2225 Overflow I connection point ' __---CB 12-371 1611 /IQFO Q 00 r � ,_ _ �-v 'KULSHAN R� / Lan \ dslid.,. w� o®ooe�� I Downstream conveyance in Paradise Ln drains into Edmonds Way conveyance system. 0 517 1250 c 77 S1 (Site 14 ' 0 71107 �22021 0 112 3 d vilh, \ WHOW PL p` 3J Landslid,.. v� p®pp/i isliuS 7�10� Edmonds Way conveyance drains to Willow Creek. < 75 \� •� \ 93 i - s 2 16 � _ 1 III 21805 1• \� - \�MAKAH RQ \ 1727 \ \ 21800 200 218 r Lantlslitl... s� po 10 csouS 'to O Willow Creek continues flow north. 21717 21801 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT �� 1113 00 0 ELMWA) I 500 r 550 T PARKS DEP DEPT -'- PI ,EST - T 1026 1011 I 1024 1021 i \ 1,30 l 10 1 � I s 15 r, A 11 \ Lan&Iid... r o®mot ann 1� V Ua dsl Willow Creek discharges to Edmonds Marsh. Edmonds Marsh drains to final conveyance piping and discharges to Puget Sound. RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES III Appendix B Geotechnical Report RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT 17 Earth Solutions NW LLC Geotechnical Engineering Geology Environmental Scientists Construction Monitoring qbP. t� , us GEOTECHNICAL ENGINEERING STUDY PROPOSED MULTI -FAMILY RESIDENCES 546 PARADISE LANE - EDMONDS, WASHINGTON - ES-5839 y 1805 - 136th PlacQ-N.E.,%Suite 201/ �+Be�le�u''�; WA'��'09 ,:. ;, ` • - • .� • , -� 425 449-4704 Fad' 4"25. 44.9.�4 �ll ,' ( ) (_ ) - - 1 . M(,Avw.eartfisoluUonsVw.com. - RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT PREPARED FOR PARADISE HEIGHTS, LLC March 5, 2018 Samuel E. Suruda, G.I.T. Staff Geologist _L;i✓W �tY .J� V Henry T. Wright, P.E. Senior Project Engineer c. Kyle R. Campbell, P.E. Principal Engineer GEOTECHNICAL ENGINEERING STUDY PROPOSED MULTI -FAMILY RESIDENCES 546 PARADISE LANE EDMONDS, WASHINGTON ES-5839 Earth Solutions NW, LLC 1805 — 136t" Place Northeast, Suite 201 Bellevue, Washington 98005 Phone: 425-449-4704 1 Fax: 425-449-4711 www.earthsolutionsnw.com RESUB r- Geotechnical Engineering Report --� Geotechnical Services Are Performed for Specific Purposes, Persons, and Projects Geotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical engineering study conducted for a civil engi- neer may not fulfill the needs of a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering report is unique, prepared solelyfor the client. No one except you should rely on your geotechnical engineering report without first conferring with the geotechnical engineer who prepared it. And no one — not even you —should apply the report for any purpose or project except the one originally contemplated. Read the Full Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical Engineering Report Is Based on A Unique Set of Project -Specific Factors Geotechnical engineers consider a number of unique, project -specific fac- tors when establishing the scope of a study. Typical factors include: the client's goals, objectives, and risk management preferences; the general nature of the structure involved, its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates oth- erwise, do not rely on a geotechnical engineering report that was: • not prepared for you, • not prepared for your project, • not prepared for the specific site explored, or • completed before important project changes were made. Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: • the function of the proposed structure, as when it's changed from a parking garage to an office building, or from a light industrial plant to a refrigerated warehouse, • elevation, configuration, location, orientation, or weight of the proposed structure, • composition of the design team, or • project ownership. As a general rule, always inform your geotechnical engineer of project changes —even minor ones —and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions Can Change A geotechnical engineering report is based on conditions that existed at the time the study was performed. Do not rely on a geotechnical engineer- ing reportwhose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natural events, such as floods, earthquakes, or groundwater fluctua- tions. Always contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems. Most Geotechnical Findings Are Professional Opinions Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engi- neers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ —sometimes significantly — from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions. A Report's Recommendations Are Not Final Do not overrely on the construction recommendations included in your report. Those recommendations are not final, because geotechnical engi- neers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual RES subsurface conditions revealed during construction. The geotechnical engineer who developed your report cannot assume responsibility or liability for the report's recommendations if that engineer does not perform construction observation. A Geotechnical Engineering Report Is Subject to Misinterpretation Other design team members' misinterpretation of geotechnical engineering reports has resulted in costly problems. Lower that risk by having your geo- technical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review perti- nent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing construction observation. Do Not Redraw the Engineer's Logs Geotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give con- tractors the complete geotechnical engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure contrac- tors have sufficient time to perform additional study. Only then might you be in a position to give contractors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other engineering disci- plines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduciM4Krasko21 of such outcomes, geotechnical engineers commonly include a uattV;0,ER° ,, explanatory provisions in their reports. Sometimes labeled "limitatio7TMENT many of these provisions indicate where geotechnical engineers' responsi- bilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvironmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform a geoenviron- mental study differ significantly from those used to perform a geotechnical study. For that reason, a geotechnical engineering report does not usually relate any geoenvironmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own geoen- vironmental information, ask your geotechnical consultant for risk man- agement guidance. Do not rely on an environmental report prepared for someone else. Obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a com- prehensive plan, and executed with diligent oversight by a professional mold prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, a num- ber of mold prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical engineering study whose findings are conveyed in -this report, the geotechnical engineer in charge of this project is not a mold prevention consultant; none of the services per- formed in connection with the geotechnical engineer's study were designed or conducted for the purpose of mold preven- tion. Proper implementation of the recommendations conveyed in this report will not of itself be sufficient to prevent mold from growing in or on the structure involved. Rely, on Your ASFE-Member Geotechncial Engineer for Additional Assistance Membership in ASFE/The Best People on Earth exposes geotechnical engineers to a wide array of risk management techniques that can be of genuine benefit for everyone involved with a construction project. Confer with you ASFE-member geotechnical engineer for more information. ASFE The Best People on Earth 8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone:301/565-2733 Facsimile:301/589-2017 e-mail: info@asfe.org www.asfe.org Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part by any means whatsoever, is strictly prohibited, except with ASFE's specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any other firm, individual, or other entity that so uses this document without being an ASFE member could be committing negligent or intentional (fraudulent) misrepresentation. IGER06045.0M March 5, 2018 ES-5839 Paradise Heights, LLC 24144 East Greystone Lane Woodway, Washington 98020 Attention: Mr. John Rettenmier Dear Mr. Rettenmier. DI=SUB tar I 02 2021 FEOMONOS e ENTSERVICES RTMENT Earth Solutions NW LLC • Geotechnical Engineering • Construction Monitoring • Environmental Sciences Earth Solutions NW, LLC (ESNW) is pleased to present this report titled "Geotechnical Engineering Study, Proposed Multi -Family Residences, 546 Paradise Lane, Edmonds, Washington". Based on the results of our study, construction of the proposed multi -family residential structures at the subject site is feasible from a geotechnical standpoint. The proposed residential structures can be supported on a conventional foundation system bearing on competent native soil, recompacted native soil, or structural fill. Competent native soils, suitable for support of foundations, should be encountered beginning at a depth of roughly two feet below existing grades across the majority of the site. Slab -on -grade floors should be supported on dense native soil, re -compacted native soil, or structural fill. Where loose, organic or other unsuitable materials are encountered at or below the footing subgrade elevation, the material should be removed and replaced with structural fill, as necessary. This report provides a geologically hazardous areas assessment, and recommendations for foundation subgrade preparation, foundation and retaining wall design parameters, drainage, the suitability of the on -site soils for use as structural fill, and other geotechnical recommendations. The opportunity to be of service to you is appreciated. If you have any questions regarding the content of this geotechnical engineering study, please call. Sincerely, EARTH SOLUTIONS NW, LLC Samuel E. Suruda, G.I.T. Staff Geologist '1805 - 136th Place N.E., Suite 201 0 Bellevue, WA 98005 • (425) 449-4704 9 FAX (425) 449-4711 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Table of Contents ES-5839 PAGE INTRODUCTION....................................................................... General........................................................................ . ProjectDescription.......................................................... SITE CONDITIONS.................................................................... 2 Surface........................................................................... 2 Subsurface...................................................................... 2 Geologic Setting ..................................................... 2 Groundwater.......................................................... 3 Geological Hazards Assessment ........................................ 3 Slope Reconnaissance ............................................ 3 Erosion Hazard Areas ............................................... 3 Landslide Hazard Areas ........................................... 4 Mapping of Geologically Hazardous Areas ................ 5 Special Study and Report Requirements ................... 5 Development Standards (General Requirements)....... 7 Development Standards (Specific Hazards) ............... 7 Analysis of Proposal ............................................... 9 DISCUSSION AND RECOMMENDATIONS ..................................... 9 General........................................................................... 9 Site Preparation and Earthwork ......................................... 9 Temporary Erosion Control ............................................. 10 In -Situ Soils....................................................................... 10 StructuralFill..................................................................... 10 Excavations and Slopes ........................................... 11 Foundations.................................................................... 11 Seismic Considerations....................................................... 12 Slab -On -Grade Floors ....................................................... 12 Retaining Walls............................................................... 12 Drainage......................................................................... 13 Infiltration Evaluation .............................................. 13 Low Impact Development ......................................... 14 Utility Trench Support and Backfill.................................... 15 Pavement Sections........................................................... 15 LIMITATIONS........................................................................... . 15 Additional Services.......................................................... 15 Earth Solutions NW, LLC GRAPHICS Plate 1 Plate 2 Plate 3 Plate 4 APPENDICES Appendix A Appendix B Table of Contents Continued ES-5839 Vicinity Map Test Pit Location Plan Retaining Wall Drainage Detail Footing Drain Detail Subsurface Exploration Test Pit Logs Laboratory Test Results RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Earth Solutions NW, LLC GEOTECHNICAL ENGINEERING STUDY PROPOSED MULTI -FAMILY RESIDENCES 546 PARADISE LANE EDMONDS, WASHINGTON ES-5839 INTRODUCTION General RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT This geotechnical engineering study was prepared for the three proposed multi -family residential structures to be constructed at 546 Paradise Lane in Edmonds, Washington. To complete the scope of services detailed in our proposal PES-5839 dated January 17, 2018 we performed the following: • Subsurface exploration and characterization of soil and groundwater conditions by way of test pits excavated at accessible areas of the site; • Laboratory testing of soil samples obtained during subsurface exploration; • An infiltration evaluation based on observed soil conditions and the results of a Small- scale Pilot Infiltration Test (PIT); • Geotechnical engineering analyses, and; • Preparation of this report. The following documents and resources were reviewed as part of our report preparation: • Preliminary Drainage and Plot Plan, prepared by Michel Construction, Inc., dated July 3, 2008; • Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangle, Washington, prepared by James P. Minard, dated 1983; • Department of Ecology Stormwater Management Manual for Western Washington, Volume III Hydrologic Analysis and Flow Control BMPs, dated August 2012; • Edmonds City Code, Chapter 23.80 (Geologically Hazardous Areas), and; • Online Web Soil Survey (WSS) resource provided by United States Department of Agriculture (USDA), Natural Resources Conservation Services. Project Description Based on the site plan provided to us, the existing single-family residential structure and garage will be demolished and three new multi -family residential structures will be constructed. We anticipate grading activities will primarily include cuts to establish the planned building alignments and roadway improvements. Based on the existing grades, we estimate cuts to establish building pad and foundation subgrade elevations will be on the order of up to four feet. Site improvements will also include underground utility installations. Earth Solutions NW. LLC Paradise Heights, LLC March 5, 2018 ES-Oa�o�Z U B 2021 PaaeD1MONDS DEYELOPMENT SERVICES DEPARTMENT At the time this report was prepared, specific building load values were not available. However, we anticipate the proposed residential structures will consist of relatively lightly loaded wood framing supported on conventional foundations. Based on our experience with similar developments, we estimate wall loads on the order of one to two kips per linear foot and slab -on - grade loading of 150 pounds per square foot (psf). If the above design assumptions are incorrect or change, ESNW should be contacted to review the recommendations in this report. ESNW should review the final design to verify the geotechnical recommendations provided in this report have been incorporated into the plans. SITE CONDITIONS Surface The subject site is located at 546 Paradise Lane in Edmonds, Washington, as illustrated on the Vicinity Map (Plate 1). The site consists of one residential tax parcel (Snohomish County parcel number 27032500302600) totaling approximately 0.91 acres of land area. The property is currently developed with a single-family residence and associated improvements. The majority of the site is relatively level with a steep slope descending on the north side of the property adjacent to Paradise Lane and gentle slope descending to the east for the driveway adjacent to Paradise Lane. Based on site observation and available topographic data, the steep slope descending to the north has a slope gradient in excess of 40 percent and elevation change of up to about 12 feet; the steep slope extends beyond the property. Vegetation within the steep slope area consists of large trees and ivy groundcover. The subject site is bordered to the west by an easement for Edmonds Way, to the east and north by Paradise Lane, and to the south by a residential property. The Test Pit Location Plan (Plate 2) illustrates the approximate limits of the property. Subsurface As part of the subsurface exploration, four test pits were excavated in accessible portions of the site for purposes of assessing soil and groundwater conditions. The test pits were advanced to a maximum depth of approximately nine feet below existing grade. Please refer to the test pit logs provided in Appendix A for a more detailed description of the subsurface conditions. Soil conditions observed at test pit locations consisted of medium dense poorly graded sand (Unified Soil Classification System: SP) outwash