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APPROVED STM RESUB 3-BLD2023-1484+Storm_Drainage_Report+5.24.2024_2.10.52_PM+4282083BLD2023-1484 RESUB May 24 2024 Drainage Report Maplewood Lot C for Landsverk Quality Homes, Inc. 24113 56th Ave W Mountlake Terrace, WA 98020 SITE LOCATION: 8811 194TH St SW Edmonds, WA 98020 Tax Parcel: 2704180031400 M. ar Prepared by: Ralph Rapanut, EIT Checked by: Joseph M. Smeby, P.E. Job No: 23-0416 October 2023 Revised: May 2024 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT COMPLIES WITH APPLICABLE CITY STORMWATER CODE .., 1 05/30/2024 1 TABLE OF CONTENTS TABLE OF CONTENTS.......................................................................................................1 LISTOF FIGURES...............................................................................................................2 1. INTRODUCTION & SITE CLASSIFICATION...............................................................3 2. MR#1: PREPARATION OFSTORMWATER SITE PLANS...........................................4 3. MR#2: CONSTRUCTION STORMWATER POLUTION PREVENTION .......................4 A. SITE GRADING/EROSION CONTROL RISK ASSESSMENT.....................................5 B. SWPPP MINIMUM ELEMENTS...................................................................................5 5. MR#4: PRESERVATION OF NATURAL DRAINAGE SYSTEM...................................8 6. MR#5: ON -SITE STORMWATER MANAGEMENT......................................................9 7. OPERATION AND MAINTENANCE MANUAL.......................................................10 8. SUMMARY..................................................................................................................10 APPENDIX......................................................................................................A Maplewood Lot C 23-0416 May 2024 Page 1 LIST OF FIGURES ITEM PAGE FIGURE 1 VICINITY MAP......................................................................................... 10 FIGURE 2 EXISTING DRAINAGE BASIN MAP ....................................................... 11 FIGURE 3 DEVELOPED DRAINAGE BASIN MAP .................................................. 12 Maplewood Lot C 23-0416 May 2024 Page 2 INTRODUCTION & SITE CLASSIFICATION This document is intended to provide engineering information necessary to support the building permit application submittal to the City of Edmonds for the new SFR and driveway proposed on this site. The site currently is undeveloped and consists of forest and pasture. The project parcel is 0.28 acres. Access to the site will be from 194th St SW to the south. The total area of disturbance including both clearing and grading does not exceed 3/4 acres and the new total impervious surfaces do not exceed 5,000 sf. Therefore, this project is classified as a category 1 project and only minimum requirements 1-5 will apply. This determination was made using figure 3.1 of the Edmonds Stormwater Addendum. The proposed project will create 4,224 sf of new plus replaced hard surfaces. All of the new and replaced hard surfaces will be mitigated using on -site stormwater management BMPs including splash blocks, a dispersion trench, permeable pavement, and amended soils. All on -site drainage improvements have been designed to meet or exceed the 2019 DOE Stormwater Management Manual as well as the 2022 Edmonds Stormwater Addendum. The site is located at 8811 194t" St SW, Edmonds, WA 98202, and in Section 18, Township 27 N, Range 4 E, Willamette Meridian. See Figure 1 - Vicinity Map. Maplewood Lot C 23-0416 May 2024 Page 3 Figure 1-3.1: Flow Chart for Determining Requirements for New Development Start Here Does the Site have 35% or more of existing hard surface coverage? No Does the Project result in 5,000 square feet, or greater, of new plus replaced hard surface area? Yes All Minimum Requirements apply to the new and replaced hard surfaces and converted vegetation areas. DEPARTMENT OF ECOLOGY State of Washington Yes See Redevelopment Project Thresholds and the Figure Flow Chart for Determining Requirements for Redevelopment". Does the Project convert 3/a acres or more of vegetation to _ lawn or landscaped areas, or NO convert 2.5 acres or more of native vegetation to pasture? Yes Minimum Requirements #1 through #5 apply to the new and replaced hard surfaces and the land disturbed. Does the Project result in 2,000 square feet, or greater, of new plus replaced hard surface area? Yes Y I No Does the Project have land disturbing activities of 7,000 square feet or greater? No Minimum Requirement #2 applies. Flow Chart for Determining Requirements for New Development Revised March 2019 Please see http://www.ecy.wa.go✓%opyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 1- Chapter 3 - Page 89 2. MR#1: PREPARATION OF STORMWATER SITE PLANS As noted in Section 1 of this report this project is only subject to minimum requirements 1- 5. Therefore, this drainage design has been prepared to address the requirements contained in the 2019 DOE manual, 2022 Edmonds Stormwater Addendum and applicable handouts. The engineering plan set submitted to the City for review along with this report contains the required information. This document is intended to provide the supporting information to justify the sizing of the BMPs and detail how the design of the selected BMPs meet the required standards. The runoff from the proposed SFR roof surfaces will be dispersed via a dispersion trench and splash blocks over vegetated surfaces. The proposed driveway, walkway, and uncovered patio will be infiltrated via permeable pavement. 3. MR#2: CONSTRUCTION STORMWATER POLUTION PREVENTION Clearing, grading, and temporary erosion and sediment control plans have been prepared as part of the drainage plan drawings. However, since a construction site is dynamic it will be necessary to reassess the erosion control BMP's during construction and install additional measures when necessary. Proposed temporary measures possible for this project will include the following BMP's: • Installation of stabilized construction entrance. • Retention of Existing Vegetation • Straw mulch, hydroseed or other mulching and planting method to stabilized unworked areas. • Silt fencing Permanent measures to reduce or eliminate erosion or water quality degradation will include the following BMP's: • Permanent landscaping in pervious areas. • Limiting cut and fill slopes to 2:1 maximum and 3:1 maximum where exposed to standing water. • Routine maintenance and inspection of the grounds and response to developing problems. The listed erosion control BMP's will be engineered for anticipated conditions in compliance with DOE guidelines. With proper installation, maintenance and inspection the proposed BMP's should result in minimal impact to the surrounding environment. The City retains the authority by code to require additional measures should the existing measures prove insufficient. Maplewood Lot C 23-0416 May 2024 Page 4 A. SITE GRADING/EROSION CONTROL RISK ASSESSMENT Area proposed to be cleared/worked: 0.20 acres Average slope for the site: 8% Erosion Hazard of Soil Low Critical Areas downslope No Site is upstream of an ESA Stream No Based on the above information and the fact that the slope of the site is steep and construction site runoff will filter through the soil, and that if site conditions warrant, additional BMP's can be implemented as corrective measures the Risk Category for this site is Low Risk. B. SWPPP MINIMUM ELEMENTS 1: Mark Clearing Limits The first step in the "Construction Sequence" included on the clearing and grading plan sheets is for the limits of clearing to be flagged and to have construction fencing placed along the limits prior to any other construction activity. 2: Establish Construction Access The SWPPP shows a new construction entrance to be installed east of the proposed pervious pavement area. Care must be taken to protect those areas from disturbance during construction. 3: Control Flow Rates Straw wattles (BMP C235) will be used along the western property line uphill from the silt fence to capture surface flow and impound the water in small areas to aid in flow attenuation during construction. The layout of the straw wattles is in an arc shape with the concave side pointing uphill. By having multiple arcs along the western property line the construction site flows will not be concentrated into one location and any runoff that seeps or overflows from these systems will be spread out along the length of the site improvements. Per the DOE SWMMWW Vol. II, straw wattles are a recommended BMP to provide flow control and as shown on the plans, they are beneficial for small sites due to their compact foot print. 4: Install Sediment Controls This site and SWPPP proposes to construct/maintain a construction entrance (BMP C105) and silt fencing (BMP C233). These features are intended to minimize the opportunity for sediment to leave the site via stormwater or on vehicles. The construction of these features is one of the first items required in the "Construction Sequence". Mulch (BMP C121), hog fuel or straw wattles (BMP C235) shall also be used on the exposed soils as necessary to limit erosion. 5: Stabilize Soils The "Construction Sequence" calls for the stabilization of soils that remain unworked for certain lengths of time based on the time of year. Stabilization techniques may include but Maplewood Lot C 23-0416 May 2024 Page 5 not limited to mulching (C121), plastic sheeting or hydroseeding, notes have been added to the plan regarding protection for the stock pile area if necessary. A stockpile area has been identified on the SWPPP and is setback a minimum of 20-feet from any down slope property line. 6: Protect Slopes All disturbed slopes on site during construction are required to be protected with mulch (BMP C121) or other means as specified in the construction sequence. No concentrated runoff or significant amounts of sheet flow will be directed to new cut or fill slopes during construction. 7: Protect Drain Inlets All new drain inlets shall be protected using inlet protection (BMP C220) such as filter socks/temporary sediment traps during construction. 8: Stabilize Channels and Outlets No new channels or outlets are proposed for this site. 9: Control Pollutants No outside chemicals are expected to be necessary for the construction of this project. All vehicles working on and around the site would need to meet the State requirements for emissions. Vehicle fueling locations will be used to limit the potential impacts from any spills. 10: Control Dewatering Dewatering will not be necessary for this project. However, the detention system will be in place during construction to collect any dewatering runoff. 11: Maintain BMPs The construction supervisor will be responsible for maintaining all BMPs during construction and working with the City to relocate or add BMPs as necessary as site conditions change. 12: Manage the Project It will be the responsibility of the Contractor and Developer to manage this project and coordinate with the City Inspector and Engineer. Inspection and Monitoring: Site inspections shall be done by a person who is knowledgeable in the principles and practices of erosion and sediment control. The person must have skills to first assess the site conditions and construction activities that could impact the quality of stormwater, and second assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. Whenever inspection and/or monitoring reveals that the BMPs identified in the Construction SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP: The construction SWPPP shall be retained on -site or within reasonable access to the site. Maplewood Lot C 23-0416 May 2024 Page 6 The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven days following inspection. 13: Protect Low Impact Development BMPs The use of infiltration BMPs will allow for the construction of the permeable pavers and level spreader or splash blocks at the end of the project to protect those areas from compaction. The areas for the future permeable pavement driveway, drywell and level spreader and dispersion areas will be protected with construction fencing to protect those areas from compaction/disturbance. Maplewood Lot C 23-0416 May 2024 Page 7 4. MR#3: SOURCE CONTROL OF POLLUTION The Edmonds Stormwater Addendum and DOE Drainage manual were reviewed to determine if the proposed land -use for this project or construction activities required any site -specific source control BMPs to be constructed. SFR projects are not listed as a proposed use that requires source control. Therefore, no site/development specific source control BMPs are required for this project. 5. MR#4: PRESERVATION OF NATURAL DRAINAGE SYSTEM The runoff from the project site in the existing condition drains in a western direction. All runoff from the existing site sheet flows west over the adjacent properties before being collected in the City conveyance system within 194th St SW or 89th PI W. Both conveyance systems consist of CBs connected by 12" concrete pipes which combine at the intersection of the two roads. All of the new PGIS surface runoff, excluding the area within the City R/W, will be collected and infiltrated via permeable pavers. Roof runoff will be directed to level spreader trench or one of two splash blocks for flow dispersion prior to runoff leaving the site over the western property line. The PGIS surface runoff in the R/W will be dispersed via sheet flow on the west side of the driveway. As noted above the conveyance systems within the City R/W combine at the intersection of 194th St SW and 891h PI W and then discharges into an open channel to the west via a 12" concrete pipe. Based on City mapping this channel is located within 194th St SW unopened R/W. The channel flows to the west and connects with Fruitdale Creek approximately 200' west of the 12" outfall. The location of the 12" outfall west of 194th St SW could not be located in the field. This area contains a very steep slope and is covered with a thick mat of leaves and debris. Though the slope was traversed the pipe outfall or any indication of the drainage course between the outfall and Fruitdale Creek was not found. The downstream was stopped at Fruitdale Creek which is considered the downstream receiving waterbody for this project. The creek in this area is at the bottom of a deep ravine, but with a broad area of flow and a shallow channel. During the site visit, no erosion or capacity issues were noted throughout the downstream system. The adjacent property to the east 8811 19411 St SW drains toward the project site. However, no grading or proposed improvements will prevent any off -site flows from flowing onto and through the site as in the existing conditions. Maplewood Lot C 23-0416 May 2024 Page 8 6. MR#5: ON -SITE STORMWATER MANAGEMENT Per the 2019 DOE manual, and the Edmonds Addendum Appendix A the following BMPs were considered, and the highest priority BMP found feasible was selected. Lawn and Landscaped Areas: 1) Post -construction soil quality and depth: Required and selected. Sheet 3 of the plan set provides both the location of the soil that shall be amended, as well as notes to inform the contractor how to amend the soil. Roofs: 1) Full Dispersion: Full dispersion was found to be infeasible due to not having the required flow path. There is also not enough native vegetation on -site to meet the requirements of full dispersion. 2) Downspout Full Infiltration Systems: Full infiltration was found to be infeasible, as the geotechnical report states that "widespread infiltration of runoff is not feasible based on the soil and anticipated groundwater conditions". 