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bld20110174_Trolson_ENG1.pdf City of EdmondsBLD20110174 TH 121 5AVENUE NORTHEDMONDS, WA 98020 • (425) 771-0220 FAX(425) 771-0221 Website: www.ci.edmonds.wa.us PUBLIC WORK DEPARTMENT Planning • Building • Engineering Engineering Plan Review Comments PermitApplication:Date: #BLD20110174March 23, 2011 Project Name/Address: Trolson –1161 ‘A’ Ave Contact Person/Address, Fax or E-mail: KevinCrandell –kevin.crandell@comcast.net Reviewer: JENNIFERLAMBERTDivision: ENGINEERING During review of the subject submittal, it was found that the following information, corrections, or clarifications would need to be addressed. All Handouts referred to in these comments can be accessed at our website: www.ci.edmonds.wa.usunder City Government / Development Services Department / Engineering Division then scroll down to Handouts: 1)Please show the impervious surface calculations as shownbelow: TypeArea (square Feet) Line Exempt 1. ExemptNon-Exempt Replaced 2. New 3. Total Replaced +New (Non- 4.Exempt) = (add numbers in blue boxes) 2)Please show the year of construction, for all impervious surface areas, on the Site Plan as shown in the Sample Site Plan provided. 3)Please fill out the stormwater worksheet provided in handout #E72 (attached)and submit with plans. 4)Please show the driveway and any other impervious surface areas on the plans. 5)Please note if the lines shown on the plans are the roof lines or foundation lines. If the roof lines are not shown please show them on the Site Plan. 6)Please clearly distinguish between existing areas and the proposed areas. DATE E-MAILED3/23/2011PAGE(1) City of EdmondsBLD20110174 TH 121 5AVENUE NORTHEDMONDS, WA 98020 • (425) 771-0220 FAX(425) 771-0221 Website: www.ci.edmonds.wa.us PUBLIC WORK DEPARTMENT Planning • Building • Engineering Engineering Plan Review Comments 7)Please label the deck as impervious or pervious (i.eslotted wood deck). 8)Please label and dimension the landing area. 9)Please show the location of the side sewer from the sewer main to the house(see attached). 10)Please show the easement along the east property line (easement attached). 11)Please show the location of the water service line from the meter to the house. 12)Please show all trees within the construction area and label to be removed or remain. a.If trees are to remain and near the construction area, please show a barrier fence around the tree to protect during construction. Please resubmit 3 copies of the siteplansand associated documents with a written response to each item to a Permit Coordinator. Please contact me at 425-771-0220ext 1321or by e-mail at jennifer.lambert@ci.edmonds.wa.usif you have specific questions regarding these plan corrections. DATE E-MAILED3/23/2011PAGE(1) #E72 City of Edmonds Development Information STORMWATER MANAGEMENT (SWM) DRAINAGE SYSTEM DESIGN, AND EROSION & SEDIMENT CONTROL REQUIREMENTS Stormwaterrunofffromdevelopment,redevelopment,andconstructionsitesisregulated underEdmondsCommunityDevelopmentCode(ECDC)Chapter18.30,includingExhibitA: %£¬®­£²3³®±¬¶ ³¤±3´¯¯«¤¬¤­³Ȩ3´¯¯«¤¬¤­³ȩȁ Overall Stormwater Management Approach This handout contains an overall summary of the requirements and options available to assist an applicant in designing, constructing, and maintaining stormwater Best Management Practices (BMPs) in the City of Edmonds to meet the intent of ECDC 18.30. The Stormwater Supplement booklet is available for use in our Development Services Department as well as on the City’s Website (www.ci.edmonds.wa.us). Please refer to the Supplement for a more detailed explanation of each requirement. Applicants are encouraged to use the Classification Worksheet on page 5 of this handout to determine the requirements for their project. Step 1 – Determine Applicability Step 4 – Plan Site and Select BMPs The first step is to determine if the Stormwater Use site planning along with BMP selection and Management code applies to your project. Use design process described in the Supplement to Figure-A, pg 3, in this handout to establish whether meet or exceed the minimum requirements for your your project or site meets any of the criteria listed project. under “applicability”. Step 5 – Submit Reports and Plans for Review Step 2 – Determine Your Project Site’s Submit all required reports and plans for review. Classification and Drainage Basin The handout for the appropriate classification of Use the Classification Worksheet, pg 5, to gather your project (Large, Small or Minor) will provide the information necessary to determine whether information regarding the submittal requirements. your project is considered a Large, Small, or Minor The stormwater submittals will be reviewed Site Project. For Small Site Projects, you will concurrently with all other permit submittals. further determine