deposits. Overall soil relative density increased with depth. Approximately nine feet below ground surface (bgs), dense to very dense silty sand with gravel glacial till was observed (USCS: SM). The glacial till was observed to be weakly cemented and exhibited iron oxide staining. Geologic Setting According to the referenced geologic map, the subject site is underlain by advance outwash (Qva) deposits. Soil conditions observed at the test pit locations were generally consistent with outwash deposits. According to the referenced NRCS soil survey, the subject site consists of Everett series soils. Everett series soils are classified as outwash deposits and are consistent with observations made in the field. Earth Solutions NW. LLC Paradise Heights, LLC March 5, 2018 Groundwater ES-0 Pa ff MONDS DPfELOPMENT SERVICES DEPARTMENT No groundwater seepage was observed during our fieldwork on January 7, 2018. Groundwater seepage rates and elevations fluctuate depending on many factors, including precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater elevations and flow rates are higher during the winter, spring and early summer months. Geological Hazards Assessment As part of this geotechnical engineering study, the referenced chapter of the Edmonds City Code (ECC) was reviewed. Per the ECC requirements, the following topics related to development plans and site conditions are addressed. Slope Reconnaissance During our fieldwork, we performed a visual slope reconnaissance of the steep slope area. The main focus of our reconnaissance was to identify signs of instability or erosion hazards along the site slopes. The typical instability indicators include features such as head scarps, tension cracks, hummocky terrain, groundwater seeps along the surface and erosion features such as gulleys and rills. During the slope reconnaissance, no signs of erosion or slope instability were observed. The slope is vegetated with large trees and ivy groundcover. In general, based on the slope reconnaissance, stability of the sloped areas within and adjacent to the property can be characterized as good. Erosion Hazard Areas — ECC 23.80.020.A. With respect to erosion hazard areas, section 23.80.020 of the ECC defines erosion hazards as "at least those areas identified by the U.S. Department of Agriculture's Natural Resources Conservation Service as having a "moderate to severe", "severe", or "very severe" rill and inter - rill erosion hazard. Erosion hazard areas are also those areas impacted by shoreland and/or stream bank erosion. Within the city of Edmonds, erosion hazard areas include: 1. Those areas of the city of Edmonds containing soils that may experience severe to very severe erosion hazard. This group of soils includes, but is not limited to, the following when they occur on slopes of 15 percent or greater: a. Alderwood soils (15 to 25 percent slopes); b. Alderwood/Everett series (25 to 70 percent slopes), and; c. Everett series (15 to 25 percent slopes). 2. Coastal and stream erosion areas which are subject to the impacts from lateral erosion related to moving water such as stream channel migration and shoreline retreat; 3. Any area with slopes of 15 percent or greater and impermeable soils interbedded with granular soils and springs or ground water seepage, and; 4. Areas with significant visible evidence of ground water seepage, and which also include existing landslide deposits regardless of slope. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 ES- Fg;UB O"r'J,2021p Pae0MONDS AA PMENT SERVICES DEPARTMENT The on -site soils are generally consistent with Everett series soils. Based on the ECC definition, the steep slope areas within and adjacent to the property classify as erosion hazard areas. Construction of the proposed engineered retaining wall is expected to be sufficient for adequately managing and mitigating the erosion potential for this project. Landslide Hazard Areas — ECC 23.80.020.13. With respect to landslide hazard areas, section 23.80.020 of the ECC defines landslide hazard areas as "areas potentially subject to landslides based on a combination of geologic, topographic, and hydrologic factors. They include areas susceptible because of any combination of soil, slope (gradient), slope aspect, structure, hydrology, or other factors. Within the city of Edmonds, landslide hazard areas specifically include: 1. Areas of ancient or historic failures in Edmonds which include all areas within the earth subsidence and landslide hazard area as identified in the 1979 report of Robert Lowe Associates and amended by the 1985 report of GeoEngineers, Inc., and further discussed in the 2007 report by Landau Associates; 2. Coastal areas mapped as class U (unstable), UOS (unstable old slides) and URS (unstable recent slides) in the Department of Ecology Washington coastal atlas; 3. Areas designated as quaternary slumps, earthflows, mudflows, or landslides on maps published by the United States Geological Survey or Washington State Department of Natural Resources; 4. Any slope of 40 percent or steeper that exceeds a vertical height of 10 feet over a 25- foot horizontal run. Except for rockeries that have been engineered and approved by the engineer as having been built according to the engineered design, all other modified slopes (including slopes where there are breaks in slopes) meeting overall average steepness and height criteria should be considered potential landslide hazard areas; 5. Any slope with all three of the following characteristics: a. Slopes steeper than 15 percent; b. Hillsides intersecting geologic contacts with relatively permeable sediment overlying a relatively impermeable sediment, and; c. Springs or ground water seepage. 6. Any area potentially unstable as a result of rapid stream incision or stream bank erosion; 7. Any area located on an alluvial fan, presently subject to, or potentially subject to, inundation by debris flow or deposition of stream -transported sediments, and; 8. Any slopes that have been modified by past development activity that still meet the slope criteria. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 RUB ES-V 2021 PaDge.&MONDS LOPMENT SERVICES DEPARTMENT Based on site observation and the referenced topographic survey, a north -descending steep slope with gradient in excess of 40 percent is located to north of the subject property; based on site observations, the steep slope area was likely over steepened by historic excavations made to construct Paradise Lane. Per the above definition of landslide hazard areas, the steep slope to the north of the subject property classifies as a potential landslide hazard area based on a slope gradient of 40 percent or steeper with a vertical relief of 10 feet or more. The overall stability of the site can be characterized as good and it is our opinion that the potential landslide hazard for the slope to the north of the site can be considered very low. Additionally, we understand grading for the proposed development will include construction of engineered retaining walls that will effectively eliminate the steep slope hazard. Mapping of Geologically Hazardous Areas — ECC 23.80.030 Review of available geologically hazardous areas mapping did not reveal geologically hazardous areas within or immediately adjacent to the subject site. Special Study and Report Requirements — ECC 23.80.050 A. This geotechnical engineering study and geological hazards assessment was completed by a professional engineer licensed in the state of Washington with experience analyzing geologic hazards throughout the Puget Sound region. B. 1. The project area includes the subject site as delineated in the referenced preliminary plans. 2. No further geologically hazardous areas are located within 200 feet of the property or will be affected by construction on the property. C. This geological hazards assessment included a field investigation and an assessment of geologic hazards. This geotechnical report has been prepared, stamped, and signed by a qualified professional. 1. It is our opinion the level of analysis completed for this geological hazards assessment is appropriate for the scale and scope of the project and scale of the geological hazard areas present. 2. A discussion of all geologically hazardous areas on the site and any geologically hazardous areas off site potentially impacted by the proposed project is provided in this report. 3. Based on the results of our study and on -site observations, the proposed project will not decrease slope stability or pose an unreasonable threat to persons or property either on or off site. These conclusions are based on the current conditions of the slope in question and proposed replacement of the slope with an engineered retaining wall. 4. This geological hazard assessment is provided as adequate information to comply with requirements of ECC geological hazards. 5. This geotechnical report generally follows the guidelines set forth in the Washington State Department of Licensing Guidelines for Preparing Engineering Geology Reports in Washington (2006). Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 ES-§§ U B Pa Ie0 DMON DEaELOPMENT SERVIVI CES DEPARTMENT 6. It is our opinion a landslide hazard minimum building setback is not necessary, and erosion hazard mitigation recommendations are provided in this report. D. We are not aware of a previous study completed for the subject site. E. The mitigation recommendations include permanent solutions, such as construction of engineered retaining walls within the slope area in question and erosion control recommendations. F. This geological hazards assessment and geotechnical engineering study should be reviewed as part of the overall submittal package. 1. Please refer to preliminary plans prepared by Michel Construction, Inc. for the site plan. a. The height of the slopes and slope gradients are discussed in this report and displayed within the preliminary plans. b. Springs, seeps, or other surface expressions of groundwater were not observed on or within 200 feet of the project area. c. No surface water runoff features were observed during our site visits. 2. a. Vegetative cover across the landslide hazard areas generally consists of non-native groundcover (i.e. ivy), shrubs, and large trees. b. Subsurface conditions are described in the Subsurface section of this report. c. Surface and groundwater conditions are discussed in previous sections of this report. Roughly two and one-half feet of fill was observed in TP-3. Based on current conditions and elevation changes present, it is evident that some degree of land modification has occurred within and adjacent to the potential landslide hazard areas. The potential landslide hazard areas were likely artificially steepened by excavations completed during construction of Paradise Lane. Local natural topography was likely more of a gradual consistent slope. d. The slopes within and adjacent to the subject site generally exhibit good overall stability. e. The slopes within and adjacent to the subject site are not characterized as bluffs and we do not anticipate a retreat of the slopes to occur. Based on the sand soils present on the site and no indications of groundwater, we would anticipate the run -out hazard of landslide debris to be confined to a distance of up to half the height of slope away from the toe. If such a landslide occurred, impacts of run -out on downslope properties or right-of-way would likely consist of a few feet of landslide debris covering the ground adjacent to the toe of the slope. Repair of the slide would likely require cleanup of debris and engineered reconstruction of the slope and/or construction of an engineered retaining wall at the toe of the slope; construction of the proposed engineered retaining wall will effectively mitigate this potential. It should be noted, based on the results of our study, likelihood of such a landslide event occurring adjacent to the subject site is very low and the proposed project will not increase the likelihood. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 ES-5 ffe UBPa�MONDS VELOPM ENT SERVICES DEPARTMENT g. We believe this report meets the criteria of a critical areas report to a degree adequate with respect to the severity of the steep slope hazard. h. Recommendations for building siting limitations are provided in this report. Proposed surface and subsurface drainage includes collecting surface water from impermeable surfaces and directing them to infiltration systems located along the eastern side of the site. The proposed drainage design is engineered and located in a manner which utilizes the native sand soils and minimizes impacts to sloped areas. The site soils are susceptible to erosion if exposed to surface water runoff without the implementation of BMP measures. However, typical temporary and permanent BMP measures will effectively mitigate the erosion potential. 3. This geotechnical engineering study was prepared by a licensed engineer. a. Geotechnical design parameters are provided within this report. b. Drainage and subdrainage recommendations are provided within this report. c. Earthwork recommendations are provided within this report. d. Recommendations for mitigation of adverse site conditions are provided within this report, as necessary. G. It is our opinion the site erosion hazard areas should be considered stable. H. Based on the results of our study, the site does not contain any seismic hazard areas. Development Standards (General Requirements) — ECC 23.80.060 Based on the results of our geological hazards assessment, the proposed project will not increase the threat of the geological hazard to adjacent properties beyond predevelopment conditions, the proposed project will not adversely impact other critical areas, the proposed project is designed so that the hazard to the project is eliminated or mitigated to a level equal to or less than predevelopment conditions, and the project is certified as safe as designed under anticipated conditions. Development Standards (Specific Hazards) — ECC 23.80.070 A. 1. We believe that with the construction of the engineered retaining wall adjacent to Paradise Lane at the toe of the slope hazard area, any structure placed atop the wall will not be at risk for landslides for the design life of the structure. 2. Based on the results of our study, it is our opinion that a buffer is not necessary for the landslide hazard areas. The proposed project will include reducing the overall height of the landslide hazard area as well as construction of engineered retaining walls in the slope area. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 ES-5 W 20 B r/��[2 2021 Page, 8EDMONDS ELOPMENT SERVICES DEPARTMENT 3. The proposed project will include construction of engineered retaining walls within the slope hazard area, effectively removing any permanent hazard found on site. The alteration will include establishing permanent erosion control and drainage measures at the top of the landslide and erosion hazard areas. Provided the recommendations in this report and subsequent geotechnical recommendations are incorporated into the design and construction of the project, the proposed alteration will not increase surface water discharge or sedimentation to adjacent properties beyond predevelopment conditions, will not decrease slope stability on adjacent properties, and such alterations will not adversely impact other critical areas. 4. a. As part of this geological hazards assessment, we assessed the current slope conditions and consider them to be stable in their current condition and configuration. We do not feel it is necessary to perform full slope stability analysis within the landslide hazard, as construction of engineered retaining walls will mitigate the hazard area prior to foundation loading and construction; however, an ESNW representative should be on -site during wall construction to observe changes to the steep slope area. b. It is our opinion that the structures and improvements have been located and engineered in a manner which sufficiently mitigates impacts to geologically hazardous areas; ESNW should review any plan changes. c. Historic development of Paradise Lane likely altered the natural contour of the slopes. The proposed project will construct an engineered retaining wall within the slope area, effectively eliminating any slope hazard. d. The structures and improvements have been located and engineered in a manner that effectively eliminates the most critical portions of the site by proposing engineered retaining walls to replace the artificially steepened slopes. e. The proposed development will not result in greater risk or a need for increased buffers on neighboring properties. f. Based on our study, building setback are not necessary. 5. We did not observe vegetation within the subject site which should be retained to maintain site and slope stability. 6. It is our opinion that this site should not be restricted to seasonal clearing and grading work. This opinion is based on the relatively small scope of the project and predominantly sandy soils, which are not as moisture sensitive as glacial till, of the geological hazard areas. 7. We are not aware of proposed point discharges. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 Analysis of Proposal ES-A8§@U B PaMar ((`/M/M��'JJ 2021 ge.W.MONDS DEVELOPMENT SERVICES DEPARTMENT The proposed development will involve demolition of the existing single-family residential structure and construction of three new multi -family residential structures. Based on the referenced site plans, the grading will involve minor cuts to establish level building pad areas; we understand that an engineered retaining wall will be constructed at the base of the slope hazard area adjacent to Paradise Lane at the north edge of the site. The proposed project will eliminate the slope hazard area without creating any new geological hazards adjacent to the property. These determinations are based on the relatively small extent of the previously modified steeply sloped areas, stable nature of the site soils, and the construction of an engineered wall to retain the site grades. DISCUSSION AND RECOMMENDATIONS General Based on the results of our study, construction of the proposed residential structures at the subject site is feasible from a geotechnical standpoint. The primary geotechnical considerations associated with the proposed development include foundation support, temporary excavations, retaining walls, infiltration and drainage, and the suitability of the on -site soils for use as structural fill. The proposed residential structures can be supported on a conventional foundation system bearing on competent native soil, recompacted native soil, or structural fill. Competent soils suitable for support of foundations should be encountered beginning at a depth of roughly two feet below existing grades across the majority of the site. Slab -on -grade floors should be supported on dense native soil, re -compacted native soil, or structural fill. Where loose, organic or other unsuitable materials are encountered at or below the footing subgrade elevation, the material should be removed and replaced with structural fill, as necessary. This study has been prepared for the exclusive use of Paradise Heights, LLC and their representatives. No warranty, expressed or implied, is made. This study has been prepared in a manner consistent with the level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. Site Preparation and Earthwork Based on the referenced site plans and given the existing topography, we anticipate grading for the project will involve cuts of up to about four feet to establish building pad and foundation subgrade alignments. Silt fencing and temporary erosion control measures should be placed along the perimeter of the site prior to beginning grading activities. Earth Solutions NK LLC Paradise Heights, LLC March 5, 2018 Temporary Erosion Control cD uB ES-'NiaO/� zoz1 Pa eITY�[HDMDNDS EVELOPM NT SERVICES DEPARTMENT Temporary construction entrances, consisting of at least six inches of quarry spalls, can be considered in order to minimize off -site soil tracking and to provide a temporary road surface. Silt fences should be placed along the margins of the property. Interceptor swales and a temporary sediment pond may be necessary for control of surface water during construction. Erosion control measures should conform to the Washington State Department of Ecology (DOE) and City of Edmonds standards. In -Situ Soils From a geotechnical standpoint, the soils encountered at the test pit locations are generally suitable for use as structural fill. However, successful use of the on -site soils will largely be dictated by the moisture content of the soils at the time of placement and compaction. The site soils were generally in a damp condition at the time of the exploration on January 7, 2018. Based on the conditions encountered during our fieldwork, the site soils generally have a low sensitivity to moisture. During periods of dry weather, the on -site soils should generally be suitable for use as structural fill, provided the moisture content is at or near the optimum level at the time of placement. If the on -site soils cannot be successfully compacted, the use of an imported soil may be necessary. Imported soil intended for use as structural fill should consist of a well -graded granular soil with a moisture content that is at or near the optimum level. During wet weather conditions, imported soil intended for use as structural fill should consist of a well - graded granular soil with a fines content of 5 percent or less defined as the percent passing the Number 200 sieve, based on the minus three-quarter inch fraction. Structural Fill Structural fill is defined as compacted soil placed in foundation, slab -on -grade, and roadway areas. Fills placed to construct permanent slopes and throughout retaining wall and utility trench backfill areas are also considered structural fill. Soils placed in structural areas should be placed in loose lifts of 12 inches or less and compacted to a relative compaction of 95 percent, based on the laboratory maximum dry density as determined by the Modified Proctor Method (ASTM D- 1557). For soil placed in utility trenches underlying structural areas, compaction requirements are dictated by the local city, county, or utility district, and in general are specified as 95 percent relative compaction. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 Excavations and Slopes ES- U B 2021 a/y/y''�� ITV AID �9E� LOT SERVICES DEPARTMENT The native soils encountered in the upper approximately nine feet of the test pit locations consist of poorly graded sands in a dense condition. Temporary slopes within this layer should maintain a gradient of no steeper than 1 H:1 V. If groundwater is present within acute the minimum gradient of a slope should be increased to 1.5HA V. The presence of perched groundwater may cause caving of the temporary slopes due to hydrostatic pressure. ESNW should observe site excavations to confirm the soil type and allowable slope inclination are appropriate for the soil exposed by the excavation. If the recommended temporary slope inclination cannot be achieved, temporary shoring may be necessary to support excavations. Permanent slopes should maintain a gradient of 2H:1V, or flatter, and should be planted with vegetation to enhance stability and to minimize erosion. A representative of ESNW should observe temporary and permanent slopes to confirm the slope inclinations are suitable for the exposed soil conditions, and to provide additional excavation and slope recommendations, as necessary. Foundations The proposed residential structures can be supported on a conventional foundation system bearing on competent native soil, recompacted native soil, or structural fill. Competent soils suitable for support of foundations should be encountered beginning at a depth of roughly two feet below existing grades across the majority of the site. Where loose, organic or other unsuitable materials are encountered at or below the footing subgrade elevation, the material should be removed and replaced with structural fill, as necessary. Provided the structures will be supported as described above, the following parameters can be used for design of the new foundations: • Allowable soil bearing capacity 2,500 psf • Passive earth pressure 300 pcf (equivalent fluid) • Coefficient of friction 0.40 A one-third increase in the allowable soil bearing capacity can be assumed for short-term wind and seismic loading conditions. With structural loading as expected, total settlement in the range of one inch is anticipated, with differential settlement of about one-half inch. The majority of the settlements should occur during construction, as dead loads are applied. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 Seismic Considerations ES-0U B 2021 Page�T,fL ENDMONDDERVS CES DEPARTMENT The 2015 IBC recognizes ASCE for seismic site class definitions. If the project will be permitted under the 2015 IBC, in accordance with Table 20.3-1 of ASCE, Minimum Design Loads for Buildings and Other Structures, Site Class D, should be used for design. In our opinion, the site is not susceptible to liquefaction. The soil relative density and the absence of an established shallow groundwater table are the primary bases for this opinion. Slab -On -Grade Floors Slab -on -grade floors should be supported on a firm and unyielding subgrade consisting of competent native soil or at least 12 inches of structural fill. Unstable or yielding areas of the subgrade should be recompacted or overexcavated and replaced with suitable structural fill prior to construction of the slab. A capillary break consisting of a minimum of four inches of free - draining crushed rock or gravel should be placed below the slab. The free -draining material should have a fines content of 5 percent or less defined as the percent passing the Number 200 sieve, based on the minus three-quarters inch fraction. In areas where slab moisture is undesirable, installation of a vapor barrier below the slab should be considered. If used, the vapor barrier should consist of a material specifically designed to function as a vapor barrier and should be installed in accordance with the manufacturer's specifications. Retaining Walls Engineered retaining walls are proposed to eliminate the slope within the slope hazard area. The following parameters can be used for retaining wall design: • Active earth pressure (yielding condition) • At -rest earth pressure (restrained condition) • Traffic surcharge (passenger vehicles) • Passive earth pressure • Coefficient of friction • Seismic surcharge *Where H equals retained height 35 pcf 55 pcf 70 psf (rectangular distribution) 300 pcf 0.40 6H* Where sloping or other surcharge conditions will be present, supplement recommendations and design earth pressure values should be provided by ESNW. Drainage should be provided behind retaining walls such that hydrostatic pressures do not develop. If drainage is not provided, hydrostatic pressures should be included in the wall design. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 ��u B TES-2021 Page�LOP `NDTSDERD. DEPARTMENT Retaining walls should be backfilled with free -draining material that extends along the height of the wall, and a distance of at least 18 inches behind the wall. The upper one foot of the wall backfill can consist of a less permeable soil, if desired. A perforated drain pipe should be placed along the base of the wall, and should be connected to an approved discharge location. A typical retaining wall drainage detail is provided as Plate 3. Drainage Groundwater seepage was not observed during our fieldwork on January 7, 2018. Groundwater seepage is possible in site excavations, particularly in the winter, spring and early summer months. Temporary measures to control groundwater seepage and surface water runoff during construction will likely involve passive elements such as interceptor trenches and sumps, as necessary. Surface water should not be allowed to runoff over sloped areas and should not be allowed to pond near the top of sloped areas or retaining structures. Surface grades must be designed to direct water away from buildings. The grade adjacent to buildings should be sloped away from the buildings at a gradient of at least 2 percent for a horizontal distance of four feet or more as setbacks allow. In our opinion, perimeter footing drains should be installed at or below the invert of the building footings. A typical footing drain detail is provided on Plate 4 of this report. Infiltration Evaluation We understand drywells, trenches or other methods will be utilized for on -site infiltration. For design, the long-term infiltration rate was evaluated using a Small-scale Pilot Infiltration Test (PIT) completed at a depth of three feet in TP-3. Based on consistent nature of the upper outwash soils, it is our opinion one PIT is sufficient; once infiltration depths and locations are determined, we should reevaluate the need for additional testing. Table 3.3.1 of the referenced DOE Manual provides criteria for estimating the long-term infiltration rate based on measured rates and applicable correction factors. The following long term infiltration rate was calculated using the following equation and correction factors: K design rate = K measured rate X CFT • Measured infiltration rate Kmeasured = 120 in/hr • Site variability; number of locations tested CF„ = 0.33 • Test method CFt = 0.50 • Degree of influent control to prevent siltation Urn = 0.90 • Total correction factor CFT = 0.15 Calculated Long Term Infiltration Rate* TP-3 = 18 in/hr *Per Stormwater Management Manual for Western Washington, August, 2012. Chapter 3.3.4 Earth Solutions NK LLC Paradise Heights, LLC March 5, 2018 ES- 402021 9UB P ag�ILO�M�DT SERDV CES DEPARTMENT We recommend the proposed infiltration systems be located with a setback of at least 25 feet from the top of slope hazard area (and proposed retaining wall upon completion) to the north of the subject site. The geotechnical engineer should observe the excavations for the proposed infiltration systems to confirm soil conditions at the time of construction. We recommend an emergency overflow provision be included in the infiltration system design. If an overflow is not incorporated, we recommend reducing the design infiltration rate by half. Low Impact Development The following table provides our evaluation and recommendations regarding low impact development BMPs for the proposed project: Limitations or ' BMP Viable? Infeasibility Criteria Lawns and Landscaped Areas T5.13: Post -construction soil quality Considered infeasible on slopes of 33 percent or and depth (Volume V, Chapter 5) I Yes I greater. Roofs T5.30: Dispersion is not recommended near the T5.30: Full dispersion (Volume V, Yes* slope hazard area/proposed retaining wall of the Chapter 5) site. T5.10A: A design infiltration of 18 inches per T5.10A: Downspout full infiltration hour should be used for preliminary design. Yes systems (Volume III, Chapter 3) Must be setback at least 25 feet from proposed retaining wall. A design infiltration of 18 inches per hour should Bioretention (Volume V, Chapter 7) Yes be used for design. Must be setback at least 25 feet from proposed retaininq wall. T5.10B: Downspout dispersion systems (Volume III, Chapter 3) T5.10C: Perforated stub -out connections (Volume III, Chapter 3 T5.30: Full dispersion (Volume V, Chapter 5) T5.15: Permeable pavement (Volume V, Chapter 5) Bioretention (Volume V, Chapter 7) Yes* Dispersion is not recommended near the slope hazard area/proposed retaining wall of the site. Yes No limitations. I Yes* Dispersion is not recommended near the slope hazard area/proposed retaining wall of the site. Near -surface soils generally have a higher fines content and a design infiltration rate of 4.5 inch Yes per hour should be used for design of permeable pavement. Must be setback at least 25 feet from proposed retaining wall. A design infiltration of 18 inches per hour should Yes be used for design. Must be setback at least 25 feet from proposed retaininq wall. T5.12: Sheet flow dispersion I Dispersion is not recommended near the slope T5.11: Concentrated flow dispersion Yes* hazard area/proposed retaining wall of the site. (Volume V, Chapter 5) 1 If dispersion is utilized all downspout areas should maintain at least a 25-foot buffer from the proposed retaining wall area. Dispersion is recommended to lead south or east boundaries of the site property where site topography is relatively level. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 Utility Trench Support and Backfill ES- W9UB Pag J.§- SD.. CES DEPARTMENT In our opinion, the soils observed at the test pit locations are generally suitable for support of utilities. In general, the soils observed at the test pit locations may not be suitable for use as structural backfill in the utility trench excavations, unless the soil is at or near the optimum moisture content at the time of placement and compaction. Moisture conditioning of the soils may be necessary at some locations prior to use as structural fill. Utility trench backfill should be placed and compacted to the specifications of structural fill provided in this report, or to the applicable requirements of the City of Edmonds. Pavement Sections The performance of site pavements is largely related to the condition of the underlying subgrade. To ensure adequate pavement performance, the subgrade should be in a firm and unyielding condition when subjected to proofrolling with a loaded dump truck. Structural fill in pavement areas should be compacted to the specifications detailed in the Site Preparation and Earthwork section of this report. It is possible that soft, wet, or otherwise unsuitable subgrade areas may still exist after base grading activities. Areas of unsuitable or yielding subgrade conditions may require remedial measures such as overexcavation and replacement with structural fill or thicker crushed rock sections prior to pavement. For relatively lightly loaded pavements subjected to automobiles and occasional truck traffic, the following sections can be considered for preliminary design: Two inches of hot mix asphalt (HMA) placed over four inches of crushed rock base (CRB), or; • Two inches of HMA placed over three inches of asphalt treated base (ATB). The HMA, CRIB and ATB materials should conform to WSDOT specifications. LIMITATIONS The recommendations and conclusions provided in this geotechnical engineering study are professional opinions consistent with the level of care and skill that is typical of other members in the profession currently practicing under similar conditions in this area. A warranty is not expressed or implied. Variations in the soil and groundwater conditions observed at the test locations may exist, and may not become evident until construction. ESNW should reevaluate the conclusions in this geotechnical engineering study if variations are encountered. Additional Services ESNW should have an opportunity to review the final design with respect to the geotechnical recommendations provided in this report. ESNW should also be retained to provide testing and consultation services during construction. Earth Solutions NW, LLC a►4� ;I Wig, • iZ02 El � W M�� OPME � EPART C PARK~ P�. ' arm •Ir R Ism t r■mr at sal IW = t sl Iltria IMTN% AINjIICA - All —A. )IT "IVI st R 1 em.. _ —IQw It ��t4ftr >d� R M SRC � • '� JJ IPO K ... 