3) Bioretention or Rain Gardens: Similar to downspout full infiltration, the soil and site conditions make bioretention and rain gardens infeasible. 4) Downspout Dispersion Systems: The minimum vegetated flow paths can be achieved on this lot. Approximately 3,100 sf of roof area is proposed for this project. Dispersion of the roof surfaces will be done via a combination of splash blocks and a dispersion trench. Two (2) splash blocks are proposed and no more than 700 feet of roof area may be directed to it. The splash block will have a vegetated flow path of 50 feet before it leaves the site. The remaining 1,700 sf of roof area will be directed to a dispersion trench. Roof areas larger than 700 sf, a dispersion trench with notched grade board must not exceed 50 ft and must provide at least 10 feet of trench length per 700 sf of roof area. For this project, a level spreader trench of 25 ft was chosen. Maplewood Lot C 23-0416 May 2024 Page 9 Other Hard Surfaces: 1. Permeable Pavement: Feasible and selected for this project. The geotechnical engineer provided a design infiltration rate of 0.162 inches per hour for the site. Even at a very conservative infiltration rate of 0.1 inches per hour, permeable pavers with a 4-inch thick top course layer (porosity = 0.25) and 6-inch thick storage course layer (porosity = 0.35) are shown to infiltrate 100 percent of accumulated runoff up to the 100 year storm. See Appendix A for "permeable pavement" WWHM printout. 7. OPERATION AND MAINTENANCE MANUAL The Property Owner will be responsible for maintaining the stormwater and landscaping facilities within this development. Specific problems can be recorded along with the appropriate action taken. Routine inspections and maintenance will improve the long-term performance of the stormwater facilities. If at any time you are unsure if a problem exists or how to address a specific problem, contact a Professional Engineer. 8. SUMMARY As documented in this report the proposed improvements for this project trigger minimum requirements 1-5 to be addressed for stormwater mitigation. Stormwater management techniques have been incorporated into the design to mitigate the proposed site changes. Therefore, the stormwater design for this project has met or exceeded all the applicable minimum requirements. Maplewood Lot C 23-0416 May 2024 Page 10 Figure 1-3.1: Flow Chart for Determining Requirements for New Development Start Here Does the Site have 35% or more of existing hard surface coverage? No Does the Project result in 5,000 square feet, or greater, of new plus replaced hard surface area? Yes All Minimum Requirements apply to the new and replaced hard surfaces and converted vegetation areas. DEPARTMENT OF ECOLOGY State of Washington Yes See Redevelopment Project Thresholds and the Figure Flow Chart for Determining Requirements for Redevelopment". Does the Project convert 3/a acres or more of vegetation to _ lawn or landscaped areas, or NO convert 2.5 acres or more of native vegetation to pasture? Yes Minimum Requirements #1 through #5 apply to the new and replaced hard surfaces and the land disturbed. Does the Project result in 2,000 square feet, or greater, of new plus replaced hard surface area? Yes Y I No Does the Project have land disturbing activities of 7,000 square feet or greater? No Minimum Requirement #2 applies. Flow Chart for Determining Requirements for New Development Revised March 2019 Please see http://www.ecy.wa.go✓%opyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 1- Chapter 3 - Page 89 2. MR#1: PREPARATION OF STORMWATER SITE PLANS As noted in Section 1 of this report this project is only subject to minimum requirements 1- 5. Therefore, this drainage design has been prepared to address the requirements contained in the 2019 DOE manual, 2022 Edmonds Stormwater Addendum and applicable handouts. The engineering plan set submitted to the City for review along with this report contains the required information. This document is intended to provide the supporting information to justify the sizing of the BMPs and detail how the design of the selected BMPs meet the required standards. The runoff from the proposed SFR roof surfaces will be dispersed via a dispersion trench and splash blocks over vegetated surfaces. The proposed driveway, walkway, and uncovered patio will be infiltrated via permeable pavement. 3. MR#2: CONSTRUCTION STORMWATER POLUTION PREVENTION Clearing, grading, and temporary erosion and sediment control plans have been prepared as part of the drainage plan drawings. However, since a construction site is dynamic it will be necessary to reassess the erosion control BMP's during construction and install additional measures when necessary. Proposed temporary measures possible for this project will include the following BMP's: • Installation of stabilized construction entrance (existing driveway to be used as construction entrance, to be modified as needed). • Retention of Existing Vegetation • Straw mulch, hydroseed or other mulching and planting method to stabilized unworked areas. • Silt fencing Permanent measures to reduce or eliminate erosion or water quality degradation will include the following BMP's: • Permanent landscaping in pervious areas. • Limiting cut and fill slopes to 2:1 maximum and 3:1 maximum where exposed to standing water. • Routine maintenance and inspection of the grounds and response to developing problems. The listed erosion control BMP's will be engineered for anticipated conditions in compliance with DOE guidelines. With proper installation, maintenance and inspection the proposed BMP's should result in minimal impact to the surrounding environment. The City retains the authority by code to require additional measures should the existing measures prove insufficient. Maplewood Lot C 23-0416 March 2024 Page 4 A. SITE GRADING/EROSION CONTROL RISK ASSESSMENT Area proposed to be cleared/worked: 0.20 acres Average slope for the site: 8% Erosion Hazard of Soil Low Critical Areas downslope No Site is upstream of an ESA Stream No Based on the above information and the fact that the slope of the site is steep and construction site runoff will filter through the soil, and that if site conditions warrant, additional BMP's can be implemented as corrective measures the Risk Category for this site is Low Risk. B. SWPPP MINIMUM ELEMENTS 1: Mark Clearing Limits The first step in the "Construction Sequence" included on the clearing and grading plan sheets is for the limits of clearing to be flagged and to have construction fencing placed along the limits prior to any other construction activity. 2: Establish Construction Access The SWPPP shows a new construction entrance to be installed east of the proposed pervious pavement area. Care must be taken to protect those areas from disturbance during construction. 3: Control Flow Rates Straw wattles (BMP C235) will be used along the western property line uphill from the silt fence to capture surface flow and impound the water in small areas to aid in flow attenuation during construction. The layout of the straw wattles is in an arc shape with the concave side pointing uphill. By having multiple arcs along the western property line the construction site flows will not be concentrated into one location and any runoff that seeps or overflows from these systems will be spread out along the length of the site improvements. Per the DOE SWMMWW Vol. II, straw wattles are a recommended BMP to provide flow control and as shown on the plans, they are beneficial for small sites due to their compact foot print. 4: Install Sediment Controls This site and SWPPP proposes to construct/maintain a construction entrance (BMP C105) and silt fencing (BMP C233). These features are intended to minimize the opportunity for sediment to leave the site via stormwater or on vehicles. The construction of these features is one of the first items required in the "Construction Sequence". Mulch (BMP C121), hog fuel or straw wattles (BMP C235) shall also be used on the exposed soils as necessary to limit erosion. 5: Stabilize Soils The "Construction Sequence" calls for the stabilization of soils that remain unworked for certain lengths of time based on the time of year. Stabilization techniques may include but Maplewood Lot C 23-0416 March 2024 Page 5 not limited to mulching (C121), plastic sheeting or hydroseeding, notes have been added to the plan regarding protection for the stock pile area if necessary. A stockpile area has been identified on the SWPPP and is setback a minimum of 20-feet from any down slope property line. 6: Protect Slopes All disturbed slopes on site during construction are required to be protected with mulch (BMP C121) or other means as specified in the construction sequence. No concentrated runoff or significant amounts of sheet flow will be directed to new cut or fill slopes during construction. 7: Protect Drain Inlets All new drain inlets shall be protected using inlet protection (BMP C220) such as filter socks/temporary sediment traps during construction. 8: Stabilize Channels and Outlets No new channels or outlets are proposed for this site. 9: Control Pollutants No outside chemicals are expected to be necessary for the construction of this project. All vehicles working on and around the site would need to meet the State requirements for emissions. Vehicle fueling locations will be used to limit the potential impacts from any spills. 10: Control Dewatering Dewatering will not be necessary for this project. However, the detention system will be in place during construction to collect any dewatering runoff. 11: Maintain BMPs The construction supervisor will be responsible for maintaining all BMPs during construction and working with the City to relocate or add BMPs as necessary as site conditions change. 12: Manage the Project It will be the responsibility of the Contractor and Developer to manage this project and coordinate with the City Inspector and Engineer. Inspection and Monitoring: Site inspections shall be done by a person who is knowledgeable in the principles and practices of erosion and sediment control. The person must have skills to first assess the site conditions and construction activities that could impact the quality of stormwater, and second assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. Whenever inspection and/or monitoring reveals that the BMPs identified in the Construction SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP: The construction SWPPP shall be retained on -site or within reasonable access to the site. Maplewood Lot C 23-0416 March 2024 Page 6 The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven days following inspection. 13: Protect Low Impact Development BMPs The use of infiltration BMPs will allow for the construction of the permeable pavers and level spreader or splash blocks at the end of the project to protect those areas from compaction. The areas for the future permeable pavement driveway, drywell and level spreader and dispersion areas will be protected with construction fencing to protect those areas from compaction/disturbance. Maplewood Lot C 23-0416 March 2024 Page 7 4. MR#3: SOURCE CONTROL OF POLLUTION The Edmonds Stormwater Addendum and DOE Drainage manual were reviewed to determine if the proposed land -use for this project or construction activities required any site -specific source control BMPs to be constructed. SFR projects are not listed as a proposed use that requires source control. Therefore, no site/development specific source control BMPs are required for this project. 5. MR#4: PRESERVATION OF NATURAL DRAINAGE SYSTEM The runoff from the project site in the existing condition drains in a western direction. All runoff from the existing site sheet flows west over the adjacent properties before being collected in the City conveyance system within 194th St SW or 89th PI W. Both conveyance systems consist of CBs connected by 12" concrete pipes which combine at the intersection of the two roads. All of the new PGIS surface runoff, excluding the area within the City R/W, will be collected and infiltrated via permeable pavers. Roof runoff will be directed to level spreader trench or one of two splash blocks for flow dispersion prior to runoff leaving the site over the western property line. The PGIS surface runoff in the R/W will be dispersed via sheet flow on the west side of the driveway. As noted above the conveyance systems within the City R/W combine at the intersection of 194th St SW and 891h PI W and then discharges into an open channel to the west via a 12" concrete pipe. Based on City mapping this channel is located within 194th St SW unopened R/W. The channel flows to the west and connects with Fruitdale Creek approximately 200' west of the 12" outfall. The location of the 12" outfall west of 194th St SW could not be located in the field. This area contains a very steep slope and is covered with a thick mat of leaves and debris. Though the slope was traversed the pipe outfall or any indication of the drainage course between the outfall and Fruitdale Creek was not found. The downstream was stopped at Fruitdale Creek which is considered the downstream receiving waterbody for this project. The creek in this area is at the bottom of a deep ravine, but with a broad area of flow and a shallow channel. During the site visit, no erosion or capacity issues were noted throughout the downstream system. The adjacent property to the east 8811 19411 St SW drains toward the project site. However, no grading or proposed improvements will prevent any off -site flows from flowing onto and through the site as in the existing conditions. Maplewood Lot C 23-0416 March 2024 Page 8 6. MR#5: ON -SITE STORMWATER MANAGEMENT Per the 2019 DOE manual, and the Edmonds Addendum Appendix A the following BMPs were considered, and the highest priority BMP found feasible was selected. Lawn and Landscaped Areas: 1) Post -construction soil quality and depth: Required and selected. Sheet 3 of the plan set provides both the location of the soil that shall be amended, as well as notes to inform the contractor how to amend the soil. Roofs: 1) Full Dispersion: Full dispersion was found to be infeasible due to not having the required flow path. There is also not enough native vegetation on -site to meet the requirements of full dispersion. 2) Downspout Full Infiltration Systems: Full infiltration was found to be infeasible, as the geotechnical report states that "widespread infiltration of runoff is not feasible based on the soil and anticipated groundwater conditions". 3) Bioretention or Rain Gardens: Similar to downspout full infiltration, the soil and site conditions make bioretention and rain gardens infeasible. 4) Downspout Dispersion Systems: The minimum vegetated flow paths can be achieved on this lot. Approximately 3,100 sf of roof area is proposed for this project. Dispersion of the roof surfaces will be done via a combination of splash blocks and a dispersion trench. Two (2) splash blocks are proposed and no more than 700 feet of roof area may be directed to it. The splash block will have a vegetated flow path of 50 feet before it leaves the site. The remaining 1,700 sf of roof area will be directed to a dispersion trench. Roof areas larger than 700 sf, a dispersion trench with notched grade board must not exceed 50 ft and must provide at least 10 feet of trench length per 700 sf of roof area. For this project, a level spreader trench of 25 ft was chosen. Maplewood Lot C 23-0416 March 2024 Page 9 Other Hard Surfaces: 1. Permeable Pavement: Feasible and selected for this project. The geotechnical engineer provided a design infiltration rate of 0.162 inches per hour for the site. Even at a very conservative infiltration rate of 0.1 inches per hour, permeable pavers with a 4-inch thick top course layer (porosity = 0.25) and 6-inch thick storage course layer (porosity = 0.35) are shown to infiltrate 100 percent of accumulated runoff up to the 100 year storm. See Appendix A for "permeable pavement" WWHM printout. 