whether it is a Category 1 or a Revision to reports and plans may be required per Category 2 project. See Figure-D, pg 8. City of Edmonds review. Identify the drainage basin for your site using the Step 6 – Construction City of Edmonds Watershed Map, Figure-B, pg 4. Erosion & Sediment Control Measures must be Step 3 – Determine the Minimum inspected and approved by the City’s Engineering Division prior to the start of construction. The Requirements Needed and Where on the Site project shall be constructed per approved plans. They Apply Any changes proposed to the approved plans must The minimum requirements are based on the be submitted to the Engineering Division for project classification determined in Step 2. A review and approval prior to construction. summary of the Minimum Requirements can be found on Pg 2 of this handout. For specific site Step 7 – Operate and Maintain BMPs requirements per classification see handout E72a Operate and maintain BMPs as required by the for Large Sites, E72b for Small Sites, or E72c approved submittals. for Minor Sites . 1 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page Overview of Stormwater Management Minimum Requirements Depending on the type, location, and size of the proposed project, different combinations of these minimum requirements apply. The following is a brief list of the overall Minimum Requirements for Large, Small, and Minor sites. Please refer to The Stormwater Supplement and the appropriate Large, Small, or Minor site Handout for additional information. LARGE SITES – See Handout E72a A project or overall development involving 1 acre or more of land disturbing activity would potentially require the following Minimum Requirements: 1. Preparation of Stormwater Site Plan 2. Construction Stormwater Pollution Prevention Plan 3. Source Control of Pollution 4. Preservation of Natural Drainage Systems and Outfalls 5. Onsite Stormwater Management 6. Runoff Treatment 7. Flow Control 8. Wetland Protection 9. Operation and Maintenance 10. Offsite Analysis and Mitigation SMALL SITES – See Handout E72b A project that involves 2,000 square feet (sf) or more of new or replaced non-exempt impervious surface, 7,000 sf of land-disturbing activity, 50 cubic yards (cyds) or more of grading, fill or excavation, conversion of ¾ acre or more of native vegetation to lawn or landscaped area, or causes an increase of 0.1 cubic feet per second (cf/s) or more in the 100 year flow frequency from a threshold discharge area would potentially require the following Small Site Minimum Requirements (SSMRs): 1. & 2. Site Plan including an Erosion and Sediment Control Plan 3. Source Control of Pollutants (for Multi-family or Commercial Projects) 4. Preservation of Natural Drainage Systems and Outfalls 5. Onsite Stormwater Management 6. Runoff Treatment 7. Flow Control 8. Wetland Protection 9. Operation and Maintenance 10. Off-Site Analysis 11. Financial Liability MINOR SITES – See Handout E72c A project that involves 500 sf or more of new development or redevelopment including land- disturbing activity or a utility project that causes land disturbance, and is not considered Large or Small Site Projects must employ Minor Site Construction Stormwater Pollution Prevention Practices. Additional Requirements may be imposed to meet the intent of the Stormwater Code based on site specific factors. Note: Terms in Bold are defined in Handout on page 9. 2 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page Figure-A Determining Applicability of Stormwater Management Code ECDC Chapter 18.30 If any of the descriptions in the Blue Boxes apply to your project or project site, the Stormwater Management Code applies. Does your Project Site require the issuance of a City permit Yes under any of the following: ECDC Title 18 - Engineering Division ECDC Title 19 - Building Division 2 A Stormwater Permit No Yes Are you submitting a Subdivision application per ECDC Chapter 20.75? No Stormwater Does your Project site involve any of the following: Management requirements of ECDC 500 square feet or more of land-disturbing Yes are Chapter 18.30 activity,new impervious surface, or replaced applicable to your impervious surface? Project or Site. A utility or other construction projects consisting of 500 lineal feet or more of trench excavation? Is located in, adjacent to, or drains into (currently or as a result of the project) a Critical Area or a Critical Area Buffer? No Stormwater Management requirements of ECDC Chapter not 18.30 are applicable to your 1 Project or Site 1 This chart provides an initial screening for determining applicability of ECDC Chapter 18.30. The results from using this chart do not substitute for a determination of applicability by the Public Works Director or Designee per ECDC Chapter 18.30.030 and the relevant portions of the Supplement. 