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Reference: NORTH Snohomish County, Washington Map 454 By The Thomas Guide Rand McNally 32nd Edition NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information Drwn. CAM Date 02/13/2018 Proj. No. 5839 resulting from black & white reproductions of this plate. Checked SES Date Feb. 2018 Plate 1 252f^� �- — , _ =-56 254 _ 258 2' \ ` 26 262 — `i 262 264— t Building A TP-�' 268 �--�— LEGEND TP-1 Approximate Location of — ■ — ESNW Test Pit, Proj. No. NORTH ES-5839, Feb. 2018 Subject Site Proposed Building Existing Building (To be Removed) NOT - TO -SCALE NOTE: The graphics shown on this plate are not intended for design purposes or precise scale measurements, but only to illustrate the approximate test locations relative to the approximate locations of existing and / or proposed site features. The information illustrated is largely based on data provided by the client at the time of our study. ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. Isolutions a" a■■ vv•aA•.•v■•v iIEW NW LLC eotechnical Engineering, Construction Moni and Environmental Sciences Test Pit LocationPlan 4• ParLane adise Edmonds, Washington -• Date Feb.2018 Mar 02 CI OF EDI DEVELOPMENT r NOTES: Mar 02 CITY OF EDP DEVELOPMENT 18" Min. 0 o ° o o ° o 0-9 0 Cr �0 o° �po0o°o°o0o °oO�p� C 0 0�0� o0o oo o ° oo o o oo 00 o� oo o-° o° o o o o n O o 0 0 o O �° o 0o0oo 0 p o 0o 0e-o 00 o O O 0 0 00° o 0 o o O o o 0 0 0 0 0 o b 0 00 o° o O 0 o �o O O °o ° Oo O b o o o b 0 Cp 00 o -o 05� �� O 000°o 0 0 00 o V O a 000o o�000 0 O o 0 0 o g o'—o oo o o �o o a o° O ° O o °�� O o 0 0 0 oa0oo 0. 0o° o o0 0 8 o ° ° o o0 O .0 o 0 • Free -draining Backfill should consist of soil having less than 5 percent fines. Percent passing No. 4 sieve should be 25 to 75 percent. • Sheet Drain may be feasible in lieu of Free -draining Backfill, per ESNW recommendations. • Drain Pipe should consist of perforated, rigid PVC Pipe surrounded with 1-inch Drain Rock. LEGEND: °o' o 0 o00 00 Free -draining Structural Backfill Structural Fill Perforated Rigid Drain Pipe (Surround in Drain Rock) SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING .f.l.r.f. .0.0.0.rti 1-inch Drain Rock RETAINING WALL DRAINAGE DETAIL 546 Paradise Lane Edmonds, Washington Drwn. CAM Date 02/13/2018 Proj. No. 5839 Checked SES Date Feb. 2018 Plate 3 Perforated Rigid Drain Pipe (Surround in Drain Rock) NOTES: • Do NOT tie roof downspouts to Footing Drain. M Surface Seal to consist of 12" of less permeable, suitable soil. Slope away from building. LEGEND: Surface Seal: native soil or other low -permeability material. r•r•r•r•r ti•ti•ti•ti• r•r•r•r•r rti•ti•ti•ti• 1-inch Drain Rock •r•r•r•r ti•ti•ti•ti• SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING Drwn. CAM Date 02/13/2018 Proj. No. 5839 Checked SES Date Feb. 2018 Plate 4 Mar 02 CITY OF EDP DEVELOPMENT RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Appendix A Subsurface Exploration ES-5839 The subsurface conditions at the site were explored by excavating two test pits at the approximate locations illustrated on Plate 2 of this report. The test pit logs are provided in this Appendix. The subsurface exploration was completed on February 7, 2018. The test pits were excavated to a maximum depth of nine feet below existing grades. Logs of the test pits advanced by ESNW are presented in Appendix A. The final logs represent the interpretations of the field logs and the results of laboratory analyses. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. Earth Solutions NW, LLC RESUB Earth Solutions NWLLC Mar 022021 CITY OF EDMONDS DEVELOPMENCES DEPARTMENT SOIL CLASSIFICATION CHART MAJOR DIVISIONS SYMBOLS TYPICAL DESCRIPTIONS GRAPH LETTER GRAVEL AND CLEAN GRAVELS ��•�� ' GW WELL GRADED GRAVELS, GRAVEL - FINES ND MIXTURES, LITTLE OR NO °p° oQ° o DDo D GP POORLY -GRADED GRAVELS, GRAVEL- SAND MIXTURES, LITTLE OR NO FINES GRAVELLY SOILS (LITTLE OR NO FINES) COARSE GRAINED SOILS MORE THAN 50% OF COARSE GRAVELS WITH FINES Q ° °° ° ° D GM SILTY GRAVELS, GRAVEL -SAND - SILT MIXTURES FRACTION GC CLAYEY GRAVELS, GRAVEL - SAND - CLAY MIXTURES RETAINED ON NO. 4 SIEVE (APPRECIABLE AMOUNT OF FINES) MORE THAN 50% OF MATERIAL IS SAND AND CLEAN SANDS SW WELL -GRADED SANDS, GRAVELLY SANDS, LITTLE OR NO FINES SP POORLY -GRADED SANDS, GRAVELLY SAND, LITTLE OR NO FINES LARGER THAN NO. 200 SIEVE SIZE SANDY SOILS (LITTLE OR NO FINES) SANDS WITH FINES `SM SILTY SANDS, SAND - SILT MIXTURES MORE THAN 50% OF COARSE FRACTION S`+ CLAYEY SANDS, SAND - CLAY MIXTURES PASSING ON NO. 4 SIEVE (APPRECIABLE AMOUNT OF FINES) INORGANIC SILTS AND VERY FINE ML SANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITH SLIGHT PLASTICITY FINE GRAINED SOILS SILTS LIQUID LIMIT AND LESS THAN 50 CLAYS CL INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS — — __ OL ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY MORE THAN 50% OF MATERIAL IS MH INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE SAND OR SMALLER THAN NO.200 SIEVE SILTY SOILS SIZE SILTS LIQUID LIMIT AND CLAYS GREATER THAN 50 CH INORGANIC CLAYS OF HIGH PLASTICITY OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY. ORGANIC SILTS HIGHLY ORGANIC SOILS ' ' ' ' ' ' ' PT PEAT, HUMUS, SWAMP SOILS WITH HIGH ORGANIC CONTENTS DUAL SYMBOLS are used to indicate borderline soil classifications. The discussion in the text of this report is necessary for a proper understanding of the nature of the material presented in the attached logs. Earth Solutions NW TEST PIT NUMB 1805 - 136th Place N.E., Suite 201 1 PMtq 1 MBellevue, Washington 98005 M0� Telephone: 425-449-4704 DEVELOPMENT SERVICES DEPARTMENT Fax: 425-449-4711 PROJECT NUMBER ES-5839 PROJECT NAME 546 Paradise Lane DATE STARTED 217/18 COMPLETED 2/7/18 GROUND ELEVATION 265 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION --- LOGGED BY SES CHECKED BY HTW AT END OF EXCAVATION --- NOTES Depth of Topsoil & Sod 6" AFTER EXCAVATION --- w _ a.W w U = as � g TESTS U a p MATERIAL DESCRIPTION QW 0- = U) J Q Z (7 V) 0 TPS =' TOPSOIL 0.5 264 5 Brown poorly graded SAND with gravel, medium dense, damp MC = 4.20% -becomes gray -caving from 2' to BOH - MC = 3.60% 5 SP - MC = 4.00% -becomes dense 9.0 -becomes moist 256.0 - MC = 9.20% Test pit terminated at 9.0 feet below existinggrade. No groundwater encountered during excavation. Caving observed from 2.0 feet to BOH. Bottom of test pit at 9.0 feet. Earth Solutions NW TEST PIT NUMB 1805 - 136th Place N.E., Suite 201 PAbEOa 2W 1 VAXBellevue, Washington 98005 CI OFEDMONDS Telephone: 425-449-4704 DEVELOPMENT SERVICES DEPARTMENT Fax: 425-449-4711 PROJECT NUMBER ES-5839 PROJECT NAME 546 Paradise Lane DATE STARTED 2/7/18 COMPLETED 2/7/18 GROUND ELEVATION 265 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION --- LOGGED BY SES CHECKED BY HTW AT END OF EXCAVATION — NOTES Depth of Topsoil & Sod 3": grass AFTER EXCAVATION — w a. W C6 U wg TESTS 0_J MATERIAL DESCRIPTION 0_ z Qz � rn 0 03_TOPSOIL ,�64� Brown poorly graded SAND with silt and gravel, medium dense, damp MC = 8.60% Fines = 5.00% [USDA Classification: very gravelly coarse SAND] SP- MC = 3.50% SM -becomes gray 5 MC = 3.40% _ 5.5 259.5 _ _ Test pit terminated at 5.5 feet below existing grade. No groundwater encountered during excavation. No caving observed. Bottom of test pit at 5.5 feet. Earth Solutions NW TEST PIT NUMB 1805 - 136th Place N.E., Suite 201 PAj§EOj 2®?1 1 Bellevue, Washington 98005 CITY OF EDMONDS Telephone: 425-449-4704 DEVELOPMENT SERVICES DEPARTMENT Fax: 425-449-4711 PROJECT NUMBER ES-5839 PROJECT NAME 546 Paradise Lane DATE STARTED 2/7118 COMPLETED - 217/18 GROUND ELEVATION 265 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION -- LOGGED BY SES CHECKED BY HTW AT END OF EXCAVATION --- NOTES Surface Conditions: grass AFTER EXCAVATION -- w a - of �w U _ a g TESTS U a p MATERIAL DESCRIPTION Qz U) 0 Brown poorly graded SAND, medium dense, damp (Fill) SP MC = 3.60% 2.5 -caving to 8' 262-5 Gray poorly graded SAND with gravel, medium dense, damp -infiltration test at 3' 5 SP MC = 10.60% Fines = 3.70% [USDA Classification: very gravelly coarse SAND] 8.0 -water from infiltration test mounding on till layer, groundwater seepage at 8' 257.0 SM g 5 Gray silty SAND with gravel, dense, damp (Unweathered Till) 258.5 ° MC = 11.20 /o -moderately cemented Test pit terminated at 8.5 feet below existing grade. Groundwater seepage encountered at 8.0 feet during excavation. Caving observed from 2.0 to 8.0 feet. Bottom of test pit at 8.5 feet. Earth Solutions NW TEST PIT NUMB 1805 - 136th Place N.E., Suite 201 Pf 0j 26011 Bellevue, Washington 98005 CITY OF EDMONDS Telephone: 425-449-4704 DEVELOPMENT SERVICES DEPARTMENT Fax: 425-449-4711 PROJECT NUMBER ES-5839 PROJECT NAME 546 Paradise Lane DATE STARTED 2/7/18 COMPLETED 2/7/18 GROUND ELEVATION 265 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION -- LOGGED BY SES CHECKED BY HTW AT END OF EXCAVATION — NOTES Depth of Topsoil & Sod 12": duff AFTER EXCAVATION — w rw U a- � TESTS MATERIAL DESCRIPTION Q Z C9 0 — Dark brown TOPSOIL, roots to 2' PS ,, , , _ — 1.0 264.0 Brown poorly graded SAND with gravel, medium dense, damp MC = 3.90% -caving to 8' -becomes gray MC = 3.90% SP 5 8.0 257.0 _ Gray silty SAND with gravel, dense to very dense, damp (Unweathered Till) SME9.0 MC = 11.20% -moderately cemented 2560 Fines = 18.50% (USDA Classification: gravelly loamy SAND) Test pit terminated at 9.0 feet below existing grade. No groundwater encountered during excavation. Caving observed from 2.0 to 8.0 feet. Bottom of test pit at 9.0 feet. RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Appendix B Laboratory Test Results ES-5839 Earth Solutions NW, LLC a C7 z J W �4 Q 7 N W M 19 cn W 0111 Ilium olillimmillill INEIIIIIII NUNN liiiiiimmiiiiiiimm 11 In IMMUNE Pq 0 BURNS lllillimm MISS in BURNS 11 solilillin liiiiiinmiiiiilmm in Millis .11 NEI Ills liimmiiiiiii 111 IIl111 111 Ell 11 lllomilli 11 ills 111 1011111111100 11 llismilli I ism ills III, 1%M 11 11 lowl lism HOW III III I I Ills lim. US mill lmmiiiiiiimm Ilium H is 11111111 111 mmiiiiiilm MINE In HIM M solli 11 lllom Sol Ism IM111 I III INS 1111110 Mill in immi Is I Mill 111 ism 11 ,in 0 1 1 111111101111 liiiiiimmiiiiiim 11111 1 MMM RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Report Distribution ES-5839 EMAIL ONLY Paradise Heights, LLC 24144 East Greystone Lane Woodway, Washington 98020 Attention: Mr. John Rettenmier Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 ES-OTu B 2021 Pag,&JZ-MONOS EVELOPMENT SERVICES DEPARTMENT Retaining walls should be backfilled with free -draining material that extends along the height of the wall, and a distance of at least 18 inches behind the wall. The upper one foot of the wall backfill can consist of a less permeable soil, if desired. A perforated drain pipe should be placed along the base of the wall, and should be connected to an approved discharge location. A typical retaining wall drainage detail is provided as Plate 3. Drainage Groundwater seepage was not observed during our fieldwork on January 7, 2018. Groundwater seepage is possible in site excavations, particularly in the winter, spring and early summer months. Temporary measures to control groundwater seepage and surface water runoff during construction will likely involve passive elements such as interceptor trenches and sumps, as necessary. Surface water should not be allowed to runoff over sloped areas and should not be allowed to pond near the top of sloped areas or retaining structures. Surface grades must be designed to direct water away from buildings. The grade adjacent to buildings should be sloped away from the buildings at a gradient of at least 2 percent for a horizontal distance of four feet or more as setbacks allow. In our opinion, perimeter footing drains should be installed at or below the invert of the building footings. A typical footing drain detail is provided on Plate 4 of this report. Infiltration Evaluation We understand drywells, trenches or other methods will be utilized for on -site infiltration. For design, the long-term infiltration rate was evaluated using a Small-scale Pilot Infiltration Test (PIT) completed at a depth of three feet in TP-3. Based on consistent nature of the upper outwash soils, it is our opinion one PIT is sufficient; once infiltration depths and locations are determined, we should reevaluate the need for additional testing. Table 3.3.1 of the referenced DOE Manual provides criteria for estimating the long-term infiltration rate based on measured rates and applicable correction factors. The following long term infiltration rate was calculated using the following equation and correction factors: K design rate = K measured rate X CFT e Measured infiltration rate Kmeasured = 120 in/hr e Site variability; number of locations tested CF„ = 0.33 e Test method CFt = 0.50 e Degree of influent control to prevent siltation Urn = 0.90 Total correction factor CFT = 0.15 Calculated Long Term Infiltration Rate* TP-3 = 18 in/hr *Per Stormwater Management Manual for Western Washington, August, 2012. Chapter 3.3.4 Earth Solutions NK LLC 19 November 15, 2019 ES-5839.01 Paradise Heights, LLC 24144 East Greystone Lane Woodway, Washington 98020 Attention: Mr. John Rettenmier Subject: Plan Review Proposed Multi -Family Residences Paradise Heights 546 Paradise Lane Edmonds, Washington Reference: Earth Solutions NW, LLC Geotechnical Engineering Study ES-5839, dated March 5, 2018 Donna Breske & Associates, LLC Civil Plans, dated November 7, 2019 BTL Engineering, P.S. Structural Plans, dated December 21, 2018 Michel Design Architectural Plans, dated October 30, 2019 Dear Mr. Rettenmier: RESUB Earth r 1022021 F EDMONDS ENT SERVICES Solution 1. ARTMENT NWLLC Earth Solutions NW LLC Geotechnical Engineering, Construction Observation/Testing and Environmental Services As requested, Earth Solutions NW, LLC (ESNW) has prepared this plan review letter for the subject project. ESNW prepared the referenced geotechnical document for the subject project. ESNW has reviewed the referenced plans and geotechnical report prepared for the subject project. Based on our review, geotechnical recommendations included in the referenced report have been incorporated into the plans. 15365 N.E. 90th Street, Suite 100 0 Redmond, WA 98052 • (425) 449-4704 • FAX (425) 449-4711 Paradise Heights, LLC November 15, 2019 RESUB ES-583%,POI 2021 P I��O DMONDS �9P T SERVICES DEPARTMENT We trust this plan review letter meets your current needs. Should you have questions, or if additional information is required, please call. Sincerely, EARTH SOLUTIONS NW, LLC %1' l S 10% �1X ' x O 531503 R� •�, Rpcyst�.KGc�' tONAt. Henry T. Wright, P.E. Senior Project Engineer cc: Michel Design Attention: Mr. Rob Michel (Email only) Earth Solutions NW, LLC RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Appendix C WWHM2012 Hydrology Print-out: Infiltration Trench Sizing, LID Performance Standard & Flow Frequency Return Compliance, & Existing & Proposed Land Cover Explanation and Exhibits. 20 Mar 02 20, CITY OF EDMON[ DEVELOPMENT SER' DEPARTMENT )BEES OF 6' CALPER & GREATER PER 2017 BOUNDARY & TOPOGRAPHY SURVEY PROVIDE BY GUY GREENE, PLS (TREE CANOPIES ARE NOT DEPICTED NOR REQUIRED BY 7HE ECDC TO WHICH THIS PROJECT IS VESTED TO BE DEPICTED) ROW SUB -BASIN BOUNDARY 12,288 SF (0.282 AC) SIN ON-517E SUB -BA PRE JULY 6, 1977 BOUNDARY IMPERVIOUS AREA OF 25,660 SF (0.589 AC) 7/�777�y / DRIVEWAY. 1,523 SF (035 AC) 1,909 SF (0438 AC) I PRE JULY 6, 1977 — IMPERWOUS AREA OF EXIS77NG HOUSE ON S17F HATCHED AREA INDICATES AREA OF SUB -BASIN FOR WWMH2O12 MODELING PURPOSES THAT REPRESEN7S THE DEVELOPED AREA WHERE STORMW47ER RUNOFF IS ROU7ED TO INRLIRA77ON 7RENCHES #i & jf2 132 SF (003 AC) PRE JULY 6, 1977 IMPERVIOUS AREA OF EXISTING WALKWAYS ON -SITE SUB -BASIN 40% 7REE CANOPY CALCULAPON..4 X .4J7 = (0.175 AC) EXIS77NG LAWN CALCULATION. a4J7 - 0.175 - 0.04J8 - 0.035 = 0.2832 AC 2,440 SF (0.056 AC) REPLACED PRE-1977 PARADISE LANE PAVEMENT LANE WIDENING I 847 SF (0.0194 AC) y, ,, NEW SIDEWALK & WALKWAY IN THE PARADISE LANE ROW 1,600 SF (0.0367 AC) 4,378 SF (0.1005 AC)) ROOFTOP ROU7ED TO INFIL7RA710N 7RENCH 12 PAVED APRON 671 SF (0.0154 AC) Z993 SF (0.0687 AC) PAVEMENT ROUTED TO INFILTRATION 7RENCH 42 4,8 SF A . 108 INFILMARON 7RENCH 02 EN /1 4,1 SF ' INFlLIRA7101V 7RENCH #2 SUB -BASIN .0959 AC) ' LANDSCAPE AREAS. • 814 SF (0.0187 AC) R EpK TRENCH /1 PREPARED BY.• DONNA BRESKE & ASSOCIATES 21 AVE A, SUITE 4 SNOHOMISH, WA 98290 PHONE: 206-715-9582 Donn oB@DONNABRESKE. COM INFlL7RA710N TRENCH 11 7,170 SF (0.1646 AC) PAVEMENT ROU7ED TO INFILTRATION 7RENCH P SUB -BASIN INFlL7RA710N 7RENCH /I LANDSCAPE AREAS" 532 SF (0.0122 AC) INFILIRA710N 7RENCH /I SUB -BASIN WALKWAYS. 