7. OPERATION AND MAINTENANCE MANUAL The Property Owner will be responsible for maintaining the stormwater and landscaping facilities within this development. Specific problems can be recorded along with the appropriate action taken. Routine inspections and maintenance will improve the long-term performance of the stormwater facilities. If at any time you are unsure if a problem exists or how to address a specific problem, contact a Professional Engineer. 8. SUMMARY As documented in this report the proposed improvements for this project trigger minimum requirements 1-5 to be addressed for stormwater mitigation. Stormwater management techniques have been incorporated into the design to mitigate the proposed site changes. Therefore, the stormwater design for this project has met or exceeded all the applicable minimum requirements. Maplewood Lot C 23-0416 March 2024 Page 10 0 Z N SI TE 2iH VICINITY MAP SCALE 1 " = 2000' FIG. 1 OMEOA VICINITY MAP ENGINEERING, INC. MAPLEWOOD LOT C 2707 WETMORE AVE. DATE JOB NO. SCALE SHEET Everett, WA 98201 (o)425.387.3820 (f) 425.259.1958 10/26/23 23-0415 1 " = 2000' 1 OF 1 I 1 \I N \ - I DRIVEWAY / / I I l / I ,GARAGE l I 90'0 x` N 0'00'00' W x 97. 5' 3 6 6 l 79.23' I- 2 M � � FIG. 2 I Flow (� g�(� RO`I.'CB RIM=371.86 P �V / / / I O N fl INV. 6'PVC(S)=370.01 -6I m l Wa 00 i olm PARCEL B w (� w 15,56 SF v o PARCEL C1ZO94 SF lJ \I / HED HE® .l L\ I W o sHE j/793 4 / CB W I / \ 29( I ® INV. 61 PVC(N)=365.82 / CONC ETE \ / \ 1 ( \ _ \ INV. 8 PVC(E)=365.02 _I 9i\.25' I\ \ 77.01' I 1 INV. 4 PVC(E)=365.39 N 190'00'o W -k90' 0'00" W INV. 8 IP(S)=364.72 \00 6 I Lo 194 TH T SW FOUND NAIL AT INTERSECTION OF 88TH W ® \ \ �� ® AVE W & 194TH ST SW �\ `ASRHALi \ � GRAVEL DRIVEWAY �® DRIVEWAY RAVEL I SSMH RIM=367.56 INV. 8"CONC(N)=358.71 \ \ \ \ \ INV. 8"CONC(E)=358.71 SSMH\RIM= 362.74 INV. 8"CONC(S)=358.61 CNTR CHNIy 349.99 I m \ \ \ \ \ GRAVEL ¢ U 1 CB RIM=363.77 \ I INV. 8'1P N=361.87 \ I INV. 8"CONC(S)=361.87 CB RIM\ 363.69 \ NOT MEASURED CB RIM=363.69 \I NOT MEASURED OMEGA EXISTING BASIN MAP ENGINEERING, INC. MAPLEWOOD LOT C 2707 WETMORE AVE. DATE JOB NO. SCALE SHEEne T Everett, WA 98201 (o)425.387.3820 (f) 425.259.1958 10/26/23 23-0415 1 = 40' 1 OF 1 ASPHALT DRIVEWAY DROP. FOUND REBA// W/0 CAP /J, ZARAGE 0.1'(W) 0F CORNER \ 366 I I - 2 . c II II II / CB RIM=371.86 J Jo N II I� INV. 6"PVC(S)=370.01 L7 00 15 6LSF �I v t PARCEL C �� / o 12,094 SF II SHED HEM i EP w Eq E ,OWER HGUSk #193V4 ---_- - r - -- d \ \ O1 APPROX. EX. WAT t�° POLE/ (TBF/) w /) �, °/t \ EH CB RIM= Q 5 CONCRETE I '< :`:.'�, n l INV. 6"PVC ( I INV. 8"PVC INV. 4"PVC INV. 8"IP(S 'W W \ o � W I — — � I — q — — FOUND NAIL AT \ © S AVE W & 194TF \ I GRAVEL \ 6 I ® DRIVEWAY \`�6 RAVEL I MIT RIM=: "CONC \ S) OF FOUN REBAR W/0 CAP E 0.8 (W) OF CORNER �� 36 S(\ I . 8 8"CONC \\ SSM�IM= 362.74 " ONC INV. 8"OONC(W) \ cl \ CNTR CHN&=349.99 \ m \ \ \ GRAVEL I 1 \ \ FIG. 3 OMEGA DEVELOPED BASIN MAP ENGINEERING, INC. MAPLEWOOD LOT C 2707 WETMORE AVE. DATE JOB NO. SCALE SHEEne T Everett, WA 98201 (o)425.387.3820 (f) 425.259.1958 10/26/23 23-0415 1 = 30' 1 OF 1 Appendix Maplewood Lot C 23-0416 May 2024 Page 11 COBALT G E 0 S C I E N C E S April 3, 2024 Landsverk Quality Homes Attn: Duane Landsverk & Joseph Rowett 24113 56th Avenue West Mountlake Terrace, Washington RE: Plan Review Proposed Development Maplewood Lot A, B, and C 8811, 8817, and 8823 194th Street SW Edmonds, Washington Cobalt Geosciences, LLC P.O. Box 1792 North Bend, WA 98045 In accordance with your authorization, Cobalt Geosciences, LLC has prepared this letter to discuss our plan review of the three building lots at or near the referenced address. Permeable driveways and walkways/patios are proposed at each lot as shown in the provided plans by Omega Engineering, Inc (March 2024). These systems are anticipated to be within 2 feet of the ground surface, which will be in the weathered glacial till deposits. We recommend stripping topsoils and vegetation and removal of any undocumented fill from these areas, exposing stable, weathered glacial till. Areas must be protected from compaction or siltation. We should be on site to verify relvent aspects of site development, including soil bearing verification, foundation drainage placement, permeable pavement subgrade verification, excavations, and fill compaction. Sincerely, Cobalt Geosciences, LLC QP�WONY OF WA �� 54896 <4� FSS�ONAL�-�� 4/3/2024 Phil Haberman, PE, LG, LEG Principal viash il 2513 www.cobaltgeo.com (2o6) 331-1097 WWHM20 PROJECT FLOW CONTROL EXEMPTION CALCULATIONS General Model Information WWHM2012 Project Name: basin Site Name: MAPLEWOOD LOT C Site Address: 8811 194th St SW City: EDMONDS Report Date: 4/17/2024 MGS Region: Puget East Data Start: 1901 /10/1 Data End: 2058/09/30 Timestep: Hourly DOT Data Number03 Version Date: 2023/01 /27 Version: 4.2.19 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year basin 4/17/2024 8:12:16 AM Page 2 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Mod 0.147 C, Lawn, Mod 0.07 Pervious Total 0.217 Impervious Land Use acre ROOF TOPS FLAT 0.016 DRIVEWAYS FLAT 0.007 Impervious Total 0.023 Basin Total 0.24 basin 4/17/2024 8:12:17 AM Page 3 Mitigated Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Mod 0.1575 Pervious Total 0.1575 Impervious Land Use acre ROOF TOPS FLAT 0.0365 Impervious Total 0.0365 Basin Total 0.194 basin 4/17/2024 8:12:17 AM Page 4 Routing Elements Predeveloped Routing basin 4/17/2024 8:12:17 AM Page 5 Mitigated Routing basin 4/17/2024 8:12:17 AM Page 6 Analysis Results POC 1 0.03 )U 0.02 0.02 0 J iL 0.01 0.01 10E-0 10E-3 10E-2 10E-1 1 10 lCiii Percerit Time Exceeding + Predeveloped Predeveloped Landuse Totals for POC #1 Total Pervious Area- 0.217 Total Impervious Area- 0.023 Mitigated Landuse Totals for POC #1 Total Pervious Area- 0.1575 Total Impervious Area- 0.0365 "1 05 7 2 x Mitigated Flow Frequency Method- Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.010056 5 year 0.015262 10 year 0.019421 25 year 0.025565 50 year 0.030838 100 year 0.036753 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.015336 5 year 0.023374 10 year 0.029953 25 year 0.039877 50 year 0.048563 100 year 0.058464 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1902 0.010 0.012 1903 0.008 0.014 1904 0.018 0.029 1905 0.006 0.010 1906 0.006 0.010 1907 0.014 0.020 1908 0.009 0.014 1909 0.011 0.015 1910 0.016 0.022 1911 0.010 0.014 Cumulative Probability - - - - %- " 5 70 20 30 50 70 W 90 95 95 99 99.5 7 basin 4/17/2024 8:12:17 AM Page 7 1912 0.035 0.050 1913 0.009 0.011 1914 0.027 0.052 1915 0.006 0.009 1916 0.009 0.014 1917 0.005 0.009 1918 0.008 0.011 1919 0.005 0.008 1920 0.009 0.014 1921 0.008 0.011 1922 0.011 0.016 1923 0.011 0.016 1924 0.008 0.012 1925 0.005 0.008 1926 0.008 0.012 1927 0.008 0.012 1928 0.009 0.013 1929 0.015 0.024 1930 0.011 0.020 1931 0.008 0.011 1932 0.009 0.013 1933 0.009 0.013 1934 0.020 0.029 1935 0.007 0.010 1936 0.008 0.014 1937 0.015 0.023 1938 0.008 0.012 1939 0.007 0.012 1940 0.012 0.022 1941 0.009 0.013 1942 0.013 0.021 1943 0.011 0.020 1944 0.021 0.035 1945 0.010 0.018 1946 0.010 0.015 1947 0.006 0.010 1948 0.015 0.019 1949 0.014 0.021 1950 0.007 0.010 1951 0.008 0.010 1952 0.032 0.047 1953 0.028 0.041 1954 0.010 0.014 1955 0.008 0.012 1956 0.005 0.008 1957 0.008 0.012 1958 0.020 0.026 1959 0.015 0.022 1960 0.008 0.011 1961 0.026 0.049 1962 0.009 0.014 1963 0.005 0.008 1964 0.024 0.042 1965 0.015 0.021 1966 0.007 0.011 1967 0.011 0.018 1968 0.008 0.012 1969 0.010 0.015 basin 4/17/2024 8:12:39 AM Page 8 1970 0.014 0.021 1971 0.016 0.022 1972 0.041 0.076 1973 0.015 0.020 1974 0.012 0.021 1975 0.025 0.037 1976 0.016 0.026 1977 0.005 0.008 1978 0.017 0.024 1979 0.009 0.017 1980 0.011 0.018 1981 0.009 0.016 1982 0.007 0.012 1983 0.012 0.021 1984 0.010 0.018 1985 0.012 0.021 1986 0.008 0.011 1987 0.015 0.021 1988 0.008 0.011 1989 0.007 0.010 1990 0.009 0.013 1991 0.010 0.018 1992 0.014 0.021 1993 0.009 0.015 1994 0.013 0.018 1995 0.005 0.008 1996 0.016 0.019 1997 0.008 0.012 1998 0.011 0.018 1999 0.007 0.011 2000 0.011 0.019 2001 0.007 0.010 2002 0.023 0.035 2003 0.009 0.013 2004 0.011 0.018 2005 0.019 0.030 2006 0.008 0.011 2007 0.011 0.020 2008 0.008 0.012 2009 0.008 0.012 2010 0.009 0.015 2011 0.006 0.009 2012 0.012 0.019 2013 0.008 0.014 2014 0.007 0.010 2015 0.028 0.046 2016 0.005 0.009 2017 0.014 0.023 2018 0.022 0.028 2019 0.027 0.037 2020 0.016 0.024 2021 0.014 0.021 2022 0.013 0.023 2023 0.010 0.017 2024 0.041 0.060 2025 0.007 0.009 2026 0.012 0.017 2027 0.010 0.017 basin 4/17/2024 8:12:39 AM Page 9 2028 0.004 0.006 2029 0.010 0.014 2030 0.017 0.023 2031 0.005 0.007 2032 0.006 0.009 2033 0.004 0.007 2034 0.007 0.011 2035 0.017 0.023 2036 0.011 0.015 2037 0.007 0.011 2038 0.015 0.021 2039 0.011 0.017 2040 0.007 0.013 2041 0.009 0.015 2042 0.020 0.025 2043 0.012 0.018 2044 0.012 0.016 2045 0.010 0.014 2046 0.010 0.013 2047 0.007 0.011 2048 0.007 0.010 2049 0.011 0.017 2050 0.009 0.013 2051 0.017 0.029 2052 0.006 0.010 2053 0.008 0.011 2054 0.024 0.038 2055 0.007 0.012 2056 0.008 0.013 2057 0.006 0.010 2058 0.007 0.013 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0410 0.0765 2 0.0409 0.0603 3 0.0346 0.0516 4 0.0318 0.0499 5 0.0283 0.0495 6 0.0282 0.0466 7 0.0273 0.0456 8 0.0270 0.0423 9 0.0264 0.0415 10 0.0254 0.0377 11 0.0238 0.0373 12 0.0237 0.0366 13 0.0226 0.0349 14 0.0220 0.0347 15 0.0215 0.0304 16 0.0204 0.0292 17 0.0203 0.0288 18 0.0197 0.0287 19 0.0186 0.0277 20 0.0184 0.0264 21 0.0174 0.0262 22 0.0173 0.0255 23 0.0172 0.0241 basin 4/17/2024 8:12:39 AM Page 10 24 0.0167 0.0241 25 0.0160 0.0235 26 0.0159 0.0234 27 0.0159 0.0230 28 0.0156 0.0229 29 0.0155 0.0227 30 0.0155 0.0226 31 0.0152 0.0223 32 0.0150 0.0218 33 0.0148 0.0217 34 0.0148 0.0216 35 0.0147 0.0215 36 0.0146 0.0214 37 0.0146 0.0213 38 0.0144 0.0212 39 0.0142 0.0210 40 0.0141 0.0210 41 0.0141 0.0209 42 0.0139 0.0209 43 0.0138 0.0207 44 0.0133 0.0207 45 0.0129 0.0206 46 0.0128 0.0202 47 0.0124 0.0200 48 0.0122 0.0198 49 0.0122 0.0197 50 0.0120 0.0196 51 0.0120 0.0191 52 0.0118 0.0190 53 0.0118 0.0189 54 0.0116 0.0188 55 0.0115 0.0184 56 0.0115 0.0183 57 0.0113 0.0183 58 0.0112 0.0182 59 0.0112 0.0182 60 0.0112 0.0182 61 0.0112 0.0181 62 0.0111 0.0181 63 0.0111 0.0176 64 0.0111 0.0174 65 0.0110 0.0173 66 0.0108 0.0171 67 0.0107 0.0170 68 0.0105 0.0169 69 0.0104 0.0168 70 0.0102 0.0164 71 0.0101 0.0162 72 0.0101 0.0162 73 0.0100 0.0159 74 0.0100 0.0155 75 0.0099 0.0154 76 0.0098 0.0154 77 0.0098 0.0151 78 0.0097 0.0150 79 0.0096 0.0148 80 0.0096 0.0147 81 0.0096 0.0145 basin 4/17/2024 8:12:39 AM Page 11 82 0.0095 0.0144 83 0.0094 0.0144 84 0.0094 0.0143 85 0.0093 0.0142 86 0.0091 0.0142 87 0.0091 0.0140 88 0.0091 0.0139 89 0.0091 0.0139 90 0.0091 0.0138 91 0.0090 0.0138 92 0.0089 0.0134 93 0.0088 0.0134 94 0.0087 0.0133 95 0.0087 0.0133 96 0.0086 0.0132 97 0.0086 0.0131 98 0.0085 0.0130 99 0.0085 0.0130 100 0.0084 0.0129 101 0.0084 0.0129 102 0.0084 0.0125 103 0.0084 0.0125 104 0.0082 0.0125 105 0.0082 0.0124 106 0.0082 0.0124 107 0.0082 0.0123 108 0.0081 0.0123 109 0.0081 0.0122 110 0.0081 0.0121 111 0.0080 0.0120 112 0.0080 0.0120 113 0.0080 0.0120 114 0.0079 0.0118 115 0.0078 0.0116 116 0.0078 0.0115 117 0.0076 0.0115 118 0.0076 0.0114 119 0.0076 0.0113 120 0.0076 0.0113 121 0.0075 0.0113 122 0.0075 0.0113 123 0.0074 0.0111 124 0.0074 0.0111 125 0.0072 0.0111 126 0.0071 0.0109 127 0.0070 0.0108 128 0.0069 0.0108 129 0.0069 0.0107 130 0.0069 0.0106 131 0.0068 0.0104 132 0.0068 0.0104 133 0.0067 0.0103 134 0.0067 0.0102 135 0.0067 0.0102 136 0.0066 0.0100 137 0.0066 0.0099 138 0.0065 0.0099 139 0.0063 0.0098 basin 4/17/2024 8:12:39 AM Page 12 140 0.0063 0.0098 141 0.0062 0.0097 142 0.0061 0.0096 143 0.0059 0.0094 144 0.0058 0.0094 145 0.0058 0.0093 146 0.0057 0.0092 147 0.0054 0.0086 148 0.0054 0.0085 149 0.0053 0.0084 150 0.0053 0.0084 151 0.0053 0.0083 152 0.0051 0.0081 153 0.0050 0.0080 154 0.0049 0.0080 155 0.0049 0.0069 156 0.0044 0.0068 157 0.0039 0.0059 basin 4/17/2024 8:12:39 AM Page 13 Duration Flows The Duration Matching Failed Flow(cfs) Predev Mit Percentage Pass/Fail 0.0050 3560 7329 205 Fail 0.0053 3092 6394 206 Fail 0.0055 2702 5553 205 Fail 0.0058 2313 4866 210 Fail 0.0061 2026 4279 211 Fail 0.0063 1795 3786 210 Fail 0.0066 1580 3380 213 Fail 0.0069 1396 3032 217 Fail 0.0071 1238 2688 217 Fail 0.0074 1084 2414 222 Fail 0.0076 950 2154 226 Fail 0.0079 841 1919 228 Fail 0.0082 738 1715 232 Fail 0.0084 642 1547 240 Fail 0.0087 583 1411 242 Fail 0.0089 534 1268 237 Fail 0.0092 480 1162 242 Fail 0.0095 440 1040 236 Fail 0.0097 400 947 236 Fail 0.0100 353 859 243 Fail 0.0102 326 786 241 Fail 0.0105 288 730 253 Fail 0.0108 263 665 252 Fail 0.0110 243 627 258 Fail 0.0113 209 574 274 Fail 0.0115 191 536 280 Fail 0.0118 180 516 286 Fail 0.0121 165 477 289 Fail 0.0123 151 440 291 Fail 0.0126 142 410 288 Fail 0.0128 131 389 296 Fail 0.0131 126 365 289 Fail 0.0134 107 344 321 Fail 0.0136 103 330 320 Fail 0.0139 99 318 321 Fail 0.0142 87 303 348 Fail 0.0144 81 277 341 Fail 0.0147 75 258 344 Fail 0.0149 69 244 353 Fail 0.0152 64 231 360 Fail 0.0155 62 218 351 Fail 0.0157 55 208 378 Fail 0.0160 51 204 400 Fail 0.0162 46 187 406 Fail 0.0165 45 176 391 Fail 0.0168 42 174 414 Fail 0.0170 41 164 400 Fail 0.0173 35 157 448 Fail 0.0175 34 150 441 Fail basin 4/17/2024 8:12:39 AM Page 14 0.0191 26 105 403 Fail 0.0194 26 100 384 Fail 0.0196 25 96 384 Fail 0.0199 24 91 379 Fail 0.0201 24 85 354 Fail 0.0204 23 84 365 Fail 0.0207 22 81 368 Fail 0.0209 22 77 350 Fail 0.0212 22 70 318 Fail 0.0215 22 66 300 Fail 0.0217 20 61 305 Fail 0.0220 20 59 295 Fail 0.0222 18 58 322 Fail 0.0225 18 56 311 Fail 0.0228 17 52 305 Fail 0.0230 16 49 306 Fail 0.0233 16 48 300 Fail 0.0235 16 46 287 Fail 0.0238 15 44 293 Fail 0.0241 14 44 314 Fail 0.0243 14 39 278 Fail 0.0246 14 39 278 Fail 0.0248 14 38 271 Fail 0.0251 13 37 284 Fail 0.0254 13 35 269 Fail 0.0256 12 33 275 Fail 0.0259 12 32 266 Fail 0.0261 12 32 266 Fail 0.0264 12 31 258 Fail 0.0267 11 29 263 Fail 0.0269 11 29 263 Fail 0.0272 10 29 290 Fail 0.0274 9 29 322 Fail 0.0277 9 28 311 Fail 0.0280 9 27 300 Fail 0.0282 8 27 337 Fail 0.0285 7 27 385 Fail 0.0288 7 26 371 Fail 0.0290 7 24 342 Fail 0.0293 7 22 314 Fail 0.0295 7 22 314 Fail 0.0298 7 22 314 Fail 0.0301 7 21 300 Fail 0.0303 7 21 300 Fail 0.0306 6 20 333 Fail 0.0308 6 19 316 Fail The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. basin 4/17/2024 8:12:39 AM Page 15 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. basin 4/17/2024 8:12:39 AM Page 16 LID Report LILTesYinique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Total Volume Infiltrated 0.00 0.00 0.00 0.00 0.00 0% No Treat. Credit Duration Compliance with LID Analysis Standard 8% of 2-yr to 50% of Result = 2 yr Failed basin 4/17/2024 8:12:39 AM Page 17 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. basin 4/17/2024 8:12:53 AM Page 18 Appendix Predeveloped Schematic L_.