2 If ECDC Chapter 18.30 is applicable to the proposed project and it does not require any other City-issued permit, a Stormwater Permit and associated fees will be required. NOTE: Terms in bold italics are defined in ECDC Chapter 18.30.010 or the Supplement. 3 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page Figure-B 1 City of Edmonds Watersheds Note: A larger version of the Edmonds Watershed Map is available in the Development Services Office and on the City of Edmonds website at ci.edmonds.wa.us. 4 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page City of Edmonds Site ClassificationWorksheet The project’s Classification serves to identify the specific Stormwater Management requirements applicable to your site. Complete the worksheet below to determine whether your project falls into the classification of Large SiteSmall SiteMinor Site a, (Category 1 or Category 2), or a . Step 1Exempt Impervious Surface Area : Determine the for your project and enter it on line 1 of the table (yellow box). Step 2Replaced Impervious Surface Area : Determine the for your project and enter it on line 2 of the table below dividing the total between Exempt and Non-Exempt (orange and blue boxes); either or both may be zero. Step 3New Impervious Surface Area : Determine the for your project. If a portion of the new impervious surface area is also Non-Exempt Replaced Impervious Surface Area subtract this from the total of the new impervious surface area. Enter the final value on line 3 of the table below (blue box). Step 4 : Add the values in the Non-exempt column for lines 2 and 3 and enter it into line 4 (green box). Where does the existing site Direct Discharge runoff discharge? Supplement Edmonds Way Basin ( Check all that apply) Chapter 2.3 See Watershed Map Creek or Lake Basin Figure-B, Handout pg 4 TypeArea(square Feet) Line Impervious surface: Exempt Supplement 1. How much and what type? Chapter 2.2 ExemptNon-Exempt (fill in colored boxes) & See Definitions, Handout pg 9 Replaced Figure-C 2. Figure-C, Handout pg 7 Examples, Handout pg 10 New 3. Total Replaced +New (Non-Exempt) = 4. (add numbers in blue boxes) Land-disturbing activity area Supplement sf Chapter 8 See Definitions, Handout pg 9 Grading, Fill or Excavation sf Area Will project convert ¾ acre or more of native vegetation to YESNO lawn or landscaped area? Project Classification Chart Proceed to the (Figure D, pg 8) and use the data collected above to follow the flow chart and determine the classification of your project. Large Site (Handout E72a)Small Site (Handout E72b)Minor Site (Handout E72c) “ 5 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page This page intentionally left blank. 6 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page Figure-C What Qualifies as New Impervious Surface? START Does the site have existing Only the impervious surfaces that Is this existing impervious after were created July 6, impervious surface Yes surfaces 1 1977? currently connected proposed with to a City-approved No stormwater the project are 3 facility located on considered Yes the project site? New Impervious 2 Surface. No Was a waiver granted stormwater for a Yes facility for this existing impervious area? No Is the site zoned as single Yes family residential (Zone RS)? No No Existing impervious surface Creek Is the site within a or since created July 6, 1977 Yes 4 Lake drainage basin? plus proposed impervious surface is considered New Impervious Surface. 1 mitigation This is the effective date of the City’s first drainage control ordinance. The intent of this cumulative impacts requirement is to adequately mitigate for impervious surfaces on project sites that are submitted under separate permits. The separate submittals could have project areas that do not meet thresholds but would meet thresholds if the projects are combined as one project. For parcels that were annexed to the City after this date, the date of annexation shall substitute for the effective date of the City’s first drainage control ordinance. For annexed parcels, a functioning Snohomish County-approved stormwater management facility can substitute for a City-approved facility. 2 For the purpose of this flowchart, it is assumed that all existing impervious surface will remain after the proposed project is complete. If any existing impervious surface will be demolished for this project, the project may contain a combination of new and replaced impervious surface. See Definitions, pg 9. 3 If there is an existing stormwater management system on site, contact the City’s Engineering Division to discuss whether the existing system has the capacity for the new impervious surface area. 4 See Figure B, pg 4, and Supplement Section 2.3. 