569 SF (0.013 AC) 7REES TO REMAIN ARE NOT DEPICTED ON 7HE ABOVE DEVELOPED 517E IMPERVIOUS/PERVIOUS MAP SINCE TREE CRED175 FOR 7REES TO REMAIN ARE NOT EXCERSISED IN 711E WWHM2012 HYDROLOGY MODEL PARADISE HEIGHTS IMPERVIOUS AREA EXHIBIT TAX NO. 27OJ2500302600 PROJECT. PARADISE HEIGHTS SCALE. N. T. S. SITE ADDRESS: ISSUE DATE. • 2-26-2021 546 PARADISE LN EDMONDS, WA 98020 SnohomishOnlino Government Information & Services County44,, Washington Structure Information Close Window General Description Parcel Number 27032500302600 (R01) Structure Class Dwelling Structure Type 1 1/2 Story wBasement Year Built 1922 Exterior Features Foundation Conc or CB Exterior Siding -Lap ROOF Type: Gable Pitch Medium Cover Composition Interior Features Bedrooms 4 Full or 3/4 Baths 2 1/2 Baths 0 Heat Heat Pump Fireplace Masonry fireplace Floor Area Floor 1 Base SF 1505 Finished SF 1505 Floor 2 Base SF 645 Finished SF 645 Floor B Base SF 962 Finished SF 0 Garage(s), Carport(s) and major outbuilding(s) Detached Garage SF 616 Other Features RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT . Any erodible elements of the manmade conveyance system must be adequately stabilized to prevent erosion under the conditions noted above. If the discharge is to a stream that leads to a wetland, or to a wetland that has an outflow to a stream, both this requirement and 1-2.5.8 Minimum Requirement #8: Wetlands Protection (p.68) apply. Local governments may petition Ecology to exempt projects in additional areas. A petition must justify the proposed exemption based upon a hydrologic analysis that demonstrates that the potential stormwater runoff from the exempted area will not significantly increase the erosion forces on the stream channel nor have near field impacts. Thresholds When assessing a project against the following thresholds, consider only those impervious, hard, and pervious surfaces that are subject to this minimum require- ment as determined in 1-2.4 Applicability of the Minimum Requirements (p.35). The following circumstances require achievement of the standard flow control requirement for western Washington: . Projects in which the total of effective impervious surfaces is 10,000 square feet or more in a threshold discharge area, or Projects that convert 3/4 acres or more of vegetation to lawn or landscape, or convert 2.5 acres or more of native vegetation to pasture in a threshold dis- charge area, and from which there is a surface discharge in a natural or man- made conveyance system from the site, or Projects that through a combination of effective hard surfaces and converted vegetation areas cause a 0.10 cubic feet per second increase in the 100-year flow frequency from a threshold discharge area as estimated using the Western Washington Hydrology Model or other approved model and one - hour time steps (or a 0.15 cfs increase using 15-minute time steps). Standard Flow Control Requirement The following requirement applies to the following counties: Clallam 1The 0.10 cfs (one -hour time steps) or 0.15 cfs (15-minute time steps) increase should be a comparison of the postproiect runoff to the existina condition runoff.For the purpose of applying this threshold, the existing condition is either the pre -project land cover, or the land cover that existed at the site as of a date when the local jurisdiction first adopted flow control requirements into code or rules. 2014 Stormwater Management Manual for Western Washington Volume 1- Chapter 2 - Page 65 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT LOGIC & DEDUCTIVE REASONING ANALYSIS FOR DETERMING EXISTING PERCENTAGE OF TREE, (FOREST COVER) FOR USE IN THE WWHWM2012 HYDROLOGY SOFTWARE MODEL The best aerial that available is that of the 1974 aerial that was provided by Kernen Lein of the City of Edmonds. Hence, this is the best timeframe representation to assist to deductively reason a fair and reasonable vegetative cover on the site as of July 6, 1977. Note the aerial can be misleading as much of the darker areas are actually shadows cast onto the ground from the trees. Secondly, is the recent survey from Guy Greene that depicts 18 trees generally peppered in the east third of the property. Additionally, there are two trees located within the west quarter of the property. Per I phone discussion with the project proponent, John Rettenmier of 2-25- 2021„ he concludes the tree cover is 40% of the site area. which I concur is fair and reasonable per this engineer's conclusion. Also, my calculations use an Existing Tree Cover of 65% for the right-of-wat RESUB )s VICES RESUB General Model Information Mar 02 2021 Project Name: CITY OF EDMONDS Rettenmier Pre 1977 Existing Impervious DEVELDEPARTMENTOPMENMENT CE5 Site Name: Paradise Heights Site Address: 546 Paradise Lane City: Edmonds Report Date: 2/26/2021 MGS Region: Puget East Data Start: 1901 /10/1 Data End: 2058/09/30 Timestep: 15 Minute DOT Data Number02 Version Date: 2016/02/25 Version: 4.2.12 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 2 Landuse Basin Data Predeveloped Land Use Predeveloped on -site Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Mod 0.2356 C, Lawn, Flat 0.2716 Pervious Total 0.5072 Impervious Land Use acre ROOF TOPS FLAT 0.0438 DRIVEWAYS MOD 0.035 SIDEWALKS FLAT 0.003 Impervious Total 0.0818 Element Flows To: Surface Interflow Groundwater RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 3 RESUB Predeveloped ROW Mar 02 2021 Bypass: CITVOEE DEVELOPMENT SERVICES No ERVI DEPARTMENT GroundWater: No Pervious Land Use acre C, Forest, Steep 0.168 Pervious Total 0.168 Impervious Land Use acre ROADS FLAT 0.065 Impervious Total 0.065 Basin Total 0.233 Element Flows To: Surface Interflow Groundwater Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 4 Mitigated Land Use On -site Trench 1 Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat 0.0122 Pervious Total 0.0122 Impervious Land Use acre ROADS FLAT 0.1646 ROOF TOPS FLAT 0.2065 SIDEWALKS FLAT 0.013 Impervious Total 0.3841 Basin Total 0.3963 Element Flows To: Surface Interflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 5 On -Site trench 2 Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat 0.0187 Pervious Total 0.0187 Impervious Land Use acre ROADS FLAT 0.073 ROOF TOPS FLAT 0.101 Impervious Total 0.174 Basin Total 0.1927 Element Flows To: Surface Interflow Groundwater Gravel Trench Bed 2 Gravel Trench Bed 2 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 6 Paradise Lane ROW Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Steep 0.063 Pervious Total 0.063 Impervious Land Use acre ROADS MOD 0.125 SIDEWALKS MOD 0.045 Impervious Total 0.17 Basin Total 0.233 Element Flows To: Surface Interflow Groundwater Catchbasin Node SymUdtchbasin Node Symbol RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 7 Routing Elements Predeveloped Routing RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 8 RESUB Mitigated Routing Mar 02 2021 CITY OF EDMONDS Gravel Trench Bed 1 DEVELOPMENT SERVICES DEPARTMENT Bottom Length: 84.00 ft. Bottom Width: 4.40 ft. Trench bottom slope 1: 0 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 2.8 Pour Space of material for first layer: 0.33 Material thickness of second layer: 0 Pour Space of material for second layer: 0 Material thickness of third layer: 0 Pour Space of material for third layer: 0 Infiltration On Infiltration rate: 18 Infiltration safety factor: 1 Wetted surface area On Total Volume Infiltrated (ac-ft.): 144.686 Total Volume Through Riser (ac-ft.): 0.01 Total Volume Through Facility (ac-ft.): 144.696 Percent Infiltrated: 99.99 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 2.8 ft. Riser Diameter: 8 in. Element Flows To: Outlet 1 Outlet 2 Catchbasin Node Symbol Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-%) Discharge(cfs) Infilt(cfs) 0.0000 0.008 0.000 0.000 0.000 0.0311 0.008 0.000 0.000 0.154 0.0622 0.008 0.000 0.000 0.154 0.0933 0.008 0.000 0.000 0.154 0.1244 0.008 0.000 0.000 0.154 0.1556 0.008 0.000 0.000 0.154 0.1867 0.008 0.000 0.000 0.154 0.2178 0.008 0.000 0.000 0.154 0.2489 0.008 0.000 0.000 0.154 0.2800 0.008 0.000 0.000 0.154 0.3111 0.008 0.000 0.000 0.154 0.3422 0.008 0.001 0.000 0.154 0.3733 0.008 0.001 0.000 0.154 0.4044 0.008 0.001 0.000 0.154 0.4356 0.008 0.001 0.000 0.154 0.4667 0.008 0.001 0.000 0.154 0.4978 0.008 0.001 0.000 0.154 0.5289 0.008 0.001 0.000 0.154 0.5600 0.008 0.001 0.000 0.154 0.5911 0.008 0.001 0.000 0.154 0.6222 0.008 0.001 0.000 0.154 0.6533 0.008 0.001 0.000 0.154 0.6844 0.008 0.001 0.000 0.154 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 9 0.7156 0.008 0.002 0.000 0.154 0.7467 0.008 0.002 0.000 0.154 0.7778 0.008 0.002 0.000 0.154 0.8089 0.008 0.002 0.000 0.154 0.8400 0.008 0.002 0.000 0.154 0.8711 0.008 0.002 0.000 0.154 0.9022 0.008 0.002 0.000 0.154 0.9333 0.008 0.002 0.000 0.154 0.9644 0.008 0.002 0.000 0.154 0.9956 0.008 0.002 0.000 0.154 1.0267 0.008 0.002 0.000 0.154 1.0578 0.008 0.003 0.000 0.154 1.0889 0.008 0.003 0.000 0.154 1.1200 0.008 0.003 0.000 0.154 1.1511 0.008 0.003 0.000 0.154 1.1822 0.008 0.003 0.000 0.154 1.2133 0.008 0.003 0.000 0.154 1.2444 0.008 0.003 0.000 0.154 1.2756 0.008 0.003 0.000 0.154 1.3067 0.008 0.003 0.000 0.154 1.3378 0.008 0.003 0.000 0.154 1.3689 0.008 0.003 0.000 0.154 1.4000 0.008 0.003 0.000 0.154 1.4311 0.008 0.004 0.000 0.154 1.4622 0.008 0.004 0.000 0.154 1.4933 0.008 0.004 0.000 0.154 1.5244 0.008 0.004 0.000 0.154 1.5556 0.008 0.004 0.000 0.154 1.5867 0.008 0.004 0.000 0.154 1.6178 0.008 0.004 0.000 0.154 1.6489 0.008 0.004 0.000 0.154 1.6800 0.008 0.004 0.000 0.154 1.7111 0.008 0.004 0.000 0.154 1.7422 0.008 0.004 0.000 0.154 1.7733 0.008 0.005 0.000 0.154 1.8044 0.008 0.005 0.000 0.154 1.8356 0.008 0.005 0.000 0.154 1.8667 0.008 0.005 0.000 0.154 1.8978 0.008 0.005 0.000 0.154 1.9289 0.008 0.005 0.000 0.154 1.9600 0.008 0.005 0.000 0.154 1.9911 0.008 0.005 0.000 0.154 2.0222 0.008 0.005 0.000 0.154 2.0533 0.008 0.005 0.000 0.154 2.0844 0.008 0.005 0.000 0.154 2.1156 0.008 0.005 0.000 0.154 2.1467 0.008 0.006 0.000 0.154 2.1778 0.008 0.006 0.000 0.154 2.2089 0.008 0.006 0.000 0.154 2.2400 0.008 0.006 0.000 0.154 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 10 2.5200 0.008 0.007 0.000 0.154 2.5511 0.008 0.007 0.000 0.154 2.5822 0.008 0.007 0.000 0.154 2.6133 0.008 0.007 0.000 0.154 2.6444 0.008 0.007 0.000 0.154 2.6756 0.008 0.007 0.000 0.154 2.7067 0.008 0.007 0.000 0.154 2.7378 0.008 0.007 0.000 0.154 2.7689 0.008 0.007 0.000 0.154 2.8000 0.008 0.007 0.000 0.154 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 11 RESUB Gravel Trench Bed 2 Mar 02 2021 Bottom Length: ONDS ET ERVIEOPMENCES 70.00 ft. CITY. Bottom Width: DEPARTMENT 3.00 ft. Trench bottom slope 1: 0 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 3 Pour Space of material for first layer: 0.33 Material thickness of second layer: 0 Pour Space of material for second layer: 0 Material thickness of third layer: 0 Pour Space of material for third layer: 0 Infiltration On Infiltration rate: 18 Infiltration safety factor: 1 Wetted surface area On Total Volume Infiltrated (ac-ft.): 65.912 Total Volume Through Riser (ac-ft.): 0.002 Total Volume Through Facility (ac-ft.): 65.913 Percent Infiltrated: 100 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 2.5 ft. Riser Diameter: 8 in. Element Flows To: Outlet 1 Outlet 2 Catchbasin Node Symbol Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.004 0.000 0.000 0.000 0.0333 0.004 0.000 0.000 0.087 0.0667 0.004 0.000 0.000 0.087 0.1000 0.004 0.000 0.000 0.087 0.1333 0.004 0.000 0.000 0.087 0.1667 0.004 0.000 0.000 0.087 0.2000 0.004 0.000 0.000 0.087 0.2333 0.004 0.000 0.000 0.087 0.2667 0.004 0.000 0.000 0.087 0.3000 0.004 0.000 0.000 0.087 0.3333 0.004 0.000 0.000 0.087 0.3667 0.004 0.000 0.000 0.087 0.4000 0.004 0.000 0.000 0.087 0.4333 0.004 0.000 0.000 0.087 0.4667 0.004 0.000 0.000 0.087 0.5000 0.004 0.000 0.000 0.087 0.5333 0.004 0.000 0.000 0.087 0.5667 0.004 0.000 0.000 0.087 0.6000 0.004 0.001 0.000 0.087 0.6333 0.004 0.001 0.000 0.087 0.6667 0.004 0.001 0.000 0.087 0.7000 0.004 0.001 0.000 0.087 0.7333 0.004 0.001 0.000 0.087 0.7667 0.004 0.001 0.000 0.087 0.8000 0.004 0.001 0.000 0.087 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 12 0.8333 0.004 0.001 0.000 0.087 0.8667 0.004 0.001 0.000 0.087 0.9000 0.004 0.001 0.000 0.087 0.9333 0.004 0.001 0.000 0.087 0.9667 0.004 0.001 0.000 0.087 1.0000 0.004 0.001 0.000 0.087 1.0333 0.004 0.001 0.000 0.087 1.0667 0.004 0.001 0.000 0.087 1.1000 0.004 0.001 0.000 0.087 1.1333 0.004 0.001 0.000 0.087 1.1667 0.004 0.001 0.000 0.087 1.2000 0.004 0.001 0.000 0.087 1.2333 0.004 0.002 0.000 0.087 1.2667 0.004 0.002 0.000 0.087 1.3000 0.004 0.002 0.000 0.087 1.3333 0.004 0.002 0.000 0.087 1.3667 0.004 0.002 0.000 0.087 1.4000 0.004 0.002 0.000 0.087 1.4333 0.004 0.002 0.000 0.087 1.4667 0.004 0.002 0.000 0.087 1.5000 0.004 0.002 0.000 0.087 1.5333 0.004 0.002 0.000 0.087 1.5667 0.004 0.002 0.000 0.087 1.6000 0.004 0.002 0.000 0.087 1.6333 0.004 0.002 0.000 0.087 1.6667 0.004 0.002 0.000 0.087 1.7000 0.004 0.002 0.000 0.087 1.7333 0.004 0.002 0.000 0.087 1.7667 0.004 0.002 0.000 0.087 1.8000 0.004 0.002 0.000 0.087 1.8333 0.004 0.002 0.000 0.087 1.8667 0.004 0.003 0.000 0.087 1.9000 0.004 0.003 0.000 0.087 1.9333 0.004 0.003 0.000 0.087 1.9667 0.004 0.003 0.000 0.087 2.0000 0.004 0.003 0.000 0.087 2.0333 0.004 0.003 0.000 0.087 2.0667 0.004 0.003 0.000 0.087 2.1000 0.004 0.003 0.000 0.087 2.1333 0.004 0.003 0.000 0.087 2.1667 0.004 0.003 0.000 0.087 2.2000 0.004 0.003 0.000 0.087 2.2333 0.004 0.003 0.000 0.087 2.2667 0.004 0.003 0.000 0.087 2.3000 0.004 0.003 0.000 0.087 2.3333 0.004 0.003 0.000 0.087 2.3667 0.004 0.003 0.000 0.087 2.4000 0.004 0.003 0.000 0.087 2.4333 0.004 0.003 0.000 0.087 2.4667 0.004 0.003 0.000 0.087 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 13 2.7667 0.004 0.004 0.711 0.087 2.8000 0.004 0.004 0.762 0.087 2.8333 0.004 0.004 0.799 0.087 2.8667 0.004 0.004 0.847 0.087 2.9000 0.004 0.004 0.885 0.087 2.9333 0.004 0.004 0.921 0.087 2.9667 0.004 0.004 0.956 0.087 3.0000 0.004 0.004 0.989 0.087 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 14 Catchbasin Node Symbol Discharge Structure Riser Height: 0 ft. Riser Diameter: 0 in. Element Flows To: Outlet 1 Outlet 2 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 15 Analysis Results POC 1 0.1 0.0 1.o o.1 LL 1I lnri o.o1 Percerttt Time Exceeding + Predeveloped Predeveloped Landuse Totals for POC #1 Total Pervious Area: 0.6752 Total Impervious Area: 0.1468 Mitigated Landuse Totals for POC #1 Total Pervious Area: 0.0939 Total Impervious Area: 0.7281 x Mitigated Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.05635 5 year 0.083166 10 year 0.10502 25 year 0.13789 50 year 0.166598 100 year 0.199285 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.056458 5 year 0.079578 10 year 0.098496 25 year 0.127024 50 year 0.152001 100 year 0.180506 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1902 0.053 0.063 1903 0.060 0.070 1904 0.098 0.083 1905 0.036 0.041 1906 0.035 0.048 1907 0.065 0.056 1908 0.047 0.046 1909 0.050 0.057 1910 0.071 0.053 1911 0.055 0.059 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:28:57 PM Page 16 1912 0.177 0.118 1913 0.040 0.049 1914 0.196 0.195 1915 0.035 0.037 1916 0.057 0.070 1917 0.032 0.033 1918 0.046 0.054 1919 0.033 0.034 1920 0.051 0.053 1921 0.042 0.038 1922 0.061 0.059 1923 0.050 0.048 1924 0.065 0.079 1925 0.033 0.034 1926 0.057 0.067 1927 0.046 0.055 1928 0.046 0.043 1929 0.073 0.075 1930 0.078 0.088 1931 0.042 0.038 1932 0.047 0.045 1933 0.047 0.044 1934 0.103 0.074 1935 0.035 0.036 1936 0.054 0.057 1937 0.080 0.068 1938 0.040 0.037 1939 0.044 0.050 1940 0.079 0.091 1941 0.073 0.092 1942 0.074 0.069 1943 0.059 0.061 1944 0.107 0.087 1945 0.060 0.066 1946 0.056 0.052 1947 0.035 0.040 1948 0.067 0.048 1949 0.081 0.091 1950 0.037 0.046 1951 0.065 0.085 1952 0.150 0.098 1953 0.132 0.089 1954 0.050 0.049 1955 0.038 0.051 1956 0.032 0.037 1957 0.045 0.047 1958 0.089 0.058 1959 0.071 0.056 1960 0.038 0.045 1961 0.156 0.136 1962 0.049 0.054 1963 0.031 0.035 1964 0.161 0.135 1965 0.080 0.077 1966 0.042 0.045 1967 0.071 0.068 1968 0.042 0.050 1969 0.045 0.043 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:30:29 PM Page 17 1970 0.069 0.059 1971 0.071 0.053 1972 0.296 0.421 1973 0.089 0.105 1974 0.071 0.073 1975 0.119 0.082 1976 0.092 0.081 1977 0.031 0.035 1978 0.077 0.057 1979 0.055 0.058 1980 0.068 0.066 1981 0.062 0.071 1982 0.044 0.046 1983 0.066 0.064 1984 0.057 0.059 1985 0.078 0.074 1986 0.039 0.035 1987 0.076 0.067 1988 0.039 0.038 1989 0.040 0.052 1990 0.050 0.046 1991 0.061 0.068 1992 0.063 0.062 1993 0.064 0.075 1994 0.057 0.050 1995 0.032 0.035 1996 0.066 0.054 1997 0.044 0.045 1998 0.060 0.054 1999 0.054 0.064 2000 0.059 0.056 2001 0.055 0.068 2002 0.121 0.092 2003 0.048 0.052 2004 0.063 0.069 2005 0.141 0.156 2006 0.046 0.054 2007 0.066 0.069 2008 0.050 0.055 2009 0.040 0.045 2010 0.052 0.056 2011 0.043 0.056 2012 0.058 0.051 2013 0.055 0.060 2014 0.038 0.045 2015 0.178 0.132 2016 0.040 0.046 2017 0.076 0.081 2018 0.090 0.058 2019 0.132 0.088 2020 0.079 0.068 2021 0.068 0.057 2022 0.077 0.079 2023 0.079 0.094 2024 0.184 0.131 2025 0.056 0.076 2026 0.062 0.074 2027 0.063 0.073 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:30:29 PM Page 18 2028 0.025 0.031 2029 0.046 0.040 2030 0.085 0.098 2031 0.026 0.030 2032 0.041 0.048 2033 0.039 0.048 2034 0.038 0.040 2035 0.076 0.055 2036 0.055 0.045 2037 0.051 0.061 2038 0.071 0.056 2039 0.086 0.102 2040 0.046 0.047 2041 0.050 0.051 2042 0.091 0.071 2043 0.061 0.076 2044 0.053 0.052 2045 0.048 0.044 2046 0.044 0.040 2047 0.045 0.054 2048 0.039 0.045 2049 0.064 0.072 2050 0.044 0.041 2051 0.084 0.070 2052 0.046 0.054 2053 0.040 0.046 2054 0.135 0.104 2055 0.044 0.058 2056 0.063 0.075 2057 0.035 0.036 2058 0.057 0.068 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Rank Predeveloped Mitigated 1 0.2961 0.4207 2 0.1957 0.1946 3 0.1837 0.1559 4 0.1782 0.1364 5 0.1773 0.1351 6 0.1613 0.1324 7 0.1560 0.1308 8 0.1503 0.1176 9 0.1408 0.1049 10 0.1354 0.1042 11 0.1318 0.1019 12 0.1318 0.0982 13 0.1214 0.0978 14 0.1195 0.0937 15 0.1068 0.0916 16 0.1027 0.0915 17 0.0978 0.0913 18 0.0916 0.0910 19 0.0911 0.0888 20 0.0897 0.0880 21 0.0887 0.0879 22 0.0887 0.0865 23 0.0856 0.0852 Mitigated. POC #1 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:30:29 PM Page 19 24 0.0853 0.0833 25 0.0841 0.0818 26 0.0809 0.0814 27 0.0805 0.0809 28 0.0798 0.0789 29 0.0794 0.0788 30 0.0791 0.0766 31 0.0787 0.0761 32 0.0779 0.0760 33 0.0778 0.0753 34 0.0774 0.0753 35 0.0766 0.0749 36 