� Basin 1 L 0.24ac basin 4/17/2024 8:12:53 AM Page 19 Mitigated Schematic L.Basin w L 0.19ac basin 4/17/2024 8:12:55 AM Page 20 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1901 10 01 END RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 END GLOBAL FILES <File> <Un#> END FILES OPN SEQUENCE 2058 09 30 UNIT SYSTEM 1 <-----------File Name ------------------------------>*** *** INGRP INDELT 00:60 PERLND 11 PERLND 17 IMPLND 4 IMPLND 5 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<---------- Title ----------- >***TRAN PIVL DIG1 FILL 1 Basin 1 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 *** in out *** 11 C, Forest, Mod 1 1 1 1 27 0 17 C, Lawn, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** 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 17 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT -INFO basin 4/17/2024 8:12:56 AM Page 21 <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 17 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 17 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 11 0 4.5 0.08 400 0.1 0.5 17 0 4.5 0.03 400 0.1 0.5 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 # - # ***PETMAX PETMIN INFEXP 11 0 0 2 17 0 0 2 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 # - # CEPSC UZSN NSUR 11 0.2 0.5 0.35 17 0.1 0.25 0.25 END PWAT-PARM4 *** INFILD DEEPFR 2 0 2 0 INTFW IRC 6 0.5 6 0.5 AGWRC 0.996 0.996 BASETP AGWETP 0 0 0 0 *** LZETP *** 0.7 0.25 PWAT-STATEl <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 17 0 0 0 0 2.5 1 0 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><------- Name ------- > 4 ROOF TOPS/FLAT 5 DRIVEWAYS/FLAT 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 ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 4 0 0 1 0 0 0 5 0 0 1 0 0 0 END ACTIVITY PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 4 0 0 4 0 0 4 1 9 5 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 *** basin 4/17/2024 8:12:56 AM Page 22 4 0 0 0 0 0 5 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 5 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 4 0 0 5 0 0 END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 4 0 0 5 0 0 END IWAT-STATEI END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 11 0.147 COPY 501 12 PERLND 11 0.147 COPY 501 13 PERLND 17 0.07 COPY 501 12 PERLND 17 0.07 COPY 501 13 IMPLND 4 0.016 COPY 501 15 IMPLND 5 0.007 COPY 501 15 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 12.1 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 basin 4/17/2024 8:12:56 AM Page 23 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 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 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 12.1 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS -LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <Name> <Name> # #<-factor-> <Name> MASS -LINK 12 PERLND PWATER SURO 0.083333 COPY END MASS -LINK 12 MASS -LINK 13 PERLND PWATER IFWO 0.083333 COPY END MASS -LINK 13 MASS -LINK 15 IMPLND IWATER SURO 0.083333 COPY END MASS -LINK 15 END MASS -LINK END RUN <-Grp> <-Member->*** <Name> # #*** INPUT MEAN INPUT MEAN INPUT MEAN basin 4/17/2024 8:12:56 AM Page 24 Mitigated UC/ File RUN GLOBAL WWHM4 model simulation START 1901 10 01 END RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 END GLOBAL FILES <File> <Un#> END FILES OPN SEQUENCE 2058 09 30 UNIT SYSTEM 1 <-----------File Name ------------------------------>*** *** INGRP INDELT 00:60 PERLND 17 IMPLND 4 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<---------- Title ----------- >***TRAN PIVL DIG1 FIL1 1 Basin 1 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 *** in out *** 17 C, Lawn, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 17 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 ********* 17 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT -INFO basin 4/17/2024 8:12:56 AM Page 25 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 17 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 17 0 4.5 0.03 400 0.1 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 17 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 17 0.1 0.25 0.25 6 0.5 0.25 END PWAT-PARM4 PWAT-STATEl <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 17 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 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 4 0 0 1 0 0 0 END ACTIVITY PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 4 0 0 4 0 0 4 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 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 4 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 4 0 0 basin 4/17/2024 8:12:56 AM Page 26 END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 4 0 0 END IWAT-STATEI END IMPLND SCHEMATIC <-Source-> <Name> # Basin 1*** PERLND 17 PERLND 17 IMPLND 4 ******Routing****** END SCHEMATIC <--Area--> <-Target-> MBLK <-factor-> <Name> # Tbl# 0.1575 COPY 501 12 0.1575 COPY 501 13 0.0365 COPY 501 15 NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 12.1 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 basin 4/17/2024 8:12:56 AM Page 27 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 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 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 1 OUTPUT MEAN 1 1 12.1 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 12.1 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS -LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <Name> <Name> # #<-factor-> <Name> MASS -LINK 12 PERLND PWATER SURO 0.083333 COPY END MASS -LINK 12 MASS -LINK 13 PERLND PWATER IFWO 0.083333 COPY END MASS -LINK 13 MASS -LINK 15 IMPLND IWATER SURD 0.083333 COPY END MASS -LINK 15 END MASS -LINK END RUN <-Grp> <-Member->*** <Name> # #*** INPUT MEAN INPUT MEAN INPUT MEAN basin 4/17/2024 8:12:56 AM Page 28 Predeveloped HSPF Message File basin 4/17/2024 8:12:56 AM Page 29 Mitigated HSPF Message File basin 4/17/2024 8:12:56 AM Page 30 Disclaimer Legal Notice 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. 2005-2024; 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 basin 4/17/2024 8:12:56 AM Page 31 WWHM2012 PROJECT REPORT PERMEABLE PAVEMENT CALCULATIONS General Model Information WWHM2012 Project Name: permeable pavement Site Name: MAPLEWOOD LOT C Site Address: 19324 88TH AVE W City: EDMONDS Report Date: 5/24/2024 MGS Region: Puget East Data Start: 1901 /10/1 Data End: 2058/09/30 Timestep: 15 Minute DOT Data Number03 Version Date: 2023/01 /27 Version: 4.2.19 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year permeable pavement 5/24/2024 9:18:11 AM Page 2 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Mod 0.016 Pervious Total 0.016 Impervious Land Use acre Impervious Total 0 Basin Total 0.016 permeable pavement 5/24/2024 9:18:11 AM Page 3 Mitigated Land Use permeable pavement 5/24/2024 9:18:11 AM Page 4 Routing Elements Predeveloped Routing permeable pavement 5/24/2024 9:18:11 AM Page 5 Mitigated Routing Permeable Pavement 1 Pavement Area:0.0162 acre.Pavement Length:35.00 ft. Pavement Width: 20.20 ft. Pavement slope Pavement thickness: 0.5 Pour Space of Pavement: 0.25 Material thickness of second layer: 1.5 Pour Space of material for second layer: 0.35 Material thickness of third layer: 0 Pour Space of material for third laver: 0 Infiltration On Infiltration rate: 0.162 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 9.106 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 9.106 Percent Infiltrated: 100 Total Precip Applied to Facility: 0 Total Evap From Facility: 0.665 1:0.02 To 1 permeable pavement 5/24/2024 9:18:11 AM Page 6 Analysis Results POC 1 Percent Time Exceetlir�g owl owl nri o.a + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area: 0.016 Total Impervious Area: 0 Mitigated Landuse Totals for POC #1 Total Pervious Area: 0 Total Impervious Area: 0.01623 Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000271 5 year 0.000421 10 year 0.000503 25 year 0.000585 50 year 0.000634 100 year 0.000675 Flow Frequency Return Periods for Mitigated Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 Annual Peaks Annual Peaks for Predeveloped and Mitigated Year Predeveloped Mitigated 1902 0.000 0.000 1903 0.000 0.000 1904 0.000 0.000 1905 0.000 0.000 1906 0.000 0.000 1907 0.000 0.000 1908 0.000 0.000 1909 0.000 0.000 1910 0.000 0.000 1911 0.000 0.000 POC #1 POC #1 permeable pavement 5/24/2024 9:18:11 AM Page 7 1912 0.001 0.000 1913 0.000 0.000 1914 0.000 0.000 1915 0.000 0.000 1916 0.000 0.000 1917 0.000 0.000 1918 0.000 0.000 1919 0.000 0.000 1920 0.000 0.000 1921 0.000 0.000 1922 0.000 0.000 1923 0.000 0.000 1924 0.000 0.000 1925 0.000 0.000 1926 0.000 0.000 1927 0.000 0.000 1928 0.000 0.000 1929 0.000 0.000 1930 0.000 0.000 1931 0.000 0.000 1932 0.000 0.000 1933 0.000 0.000 1934 0.001 0.000 1935 0.000 0.000 1936 0.000 0.000 1937 0.000 0.000 1938 0.000 0.000 1939 0.000 0.000 1940 0.000 0.000 1941 0.000 0.000 1942 0.000 0.000 1943 0.000 0.000 1944 0.000 0.000 1945 0.000 0.000 1946 0.000 0.000 1947 0.000 0.000 1948 0.001 0.000 1949 0.000 0.000 1950 0.000 0.000 1951 0.000 0.000 1952 0.001 0.000 1953 0.001 0.000 1954 0.000 0.000 1955 0.000 0.000 1956 0.000 0.000 1957 0.000 0.000 1958 0.001 0.000 1959 0.000 0.000 1960 0.000 0.000 1961 0.000 0.000 1962 0.000 0.000 1963 0.000 0.000 1964 0.000 0.000 1965 0.001 0.000 1966 0.000 0.000 1967 0.000 0.000 1968 0.000 0.000 1969 0.000 0.000 permeable pavement 5/24/2024 11:35:58 AM Page 8 1970 0.000 0.000 1971 0.001 0.000 1972 0.000 0.000 1973 0.000 0.000 1974 0.000 0.000 1975 0.001 0.000 1976 0.000 0.000 1977 0.000 0.000 1978 0.001 0.000 1979 0.000 0.000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.000 1983 0.000 0.000 1984 0.000 0.000 1985 0.000 0.000 1986 0.000 0.000 1987 0.000 0.000 1988 0.000 0.000 1989 0.000 0.000 1990 0.000 0.000 1991 0.000 0.000 1992 0.000 0.000 1993 0.000 0.000 1994 0.001 0.000 1995 0.000 0.000 1996 0.001 0.000 1997 0.000 0.000 1998 0.000 0.000 1999 0.000 0.000 2000 0.000 0.000 2001 0.000 0.000 2002 0.000 0.000 2003 0.000 0.000 2004 0.000 0.000 2005 0.000 0.000 2006 0.000 0.000 2007 0.000 0.000 2008 0.000 0.000 2009 0.000 0.000 2010 0.000 0.000 2011 0.000 0.000 2012 0.000 0.000 2013 0.000 0.000 2014 0.000 0.000 2015 0.001 0.000 2016 0.000 0.000 2017 0.000 0.000 2018 0.001 0.000 2019 0.001 0.000 2020 0.000 0.000 2021 0.000 0.000 2022 0.000 0.000 2023 0.000 0.000 2024 0.001 0.000 2025 0.000 0.000 2026 0.000 0.000 2027 0.000 0.000 permeable pavement 5/24/2024 11:35:58 AM Page 9 2028 0.000 0.000 2029 0.000 0.000 2030 0.001 0.000 2031 0.000 0.000 2032 0.000 0.000 2033 0.000 0.000 2034 0.000 0.000 2035 0.001 0.000 2036 0.000 0.000 2037 0.000 0.000 2038 0.000 0.000 2039 0.000 0.000 2040 0.000 0.000 2041 0.000 0.000 2042 0.001 0.000 2043 0.000 0.000 2044 0.000 0.000 2045 0.000 0.000 2046 0.000 0.000 2047 0.000 0.000 2048 0.000 0.000 2049 0.000 0.000 2050 0.000 0.000 2051 0.000 0.000 2052 0.000 0.000 2053 0.000 0.000 2054 0.000 0.000 2055 0.000 0.000 2056 0.000 0.000 2057 0.000 0.000 2058 0.000 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0008 0.0000 2 0.0008 0.0000 3 0.0008 0.0000 4 0.0008 0.0000 5 0.0007 0.0000 6 0.0007 0.0000 7 0.0007 0.0000 8 0.0007 0.0000 9 0.0006 0.0000 10 0.0006 0.0000 11 0.0006 0.0000 12 0.0006 0.0000 13 0.0006 0.0000 14 0.0006 0.0000 15 0.0006 0.0000 16 0.0006 0.0000 17 0.0005 0.0000 18 0.0005 0.0000 19 0.0005 0.0000 20 0.0005 0.0000 21 0.0005 0.0000 22 0.0005 0.0000 23 0.0005 0.0000 permeable pavement 5/24/2024 11:35:58 AM Page 10 24 0.0004 0.0000 25 0.0004 0.0000 26 0.0004 0.0000 27 0.0004 0.0000 28 0.0004 0.0000 29 0.0004 0.0000 30 0.0004 0.0000 31 0.0004 0.0000 32 0.0004 0.0000 33 0.0004 0.0000 34 0.0004 0.0000 35 0.0004 0.0000 36 0.0004 0.0000 37 0.0004 0.0000 38 0.0004 0.0000 39 0.0004 0.0000 40 0.0004 0.0000 41 0.0004 0.0000 42 0.0003 0.0000 43 0.0003 0.0000 44 0.0003 0.0000 45 0.0003 0.0000 46 0.0003 0.0000 47 0.0003 0.0000 48 0.0003 0.0000 49 0.0003 0.0000 50 0.0003 0.0000 51 0.0003 0.0000 52 0.0003 0.0000 53 0.0003 0.0000 54 0.0003 0.0000 55 0.0003 0.0000 56 0.0003 0.0000 57 0.0003 0.0000 58 0.0003 0.0000 59 0.0003 0.0000 60 0.0003 0.0000 61 0.0003 0.0000 62 0.0003 0.0000 63 0.0003 0.0000 64 0.0003 0.0000 65 0.0003 0.0000 66 0.0003 0.0000 67 0.0003 0.0000 68 0.0003 0.0000 69 0.0003 0.0000 70 0.0003 0.0000 71 0.0003 0.0000 72 0.0003 0.0000 73 0.0003 0.0000 74 0.0003 0.0000 75 0.0003 0.0000 76 0.0003 0.0000 77 0.0003 0.0000 78 0.0003 0.0000 79 0.0003 0.0000 80 0.0003 0.0000 81 0.0002 0.0000 permeable pavement 5/24/2024 11:35:58 AM Page 11 82 0.0002 0.0000 83 0.0002 0.0000 84 0.0002 0.0000 85 0.0002 0.0000 86 0.0002 0.0000 87 0.0002 0.0000 88 0.0002 0.0000 89 0.0002 0.0000 90 0.0002 0.0000 91 0.0002 0.0000 92 0.0002 0.0000 93 0.0002 0.0000 94 0.0002 0.0000 95 0.0002 0.0000 96 0.0002 0.0000 97 0.0002 0.0000 98 0.0002 0.0000 99 0.0002 0.0000 100 0.0002 0.0000 101 0.0002 0.0000 102 0.0002 0.0000 103 0.0002 0.0000 104 0.0002 0.0000 105 0.0002 0.0000 106 0.0002 0.0000 107 0.0002 0.0000 108 0.0002 0.0000 109 0.0002 0.0000 110 0.0002 0.0000 111 0.0002 0.0000 112 0.0002 0.0000 113 0.0002 0.0000 114 0.0002 0.0000 115 0.0002 0.0000 116 0.0002 0.0000 117 0.0002 0.0000 118 0.0002 0.0000 119 0.0002 0.0000 120 0.0002 0.0000 121 0.0002 0.0000 122 0.0002 0.0000 123 0.0002 0.0000 124 0.0002 0.0000 125 0.0002 0.0000 126 0.0002 0.0000 127 0.0002 0.0000 128 0.0002 0.0000 129 0.0001 0.0000 130 0.0001 0.0000 131 0.0001 0.0000 132 0.0001 0.0000 133 0.0001 0.0000 134 0.0001 0.0000 135 0.0001 0.0000 136 0.0001 0.0000 137 0.0001 0.0000 138 0.0001 0.0000 139 0.0001 0.0000 permeable pavement 5/24/2024 11:35:58 AM Page 12 140 0.0001 0.0000 141 0.0001 0.0000 142 0.0001 0.0000 143 0.0001 0.0000 144 0.0001 0.0000 145 0.0001 0.0000 146 0.0001 0.0000 147 0.0001 0.0000 148 0.0001 0.0000 149 0.0001 0.0000 150 0.0001 0.0000 151 0.0001 0.0000 152 0.0001 0.0000 153 0.0001 0.0000 154 0.0001 0.0000 155 0.0000 0.0000 156 0.0000 0.0000 157 0.0000 0.0000 permeable pavement 5/24/2024 11:35:58 AM Page 13 Duration Flows The Facility PASSED Flow(cfs) Predev Mit Percentage Pass/Fail 0.0001 53933 0 0 Pass 0.0001 49666 0 0 Pass 0.0001 45730 0 0 Pass 0.0002 42312 0 0 Pass 0.0002 39146 0 0 Pass 0.0002 36295 0 0 Pass 0.0002 33663 0 0 Pass 0.0002 31357 0 0 Pass 0.0002 29276 0 0 Pass 0.0002 27354 0 0 Pass 0.0002 25532 0 0 Pass 0.0002 23804 0 0 Pass 0.0002 22240 0 0 Pass 0.0002 20682 0 0 Pass 0.0002 19262 0 0 Pass 0.0002 17732 0 0 Pass 0.0002 16581 0 0 Pass 0.0002 15530 0 0 Pass 0.0002 14544 0 0 Pass 0.0002 13586 0 0 Pass 0.0002 12684 0 0 Pass 0.0002 11874 0 0 Pass 0.0002 11142 0 0 Pass 0.0003 10482 0 0 Pass 0.0003 9904 0 0 Pass 0.0003 9392 0 0 Pass 0.0003 8847 0 0 Pass 0.0003 8357 0 0 Pass 0.0003 7911 0 0 Pass 0.0003 7465 0 0 Pass 0.0003 7090 0 0 Pass 0.0003 6738 0 0 Pass 0.0003 6402 0 0 Pass 0.0003 6094 0 0 Pass 0.0003 5797 0 0 Pass 0.0003 5527 0 0 Pass 0.0003 5269 0 0 Pass 0.0003 5038 0 0 Pass 0.0003 4811 0 0 Pass 0.0003 4592 0 0 Pass 0.0003 4389 0 0 Pass 0.0003 4179 0 0 Pass 0.0003 3976 0 0 Pass 0.0004 3782 0 0 Pass 0.0004 3639 0 0 Pass 0.0004 3502 0 0 Pass 0.0004 3375 0 0 Pass 0.0004 3266 0 0 Pass 0.0004 3157 0 0 Pass permeable pavement 5/24/2024 11:35:58 AM Page 14 0.0004 2698 0 0 Pass 0.0004 2607 0 0 Pass 0.0004 2503 0 0 Pass 0.0004 2403 0 0 Pass 0.0004 2297 0 0 Pass 0.0004 2197 0 0 Pass 0.0004 2099 0 0 Pass 0.0004 2011 0 0 Pass 0.0004 1942 0 0 Pass 0.0004 1876 0 0 Pass 0.0005 1805 0 0 Pass 0.0005 1733 0 0 Pass 0.0005 1677 0 0 Pass 0.0005 1610 0 0 Pass 0.0005 1551 0 0 Pass 0.0005 1494 0 0 Pass 0.0005 1435 0 0 Pass 0.0005 1374 0 0 Pass 0.0005 1304 0 0 Pass 0.0005 1247 0 0 Pass 0.0005 1190 0 0 Pass 0.0005 1148 0 0 Pass 0.0005 1107 0 0 Pass 0.0005 1050 0 0 Pass 0.0005 1002 0 0 Pass 0.0005 961 0 0 Pass 0.0005 920 0 0 Pass 0.0005 878 0 0 Pass 0.0005 842 0 0 Pass 0.0005 795 0 0 Pass 0.0006 757 0 0 Pass 0.0006 711 0 0 Pass 0.0006 675 0 0 Pass 0.0006 634 0 0 Pass 0.0006 598 0 0 Pass 0.0006 567 0 0 Pass 0.0006 521 0 0 Pass 0.0006 471 0 0 Pass 0.0006 430 0 0 Pass 0.0006 397 0 0 Pass 0.0006 366 0 0 Pass 0.0006 348 0 0 Pass 0.0006 309 0 0 Pass 0.0006 291 0 0 Pass 0.0006 269 0 0 Pass 0.0006 250 0 0 Pass 0.0006 235 0 0 Pass permeable pavement 5/24/2024 11:35:58 AM Page 15 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. permeable pavement 5/24/2024 11:35:58 AM Page 16 LID Report LID Technique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Permeable Pavement 1 POC ❑ 8.29 ❑ 100.00 Total Volume Infiltrated 8.29 1 1 [i 00 100.00 0.00 0% No Treat. Credit Duration Compliance with LID Analysis Standard 8% of 2-yr to 50% of Result= 2 yr Passed permeable pavement 5/24/2024 11:35:58 AM Page 17 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. permeable pavement 5/24/2024 11:36:41 AM Page 18 Appendix Predeveloped Schematic L_.