7 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page Figure-D Project Classification If you have determined that your project meets the requirements for a Stormwater Review using Figure 1, follow the Blue boxes in chart below to determine the Classification of your project. Yes Does the project involve 1- land- acre or more of Large Site Project : 1 disturbing activity ? See Handout E72a for No specific requirements . Yes Is the project part of a larger common plan of development or sale where the total disturbed area Does the project create or add 5,000 square feet of for the entire plan will total 1-acre new impervious surface, replaced non-exempt land-disturbing activity or more of ? impervious surfacereplaced non- or new plus exemptimpervious surface ? No OR native vegetation Convert ¾ acre or more of to Does the Project involve one or more of the lawn or landscaped area Yes following: OR new impervious 2,000 square feet or more of effective Through a combination of creating surfacereplaced non-exempt impervious , impervious surface converted pervious and surfacereplaced non-exempt or new plus surfaces , causes an increase of 0.1 cubic feet per impervious surface ? second in the 100-year flow frequency from a OR threshold discharge area as estimated using an land-disturbing activity 7,000 square feet of ? approved model? OR grading, fill, 50 cubic yards or more of either excavation or as defined in Chapter No Yes No Category 1 Small Site Project:Category 2 Small Site Project: See Handout E72b for specific See Handout E72b for specific Minor Site Project : requirements requirements See Handout E72c for specific requirements 1 Land-disturbing Activity: Any activity that results in movement of earth, or a change in the existing soil cover (both vegetative and non-vegetative) or the existing soil topography. Land disturbing activities include, but are not limited to grading, filling, excavation, and compaction associated with stabilization of structures and road construction. NOTES: Additional terms in bold italics are defined on pg 9 or can be found in ECDC Chapter 18.30.010 or the Supplement Classification chart assumes the project in question meets applicability requirements of ECDC18.30.030. 8 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page DEFINITIONS Impervious Surface: Hard surface area that either prevents or retards the entry of water into the ground as it would occur in natural, undeveloped conditions. Impervious surfaces include, but are not limited to, rooftops, driveways, walkways, concrete, asphalt, and packed earthen materials. Decks will be considered impervious if one or more of the following apply: Deck is made of “solid” material that does not allow rain water to run through it Deck has “slots” where rainwater can run through but the ground under the deck does not allow the rainwater to infiltrate into the ground. is divided For the purpose of determining stormwater control requirements, impervious surface into four categories: “exempt”, “replaced exempt”, “replaced non-exempt”, and “new”. See definitions below: Exempt Impervious Surface: All impervious surface area installed prior to July 7, 1977 or prior to the date the parcel was annexed into the City from Snohomish County.. Replaced Impervious Surface : Any impervious surface on the project site that exists at the time of application that is proposed to be removed* and re-established in the same footprint. This does not include impervious surface removed for the sole purpose of installing utilities or performing maintenance. Replaced impervious surface is further categorized as Exempt or Non-Exempt. th Exempt: impervious surface on site originally installed prior to July 7, 1977 or prior to the date the parcel was annexed by the City from Snohomish County. Non-Exempt:impervious surface on site originally installed on or after July 7, 1977 or on or after the date the parcel was annexed into the City from Snohomish County. *Removed, for the purposes of this definition, refers to the removal of building down to bare soil, or the removal of concrete (PCC) or asphalt (AC) slabs, driveways, sidewalks etc. down to bare soil or base course. New Impervious Surface: Any impervious surface on the project site created on or after July 7, 1077 or on or after the date the parcel was annexed into the City from Snohomish County that is not considered Replaced Impervious Surface. Land-disturbing Activity: Any activity that results in movement of earth, a change in the existing soil cover (both vegetative and non-vegetative), or in the existing soil topography. Land-disturbing activities include but are not limited to clearing, grading, filling, excavation, and compaction of soils associated with structure stabilization and road construction. Pervious Surface: Any surface that allows the entry of water into the ground as it would occur in nature. Note: This information should not be used as a substitute for City codes and regulations. The Edmonds Community Development Code (ECDC) may be viewed at www.ci.edmonds.wa.us/codes.stm. The applicant is responsible for ensuring compliance with the fees and regulations that are applicable at the time of submittal. If you have a specific question about a certain aspect of your project, please contact the Engineering Division at 121 Fifth Avenue North, (425) 771-0220. Please note that other local, state, and/or federal permits or approvals may be required. 