0.0760 0.0739 37 0.0758 0.0737 38 0.0758 0.0736 39 0.0744 0.0734 40 0.0731 0.0728 41 0.0730 0.0721 42 0.0715 0.0715 43 0.0713 0.0707 44 0.0712 0.0704 45 0.0709 0.0701 46 0.0709 0.0697 47 0.0708 0.0694 48 0.0693 0.0690 49 0.0682 0.0690 50 0.0681 0.0684 51 0.0670 0.0684 52 0.0664 0.0683 53 0.0659 0.0683 54 0.0659 0.0677 55 0.0655 0.0675 56 0.0648 0.0673 57 0.0645 0.0672 58 0.0645 0.0661 59 0.0638 0.0659 60 0.0633 0.0643 61 0.0632 0.0637 62 0.0627 0.0632 63 0.0627 0.0621 64 0.0624 0.0613 65 0.0616 0.0611 66 0.0612 0.0596 67 0.0612 0.0591 68 0.0607 0.0590 69 0.0605 0.0587 70 0.0604 0.0587 71 0.0601 0.0581 72 0.0593 0.0580 73 0.0586 0.0579 74 0.0577 0.0578 75 0.0573 0.0573 76 0.0573 0.0570 77 0.0572 0.0568 78 0.0571 0.0565 79 0.0568 0.0564 80 0.0562 0.0564 81 0.0557 0.0561 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:30:29 PM Page 20 82 0.0555 0.0560 83 0.0554 0.0559 84 0.0549 0.0557 85 0.0547 0.0553 86 0.0546 0.0553 87 0.0537 0.0549 88 0.0536 0.0545 89 0.0531 0.0544 90 0.0529 0.0543 91 0.0515 0.0543 92 0.0511 0.0541 93 0.0505 0.0539 94 0.0505 0.0538 95 0.0502 0.0532 96 0.0498 0.0529 97 0.0496 0.0529 98 0.0495 0.0523 99 0.0495 0.0521 100 0.0489 0.0518 101 0.0482 0.0516 102 0.0480 0.0515 103 0.0475 0.0508 104 0.0469 0.0507 105 0.0468 0.0504 106 0.0463 0.0500 107 0.0460 0.0497 108 0.0460 0.0495 109 0.0458 0.0495 110 0.0458 0.0483 111 0.0457 0.0483 112 0.0456 0.0480 113 0.0453 0.0480 114 0.0449 0.0477 115 0.0449 0.0471 116 0.0444 0.0470 117 0.0441 0.0464 118 0.0440 0.0461 119 0.0440 0.0460 120 0.0440 0.0459 121 0.0438 0.0457 122 0.0433 0.0456 123 0.0423 0.0452 124 0.0422 0.0452 125 0.0422 0.0452 126 0.0420 0.0452 127 0.0409 0.0450 128 0.0403 0.0450 129 0.0403 0.0447 130 0.0402 0.0446 131 0.0401 0.0437 132 0.0399 0.0436 133 0.0397 0.0429 134 0.0393 0.0426 135 0.0391 0.0414 136 0.0389 0.0405 137 0.0389 0.0404 138 0.0383 0.0402 139 0.0379 0.0397 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:30:29 PM Page 21 140 0.0378 0.0395 141 0.0378 0.0382 142 0.0370 0.0378 143 0.0361 0.0377 144 0.0355 0.0369 145 0.0354 0.0368 146 0.0353 0.0368 147 0.0351 0.0365 148 0.0350 0.0360 149 0.0327 0.0354 150 0.0327 0.0350 151 0.0322 0.0348 152 0.0321 0.0347 153 0.0318 0.0342 154 0.0307 0.0337 155 0.0306 0.0333 156 0.0259 0.0305 157 0.0247 0.0300 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:30:29 PM Page 22 Duration Flows The Facility PASSED Flow(cfs) Predev Mit Percentage Pass/Fail 0.0282 8483 6408 75 Pass 0.0296 7101 5349 75 Pass 0.0310 5984 4403 73 Pass 0.0324 5019 3601 71 Pass 0.0338 4250 2919 68 Pass 0.0352 3629 2448 67 Pass 0.0366 3118 2090 67 Pass 0.0380 2697 1851 68 Pass 0.0394 2338 1635 69 Pass 0.0408 2064 1435 69 Pass 0.0422 1823 1263 69 Pass 0.0436 1614 1099 68 Pass 0.0450 1428 977 68 Pass 0.0464 1282 872 68 Pass 0.0477 1134 777 68 Pass 0.0491 998 690 69 Pass 0.0505 891 607 68 Pass 0.0519 813 550 67 Pass 0.0533 722 474 65 Pass 0.0547 656 422 64 Pass 0.0561 576 370 64 Pass 0.0575 520 325 62 Pass 0.0589 462 298 64 Pass 0.0603 414 271 65 Pass 0.0617 366 246 67 Pass 0.0631 334 228 68 Pass 0.0645 297 208 70 Pass 0.0659 265 189 71 Pass 0.0673 246 173 70 Pass 0.0687 217 162 74 Pass 0.0701 205 146 71 Pass 0.0715 181 134 74 Pass 0.0729 167 126 75 Pass 0.0743 160 117 73 Pass 0.0757 154 106 68 Pass 0.0771 142 95 66 Pass 0.0785 133 93 69 Pass 0.0799 125 87 69 Pass 0.0813 116 79 68 Pass 0.0827 113 77 68 Pass 0.0841 108 70 64 Pass 0.0855 104 64 61 Pass 0.0869 99 57 57 Pass 0.0883 95 51 53 Pass 0.0897 85 46 54 Pass 0.0911 79 45 56 Pass 0.0925 77 41 53 Pass 0.0939 73 40 54 Pass 0.0953 70 38 54 Pass Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:30:29 PM Page 23 1023 57 29 50 Pass 1037 56 29 51 Pass 1051 54 27 50 Pass 1065 50 26 52 Pass 1079 48 25 52 Pass 1093 47 25 53 Pass 1107 45 24 53 Pass 1121 43 23 53 Pass 1135 42 23 54 Pass 1149 42 23 54 Pass 1163 39 22 56 Pass 1177 38 20 52 Pass 1191 36 19 52 Pass 1205 35 19 54 Pass 1219 34 19 55 Pass 1233 34 16 47 Pass 1247 32 14 43 Pass 1260 32 14 43 Pass 1274 32 14 43 Pass 1288 31 14 45 Pass 1302 30 14 46 Pass 1316 29 13 44 Pass 1330 26 11 42 Pass 1344 26 10 38 Pass 1358 25 9 36 Pass 1372 24 7 29 Pass 1386 24 7 29 Pass 1400 23 7 30 Pass 1414 20 7 35 Pass 1428 19 7 36 Pass 1442 19 7 36 Pass 1456 19 7 36 Pass 1470 19 7 36 Pass 1484 17 7 41 Pass 1498 16 7 43 Pass 1512 15 7 46 Pass 1526 14 7 50 Pass 1540 14 7 50 Pass 1554 14 7 50 Pass 1568 13 6 46 Pass 1582 13 6 46 Pass 1596 13 6 46 Pass 1610 13 6 46 Pass 1624 11 6 54 Pass 1638 11 6 54 Pass 1652 11 6 54 Pass 1666 11 6 54 Pass RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:30:29 PM Page 24 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:30:29 PM Page 25 RESUB LID Report Mar 02 2021 CITY OF EDMONDS DEVELOPMENTSERVICES EPAR MENT LIDTeerinique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Commend Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft) Infiltration Infiltrated Treated iac-ft) iac-ft) Credit Catchbasin Node Symbol ❑ 69.41 ❑ 0.00 Gravel Trench Bed 1 ❑ 134.34 ❑ 98.01 Gravel Trench Bed 2 ❑ 62.74 ❑ 95.59 Total Volume Infiltrated 266.49 0 00 0 00 71.91 0.00 0% No Treat. Credit Duration Compliance with LID Analysis Standard 8% of 2-yr to 50% of Result= 2 yr Passed Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:30:29 PM Page 26 Western Washington Hydrology Model 2012 User Manual INFILTRATION Infiltration of stormwater runoff is a recommended solution if certain ' conditions are met. These Facility Name (Trapezoidal Pond l Outlet 1 Facility Type (Trapezoidal Pond Outlet 2 Outlet 3 conditions include: a soils report, testing, groundwater protection, Downstream Connections r Precipitation Applied to Facility r Evaporation Applied to Facility Auto Pond I Quick Pond Facility Dimension Diagram pre -settling and appropriate t construction techniques (see Ecology's 2012 Stormwater Management Manual for Western Facility Dimensions Facility Bottom Elevation (ft) Bottom Length (it) Bottom Width Ili) Effective Depth(ft) Le It Side Slope NN) Bottom Side Slope (HIM 0 p 0 p� 0� Outlet Structure Data Riser Height Iltl F0 --- i Riser Diameter (in) Fo_—� Riser Type Flat Notch Type Washington for details). Right Side Slope(HN) Top Side Slope(HNJ Infiltration 0� yE5 Orifice Diameter Height Number (in) (R) The user clicks on the Infiltration option arrow to change infiltration Measured Infiltration Rate(in/hr) Reduction Factolinfilt"factor) Wetted Surface Arec-11) walls) �=-{ FO—?-1 NO l 1 10 ' 1 �� 2 Fo--- --H Fo--- 1 3 �� r0 'j from NO to YES. This activates Tot Total Volume Infiltrated (arltJ Total Volume Through Riser(ac-ft) 0 D Pond Volume at Riser Head(ac-ft) 0 the infiltration input options: measured infiltration rate, Total Volume Through Facility(aclt) Percent lrifiltrated Size Infiltration Pond [Targetili,: 0.00 0 Show Pond Table Open Table J Initial Stage(ft) infiltration reduction factor, and loo whether or not to allow infiltration through the wetted side slopes/walls. The infiltration reduction factor is a multiplier for the measured infiltration rate and should be less than one. It is the same as the inverse of a safety factor. For example, a safety factor of 2 is equal to a reduction factor of 0.5. Infiltration occurs only through the bottom of the facility. If the wetted surface area option is turned on then infiltration also occurs thr ugh the wetted side walls. RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT After the model is run and flow is routed through jhe infiltration facility the total volume infiltrated, total volume through the riser, total v ume through the facility, and percent infiltrated are reported on the screen. If the erc nt infiltrated is 100° then there surface discharge from the facilit The percen filtrated can be less than 100% as long as the surface discharge does not exceed Ecology's flow control standards. Infiltration facilities have the option to allow users to automatically size the facility to meet an infiltration target percentage. The user can set the target percentage for being filtered/infiltrated to 91 % to meet the Ecology water quality treatment standard. 59 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:34 PM Page 27 Appendix Predeveloped Schematic RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT �aFrede on -site 0.59ac rede elope 1 ROW 0.23ac Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:34 PM Page 28 Mitigated Schematic RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES L,i n-sit ,On-SitE Pararench .,trenchLaneW .40ac 0.19ac .23i-- SI SI ravel ravel'{ rench renclt�ed 2 \I � atchbasin Node Symbol Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 29 RESUB Predeveloped UCI File Mar 02 2021 CITY OF EDMONDS RUN DEVELOPMENT SERVICES DEPARTMENT GLOBAL WWHM4 model simulation START 1901 10 01 END 2058 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <----------- File Name ------------------------------ >*** <-ID-> *** WDM 26 Rettenmier Pre 1977 Existing Impervious.wdm MESSU 25 PreRettenmier Pre 1977 Existing Impervious.MES 27 PreRettenmier Pre 1977 Existing Impervious.L61 28 PreRettenmier Pre 1977 Existing Impervious.1,62 30 PreRettenmier Pre 1977 Existing Imperviousl.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 11 PERLND 16 IMPLND 4 IMPLND 6 IMPLND 8 PERLND 12 IMPLND 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<---------- Title ----------- >***TRAN PIVL DIG1 FIL1 1 Predeveloped on -site MAX END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO PYR DIG2 FIL2 YRND 1 2 30 9 <PLS ><------- Name ------- >NBLKS Unit -systems Printer *** # - # User t-series Engl Metr *** 11 C, Forest, Mod 16 C, Lawn, Flat 12 C, Forest, Steep END GEN-INFO *** Section PWATER*** in out *** 1 1 1 1 27 0 1 1 1 1 27 0 1 1 1 1 27 0 ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 11 0 0 1 0 0 0 0 0 0 0 0 0 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 30 RESUB 16) 0 0 1 0 0 0 0 0 0 0 0 0 Mar 02 2021 12 0 0 1 0 0 0 0 0 0 0 0 O CITY OF E ERVI DEVELOPMENTT SERVICES END ACTIVITY DEPARTMENT PRINT -INFO <PLS > ***************** Print -flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 11 0 0 4 0 0 0 0 0 0 0 0 0 1 9 16 0 0 4 0 0 0 0 0 0 0 0 0 1 9 12 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT -INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 11 0 0 0 0 0 0 0 0 0 0 0 16 0 0 0 0 0 0 0 0 0 0 0 12 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 11 0 4.5 0.08 400 0.1 0.5 0.996 16 0 4.5 0.03 400 0.05 0.5 0.996 12 0 4.5 0.08 400 0.15 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 11 0 0 2 2 0 0 0 16 0 0 2 2 0 0 0 12 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 11 0.2 0.5 0.35 6 0.5 0.7 16 0.1 0.25 0.25 6 0.5 0.25 12 0.2 0.3 0.35 6 0.3 0.7 END PWAT-PARM4 PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 11 0 0 0 0 2.5 1 0 16 0 0 0 0 2.5 1 0 12 0 0 0 0 2.5 1 0 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><------- Name ------- > Unit -systems Printer *** # - # User t-series Engl Metr *** in out *** 4 ROOF TOPS/FLAT 1 1 1 27 0 6 DRIVEWAYS/MOD 1 1 1 27 0 8 SIDEWALKS/FLAT 1 1 1 27 0 1 ROADS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 4 0 0 1 0 0 0 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 31 RESUB 6 0 0 1 0 0 0 Mar 02 2021 8 O 0 1 O O O CITY OF EDMONDS DEVELOPMENT SERVICES 1 0 0 1 0 0 0 DEPARTMENT END ACTIVITY PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 4 0 0 4 0 0 0 1 9 6 0 0 4 0 0 0 1 9 8 0 0 4 0 0 0 1 9 1 0 0 4 0 0 0 1 9 END PRINT -INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 4 0 0 0 0 0 6 0 0 0 0 0 8 0 0 0 0 0 1 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 4 400 0.01 0.1 0.1 6 400 0.05 0.1 0.08 8 400 0.01 0.1 0.1 1 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 4 0 0 6 0 0 8 0 0 1 0 0 END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 4 0 0 6 0 0 8 0 0 1 0 0 END IWAT-STATEI END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Predeveloped on -site*** PERLND 11 0.2356 COPY 501 12 PERLND 11 0.2356 COPY 501 13 PERLND 16 0.2716 COPY 501 12 PERLND 16 0.2716 COPY 501 13 IMPLND 4 0.0438 COPY 501 15 IMPLND 6 0.035 COPY 501 15 IMPLND 8 0.003 COPY 501 15 Predeveloped ROW*** PERLND 12 0.168 COPY 501 12 PERLND 12 0.168 COPY 501 13 IMPLND 1 0.065 COPY 501 15 ******Routing****** END SCHEMATIC Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 32 NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------ >< --- > User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT -INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------ ><-------- ><-------- ><-------- ><-------- ><-------- ><-------- > *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------ ><-------- > <--- ><--- ><--- ><--- >< --- > *** <--- ><--- ><--- ><--- >< --- > END HYDR-INIT END RCHRES SPEC -ACTIONS END SPEC -ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 DIV PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 DIV IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 33 MASS -LINK <Volume> <-Grp> <-Member-><--Mult--> <Name> <Name> # #<-factor-> MASS -LINK 12 PERLND PWATER SURO 0.083333 END MASS -LINK 12 MASS -LINK 13 PERLND PWATER IFWO 0.083333 END MASS -LINK 13 MASS -LINK 15 IMPLND IWATER SURO 0.083333 END MASS -LINK 15 END MASS -LINK END RUN <Target> <-Grp> <-Member->*** <Name> <Name> # #*** COPY INPUT MEAN COPY INPUT MEAN COPY INPUT MEAN RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 34 RESUB Mitigated UC/ File Mar 02 2021 CITY OF EDMONDS RUN DEVELOPMENT SERVICES DEPARTMENT GLOBAL WWHM4 model simulation START 1901 10 01 END 2058 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <----------- File Name ------------------------------ >*** <-ID-> *** WDM 26 Rettenmier Pre 1977 Existing Impervious.wdm MESSU 25 MitRettenmier Pre 1977 Existing Impervious.MES 27 MitRettenmier Pre 1977 Existing Impervious.L61 28 MitRettenmier Pre 1977 Existing Impervious.L62 30 POCRettenmier Pre 1977 Existing Imperviousl.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 IMPLND 1 IMPLND 4 IMPLND 8 PERLND 18 IMPLND 2 IMPLND 9 RCHRES 1 RCHRES 2 RCHRES 3 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INF01 # - #<---------- Title ----------- >***TRAN PIVL DIG1 FIL1 1 Catchbasin Node Symbol MAX END DISPLY-INF01 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO PYR DIG2 FIL2 YRND 1 2 30 9 <PLS ><------- Name ------- >NBLKS Unit -systems Printer *** # - # User t-series Engl Metr *** 16 C, Lawn, Flat 18 C, Lawn, Steep END GEN-INFO *** Section PWATER*** ACTIVITY in out *** 1 1 1 1 27 0 1 1 1 1 27 0 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 35 RESUB <PLS > ************* Active Sections ***************************** Mar 022021 # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** CITYOFEERVI DEVELOPMENTT SERVICES 16 0 0 1 0 0 0 0 0 0 0 0 0 DEPARTMENT 18 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 16 0 0 4 0 0 0 0 0 0 0 0 0 1 9 18 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT -INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 16 0 0 0 0 0 0 0 0 0 0 0 18 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 16 0 4.5 0.03 400 0.05 0.5 0.996 18 0 4.5 0.03 400 0.15 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 16 0 0 2 2 0 0 0 18 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 16 0.1 0.25 0.25 6 0.5 0.25 18 0.1 0.15 0.25 6 0.3 0.25 END PWAT-PARM4 PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 16 0 0 0 0 2.5 1 0 18 0 0 0 0 2.5 1 0 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><------- Name ------- > 1 ROADS/FLAT 4 ROOF TOPS/FLAT 8 SIDEWALKS/FLAT 2 ROADS/MOD 9 SIDEWALKS/MOD END GEN-INFO *** Section IWATER*** Unit -systems Printer *** User t-series Engl Metr *** in out *** 1 1 1 27 0 1 1 1 27 0 1 1 1 27 0 1 1 1 27 0 1 1 1 27 0 ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 4 0 0 1 0 0 0 8 0 0 1 0 0 0 2 0 0 1 0 0 0 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 36 RESUB 9 0 0 1 0 0 0 Mar 02 2021 END ACTIVITY CITYOFET ERVI DEVELOP ART EERVICEE DEPARTMENT PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 0 1 9 4 0 0 4 0 0 0 1 9 8 0 0 4 0 0 0 1 9 2 0 0 4 0 0 0 1 9 9 0 0 4 0 0 0 1 9 END PRINT -INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 4 0 0 0 0 0 8 0 0 0 0 0 2 0 0 0 0 0 9 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 4 400 0.01 0.1 0.1 8 400 0.01 0.1 0.1 2 400 0.05 0.1 0.08 9 400 0.05 0.1 0.08 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 4 0 0 8 0 0 2 0 0 9 0 0 END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 4 0 0 8 0 0 2 0 0 9 0 0 END IWAT-STATEI END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** On -site Trench 1*** PERLND 16 0.0122 RCHRES 1 2 PERLND 16 0.0122 RCHRES 1 3 IMPLND 1 0.1646 RCHRES 1 5 IMPLND 4 0.2065 RCHRES 1 5 IMPLND 8 0.013 RCHRES 1 5 On -Site trench 2*** PERLND 16 0.0187 RCHRES 2 2 PERLND 16 0.0187 RCHRES 2 3 IMPLND 1 0.073 RCHRES 2 5 IMPLND 4 0.101 RCHRES 2 5 Paradise Lane ROW*** Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 37 PERLND 18 0.063 RCHRES 3 2 PERLND 18 0.063 RCHRES 3 3 IMPLND 2 0.125 RCHRES 3 5 IMPLND 9 0.045 RCHRES 3 5 ******Routing****** RCHRES 1 1 RCHRES 3 7 RCHRES 1 COPY 1 17 RCHRES 2 1 RCHRES 3 7 RCHRES 2 COPY 1 17 PERLND 18 0.063 COPY 1 12 IMPLND 2 0.125 COPY 1 15 IMPLND 9 0.045 COPY 1 15 PERLND 18 0.063 COPY 1 13 RCHRES 3 1 COPY 501 16 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems # - #<------------------ >< --- > User T-series in out 1 Gravel Trench Be-008 2 1 1 1 2 Gravel Trench Be-009 2 1 1 1 3 Catchbasin Node -011 1 1 1 1 END GEN-INFO *** Section RCHRES*** Printer *** Engl Metr LKFG *** *** 28 0 1 28 0 1 28 0 1 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 2 1 0 0 0 0 0 0 0 0 0 3 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 2 4 0 0 0 0 0 0 0 0 0 1 9 3 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT -INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** 1 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 2 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 3 0 1 0 0 4 0 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><-------->< -------- >< -------- ><-------- ><-------- ><-------- > *** 1 1 0.02 0.0 0.0 0.5 0.0 2 2 0.01 0.0 0.0 0.5 0.0 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 38 3 3 0.01 0.0 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section # - # *** VOL Initial value of COLIND *** ac-ft for each possible exit <------ ><-------- > <--- ><--- ><--- ><--- >< --- > 1 0 4.0 5.0 0.0 0.0 0.0 2 0 4.0 5.0 0.0 0.0 0.0 3 0 4.