� Basin 1 L 0.02ac permeable pavement 5/24/2024 11:36:41 AM Page 19 Mitigated Schematic Perm e ble Pave ent 1 u permeable pavement 5/24/2024 11:36:42 AM Page 20 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1901 10 01 END RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 END GLOBAL 2058 09 30 FILES <File> <Un#> OPN SEQUENCE UNIT SYSTEM 1 <----------- File Name----- ------------------------->*** *** INGRP INDELT 00:15 PERLND 11 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<---------- Title ----------- >***TRAN PIVL DIG1 FIL1 1 Basin 1 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 *** in out *** 11 C, Forest, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** 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 END ACTIVITY 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 END PRINT -INFO permeable pavement 5/24/2024 11:36:43 AM Page 21 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 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY 11 0 4.5 0.08 400 0.1 0.5 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 # - # ***PETMAX PETMIN INFEXP 11 0 0 2 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 # - # CEPSC UZSN NSUR 11 0.2 0.5 0.35 END PWAT-PARM4 AGWRC 0.996 *** INFILD DEEPFR BASETP AGWETP 2 0 0 0 *** INTFW IRC LZETP *** 6 0.5 0.7 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 11 0 0 0 0 2.5 1 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><------- Name ------- > END GEN-INFO *** Section IWATER*** Unit -systems Printer *** User t-series Engl Metr *** in out *** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT -INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATEI GWVS 0 permeable pavement 5/24/2024 11:36:43 AM Page 22 END IMPLND SCHEMATIC <-Source-> <Name> # Basin 1*** PERLND 11 PERLND 11 ******Routing****** END SCHEMATIC <--Area--> <-Target-> MBLK <-factor-> <Name> # Tbl# 0.016 COPY 501 12 0.016 COPY 501 13 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 permeable pavement 5/24/2024 11:36:43 AM Page 23 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 MASS -LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS -LINK 12 PERLND PWATER SURD 0.083333 COPY INPUT MEAN END MASS -LINK 12 MASS -LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS -LINK 13 END MASS -LINK END RUN permeable pavement 5/24/2024 11:36:43 AM Page 24 Mitigated UC/ File RUN GLOBAL WWHM4 model simulation START 1901 10 01 END RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 END GLOBAL 2058 09 30 FILES <File> <Un#> OPN SEQUENCE UNIT SYSTEM 1 <----------- File Name----- ------------------------->*** *** INGRP INDELT 00:15 IMPLND 18 RCHRES 1 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<---------- Title ----------- >***TRAN PIVL DIG1 FIL1 1 Permeable Pavement 1 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 *** in out *** END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* END PRINT -INFO PWAT-PARM1 permeable pavement 5/24/2024 11:36:43 AM Page 25 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 # - # ***PETMAX PETMIN INFEXP END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 # - # CEPSC UZSN NSUR END PWAT-PARM4 AGWRC *** INFILD DEEPFR BASETP AGWETP *** INTFW IRC LZETP *** 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 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><------- Name ------- > 18 Porous Pavement END GEN-INFO *** Section IWATER*** Unit -systems Printer *** User t-series Engl Metr *** in out *** 1 1 1 27 0 ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 18 0 0 1 0 0 0 END ACTIVITY PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 18 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 *** 18 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 18 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 18 0 0 END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 18 0 0 END IWAT-STATEI GWVS permeable pavement 5/24/2024 11:36:43 AM Page 26 END IMPLND SCHEMATIC <-Source-> <--Area--> <Name> # <-factor-> IMPLND 18 0.0258 ******Routing****** RCHRES 1 1 END SCHEMATIC <-Target-> MBLK *** <Name> # Tbl# *** RCHRES 1 5 COPY 501 17 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 Permeable Paveme-008 2 1 1 1 END GEN-INFO *** Section RCHRES*** Printer *** Engl Metr LKFG *** *** 28 0 1 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 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 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 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------ ><-------->< -------- ><-------- >< -------- ><-------- ><-------- > *** 1 1 0.11 0.0 0.0 0.5 0.0 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 <------><-------- > <--- ><--- ><--- >< --- ><---> *** <--- ><--- ><--- ><--- ><---> 1 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC -ACTIONS END SPEC -ACTIONS FTABLES FTABLE 1 permeable pavement 5/24/2024 11:36:43 AM Page 27 91 5 Depth Area Volume Outflowl Outflow2 (ft) (acres) (acre-ft) (cfs) (cfs) 0.000000 0.025803 0.000000 0.000000 0.000000 0.016667 0.025803 0.000151 0.000000 0.004215 0.033333 0.025803 0.000301 0.000000 0.004215 0.050000 0.025803 0.000452 0.000000 0.004215 0.066667 0.025803 0.000602 0.000000 0.004215 0.083333 0.025803 0.000753 0.000000 0.004215 0.100000 0.025803 0.000903 0.000000 0.004215 0.116667 0.025803 0.001054 0.000000 0.004215 0.133333 0.025803 0.001204 0.000000 0.004215 0.150000 0.025803 0.001355 0.000000 0.004215 0.166667 0.025803 0.001505 0.000000 0.004215 0.183333 0.025803 0.001656 0.000000 0.004215 0.200000 0.025803 0.001806 0.000000 0.004215 0.216667 0.025803 0.001957 0.000000 0.004215 0.233333 0.025803 0.002107 0.000000 0.004215 0.250000 0.025803 0.002258 0.000000 0.004215 0.266667 0.025803 0.002408 0.000000 0.004215 0.283333 0.025803 0.002559 0.000000 0.004215 0.300000 0.025803 0.002709 0.000000 0.004215 0.316667 0.025803 0.002860 0.000000 0.004215 0.333333 0.025803 0.003010 0.000000 0.004215 0.350000 0.025803 0.003161 0.000000 0.004215 0.366667 0.025803 0.003311 0.000000 0.004215 0.383333 0.025803 0.003462 0.000000 0.004215 0.400000 0.025803 0.003612 0.000000 0.004215 0.416667 0.025803 0.003763 0.000000 0.004215 0.433333 0.025803 0.003914 0.000000 0.004215 0.450000 0.025803 0.004064 0.000000 0.004215 0.466667 0.025803 0.004215 0.000000 0.004215 0.483333 0.025803 0.004365 0.000000 0.004215 0.500000 0.025803 0.004516 0.000000 0.004215 0.516667 0.025803 0.004666 0.000000 0.004215 0.533333 0.025803 0.004817 0.000000 0.004215 0.550000 0.025803 0.004967 0.000000 0.004215 0.566667 0.025803 0.005118 0.000000 0.004215 0.583333 0.025803 0.005268 0.000000 0.004215 0.600000 0.025803 0.005419 0.000000 0.004215 0.616667 0.025803 0.005569 0.000000 0.004215 0.633333 0.025803 0.005720 0.000000 0.004215 0.650000 0.025803 0.005870 0.000000 0.004215 0.666667 0.025803 0.006021 0.000000 0.004215 0.683333 0.025803 0.006171 0.000000 0.004215 0.700000 0.025803 0.006322 0.000000 0.004215 0.716667 0.025803 0.006472 0.000000 0.004215 0.733333 0.025803 0.006623 0.000000 0.004215 0.750000 0.025803 0.006773 0.000000 0.004215 0.766667 0.025803 0.006924 0.000000 0.004215 0.783333 0.025803 0.007074 0.000000 0.004215 0.800000 0.025803 0.007225 0.000000 0.004215 0.816667 0.025803 0.007375 0.000000 0.004215 0.833333 0.025803 0.007526 0.000000 0.004215 0.850000 0.025803 0.007677 0.000000 0.004215 0.866667 0.025803 0.007827 0.000000 0.004215 0.883333 0.025803 0.007978 0.000000 0.004215 0.900000 0.025803 0.008128 0.000000 0.004215 0.916667 0.025803 0.008279 0.000000 0.004215 0.933333 0.025803 0.008429 0.000000 0.004215 0.950000 0.025803 0.008580 0.000000 0.004215 0.966667 0.025803 0.008730 0.000000 0.004215 0.983333 0.025803 0.008881 0.000000 0.004215 1.000000 0.025803 0.009031 0.000000 0.004215 1.016667 0.025803 0.009182 0.000000 0.004215 1.033333 0.025803 0.009332 0.000000 0.004215 1.050000 0.025803 0.009483 0.000000 0.004215 1.066667 0.025803 0.009633 0.000000 0.004215 1.083333 0.025803 0.009784 0.000000 0.004215 1.100000 0.025803 0.009934 0.000000 0.004215 Velocity Travel Time*** (ft/sec) (Minutes)*** permeable pavement 5/24/2024 11:36:43 AM Page 28 1.116667 0.025803 0.010085 0.000000 0.004215 1.133333 0.025803 0.010235 0.000000 0.004215 1.150000 0.025803 0.010386 0.000000 0.004215 1.166667 0.025803 0.010536 0.000000 0.004215 1.183333 0.025803 0.010687 0.000000 0.004215 1.200000 0.025803 0.010837 0.000000 0.004215 1.216667 0.025803 0.010988 0.000000 0.004215 1.233333 0.025803 0.011139 0.000000 0.004215 1.250000 0.025803 0.011289 0.000000 0.004215 1.266667 0.025803 0.011440 0.000000 0.004215 1.283333 0.025803 0.011590 0.000000 0.004215 1.300000 0.025803 0.011741 0.000000 0.004215 1.316667 0.025803 0.011891 0.000000 0.004215 1.333333 0.025803 0.012042 0.000000 0.004215 1.350000 0.025803 0.012192 0.000000 0.004215 1.366667 0.025803 0.012343 0.000000 0.004215 1.383333 0.025803 0.012493 0.000000 0.004215 1.400000 0.025803 0.012644 0.000000 0.004215 1.416667 0.025803 0.012794 0.000000 0.004215 1.433333 0.025803 0.012945 0.000000 0.004215 1.450000 0.025803 0.013095 0.000000 0.004215 1.466667 0.025803 0.013246 0.000000 0.004215 1.483333 0.025803 0.013396 0.000000 0.004215 1.500000 0.025803 0.013547 0.000000 0.004215 END FTABLE 1 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 WDM 1 EVAP ENGL 0.76 RCHRES 1 EXTNL POTEV END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** RCHRES 1 HYDR RO 1 1 1 WDM 1008 FLOW ENGL REPL RCHRES 1 HYDR 0 1 1 1 WDM 1009 FLOW ENGL REPL RCHRES 1 HYDR 0 2 1 1 WDM 1010 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1011 STAG ENGL REPL COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS -LINK <Volume> <-Grp> <Name> MASS -LINK IMPLND IWATER END MASS -LINK MASS -LINK RCHRES OFLOW END MASS -LINK END MASS -LINK END RUN <-Member-><--Mult--> <Name> # #<-factor-> 5 SURO 0.083333 5 17 OVOL 17 <Target> <Name> RCHRES COPY <-Grp> <-Member->*** <Name> # #*** INFLOW IVOL INPUT MEAN permeable pavement 5/24/2024 11:36:43 AM Page 29 Predeveloped HSPF Message File permeable pavement 5/24/2024 11:36:43 AM Page 30 Mitigated HSPF Message File permeable pavement 5/24/2024 11:36:43 AM Page 31 Disclaimer Legal Notice 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. 2005-2024; 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 permeable pavement 5/24/2024 11:36:43 AM Page 32 COBALT G E 0 S C I E N C E S January 20, 2023 Landsverk Quality Homes Attn: Duane Landsverk & Joseph Rowett 24113 56th Avenue West Mountlake Terrace, Washington RE: Geotechnical Evaluation Proposed Development 19324 88th Avenue West Edmonds, Washington Cobalt Geosciences, LLC P.O. Box 82243 Kenmore, Washington 98028 In accordance with your authorization, Cobalt Geosciences, LLC has prepared this letter to discuss the results of our geotechnical evaluation at the referenced site. The purpose of our evaluation was to provide recommendations for foundation design, stormwater management, grading, and earthwork. Site Description The site is located at 19324 88th Avenue West in Edmonds, Washington. The site consists of one rectangular parcel (No. 270418003o1800) with a total area of about 0.97 acres. The southeast portion of the site is developed with a residence, driveway, and accessory buildings. The remainder of the site is undeveloped and vegetated with grasses, ferns, ivy, blackberry vines, and variable diameter trees. The site slopes downward from east to west at magnitudes of 5 to 15 percent and relief of about 22 feet. The site is bordered to the north and west by residential properties, to the east by 88th Avenue West, and to the south by 194th Street SW. The proposed development includes three new residences and driveways. Stormwater will include infiltration or other systems depending on feasibility. Site grading may include cuts and fills of 3 feet or less and foundation loads are expected to be light. We should be provided with the final plans to verify if our recommendations remain valid or require updating. Area Geology The Geologic Map of the Edmonds East Quadrangle, indicates that the site is underlain by Vashon Glacial Till. Vashon Glacial Till includes mixtures of silt, sand, clay, and gravel. These materials are usually impermeable and are typically dense to very dense below a weathered zone. www.cobaltgeo.com (2o6) 331-1097 January 20, 2023 Page 2 of 10 Geotechnical Evaluation Soil & Groundwater Conditions As part of our evaluation, we observed the excavation of three test pits within the property areas, where accessible. The explorations encountered approximately 6 inches of grass and topsoil underlain by approximately 2.5 to 5.5 feet of loose to medium dense, silty -fine to medium grained sand with gravel (Weathered Glacial Till). These materials were underlain by dense to very dense, silty -fine to medium grained sand trace to with gravel (Vashon Glacial Till), which continued to the termination depths of the explorations. The till was locally well cemented. Groundwater was not encountered; however, the shallow soils were locally mottled. There is a chance that light volumes of groundwater may develop on the denser glacial till at variable depths below the site. Groundwater would most likely be present during the wet season and on the denser till. Water table elevations often fluctuate over time. The groundwater level will depend on a variety of factors that may include seasonal precipitation, irrigation, land use, climatic conditions and soil permeability. Water levels at the time of the field investigation may be different from those encountered during the construction phase of the project. Erosion Hazard The Natural Resources Conservation Services (NRCS) maps for Snohomish County indicate that the site is underlain by Alderwood Urban land complex (2 to 15 percent slopes). These soils would have a slight to moderate erosion potential in a disturbed state depending on the slope magnitude. It is our opinion that soil erosion potential at this project site can be reduced through landscaping and surface water runoff control. Typically, erosion of exposed soils will be most noticeable during periods of rainfall and may be controlled by the use of normal temporary erosion control measures, such as silt fences, hay bales, mulching, control ditches and diversion trenches. The typical wet weather season, with regard to site grading, is from October 31st to April ist. Erosion control measures should be in place before the onset of wet weather. Seismic Hazard The overall subsurface profile below the fill corresponds to a Site Class D as defined by Table 1613.5.2 of the International Building Code (IBC). A Site Class D applies to an overall profile consisting of medium dense to very dense soils within the upper too feet. We referenced the U.S. Geological Survey (USGS) Earthquake Hazards Program Website to obtain values for Ss, Sl, FQ, and F,,. The USGS website includes the most updated published data on seismic conditions. The following tables provide seismic parameters from the USGS web site with referenced parameters from ASCE 7-16. www.cobaltgeo.com (2o6) 331-1097 January 20, 2023 Page 3 of 10 Geotechnical Evaluation Seismic Design Parameters (ASCE 7-16) Site Spectral Spectral Site Design Spectral Design Class Acceleration Acceleration Coefficients Response Parameters PGA at 0.2 sec. (g) at l.o sec. (g) Fa F, SDs SD1 D 1.295 0.457 1.0 Null o.864 Null 0.553 Additional seismic considerations include liquefaction potential and amplification of ground motions by soft/loose soil deposits. The liquefaction potential is highest for loose sand with a high groundwater table. The site has a low likelihood of liquefaction. For items listed as "Null" see Section 11.4.8 of the ASCE. Conclusions and Recommendations General The site is underlain by weathered and unweathered glacial till which becomes denser with depth. The proposed residential structures may be supported on shallow foundation systems bearing on medium dense or firmer native soils or on structural fill placed on the native soils. Widespread infiltration of runoff is not feasible based on the soil and anticipated groundwater conditions. In general, dispersion systems are suitable in areas with adequate space for flopwaths. Other systems that may be feasible include detention with overflow to City/County infrastructure, rain gardens, and permeable pavements. The feasibility of any system depends on their location and elevations. We can provide additional recommendations upon request. Site Preparation Trees, shrubs and other vegetation should be removed prior to stripping of surficial organic -rich soil and fill. Based on observations from the site investigation program, it is anticipated that the stripping depth will be 6 to 18 inches. Deeper excavations will be necessary below former foundation areas in any areas underlain by undocumented fill. The native soils consist of silty -sand with gravel. These soils may be used as structural fill provided they achieve compaction requirements and are within 3 percent of the optimum moisture. Some of these soils may only be suitable for use as fill during the summer months, as they will be above the optimum moisture levels in their current state. These soils are moisture sensitive and may degrade during periods of wet weather and under equipment traffic. Imported structural fill should consist of a sand and gravel mixture with a maximum grain size of 3 inches and less than 5 percent fines (material passing the U.S. Standard No. 200 Sieve). Structural fill should be placed in maximum lift thicknesses of 12 inches and should be compacted to a minimum of 95 percent of the modified proctor maximum dry density, as determined by the ASTM D 1557 test method. www.cobaltgeo.com (2o6) 331-1097 January 20, 2023 Page 4 of io Geotechnical Evaluation Temporary Excavations Based on our understanding of the project, we anticipate that the grading could include local cuts on the order of approximately 3 feet or less for foundation and most of the utility placement. Any deeper temporary excavations should be sloped no steeper than 1.511:1V (Horizontal:Vertical) in loose native soils and fill, 111:1V in medium dense native soils and 3/41-1:1V in dense to very dense native soils. If an excavation is subject to heavy vibration or surcharge loads, we recommend that the excavations be sloped no steeper than 2H:1V, where room permits. Temporary cuts should be in accordance with the Washington Administrative Code (WAC) Part N, Excavation, Trenching, and Shoring. Temporary slopes should be visually inspected daily by a qualified person during construction activities and the inspections should be documented in daily reports. The contractor is responsible for maintaining the stability of the temporary cut slopes and reducing slope erosion during construction. Temporary cut slopes should be covered with visqueen to help reduce erosion during wet weather, and the slopes should be closely monitored until the permanent retaining systems or slope configurations are complete. Materials should not be stored or equipment operated within 10 feet of the top of any temporary cut slope. Soil conditions may not be completely known from the geotechnical investigation. In the case of temporary cuts, the existing soil conditions may not be completely revealed until the excavation work exposes the soil. Typically, as excavation work progresses the maximum inclination of temporary slopes will need to be re-evaluated by the geotechnical engineer so that supplemental recommendations can be made. Soil and groundwater conditions can be highly variable. Scheduling for soil work will need to be adjustable, to deal with unanticipated conditions, so that the project can proceed and required deadlines can be met. If any variations or undesirable conditions are encountered during construction, we should be notified so that supplemental recommendations can be made. If room constraints or groundwater conditions do not permit temporary slopes to be cut to the maximum angles allowed by the WAC, temporary shoring systems may be required. The contractor should be responsible for developing temporary shoring systems, if needed. We recommend that Cobalt Geosciences and the project structural engineer review temporary shoring designs prior to installation, to verify the suitability of the proposed systems. Foundation Design The proposed structures may be supported on shallow spread footing foundation systems bearing on undisturbed medium dense or firmer native soils or on properly compacted structural fill placed on the suitable native soils. Any undocumented fill and/or loose native soils should be removed and replaced with structural fill below foundation elements. For shallow foundation support, we recommend widths of at least 16 and 24 inches, respectively, for continuous wall and isolated column footings supporting the proposed structure. Provided that the footings are supported as recommended above, a net allowable bearing pressure of 2,500 pounds per square foot (psf) may be used for design. Detention vaults set at least 5 feet below grade may be designed with a bearing pressure of 4,000 psf. A 1/3 increase in the above value may be used for short duration loads, such as those imposed by wind and seismic events. Structural fill placed on bearing, native subgrade should be compacted to at least 95 percent of the maximum dry density based on ASTM Test Method D1557. Footing excavations should be inspected to verify that the foundations will bear on suitable material. www.cobaltgeo.com (2o6) 331-1097 January 20, 2023 Page 5 of io Geotechnical Evaluation Exterior footings should have a minimum depth of 18 inches below pad subgrade (soil grade) or adjacent exterior grade, whichever is lower. Interior footings should have a minimum depth of 12 inches below pad subgrade (soil grade) or adjacent exterior grade, whichever is lower. If constructed as recommended, the total foundation settlement is not expected to exceed 1 inch. Differential settlement, along a 25-foot exterior wall footing, or between adjoining column footings, should be less than 1/2 inch. This translates to an angular distortion of 0.002. Most settlement is expected to occur during construction, as the loads are applied. However, additional post -construction settlement may occur if the foundation soils are flooded or saturated. All footing excavations should be observed by a qualified geotechnical consultant. Resistance to lateral footing displacement can be determined using an allowable friction factor of 0.4o acting between the base of foundations and the supporting subgrades. Lateral resistance for footings can also be developed using an allowable equivalent fluid passive pressure of 225 pounds per cubic foot (pcf) acting against the appropriate vertical footing faces (neglect the upper 12 inches below grade in exterior areas). The frictional and passive resistance of the soil may be combined without reduction in determining the total lateral resistance. Care should be taken to prevent wetting or drying of the bearing materials during construction. Any extremely wet or dry materials, or any loose or disturbed materials at the bottom of the footing excavations, should be removed prior to placing concrete. The potential for wetting or drying of the bearing materials can be reduced by pouring concrete as soon as possible after completing the footing excavation and evaluating the bearing surface by the geotechnical engineer or his representative. Concrete Retaining Walls The following table, titled Wall Design Criteria, presents the recommended soil related design parameters for retaining walls with a level backslope. Contact Cobalt if an alternate retaining wall system is used. This has been included for new cast in place walls. Wall Design Criteria "At -rest" Conditions (Lateral Earth Pressure — EFD+) 55 pcf (Equivalent Fluid Density) "Active" Conditions (Lateral Earth Pressure — EFD+) 35 pcf (Equivalent Fluid Density) Seismic Increase for "At -rest" Conditions (Lateral Earth Pressure) 14H* (Uniform Distribution) Seismic Increase for "Active" Conditions (Lateral Earth Pressure) 7H* (Uniform Distribution) Passive Earth Pressure on Low Side of Wall (Allowable, includes F.S. = 1.5) Neglect upper 2 feet, then 275 pcf EFD+ Soil -Footing Coefficient of Sliding Friction (Allowable; includes F.S. = 1.5) 0.40 'H is the height of the wall; Increase based on one in 500 year seismic event (10 percent probability of being exceeded in 50 years), ,EFD — Equivalent Fluid Density www.cobaltgeo.com (2o6) 331-1097 January 20, 2023 Page 6 of io Geotechnical Evaluation The stated lateral earth pressures do not include the effects of hydrostatic pressure generated by water accumulation behind the retaining walls. Uniform horizontal lateral active and at -rest pressures on the retaining walls from vertical surcharges behind the wall may be calculated using active and at -rest lateral earth pressure coefficients of 0.3 and 0.5, respectively. A soil unit weight Of 125 pcf may be used to calculate vertical earth surcharges. To reduce the potential for the buildup of water pressure against the walls, continuous footing drains (with cleanouts) should be provided at the bases of the walls. The footing drains should consist of a minimum 4-inch diameter perforated pipe, sloped to drain, with perforations placed down and enveloped by a minimum 6 inches of pea gravel in all directions. The backfill adjacent to and extending a lateral distance behind the walls at least 2 feet should consist of free -draining granular material. All free draining backfill should contain less than 3 percent fines (passing the U.S. Standard No. 200 Sieve) based upon the fraction passing the U.S. Standard No. 4 Sieve with at least 30 percent of the material being retained on the U.S. Standard No. 4 Sieve. The primary purpose of the free -draining material is the reduction of hydrostatic pressure. Some potential for the moisture to contact the back face of the wall may exist, even with treatment, which may require that more extensive waterproofing be specified for walls, which require interior moisture sensitive finishes. We recommend that the backfill be compacted to at least go percent of the maximum dry density based on ASTM Test Method D1557. In place density tests should be performed to verify adequate compaction. Soil compactors place transient surcharges on the backfill. Consequently, only light hand operated equipment is recommended within 3 feet of walls so that excessive stress is not imposed on the walls. Stormwater Management Feasibility The site is underlain by soils consistent with weathered and unweathered glacial till. The unweathered glacial till acts as an aquitard, causing infiltrating runoff to become perched groundwater. This groundwater is typically seasonal in nature, and tends to migrate laterally along the denser till. We performed a falling head infiltration test in TP-1 at a depth of 3 feet below grade. The design infiltration rate was determined by applying correction factors to the observed infiltration rate as prescribed in Volume III, Section 3.3.6 of the DOE. The observed rate must be reduced through appropriate correction factors for site variability (CFv), uncertainty of test method (CFT), and degree of influent control (CFM) to prevent siltation and bio-buildup. It should be noted that construction traffic or other disturbance to the target infiltration area could compact the soil, which may decrease the effective infiltration rates. The correction factors and resulting design infiltration rate are also shown in the table below. Test Pit Sample Observed Correction Factors Design Number Depth (ft) Infiltration Infiltration Rate (in/hr) Rate CFv CFT CFM (in/hr) TP-1 3 0.45 o.8 0.5 o.g o.162 www.cobaltgeo.com (2o6) 331-1097 January 20, 2023 Page 7 of 10 Geotechnical Evaluation Widespread infiltration of runoff is not feasible based on the soil and anticipated groundwater conditions. The shallow soils become very dense and cemented below a thin weathered zone of mottled soils. The presence of the soil mottling indicates that seasonal groundwater will tend to develop during the late winter and spring months. In general, dispersion systems are suitable in areas with adequate space for flopwaths. Other systems that may be feasible include detention with overflow to City/County infrastructure, rain gardens, and permeable pavements. The feasibility of any system depends on their location and elevations. We can provide additional recommendations upon request. We recommend collection of runoff from new impervious surfaces with direct or perforated connection to City infrastructure. We can provide additional recommendations upon request. Slab -on -Grade We recommend that the upper 12 inches of the native soils within slab areas be re -compacted to at least 95 percent of the modified proctor (ASTM D1557 Test Method). Often, a vapor barrier is considered below concrete slab areas. However, the usage of a vapor barrier could result in curling of the concrete slab at joints. Floor covers sensitive to moisture typically requires the usage of a vapor barrier. A materials or structural engineer should be consulted regarding the detailing of the vapor barrier below concrete slabs. Exterior slabs typically do not utilize vapor barriers. The American Concrete Institutes ACI 36oR-o6 Design of Slabs on Grade and ACI 302.1R-04 Guide for Concrete Floor and Slab Construction are recommended references for vapor barrier selection and floor slab detailing. Slabs on grade may be designed using a coefficient of subgrade reaction of 18o pounds per cubic inch (pci) assuming the slab -on -grade base course is underlain by structural fill placed and compacted as outlined above. A 4- to 6-inch-thick capillary break layer should be placed over the prepared subgrade. This material should consist of pea gravel or 5/8 inch clean angular rock. A perimeter drainage system is recommended unless interior slab areas are elevated a minimum Of 12 inches above adjacent exterior grades. If installed, a perimeter drainage system should consist of a 4-inch diameter perforated drain pipe surrounded by a minimum 6 inches of drain rock wrapped in a non -woven geosynthetic filter fabric to reduce migration of soil particles into the drainage system. The perimeter drainage system should discharge by gravity flow to a suitable stormwater system. Exterior grades surrounding buildings should be sloped at a minimum of one percent to facilitate surface water flow away from the building and preferably with a relatively impermeable surface cover immediately adjacent to the building. Erosion and Sediment Control Erosion and