9 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page EXAMPLES ExemptReplaced ExemptReplaced Non- The following are examples of how to determine the “,” “”, “ ExemptNew ” and “” impervious surface totals for a specific project. If you have any questions, please contact an Engineering Technician. Example 1: 1972 House 1200 square feet (sf) roofline Driveway (paved) 60 sf 1999 House Addition 400 sf 2004 Detached Garage 600 sf with no stormwater system installed Proposal: Garage Addition 140 sf roofline The 1972 House and Driveway were constructed before to July 7,1977 so are considered “Exempt” impervious area. The 1999 Addition and 2004 Detached garage and current proposal are considered “New” impervious surface since built after July 7, 1977. Total New + Non-Exempt Impervious Surface: 1,140 sf (400sf + 600sf + 140sf) + 0 = 1,140 sf Example 2 : 1968 House 1,500 sf roofline Gravel Driveway 400 sf Sidewalks/Patios 55 sf Proposal: Pave Driveway with asphalt, same footprint as gravel driveway (400 sf). Paving the gravel driveway counts as “Replaced Exempt” impervious surface. The driveway is a combination of gravel and packed earthen material, this meets the definition of impervious surface. The proposed paving will be in same footprint of the original driveway installed before July 7, 1977. Total New + Non-Exempt Impervious Surface: 0 sf Example 3a : 1976 House 2,000 sf Concrete Driveway 200 sf 1999 Garage w/concrete slab (no stormwater system) 300 sf Proposal: New garage (300 sf) – demolish existing garage and slab, new garage will be same size and in same location of the concrete slab and original garage to be replaced. Proposed garage will be considered “Replaced Non-Exempt” because the existing impervious surface (garage & slab) to be replaced was built afterJuly 7, 1977. Total New + Non-Exempt Impervious: 0 + 300 sf = 300 sf Example 3b : Same as above except concrete slab is not removed during garage demolition. If slab remains and new garage has same roofline then no impervious surface is added or replaced. Total New + Non-Exempt Impervious Surface: 0 sf 10 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page Example 4: 1979 House 1,200 sf Gravel driveway 300 sf Patio/Walkways 100 sf 1989 Garage 250 sf Proposal: Garage addition 200 sf and replacing gravel driveway with asphalt (300 sf) House, patio/walkways, garage built afterJuly 7, 1977 with no storm system and therefore are considered “New” impervious surface: 1,750 sf (1,200+100+250 +200) Driveway was installed after July 7, 1977 so even though changing from gravel to asphalt in same footprint it is considered “Replaced Non-Exempt” impervious surface: 300 sf Total New + Non-Exempt Impervious: 1,750 sf + 300 sf = 2,050 sf Example 5: 1989 House 2,800 sf Driveway/patio/walkways 700 sf The 1989 construction was approved with a detention system sized for 3500 sf of impervious surface that was adequate under the provisions of the stormwater code effective at that time. Proposal: 300 sf addition to house Revised “New” impervious total 3,800 sf (zero replaced impervious). The house, patio and walkways were installed after July 7, 1977 with a storm system. The existing system does not meet the sizing requirements of today’s stormwater code for 3500 sf of impervious surface. In this case, there are two options available to meet the stormwater flow control requirements. Option 1 Install a separate stormwater system that is sized only for the new addition 300sf. Since the existing system was approved at the time of construction for requirements of the code in effect at that time, resizing is not required. Option 2 Upgrade the existing system to meet to handle both the existing impervious surface of (3500 sf) and the proposed impervious surface (300 sf). The existing system would need to be sized for 3800 sf under the sizing requirements of the current code. In this case: 1989 Code requirements for 3500sf of impervious surface (existing system); 49 lineal ft of 18” diameter pipe with ¾” orifice. Current Code requirements for 3800sf of impervious surface: 81 lineal ft of 18” diameter pipe with ¾” orifice. Therefore applicant would need to add 32 lineal feet of 18”diameter pipe to existing detention system. 11 of 11 Revised on 7/9/10 E72 - Stormwater Management Erosion Control-FINAL2 Page