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC -ACTIONS END SPEC -ACTIONS FTABLES FTABLE 1 92 5 Depth Area Volume Outflowl Outflow2 (ft) (acres) (acre-ft) (cfs) (cfs) 0.000000 0.008485 0.000000 0.000000 0.000000 0.031111 0.008485 0.000087 0.000000 0.154000 0.062222 0.008485 0.000174 0.000000 0.154000 0.093333 0.008485 0.000261 0.000000 0.154000 0.124444 0.008485 0.000348 0.000000 0.154000 0.155556 0.008485 0.000436 0.000000 0.154000 0.186667 0.008485 0.000523 0.000000 0.154000 0.217778 0.008485 0.000610 0.000000 0.154000 0.248889 0.008485 0.000697 0.000000 0.154000 0.280000 0.008485 0.000784 0.000000 0.154000 0.311111 0.008485 0.000871 0.000000 0.154000 0.342222 0.008485 0.000958 0.000000 0.154000 0.373333 0.008485 0.001045 0.000000 0.154000 0.404444 0.008485 0.001132 0.000000 0.154000 0.435556 0.008485 0.001220 0.000000 0.154000 0.466667 0.008485 0.001307 0.000000 0.154000 0.497778 0.008485 0.001394 0.000000 0.154000 0.528889 0.008485 0.001481 0.000000 0.154000 0.560000 0.008485 0.001568 0.000000 0.154000 0.591111 0.008485 0.001655 0.000000 0.154000 0.622222 0.008485 0.001742 0.000000 0.154000 0.653333 0.008485 0.001829 0.000000 0.154000 0.684444 0.008485 0.001916 0.000000 0.154000 0.715556 0.008485 0.002004 0.000000 0.154000 0.746667 0.008485 0.002091 0.000000 0.154000 0.777778 0.008485 0.002178 0.000000 0.154000 0.808889 0.008485 0.002265 0.000000 0.154000 0.840000 0.008485 0.002352 0.000000 0.154000 0.871111 0.008485 0.002439 0.000000 0.154000 0.902222 0.008485 0.002526 0.000000 0.154000 0.933333 0.008485 0.002613 0.000000 0.154000 0.964444 0.008485 0.002700 0.000000 0.154000 0.995556 0.008485 0.002788 0.000000 0.154000 1.026667 0.008485 0.002875 0.000000 0.154000 1.057778 0.008485 0.002962 0.000000 0.154000 1.088889 0.008485 0.003049 0.000000 0.154000 1.120000 0.008485 0.003136 0.000000 0.154000 1.151111 0.008485 0.003223 0.000000 0.154000 1.182222 0.008485 0.003310 0.000000 0.154000 1.213333 0.008485 0.003397 0.000000 0.154000 1.244444 0.008485 0.003484 0.000000 0.154000 1.275556 0.008485 0.003572 0.000000 0.154000 1.306667 0.008485 0.003659 0.000000 0.154000 1.337778 0.008485 0.003746 0.000000 0.154000 1.368889 0.008485 0.003833 0.000000 0.154000 1.400000 0.008485 0.003920 0.000000 0.154000 1.431111 0.008485 0.004007 0.000000 0.154000 1.462222 0.008485 0.004094 0.000000 0.154000 1.493333 0.008485 0.004181 0.000000 0.154000 1.524444 0.008485 0.004268 0.000000 0.154000 0.5 0.0 *** Initial value of OUTDGT for each possible exit ** <--- ><--- ><--- ><--- >< --- > 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Velocity Travel Time*** (ft/sec) (Minutes)*** RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 39 RESUB 1.555556 0.008485 0.004356 0.000000 0.154000 Mar 022021 1.586667 0.008485 0.004443 0.000000 0.154000 CITYOFEERVI DEVELOPMENTT SERVICES 1.617778 0.008485 0.004530 0.000000 0.154000 DEPARTMENT 1.648889 0.008485 0.004617 0.000000 0.154000 1.680000 0.008485 0.004704 0.000000 0.154000 1.711111 0.008485 0.004791 0.000000 0.154000 1.742222 0.008485 0.004878 0.000000 0.154000 1.773333 0.008485 0.004965 0.000000 0.154000 1.804444 0.008485 0.005052 0.000000 0.154000 1.835556 0.008485 0.005140 0.000000 0.154000 1.866667 0.008485 0.005227 0.000000 0.154000 1.897778 0.008485 0.005314 0.000000 0.154000 1.928889 0.008485 0.005401 0.000000 0.154000 1.960000 0.008485 0.005488 0.000000 0.154000 1.991111 0.008485 0.005575 0.000000 0.154000 2.022222 0.008485 0.005662 0.000000 0.154000 2.053333 0.008485 0.005749 0.000000 0.154000 2.084444 0.008485 0.005836 0.000000 0.154000 2.115556 0.008485 0.005924 0.000000 0.154000 2.146667 0.008485 0.006011 0.000000 0.154000 2.177778 0.008485 0.006098 0.000000 0.154000 2.208889 0.008485 0.006185 0.000000 0.154000 2.240000 0.008485 0.006272 0.000000 0.154000 2.271111 0.008485 0.006359 0.000000 0.154000 2.302222 0.008485 0.006446 0.000000 0.154000 2.333333 0.008485 0.006533 0.000000 0.154000 2.364444 0.008485 0.006620 0.000000 0.154000 2.395556 0.008485 0.006708 0.000000 0.154000 2.426667 0.008485 0.006795 0.000000 0.154000 2.457778 0.008485 0.006882 0.000000 0.154000 2.488889 0.008485 0.006969 0.000000 0.154000 2.520000 0.008485 0.007056 0.000000 0.154000 2.551111 0.008485 0.007143 0.000000 0.154000 2.582222 0.008485 0.007230 0.000000 0.154000 2.613333 0.008485 0.007317 0.000000 0.154000 2.644444 0.008485 0.007404 0.000000 0.154000 2.675556 0.008485 0.007492 0.000000 0.154000 2.706667 0.008485 0.007579 0.000000 0.154000 2.737778 0.008485 0.007666 0.000000 0.154000 2.768889 0.008485 0.007753 0.000000 0.154000 2.800000 0.008485 0.007840 0.000000 0.154000 2.831111 0.008485 0.008104 0.038775 0.154000 END FTABLE 1 FTABLE 2 92 5 Depth Area Volume Outflowl Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.004821 0.000000 0.000000 0.000000 0.033333 0.004821 0.000053 0.000000 0.087500 0.066667 0.004821 0.000106 0.000000 0.087500 0.100000 0.004821 0.000159 0.000000 0.087500 0.133333 0.004821 0.000212 0.000000 0.087500 0.166667 0.004821 0.000265 0.000000 0.087500 0.200000 0.004821 0.000318 0.000000 0.087500 0.233333 0.004821 0.000371 0.000000 0.087500 0.266667 0.004821 0.000424 0.000000 0.087500 0.300000 0.004821 0.000477 0.000000 0.087500 0.333333 0.004821 0.000530 0.000000 0.087500 0.366667 0.004821 0.000583 0.000000 0.087500 0.400000 0.004821 0.000636 0.000000 0.087500 0.433333 0.004821 0.000689 0.000000 0.087500 0.466667 0.004821 0.000742 0.000000 0.087500 0.500000 0.004821 0.000795 0.000000 0.087500 0.533333 0.004821 0.000848 0.000000 0.087500 0.566667 0.004821 0.000902 0.000000 0.087500 0.600000 0.004821 0.000955 0.000000 0.087500 0.633333 0.004821 0.001008 0.000000 0.087500 0.666667 0.004821 0.001061 0.000000 0.087500 0.700000 0.004821 0.001114 0.000000 0.087500 0.733333 0.004821 0.001167 0.000000 0.087500 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 40 RESUB 0.766667 0.004821 0.001220 0.000000 0.087500 Mar 022021 0. 800000 0. 004821 0. 001273 0. 000000 0. 087500 CITYOFEERVI DEVELOPMENTT SERVICES 0.833333 0.004821 0.001326 0.000000 0.087500 DEPARTMENT 0.866667 0.004821 0.001379 0.000000 0.087500 0.900000 0.004821 0.001432 0.000000 0.087500 0.933333 0.004821 0.001485 0.000000 0.087500 0.966667 0.004821 0.001538 0.000000 0.087500 1.000000 0.004821 0.001591 0.000000 0.087500 1.033333 0.004821 0.001644 0.000000 0.087500 1.066667 0.004821 0.001697 0.000000 0.087500 1.100000 0.004821 0.001750 0.000000 0.087500 1.133333 0.004821 0.001803 0.000000 0.087500 1.166667 0.004821 0.001856 0.000000 0.087500 1.200000 0.004821 0.001909 0.000000 0.087500 1.233333 0.004821 0.001962 0.000000 0.087500 1.266667 0.004821 0.002015 0.000000 0.087500 1.300000 0.004821 0.002068 0.000000 0.087500 1.333333 0.004821 0.002121 0.000000 0.087500 1.366667 0.004821 0.002174 0.000000 0.087500 1.400000 0.004821 0.002227 0.000000 0.087500 1.433333 0.004821 0.002280 0.000000 0.087500 1.466667 0.004821 0.002333 0.000000 0.087500 1.500000 0.004821 0.002386 0.000000 0.087500 1.533333 0.004821 0.002439 0.000000 0.087500 1.566667 0.004821 0.002492 0.000000 0.087500 1.600000 0.004821 0.002545 0.000000 0.087500 1.633333 0.004821 0.002598 0.000000 0.087500 1.666667 0.004821 0.002652 0.000000 0.087500 1.700000 0.004821 0.002705 0.000000 0.087500 1.733333 0.004821 0.002758 0.000000 0.087500 1.766667 0.004821 0.002811 0.000000 0.087500 1.800000 0.004821 0.002864 0.000000 0.087500 1.833333 0.004821 0.002917 0.000000 0.087500 1.866667 0.004821 0.002970 0.000000 0.087500 1.900000 0.004821 0.003023 0.000000 0.087500 1.933333 0.004821 0.003076 0.000000 0.087500 1.966667 0.004821 0.003129 0.000000 0.087500 2.000000 0.004821 0.003182 0.000000 0.087500 2.033333 0.004821 0.003235 0.000000 0.087500 2.066667 0.004821 0.003288 0.000000 0.087500 2.100000 0.004821 0.003341 0.000000 0.087500 2.133333 0.004821 0.003394 0.000000 0.087500 2.166667 0.004821 0.003447 0.000000 0.087500 2.200000 0.004821 0.003500 0.000000 0.087500 2.233333 0.004821 0.003553 0.000000 0.087500 2.266667 0.004821 0.003606 0.000000 0.087500 2.300000 0.004821 0.003659 0.000000 0.087500 2.333333 0.004821 0.003712 0.000000 0.087500 2.366667 0.004821 0.003765 0.000000 0.087500 2.400000 0.004821 0.003818 0.000000 0.087500 2.433333 0.004821 0.003871 0.000000 0.087500 2.466667 0.004821 0.003924 0.000000 0.087500 2.500000 0.004821 0.003977 0.000000 0.087500 2.533333 0.004821 0.004030 0.042996 0.087500 2.566667 0.004821 0.004083 0.121030 0.087500 2.600000 0.004821 0.004136 0.219469 0.087500 2.633333 0.004821 0.004189 0.329384 0.087500 2.666667 0.004821 0.004242 0.441835 0.087500 2.700000 0.004821 0.004295 0.547841 0.087500 2.733333 0.004821 0.004348 0.639435 0.087500 2.766667 0.004821 0.004402 0.711272 0.087500 2.800000 0.004821 0.004455 0.762603 0.087500 2.833333 0.004821 0.004508 0.799562 0.087500 2.866667 0.004821 0.004561 0.847643 0.087500 2.900000 0.004821 0.004614 0.885334 0.087500 2.933333 0.004821 0.004667 0.921485 0.087500 2.966667 0.004821 0.004720 0.956270 0.087500 3.000000 0.004821 0.004773 0.989833 0.087500 3.033333 0.004821 0.004933 1.022295 0.087500 END FTABLE 2 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 41 FTABLE 3 91 4 Depth Area Volume Outflowl (ft) (acres) (acre-ft) (cfs) 0.000000 0.000000 0.000000 0.000000 0.011111 0.000096 0.000001 0.000887 0.022222 0.000135 0.000002 0.003956 0.033333 0.000165 0.000004 0.009457 0.044444 0.000189 0.000006 0.017515 0.055556 0.000210 0.000008 0.028205 0.066667 0.000229 0.000010 0.041574 0.077778 0.000246 0.000013 0.057646 0.088889 0.000261 0.000016 0.076435 0.100000 0.000275 0.000019 0.097943 0.111111 0.000289 0.000022 0.122163 0.122222 0.000301 0.000025 0.149082 0.133333 0.000312 0.000029 0.178678 0.144444 0.000323 0.000032 0.210928 0.155556 0.000333 0.000036 0.245802 0.166667 0.000342 0.000040 0.283267 0.177778 0.000351 0.000043 0.323286 0.188889 0.000359 0.000047 0.365818 0.200000 0.000367 0.000051 0.410820 0.211111 0.000375 0.000055 0.458247 0.222222 0.000382 0.000060 0.508051 0.233333 0.000388 0.000064 0.560179 0.244444 0.000395 0.000068 0.614581 0.255556 0.000401 0.000073 0.671201 0.266667 0.000406 0.000077 0.729982 0.277778 0.000411 0.000082 0.790866 0.288889 0.000416 0.000086 0.853791 0.300000 0.000421 0.000091 0.918696 0.311111 0.000425 0.000096 0.985516 0.322222 0.000429 0.000100 1.054188 0.333333 0.000433 0.000105 1.124643 0.344444 0.000436 0.000110 1.196813 0.355556 0.000440 0.000115 1.270629 0.366667 0.000443 0.000120 1.346019 0.377778 0.000445 0.000125 1.422910 0.388889 0.000448 0.000130 1.501228 0.400000 0.000450 0.000135 1.580898 0.411111 0.000452 0.000140 1.661843 0.422222 0.000454 0.000145 1.743985 0.433333 0.000455 0.000150 1.827244 0.444444 0.000456 0.000155 1.911540 0.455556 0.000457 0.000160 1.996789 0.466667 0.000458 0.000165 2.082908 0.477778 0.000459 0.000170 2.169813 0.488889 0.000459 0.000175 2.257417 0.500000 0.000459 0.000180 2.345632 0.511111 0.000459 0.000185 2.434367 0.522222 0.000459 0.000191 2.523535 0.533333 0.000458 0.000196 2.613039 0.544444 0.000457 0.000201 2.702788 0.555556 0.000456 0.000206 2.792685 0.566667 0.000455 0.000211 2.882633 0.577778 0.000454 0.000216 2.972532 0.588889 0.000452 0.000221 3.062282 0.600000 0.000450 0.000226 3.151779 0.611111 0.000448 0.000231 3.240918 0.622222 0.000445 0.000236 3.329591 0.633333 0.000443 0.000241 3.417689 0.644444 0.000440 0.000246 3.505100 0.655556 0.000436 0.000251 3.591707 0.666667 0.000433 0.000255 3.677394 0.677778 0.000429 0.000260 3.762039 0.688889 0.000425 0.000265 3.845518 0.700000 0.000421 0.000270 3.927702 0.711111 0.000416 0.000274 4.008460 0.722222 0.000411 0.000279 4.087655 Velocity Travel Time*** (ft/sec) (Minutes)*** RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 42 0.733333 0.000406 0.000283 4.165144 0.744444 0.000401 0.000288 4.240781 0.755556 0.000395 0.000292 4.314414 0.766667 0.000388 0.000297 4.385880 0.777778 0.000382 0.000301 4.455012 0.788889 0.000375 0.000305 4.521633 0.800000 0.000367 0.000309 4.585554 0.811111 0.000359 0.000313 4.646577 0.822222 0.000351 0.000317 4.704486 0.833333 0.000342 0.000321 4.759050 0.844444 0.000333 0.000325 4.810017 0.855556 0.000323 0.000328 4.857111 0.866667 0.000312 0.000332 4.900024 0.877778 0.000301 0.000335 4.938408 0.888889 0.000289 0.000339 4.971867 0.900000 0.000275 0.000342 4.999936 0.911111 0.000261 0.000345 5.022060 0.922222 0.000246 0.000348 5.037559 0.933333 0.000229 0.000350 5.045560 0.944444 0.000210 0.000353 5.045560 0.955556 0.000189 0.000355 5.045560 0.966667 0.000165 0.000357 5.045560 0.977778 0.000135 0.000359 5.045560 0.988889 0.000096 0.000360 5.045560 1.000000 0.000000 0.000361 5.045560 END FTABLE 3 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 DIV PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 DIV IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Name> # <Name> # #<-factor->strg <Name> # RCHRES 3 HYDR RO 1 1 1 WDM 1000 RCHRES 3 HYDR STAGE 1 1 1 WDM 1001 COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 END EXT TARGETS MASS -LINK <Volume> <-Grp> <-Member-><--Mult--> <Name> <Name> # #<-factor-> MASS -LINK 2 PERLND PWATER SURD 0.083333 END MASS -LINK 2 MASS -LINK 3 PERLND PWATER IFWO END MASS -LINK 3 MASS -LINK 5 IMPLND IWATER SURO END MASS -LINK 5 MASS -LINK 7 RCHRES OFLOW OVOL END MASS -LINK 7 MASS -LINK 12 PERLND PWATER SURO END MASS -LINK 12 <Target> <Name> RCHRES 0.083333 RCHRES 0.083333 RCHRES 1 RCHRES 0.083333 COPY <Member> Tsys Tgap Amd *** <Name> tem strg strg*** FLOW ENGL REPL STAG ENGL REPL FLOW ENGL REPL FLOW ENGL REPL <-Grp> <-Member->*** <Name> # #*** INFLOW IVOL INFLOW IVOL INFLOW IVOL INFLOW IVOL INPUT MEAN RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 43 MASS —LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS —LINK 13 MASS —LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS —LINK 15 MASS —LINK 16 RCHRES ROFLOW COPY INPUT MEAN END MASS —LINK 16 MASS —LINK 17 RCHRES OFLOW OVOL 1 COPY INPUT MEAN END MASS —LINK 17 END MASS —LINK END RUN RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 44 Predeveloped HSPF Message File RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 45 Mitigated HSPF Message File ERROR/WARNING ID: 341 6 DATE/TIME: 1914/ 6/30 18:15 RCHRES: 1 The volume of water in this reach/mixed reservoir is greater than the value in the "volume" column of the last row of RCHTAB(). To continue the simulation the table has been extrapolated, based on information contained in the last two rows. This will usually result in some loss of accuracy. If depth is being calculated it will also cause an error condition. Relevant data are: NROWS V1 V2 VOL 92 341.51 353.01 356.87 ERROR/WARNING ID: 341 5 DATE/TIME: 1914/ 6/30 18:15 RCHRES: 1 Calculation of relative depth, using Newton's method of successive approximations, converged to an invalid value (not in range 0.0 to 1.0). Probably ftable was extrapolated. If extrapolation was small, no problem. Remedy; extend ftable. Relevant data are: A B C RDEP1 RDEP2 COUNT 0.0000E+00 739.21-987.31 1.3356 1.3356E+00 2 ERROR/WARNING ID: 341 6 DATE/TIME: 1972/ 6/10 19: 0 RCHRES: 1 The volume of water in this reach/mixed reservoir is greater than the value in the "volume" column of the last row of RCHTAB(). To continue the simulation the table has been extrapolated, based on information contained in the last two rows. This will usually result in some loss of accuracy. If depth is being calculated it will also cause an error condition. Relevant data are: NROWS V1 V2 VOL 92 3.4151E+02 353.01 430.73 ERROR/WARNING ID: 341 5 DATE/TIME: 1972/ 6/10 19: 0 RCHRES: 1 Calculation of relative depth, using Newton's method of successive approximations, converged to an invalid value (not in range 0.0 to 1.0). Probably ftable was extrapolated. If extrapolation was small, no problem. Remedy; extend ftable. Relevant data are: A B C RDEP1 RDEP2 COUNT 0.0000E+00 739.21 -5.735E+03 7.7581 7.7581E+00 2 ERROR/WARNING ID: 341 6 DATE/TIME: 1972/ 6/10 19:15 RCHRES: 1 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 46 RESUB The volume of water in this reach/mixed reservoir is greater than the value Mar 022021 in the "volume" column of the last row of RCHTAB ( ) . To continue the CITY METSERVI DEVELOPMENT SERVICES simulation the table has been extrapolated, based on information contained DEPARTMENT in the last two rows. This will usually result in some loss of accuracy. If depth is being calculated it will also cause an error condition. Relevant data are: NROWS V1 V2 VOL 92 3.4151E+02 353.01 359.46 ERROR/WARNING ID: 341 5 DATE/TIME: 1972/ 6/10 19:15 RCHRES: 1 Calculation of relative depth, using Newton's method of successive approximations, converged to an invalid value (not in range 0.0 to 1.0). Probably ftable was extrapolated. If extrapolation was small, no problem. Remedy; extend ftable. Relevant data are: A B C RDEP1 RDEP2 COUNT 0.0000E+00 739.21 -1.154E+03 1.5610 1.5610E+00 2 Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 47 Disclaimer RESUB Mar 02 2021 Legal Notice CITY OFMONDS DEVELOPMENT SERVICES DEPARTMENT RTTMENT This program and accompanying documentation are provided 'as -is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by: Clear Creek Solutions, Inc. 2005-2021; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com Rettenmier Pre 1977 Existing Impervious 2/26/2021 12:31:35 PM Page 48 