sediment control (ESC) is used to reduce the transportation of eroded sediment to wetlands, streams, lakes, drainage systems, and adjacent properties. Erosion and sediment control measures should be implemented, and these measures should be in general accordance with local regulations. At a minimum, the following basic recommendations should be incorporated into the design of the erosion and sediment control features for the site: • Schedule the soil, foundation, utility, and other work requiring excavation or the disturbance of the site soils, to take place during the dry season (generally May through September). www.cobaltgeo.com (2o6) 331-1097 January ao, 2023 Page 8 of io Geotechnical Evaluation However, provided precautions are taken using Best Management Practices (BMP's), grading activities can be completed during the wet season (generally October through April). • All site work should be completed and stabilized as quickly as possible. • Additional perimeter erosion and sediment control features may be required to reduce the possibility of sediment entering the surface water. This may include additional silt fences, silt fences with a higher Apparent Opening Size (AOS), construction of a berm, or other filtration systems. • Any runoff generated by dewatering discharge should be treated through construction of a sediment trap if there is sufficient space. If space is limited other filtration methods will need to be incorporated. Utilities Utility trenches should be excavated according to accepted engineering practices following OSHA (Occupational Safety and Health Administration) standards, by a contractor experienced in such work. The contractor is responsible for the safety of open trenches. Traffic and vibration adjacent to trench walls should be reduced; cyclic wetting and drying of excavation side slopes should be avoided. Depending upon the location and depth of some utility trenches, groundwater flow into open excavations could be experienced, especially during or shortly following periods of precipitation. In general, silty and sandy soils were encountered at shallow depths in the explorations at this site. These soils have low cohesion and density and will have a tendency to cave or slough in excavations. Shoring or sloping back trench sidewalls is required within these soils in excavations greater than 4 feet deep. All utility trench backfill should consist of imported structural fill or suitable on site soils. Utility trench backfill placed in or adjacent to buildings and exterior slabs should be compacted to at least 95 percent of the maximum dry density based on ASTM Test Method D1557. The upper 5 feet of utility trench backfill placed in pavement areas should be compacted to at least 95 percent of the maximum dry density based on ASTM Test Method D1557. Below 5 feet, utility trench backfill in pavement areas should be compacted to at least 90 percent of the maximum dry density based on ASTM Test Method D1557. Pipe bedding should be in accordance with the pipe manufacturer's recommendations. The contractor is responsible for removing all water -sensitive soils from the trenches regardless of the backfill location and compaction requirements. Depending on the depth and location of the proposed utilities, we anticipate the need to re -compact existing fill soils below the utility structures and pipes. The contractor should use appropriate equipment and methods to avoid damage to the utilities and/or structures during fill placement and compaction procedures. CONSTRUCTION FIELD REVIEWS Cobalt Geosciences should be retained to provide part time field review during construction in order to verify that the soil conditions encountered are consistent with our design assumptions and that the intent of our recommendations is being met. This will require field and engineering review to: ■ Monitor and test structural fill placement and soil compaction ■ Observe bearing capacity at foundation locations ■ Observe slab -on -grade preparation ■ Monitor foundation drainage placement www.cobaltgeo.com (2o6) 331-1097 January ao, 2023 Page 9 of io Geotechnical Evaluation ■ Verify soil conditions at stormwater systems (if utilized) ■ Observe excavation stability Geotechnical design services should also be anticipated during the subsequent final design phase to support the structural design and address specific issues arising during this phase. Field and engineering review services will also be required during the construction phase in order to provide a Final Letter for the project. CLOSURE This report was prepared for the exclusive use of Landsverk Quality Homes and their appointed consultants. Any use of this report or the material contained herein by third parties, or for other than the intended purpose, should first be approved in writing by Cobalt Geosciences, LLC. The recommendations contained in this report are based on assumed continuity of soils with those of our test holes and assumed structural loads. Cobalt Geosciences should be provided with final architectural and civil drawings when they become available in order that we may review our design recommendations and advise of any revisions, if necessary. Use of this report is subject to the Statement of General Conditions provided in Appendix A. It is the responsibility of Landsverk Quality Homes who is identified as "the Client" within the Statement of General Conditions, and its agents to review the conditions and to notify Cobalt Geosciences should any of these not be satisfied. Sincerely, Cobalt Geosciences, LLC a�"0Nrti of y��� a �548960 FSS�ONAL 1/20/2023 Phil Haberman, PE, LG, LEG Principal www.cobaltgeo.com (2o6) 331-1097 January 20, 2023 Page io of io Geotechnical Evaluation Statement of General Conditions USE OF THIS REPORT: This report has been prepared for the sole benefit of the Client or its agent and may not be used by any third party without the express written consent of Cobalt Geosciences and the Client. Any use which a third party makes of this report is the responsibility of such third parry. BASIS OF THE REPORT: The information, opinions, and/or recommendations made in this report are in accordance with Cobalt Geosciences present understanding of the site specific project as described by the Client. The applicability of these is restricted to the site conditions encountered at the time of the investigation or study. If the proposed site specific project differs or is modified from what is described in this report or if the site conditions are altered, this report is no longer valid unless Cobalt Geosciences is requested by the Client to review and revise the report to reflect the differing or modified project specifics and/or the altered site conditions. STANDARD OF CARE: Preparation of this report, and all associated work, was carried out in accordance with the normally accepted standard of care in the state of execution for the specific professional service provided to the Client. No other warranty is made. INTERPRETATION OF SITE CONDITIONS: Soil, rock, or other material descriptions, and statements regarding their condition, made in this report are based on site conditions encountered by Cobalt Geosciences at the time of the work and at the specific testing and/or sampling locations. Classifications and statements of condition have been made in accordance with normally accepted practices which are judgmental in nature; no specific description should be considered exact, but rather reflective of the anticipated material behavior. Extrapolation of in situ conditions can only be made to some limited extent beyond the sampling or test points. The extent depends on variability of the soil, rock and groundwater conditions as influenced by geological processes, construction activity, and site use. VARYING OR UNEXPECTED CONDITIONS: Should any site or subsurface conditions be encountered that are different from those described in this report or encountered at the test locations, Cobalt Geosciences must be notified immediately to assess if the varying or unexpected conditions are substantial and if reassessments of the report conclusions or recommendations are required. Cobalt Geosciences will not be responsible to any parry for damages incurred as a result of failing to notify Cobalt Geosciences that differing site or sub -surface conditions are present upon becoming aware of such conditions. PLANNING, DESIGN, OR CONSTRUCTION: Development or design plans and specifications should be reviewed by Cobalt Geosciences, sufficiently ahead of initiating the next project stage (property acquisition, tender, construction, etc), to confirm that this report completely addresses the elaborated project specifics and that the contents of this report have been properly interpreted. Specialty quality assurance services (field observations and testing) during construction are a necessary part of the evaluation of sub -subsurface conditions and site preparation works. Site work relating to the recommendations included in this report should only be carried out in the presence of a qualified geotechnical engineer; Cobalt Geosciences cannot be responsible for site work carried out without being present. www.cobaltgeo.com (2o6) 331-1097 j INES I 'G. 75 i I { I r 4 7' I ASPWT I I JtEBIR/CAP I 3.3' r4'x 4.0' ; / 3.0', DR✓V�191Y� 1 j I a os(W) of I J 0.6'2.4 18- , :.� ; GARAGE I I I RLECdES.E' �,+6' WDOD4FFNCE F C ' iv CORNER IS 0.3 (w) 910, , - 7�2d' - 3. -- �, OF CORNER i i '� 9. 5�� r2` t 1 1 1e• FOUND REBAa W/O CAP 18�yr4 0.1'(W) OF CORNER I, 1 f RS' Y/- ryS�C lyy 8' 0.4 i iiifff ----------I O• ' I I14 ` I ,: ,1 1'(,' (S1TE AREA I I Q �wr I tz• ) 42,207 SF ; I aq \27041800301R00I "-I=+I ao W' pp 00 PARCEL A r�.y t WI 7,,PAtCEL C 1e zTP-3 V''r `, I : \ ZI Z I TP-2`',WOOD FENCE' I 1 E NGAE " i1't' I '� I FOUND RMRICM 0.1'(5) �19324At— OF CORNER SIAMPEO �f2J I BROIOCE CS16194 FOUND RF W/G4P O,X(N1 i �� I / !LL(!!/QQ� c:z� � M `��� o I ® I 8' Nt7O0 FENCE(N)OF CORNER STAMPED I I M N4D PEW W/0 CAP o 25' I 41roQ6 FENCE(W) aROKKF tslst 2 2: I ) 1 1 o.2'(In of carrrtR I I �Cf CORA" IS 97.2A5 92.25' .01' 3.9'(W) k 52'(N) \ n - 26 N 9COOb0- W 2�52' Of CORNER R - 194 S S l I ' 366 SS-1— yk GRAVEL ASPNNLi Yr-- —-----------------=1----------�—Y ®T `_ ORNEWAY I RMDMNY•�j^ I r I CR R1M-347.64 1 AV. 8XV C(w) I II I WV. 12Y.ONC(N)=345.49 am CwQ49.99 <,::4'•, Y� I I r W I CB RW= 347.12 }, WV.. 8 ONC(N)=345.82 Provided topo survey TP-i N � Approximate Test Pit Location Not to Scale Cobalt Geosciences, LLC Proposed Development SITE MAP P.O. Box 82243 19324 88th Avenue West en or , WA 98028 COBALTEdmonds Washington () 33 • ' g FIGURE i www•cobaltgeoeo.com cob altgeo p gmail. com Slab on Grade Basement or Shallow Foundation Wall 12" Free Draining Backfill and/or Drainage Mat Attached to Wall Backfill Soils Compacted per Geotechnical Report 4" Diameter Perforated Pipe -- --�H H Native Soils Benched as Required Filter Fabric Over Rock (Mirafi 14oN) 3//4" Washed Rock or Clean Angular Rock Not to Scale Cobalt Geosciences, LLC PO Box 1792 Typical Foundation Drain Detail Attachment North Bend, WA 98045 • _ (2o6) 331-1097 GEOSCIENCES www.cobaltgeo.com Philpcobaltgeo.com Unified Soil Classification System (USCS) MAJOR DIVISIONS SYMBOL TYPICAL DESCRIPTION Clean Gravels Gw Well -graded gravels, gravels, gravel -sand mixtures, little or no fines Gravels (more than 50% (less than 5% fines) GP Poorly graded gravels, gravel -sand mixtures, little or no fines COARSE GRAINED SOILS of coarse fraction retained on No. 4 sieve) Gravels with Fines (more than 12% fines) GM Silty gravels, gravel -sand -silt mixtures GC Clayey gravels, gravel -sand -clay mixtures (more than 50% retained on Clean Sands :•: sw Well -graded sands, gravelly sands, little or no fines No. 200 sieve) Sands (50% or more of coarse fraction (less than 5% fines) sP Poorly graded sand, gravelly sands, little or no fines passes the No. 4 sieve) Sands with Fines sM Silty sands, sand -silt mixtures (more than 12% fines) sc Clayey sands, sand -clay mixtures ML Inorganic silts of low to medium plasticity, sandy silts, gravelly silts, FINE GRAINED (50% or more Silts and Clays (liquid limit less than 50) Inorganic cL or clayey silts with slight plasticity Inorganic clays of low to medium plasticity, gravelly clays, sandy clays silty clays, lean clays Organic rganic oL Organic silts and organic silty clays of low plasticity passes the MH Inorganic silts, micaceous or diatomaceous fine sands or silty soils, No. 200 sieve) Silts and Clays (liquid limit 50 or more) Inorganic elastic silt CH Inorganic clays of medium to high plasticity, sandy fat clay, or gravelly fat clay Organic OHOrganic clays of medium to high plasticity, organic silts HIGHLY ORGANIC SOILS Primarily organic matter, dark in color, and organic odor PT Peat, humus, swamp soils with high organic content (ASTM D4427) Classification of Soil Constituents MAJOR constituents compose more than 50 percent, by weight, of the soil. Major constituents are capitalized (i.e., SAND). Minor constituents compose 12 to 50 percent of the soil and precede the major constituents (i.e., silty SAND). Minor constituents preceded by "slightly" compose 5 to 12 percent of the soil (i.e., slightly silty SAND). Trace constituents compose o to 5 percent of the soil (i.e., slightly silty SAND, trace gravel). Relative Density (Coarse Grained Soils) Consistency (Fine Grained Soils) N, SPT, Relative N, SPT, Relative Blows/FT Density Blows/FT Consistency 0-4 Very loose Under 2 Very soft 4 -10 Loose 2-4 Soft 10 - 30 Medium dense 4-8 Medium stiff 30 - 50 Dense 8 -15 Stiff Over 50 Very dense 15 - 30 Very stiff Over 3o Hard Grain Size Definitions Description Sieve Number and/or Size Fines <#200 (o.o8 mm) Sand -Fine #200 to #40 (o.o8 to 0.4 mm) -Medium #40 to #10 (0.4 to 2 mm) -Coarse #10 to #4 (2 to 5 mm) Gravel -Fine #4 to 3/4 inch (5 to 19 mm) -Coarse 3/4 to 3 inches (19 to 76 mm) Cobbles 3 to 12 inches (75 to 305 mm) Boulders >12 inches (305 mm) 1 Moisture Content Definitions 1 Dry Absence of moisture, dusty, dry to the touch Moist Damp but no visible water Wet Visible free water, from below water table Cobalt Geosciences, LLC P.O. Box 82243 Kenmore, WA 98028 Soil Classification Chart Figure Ci (2o6) 331-1097 _ www.cobaltgeo.com cobaltgeo(&gmail.com Test Pit TP-1 Date: October 2022 Depth: 8' Groundwater: None Contractor: Client provided Elevation: N/A Logged By: PH Checked By: SC N 0) o Moisture Content (%) u Q E Plastic I Limit I Liquid Limit � � L Material Description DCP Equivalent N-Value o C ? o G 0 10 20 30 40 50 Cobalt Geosciences, LLC Proposed Development P.O. Box 82243 COBALT 19324 88th Avenue West Test Pit Kenmore, WA 98028 (2o6) 331-1097 GEOSCIENCES Edmonds, Washington Logs www.cobaltgeo.com cobaltgeopgmail.com Topsoil and Grass 1 , , SM Loose to medium dense, silty -fine to fine grained sand with gravel, mottled yellowish brown to grayish brown. (Weathered Glacial Till 2 SM Dense to very dense, silty -fine to medium grained sand with gravel, 4 ottled yellowish brown to grayish brown, moist. (Glacial Till) 5 6 7 End of Test Pit 8' 9 10 Test Pit TP-2 Date: October 2022 Depth: 8' Groundwater: None Contractor: Client provided Elevation: N/A Logged By: PH Checked By: SC N 0) o Moisture Content (%) u Q E Plastic I Limit I Liquid Limit � � L Material Description DCP Equivalent N-Value o C ? o G 0 10 20 30 40 50T. Cobalt Geosciences, LLC Proposed Development P.O. Box 82243 COBALT 19324 88th Avenue West Test Pit Kenmore, WA 98028 (2o6) 331-1097 GEOSCIENCES Edmonds, Washington Logs www.cobaltgeo.com cobaltgeopgmail.com Topsoil and Grass 1 , , SM Loose to medium dense, silty -fine to fine grained sand with gravel, mottled yellowish brown to grayish brown. (Weathered Glacial Till 2 3 4 Dense to very dense, silty -fine to medium grained sand with gravel, 6 mottled yellowish brown to grayish brown, moist. (Glacial Till) 7 End of Test Pit 8' 9 10 Test Pit TP-3 Date: October 2022 Depth. 