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Appendix D WATER QUALITY SIZING OF CONTECH CATCH BASIN STORM FILTERS 4'SI RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT 610� WA SH IN 6T0N STATE O EPAHTMENT OF ECOLOGY April 2017 GENERAL USE LEVEL DESIGNATION FOR BASIC (TSS) AND PHOSPHORUS TREATMENT For CONTECH Engineered Solutions Stormwater Management StormFilter® with PhosghoSorb® media Ecology's Decision: 1. Based on Contech Engineered Solutions application, Ecology hereby issues the following use level designation for the Stormwater Management StormFilter® using PhosghoSorb® media cartridges: • General Use Level Designation (GULD) for Basic Treatment (total suspended solids) and for Phosphorus (total phosphorus) treatment. o Sized at a hydraulic loading rate of no greater than 1.67 gallon per minute (gpm) per square foot (sq ft.) of media surface, per Table 1. o Using Contech's PhosghoSorb media. Specifications for the media shall match the specifications provided by the manufacturer and approved by Ecology. Table 1. StormFilter cartridge design flow rates for 18-inch diameter cartridges with PhosphoSorb media operating at 1.67 gpm/sq ft. Effective cartridge height (in) Cartridge flow rate (gpm/cartridge) 12 8.35 18 12.53 27 18.79 C1y ILI Wales Que redeveloped Wald Quality Run On -Line BMP Off -Line 8MP Analysis 24 hour Volume (ac-ft) Standard Flow Rate (cis) 0.0259 Standard Row Rate (cis) 0.0165 CB#7&8 inflow 10.23 gpm Stream Protection Duration LID Duration I Flow Frequency Water Quality Hydrograph Wetland Input Volumes I UDRepod I Recharge Duration Recharge Predeveloped I Recharge Mitigated Analyze dalasels Compact WDM Delete Selected r Monthly FF 1003 Gravel Trench Bad 3 STAGE M� n rr r 1005 Gravel Trench Bed 1 OUTLET 1 Mitigated 1006 Gravel Trench Bed 1 OUTLET 2 Mitigated 1007 Gravel Trench Bed 1 STAGE Mitigated 1008 Gravel Trench Bed 2ALL OUTLETS Mitigated 1009 Gravel Trench Bed 2 OUTLET 1 Mitigated ,thod 1010 Gravel Trench Bed 2 OUTLET 2 Mitigated v pe III 170 All Datasets Flow I Stage Precip EVaD POC 1 Flood Frequency Method (: Log Pearson Type III 178 Weibull Cunnane f Gringorten J I —oil , Deselect Zero Select By:F— GO £3 Water Quality Run On -Line BMP Off -Line BMP Analysis 24 hour Volume (ac-ft) 0.0D59 Standard Flow Rate (cis) 0.0101 Standard Flow Rate (cis) D.OI%6 10 1 ICB #6A inflow 4.53 ed I Stream Protection Duration I LID Duration I Flow Frequency Water Quality Hydrograph Wetland Input Volumes LID Report Recharge Duration Recharge Predeveloped Recharge Mitigated Analyze datasets Compact WDM Delete Selected r Monthly FF 1003 Gravel Trench Bed 3 STAGE Mitigated n 1004 Gravel Trench Bed 1 ALL OUTLETS Mitigated 1005 Gravel Trench Bed 1 OUTLET 1 Mitigated 1006 Gravel Trench Bed 1 OUTLET 2 Mitigated 1007 Gravel Trench Bed 1 STAGE MiI ated t a 1009 Gravel Trench Bed 2 OUTLET 1 Mitigated 1010 Gravel Trench Bed 2 OUTLET 2 Mitigated All Datasets Flow Stage Precip Evap POC 1 Flood Frequency Method r: Log Pearson Type III 17B W eibull Cunnane Gringorten RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Cfl C=::NTECH® ENGINEERED SOLUTIONS CatchBasin StormFilter'" Important: These guidelines should be used as a part of your site stormwater plan. Overview The CatchBasin Storm Filter— (CBSF) consists of a multi -chamber steel, concrete, or plastic catch basin unit that can contain up to four Storm Filter cartridges. The steel CBSF is offered both as a standard and as a deep unit. The CBSF is installed flush with the finished grade and is applicable for both constrained lot and retrofit applications. It can also be fitted with an inlet pipe for roof leaders or similar applications. The CBSF unit treats peak water quality design flows up to 0.13 cfs, coupled with an internal weir overflow capacity of 1.0 cfs for the standard unit, and 1.8 cfs for the deep steel and concrete units. Plastic units have an internal weir overflow capacity of 0.5 cfs. Design Operation The CBSF is installed as the primary receiver of runoff, similar to a standard, grated catch basin. The steel and concrete CBSF units have an H-20 rated, traffic bearing lid that allows the filter to be installed in parking lots, and for all practical purposes, takes up no land area. Plastic units can be used in landscaped areas and for other non -traffic -bearing applications. The CBSF consists of a sumped inlet chamber and a cartridge chamber(s). Runoff enters the lumped inlet chamber either by sheet flow from a paved surface or from an inlet pipe discharging directly to the unit vault. The inlet chamber is equipped with an internal baffle, which traps debris and floating oil and grease, and an overflow weir. While in the inlet chamber, heavier solids are allowed to settle into the deep sump, while lighter solids and soluble pollutants are directed under the baffle and into the cartridge chamber through a port between the baffle and the overflow weir. OPERATION AND MAINTENISMitt Once in the cartridge chamber, polluted water ponds and percolates horizontally through the media in the filter cartridges. Treated water collects in the cartridge's center tube from where it is directed by an under -drain manifold to the outlet pipe on the downstream side of the overflow weir and discharged. When flows into the CBSF exceed the water quality design value, excess water spills over the overflow weir, bypassing the cartridge bay, and discharges to the outlet pipe. Applications The CBSF is particularly useful where small flows are being treated or for sites that are flat and have little available hydraulic head to spare. The unit is ideal for applications in which standard catch basins are to be used. Both water quality and catchment issues can be resolved with the use of the CBSF. Retro-Fit The retrofit market has many possible applications for the CBSF. The CBSF can be installed by replacing an existing catch basin without having to "chase the grade," thus reducing the high cost of re piping the storm system. URBANUEENTM Stormwater Solutions from Contech® Qc, Page 1 www.ContechES.com/sformwafer 800-338-1 122 © 2013 Contech Engineered SolutMs C=::NTECH® ENGINEERED SOLUTIONS CatchBasin StormFilter'" Maintenance Guidelines Maintenance procedures for typical catch basins can be applied to the CatchBasin StormFilter (CBSF). The filter cartridges contained in the CBSF are easily removed and replaced during maintenance activities according to the following guidelines. 1. Establish a safe working area as per typical catch basin service activity. 2. Remove steel grate and diamond plate cover (weight 100 lbs. each). 3. Turn cartridge(s) counter -clockwise to disconnect from pipe manifold. 4. Remove 4" center cap from cartridge and replace with lifting cap. 5. Remove cartridge(s) from catch basin by hand or with vactor truck boom. 6. Remove accumulated sediment via vactor truck (min. clearance 13" x 24" ). 7. Remove accumulated sediment from cartridge bay. (min. clearance 9.25" x 11 "). 8. Rinse interior of both bays and vactor remaining water and sediment. 9. Install fresh cartridge(s) threading clockwise to pipe manifold. 10. Replace cover and grate. 1 1. Return original cartridges to Contech for cleaning Media may be removed from the filter cartridges using the vactor truck before the cartridges are removed from the catch basin structure. Empty cartridges can be easily removed from the catch basin structure by hand. Empty cartridges should be reassembled and returned to Contech as appropriate. Materials required include a lifting cap, vactor truck and fresh filter cartridges. Contact Contech for specifications and availability of the lifting cap. The vactor truck must be equipped with a hose capable of reaching areas of restricted clearance. the owner may refresh spent cartridges. Refreshed cartridges are also available from Contech on an exchange basis. Contact the maintenance department of Contech at 503-258-3157 for more information. Maintenance is estimated at 26 minutes of site time. For units with more than one cartridge, add approximately 5 minutes for each additional cartridge. Add travel time as required. OPERATION AND MAINTENAMitt Mosquito Abatement In certain areas of the United States, mosquito abatement is desirable to reduce the incidence of vectors. In BMPs with standing water, which could provide mosquito breeding habitat, certain abatement measures can be taken. 1. Periodic observation of the standing water to determine if the facility is harboring mosquito larvae. 2. Regular catch basin maintenance. 3. Use of larvicides containing Bacillus thuringiensis israelensis (BTI). BTI is a bacterium toxic to mosquito and black fly larvae. In some cases, the presence of petroleum hydrocarbons may interrupt the mosquito growth cycle. Using Larvicides in the CatchBasin StormFilter Larvicides should be used according to manufacturer's recommendations. Two widely available products are Mosquito Dunks and Summit B.t.i. Briquets. For more information, visit http://www. summitchemical.com/mos—ctrl/d efault.htm. The larvicide must be in contact with the permanent pool. The larvicide should also be fastened to the CatchBasin StormFilter by string or wire to prevent displacement by high flows. A magnet can be used with a steel catch basin. For more information on mosquito abatement in stormwater BMPs, refer to the following: http://www.ucmrp.ucdavis.edu/ publications/ma nag ingmosquitoesstormwater8125.pdf s P/ .� i URBANUEENTM Stormwater Solutions from Contech®c. Page 2 www.ContechES.com/sformwafer 800-338-1 122 © 2013 Contech Engineered SolutiNs Appendix E Operations and Maintenance RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT 51 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Table V-4.5.2(1) Maintenance Standards - Detention Ponds (continued) Maintenance Conditions When Results Expected When Component Defect Maintenance Is Maintenance Is Per - Needed formed potential for erosion to continue. (Recommend a Goeth- echnical engineer be called in to inspect and evaluate condition and recommend repair of condition. Only one layer of rock exists above native soil in area five square feet or larger, or any expos - Emergency Over- Emergency Over- ure of native soil at the Rocks and pad depth are flow/Spillway flow/Spillway top of outflow path of restored to design stand - spillway. ards. (Rip -rap on inside slopes need not be replaced.) Erosion See "Side Slopes of Pond" Table V-4.5.2(2) Maintenance Standards - Infiltration Results Expec Maintenance Conditions When Maintenance Is ted When Component Defect Needed Maintenance Is Performed Trash & Debris See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1). Poisonous/Noxious "Detention See "Detention Vegetation See Ponds" (No. 1). Ponds" (No. 1). General Contaminants and See "Detention Ponds" (No. 1). See "Detention Pollution Ponds" (No. 1). Rodent Holes See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1) Water ponding in infiltration pond Sediment is Storage Area Sediment after rainfall ceases and appropriate removed 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 833 52 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Table V-4.5.2(2) Maintenance Standards - Infiltration (continued) Results Expec Maintenance Defect Conditions When Maintenance Is ted When Component Needed Maintenance Is Performed time allowed for infiltration. Treat- ment basins should infiltrate Water Quality Design Storm Volume within and/or facility is 48 hours, and empty within 24 hours cleaned so that after cessation of most rain events. infiltration sys- (A percolation test pit or test of facility tem works indicates facility is only working at according to 90% of its designed capabilities. Testdesign. every 2 to 5 years. If two inches or more sediment is present, remove). Filter bag is Filter Bags (if Filled with Sed- Sediment and debris fill bag more replaced or sys applicable) iment and Debris than 1/2 full. tem is redesigned. Sediment and By visual inspection, little or no water Gravel in rock Rock Filters flows through filter during heavy rain filter is Debris storms. replaced. Side Slopes Erosion See "Detention Ponds" (No. 1). See "Detention of Pond Ponds" (No. 1). E Emergency See "Detention Overflow Tree Growth See "Detention Ponds" (No. 1). Ponds" (No. 1). Spillway and Berms over 4 Piping See "Detention Ponds" (No. 1). See "Detention feet in height. Ponds" (No. 1). Emergency Rock Missing See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1). Overflow Spillway Erosion See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1). Pre -settling Facility or sump 6" or designed sediment trap depth Sediment is Ponds and filled with Sediment of sediment. removed. Vaults and/or debris 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 834 53 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Table V-4.5.2(5) Maintenance Standards - Catch Basins Results Maintenance Conditions When Maintenance is Expected Defect When Main- Component Needed tenance is performed No Trash or debris loc- Trash or debris which is located imme- ated imme- diately in front of the catch basin opening or diately in is blocking inletting capacity of the basin by front of catch more than 10%. basin or on Trash or debris (in the basin) that exceeds grate open- 60 percent of the sump depth as measured ing. from the bottom of basin to invert of the low- No trash or est pipe into or out of the basin, but in no debris in the Trash & case less than a minimum of six inches catch basin. Debris clearance from the debris surface to the invert of the lowest pipe. Inlet and out- let pipes free Trash or debris in any inlet or outlet pipe of trash or blocking more than 1/3 of its height. debris. General Dead animals or vegetation that could gen- No dead erate odors that could cause complaints or animals or dangerous gases (e.g., methane). vegetation present within the catch basin. Sediment (in the basin) that exceeds 60 per- cent of the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case No sediment Sediment less than a minimum of 6 inches clearance in the catch from the sediment surface to the invert of the basin lowest pipe. Structure Top slab has holes larger than 2 square Top slab is Damage to inches or cracks wider than 1/4 inch. (Intent free of holes Frame and/or is to make sure no material is running into and cracks. Top Slab basin). Frame is sit- 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 838 54 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Table V-4.5.2(5) Maintenance Standards - Catch Basins (continued) Results Maintenance Conditions When Maintenance is Expected Component Defect Needed When Main- tenance is performed Frame not sitting flush on top slab, i.e., sep- ting flush on aration of more than 3/4 inch of the frame the riser rings from the top slab. Frame not securely or top slab attached and firmly attached. Basin Maintenance person judges that structure is replaced or unsound. repaired to Fractures or design stand - Cracks in Grout fillet has separated or cracked wider ards. Basin Walls/ longer than 1 foot at the than 1/2 inch and Ion g Bottom joint of any inlet/outlet pipe or any evidence Pipe is of soil particles entering catch basin through regrouted cracks. and secure at basin wall. Basin Settlement/ If failure of basin has created a safety, func- replaced or Misalignment tion, or design problem. repaired to design stand- ards. No veget- Vegetation growing across and blocking ation block - more than 10% of the basin opening. ing opening to basin. Vegetation Vegetation growing in inlet/outlet pipe joints No that is more than six inches tall and less veget- than six inches apart. ation or root growth present. Contamination See "Detention Ponds" (No. 1). No pollution and Pollution present. Cover Not in Cover is missing or only partially in place. Catch basin Catch Basin Place Any open catch basin requires main- cover is tenance. closed Cover Locking Mech- Mechanism cannot be opened by one main- Mechanism anism Not tenance person with proper tools. Bolts into opens with 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 839 55 RESUB Mar 02 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT Table V-4.5.2(5) Maintenance Standards - Catch Basins (continued) Results Maintenance Conditions When Maintenance is Expected Component Defect Needed When Main- tenance is performed Working frame have less than 1 /2 inch of thread. proper tools. One maintenance person cannot remove lid Cover can be Cover Difficult after applying normal lifting pressure. removed by to Remove (Intent is keep cover from sealing off access one main - tenance per - to maintenance.) son. Ladder meets design stand Ladder Rungs Ladder is unsafe due to missing rungs, not ards and Ladder Unsafe securely attached to basin wall, mis- allows main - alignment, rust, cracks, or sharp edges. tenance per- son safe access. Grate open - Grate opening Grate with opening wider than 7/8 inch. ing meets Unsafe design stand- ards. Metal Grates Trash and Trash and debris that is blocking more than Grate free of (If Applic- Debris 20% of grate surface inletting capacity. trash and able) debris. Grate is in Damaged or Grate missing or broken member(s) of the place and Missing. grate. meets design standards. Table V-4.5.2(6) Maintenance Standards - Debris Barriers (e.g., Trash Racks) Maintenance Condition When Maintenance is Results Expected Com- Defect When Maintenance is ponents Needed Performed Trash and Trash or debris that is plugging Barrier cleared to design General Debris more than 20% of the openings in flow capacity. the barrier. Damaged/ Bars are bent out of shape more Bars in place with no Metal Missing than 3 inches. bends more than 3/4 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 840 56