8' Groundwater: None Contractor: Client provided Elevation: N/A Logged By: PH Checked By: SC N 0) o Moisture Content (%) u Q E Plastic I Limit I Liquid Limit � � L Material Description DCP Equivalent N-Value o C ? o G 0 10 20 30 40 50 Cobalt Geosciences, LLC Proposed Development P.O. Box 82243 COBALT 19324 88th Avenue West Test Pit Kenmore, WA 98028 (2o6) 331-1097 GEOSCIENCES Edmonds, Washington Logs www.cobaltgeo.com cobaltgeopgmail.com Topsoil and Grass 1 , , SM Loose to medium dense, silty -fine to fine grained sand with gravel, mottled yellowish brown to grayish brown. (Weathered Glacial Till 2 3 4 5 -' SM Dense to very dense, silty -fine to medium grained sand with gravel, 7 mottled yellowish brown to grayish brown, moist. (Glacial Till) End of Test Pit 8' 9 10 TREMRON WE MAKE IT EASY 11roor INTERLOCKING CONCRETE PAVERS SECTION 02780 NOTE: This is a guide specification for the construction of Tremron Interlocking Concrete Pavers and bedding sand over a dense -graded, compacted aggregate base. This specification should be edited by an engineer/architect to conform to project conditions and location. Notes are provided on the use of a compacted aggregate base under the bedding sand and pavers. Other base materials may be used. The user should refer to Interlocking Concrete Pave- ment, Institute ICPI Software, Zaphers rM Detail and Specifications for Interlocking Concrete Pavement, for various guide specifications and detailed drawings. TREMRON WE MAKE IT EASY W PART 1 - GENERAL 1.01 Section Includes A. Concrete paver units. B. Bedding and joint sand. C. Edge restraints. 1.02 Related Sections Tech Data: A. Glossary of Terms used in the Production, Design, Construction, and Testing of Interlocking Concrete Pavement - ICPI Tech Spec #1 B. Construction of Interlocking Concrete Pavement - ICPI Tech Spec #2 C. Edge Restraints for Interlocking Concrete Pavement - ICPI Tech Spec #3 D. Structual Designing of Interlocking Concrete Pavement for Roads and Parking Lots - ICPI Tech Spec #4 E. Cleaning and Sealing - A Maintenance and Protection Guide - ICPI Tech Spec #5 E Application Guide for Interlocking Concrete Pavements - ICPI Tech Spec #10 1.03 References Note: Pavements subject to vehicles should be designed in consultation with a qualified civil engineer, in accordance with established flexible pavement design procedures, Pavespec Software, and in accordance with the ICPI "Tech Spec" Technical Bulletins. A. American Society of Testing and Materials (ASTM): 1. C 33. Specification for Concrete Aggregates. 2. C 136. Method for Sieve Analysis. 3. C 140. Sampling and Testing Concrete Masonry Units. 4. C 144. Standard Specification for Aggregate for Masonry Mortar. 5. C 936. Specification for Solid Interlocking Concrete Paving Units. 6. C 979. Specification for Pigments for Integrally Colored Concrete. 7. D 698. Test Methods for Moisture Density Relations of Soil and Soil Aggregate Mixtures using a 5.5 lb. (2.49kg) Rammer and 12 in. (305 mm) drop. 8. D 1557. Test Methods for Moisture Density. 9. D 2940. Graded Aggregate Material for Bases or Subbases for Highways or Airports. B. Interlocking Concrete Pavement Institute (ICPI): 1. Tech Spec Technical Bulletins. MEN 2 TREMRON WE MAKE IT EASY `pro 1.04 Qualify Assurance A. Installation shall be by a contractor and crew with at least one year of experience in placing interlocking concrete pavers on projects of similar nature or dollar cost. B. Contractor shall hold a current certificate from the Interlocking Concrete Pavement Institute Concrete Paver Installer Certification program. C. Contractor shall conform to all local, state/provincial licensing and bonding requirements. 1.05 Submittals A. Shop or product drawing and product data. B. Full size samples of concrete paving units to indicate color and shape selections. Color will be selected by Architect/Engineer/Landscape Architect/Owner from manufacturer's available colors. C. Sieve analysis for grading of bedding and joint sand. D. Test result from an independent testing laboratory for compliance of paving unit requirements to (ASTM C 936) (CSA) or other applicable requirements. E. Indicate layout, pattern, and relationship of paving joints to fixtures and project formed details. 1.06 Mock-ups A. Install a 7 ft. x 7 ft. (2 m x 2 m) paver area as described in Article 3.02. B. This area will be used to determine surcharge of the bedding sand layer, joint sizes, lines, laying pattern(s), color(s), and texture of the job. C. This area shall be the standard from which the work will be judged and it shall be incorporated into the work. 1.07 Delivery, Storage, and Handling A. Deliver concrete pavers to the site in steel banded, or plastic banded, or plastic wrapped cubes capable of transfer by fork lift or clamp lift. Unload pavers at job site in such a manner that no damage occurs to the product. B. Cover sand with waterproof covering to prevent exposure to rainfall or removal by wind. C. Coordinate delivery and paving schedule to minimize interface with normal use of building adjacent to paving. 1.08 Environmental Conditions A. Do not install sand or pavers during heavy rain or snowfall. B. Do not install sand or pavers over frozen base materials. C. Do not install frozen sand. TREMRON WE MAKE IT EASY W PART 2 - PRODUCTS 2.01 Concrete Pavers A. Manufacturer: 1.2885 St. Clair Street, Jacksonville, Florida 32254, (904) 359-5900 2. 11321 NW 112th Court, Medley, Florida 33178, (305) 825-9000 3. 1030 Airport Road, Lakeland, Florida 33811, (863) 603-0995 4. 3144 Highway 17 NE, Arcadia, Florida 34266, (863) 491-0990 5. 1436 Municipal Pkwy, Douglasville, Georgia 30134, (404) 968-8280 B. Meet the following requirements set forth in ASTM C 936, Standard Specification for Interlocking Concrete Paving Units: 1. Average compressive strength of 8,000 psi (55 MPa) with no individual unit under 7,200 psi (50 MPa). 2. Average absorption of 5% with no unit greater than 7% when tested in accordance with ASTM C 140. 3. Resistance to 50 freeze -thaw cycles when tested according to ASTM C 67. C. Pigment shall conform to ASTM C 979. MEN 4 TREMRON WE MAKE IT EASY W D. Product name(s), shape(s), overall dimensions, and thickness: Paver Thickness Dimensions SFperCube CubeWeight •. Olde Towne 2-3/8" (60mm) 6"x4", 6"x6", 6"x9" 124 3225 Ibs lie Olde Towne 2PC 2-3/8" (60mm) 6"x6", 6"x9" 124 3225 Ibs Olde Towne 6x9 2-3/8" (60mm) 6"x9" 124 3225 Ibs ` Mega Olde Towne 2-3/8" (60mm) 3-1/8" (80mm) 6"x9", 9"x9", 9"x12" 116 93 3015 Ibs 3160 Ibs ' Stonehurst 2-3/8" (60mm) 3-1/8" 6"x9", 9"x9", 9"x12" 116 93 3015 Ibs 3160 Ibs (80mm) 4x8 Brick 2-3/8" (60mm) 3-1/8" (80mm) 4"x8„ 120 96 3120 Ibs 3265 Ibs �,. Bluestone 2-3/8" (60mm) 6.5"x13", 13"x13",13"x19.5" 105 2730 Ibs •. Templehurst 2-3/8" (60mm) 22"x12.5",12.5"x12.5",12.5"x9.25" 116 3015 Ibs Roma 2-3/8" (60mm) 4"'x8", 8"W',12"x8" 114 2965 Ibs Tuscany 4" (100mm) 4"x4" 72 2415 Ibs • • '1. Romanesque Circles 2-3/8" (60mm) 10' Diameter Circle 94 2445 Ibs ■ ■ ■ TREMRON WE MAKE IT EASY W Paver Thickness • Plank 4x12 2-3/8" (60mm) 4"x12" 102 2652 Ibs Plank 4x16 2-3/8" (60mm) 4"x16" 101 2626 Ibs #as Plank Combo 4" (100mm) 4"x12", 4"x16" 58 2100 Ibs Park Plaza 8x8 2-3/8" (60mm) 8"x8" 106 2775 Ibs too;p Park Plaza 8x12 2-3/8" (60mm) 8"x12" 106 2756 Ibs + Park Plaza 12x12 2-3/8" (60mm) 12"x12" 120 3120 Ibs Park Plaza 16x16 2-3/8" (60mm) 16"x16" 107 2780 Ibs ■ ■ TREMRON WE MAKE IT EASY W 2.02 Bedding and Joint Sand Note: The type of sand used for bedding is often called concrete sand. Sands vary regionally. Screenings and stone dust can be unevenly graded and have material passing the No. 200 (0.075mm) sieve. Bedding sands with these characteristics should not be used. Contact paver contractors or manufacturers local to the project and confirm sand(s) successfully used in previous similar applications. A. Clean, non -plastic, free from deleterious or foreign matter, natural or manufactured from crushed rock. Do not use limestone screenings or stone dust that do not conform to the grading requirements in Tables 1 & 2 below. When concrete pavers are subject to vehicle traffic, the sands shall be as hard as practically available. Note: If the hardness of the bedding sand is not sufficient or questionable for the application (usually a heavily trafficked thoroughfare) contact the ICPI for information and specifications on assessing bedding sand durabiiity under heavy traffic loads. B. Sieve according to (ASTM C 136) (CSA-A-A23.2A). C. Conform to the grading requirements as shown in Tables 1 & 2 below. Note: Use ASTM or CSA standards as applicable. GRADING REOUIREMENTS FOR BEDDING SAND ASTM C 33 Sieve Size Percent Passing 3/8" (9.5 mm) 100 No. 4 (4.75 mm) 95 to 100 No. 8 (2.36 mm) 85 to 100 No. 16 (1.18 mm) 50 to 85 No. 30 (0.600 mm) 25 to 60 No. 50 (0.300 mm) 10 to 30 No. 100 (0.150 mm) 2 to 10 Table 1 CSA A23. 1-M94 Sieve Size Percent Passing 10 mm 100 5 mm 95 to 100 2.5 mm 80 to 100 1.25 mm 50 to 90 0.630 mm 25 to 65 0.315mm 10to35 0.160 mm 2 to 10 Table 2 L. 7 TREMRON WE MAKE IT EASY W Note: Bedding sand may be used for joint sand. However, some extra effort in sweeping and compacting the pavers may be required in order to completely fill the joints. If joint sand other than bedding sand is used, the gradations shown in Table 2 are recommended. Joint sand should never be used for bedding sand. D. The joint sand shall conform to the grading requirements as shown in Tables 3, 4 & 5 below: Note: Use ASTM or CSA standards as applicable. GRADING ASTM C 33 Natural Sand Sieve Size Percent Passing No. 4 (4.75 mm) 100 No. 8 (2.36 mm) 95 to 100 No. 16 (1.18 mm) 70 to 100 No. 30 (0.600 mm) 40 to 75 No. 50 (0.300 ram) 10 to 35 No. 100 (0.150 mm) 2 to 15 No. 200 (0.075 mm) 0 Table 3 2.03 Edge Restraints UIREMENTS FOR TOINT SAND ASTM C 144 Manufactured Sand Sieve Size Percent Passing No. 4 (4.75 mm) 100 No. 8 (2.36 mm) 95 to 100 No. 16 (1.18 mm) 705 to 100 No. 30 (0.600 mm) 40 to 100 No. 50 (0.300 mm) 20 to 100 No. 100 (0.150 mm) 10 to 25 No. 200 (0.075 mm) 0 to 10 Table 4 CSA A23. 1-M94 Sieve Size Percent Passing 5 mm 100 2.5 mm 95 to 100 1.25 mm 90 to 100 0.600 mm 35 to 80 0.300 mm 15 to 50 0.150 mm 2 to 15 Table 5 A. See ICPI Tech Spec #3. Edge Restraints for Interlocking Concrete Pavements (Included In Tech Data Section) for guidance on selecting edge restraints for various applications. B. See Details / Design Considerations in Tech Data Section. MEN TREMRON WE MAKE IT EASY W PART 3 - Execution 3.01 Examination Note: For installation on a compact aggregate base and soil subgrade, the specifier should be aware that the top surface of the pavers maybe 1/8 to 1/4 in. (3 to 6 mm) above the final elevations after compaction. This difference in initial and final elevation is to compensate for possible minor settling. A. Verify that subgrade preparation, compacted density and elevations conform to the specifications. Note: Compaction of the soil subgrade is recommended to at least 95% standard Proctor density per ASTM D 698 for pedestrian areas and residential driveways. Compaction to at least 95% modified Proctor density per ASTM D 1557 is recommended for areas subject to heavy vehicular traffic. Stabilization of the subgrade and/or base material may be necessary with weak or saturated subgrade soils. The Architect/Engineer should inspect subgrade preparation, elevation, and conduct density tests for conformance to specifications. B. Verify that geotextiles, if applicable, have been placed according to specifications and drawings. C. Verify that aggregate base materials, thickness, compaction, surface tolerances, and elevations conform to the specifications. Note: Local aggregate base materials typical to those used for highway flexible pavements are recommended for those conforming to ASTM D 2940. Compaction is recommended to not less than 95% Proctor density in accordance with ASTM D 698 for pedestrian areas and residential driveways. Compaction is recommended to not less than 98% modified Proctor density according to ASTM D 1557 for vehicular areas. Note: Tile aggregate base should be spread and compacted in uniform layers not exceeding 6 in. (150 mm) thickness. Recommended base surface tolerance should be plus or minus 3/8 in. (10 mm) over a 10 ft. (3 m) straight edge. The Architect/Engineer should inspect geotextlle materials and placement (if applicable), base preparation, surface tolerances, elevation, and conduct density tests for conformance to specifications. See ICPI Tech Spec 2, "Construction of Interlocking Concrete Pavement" for further guidance on construction practices. Note: Mechanical tampers are recommended for compaction of soil subgrade and aggregate base around lamp standards, utility structures, building edges, curbs, tree wells and other protusions. In areas not accessible to large compaction equipment, compact to specified density with mechanical tampers. D. Verify location, type, installation and elevations of edge restraints around the perimeter area to be paved. MEN 6 TREMRON WE MAKE IT EASY W E. Install edge restraints per the drawings [and manufacturer's recommendations] at the indicated elevations. E Verify that base is dry, uniform, even, and ready to support sand, pavers, and imposed loads. G. Beginning of bedding sand and paver installation means acceptance of base and edge restraints. 3.02 Installation A. Spread the bedding sand evenly over the base course and screed to a nominal 1 in. (25 mm) thickness, not exceeding 1-1/2 in. (40 mm) thickness. The screeded sand should not be disturbed. Place sufficient sand to stay ahead of the laid pavers. Do not use the bedding sand to fill depressions in the base surface. B. Ensure that pavers are free of foreign material before installation. C. Lay the pavers in the pattern(s) as shown on the drawings. Maintain straight pattern and joint lines. D. Joints between the pavers shall be between 1/16 in. and 3/16 in. (2 mm to 5 mm) wide. Note: Some paver shapes require a larger joint. Consult manufacturer for recommended joint widths. E. Fill gaps at the edges of the paved area with cut pavers or edge units. Note: Units cut no smaller than one-third of a whole paver are recommended along edges subject to vehicular traffic. E Cut pavers to be placed along the edge with (a double blade paver splitter or) masonry saw. G. Use a low -amplitude plate compactor capable of at least 5,000 Ibf (22 kN) at a frequency of 75 hz - 100hz to vibrate the pavers into the sand. H. Compact the pavers again, sweeping dry joint sand into the joints and vibrating until they are full. This will require at least two or three passes with the compactor. Do not compact within 3 ft. (1 m) of the un restrained edges of the paving units. I. All work to within 3 ft. (1 m) of the laying lace must be left fully compacted with sand -filled joints at the end of each day. Cover the laying face with plastic sheets overnight if not closed with cut and compacted pavers. J. Sweep off excess sand when the job is complete. K. The final surface elevations shall not deviate more than 3/8 in. (10 mm) under a 10 ft. (3 m) long straight edge. L. The surface elevation of pavers shall be 1/8 to 1/4 in. (3 to 6 mm) above adjacent drainage inlets, concrete collars or channels. 3.03 Field Quality Control A. After removal of excess sand, check final elevations for conformance to the drawings. MEN 10 TREMRON WE MAKE IT EASY `pro ■ ■ 11 TREMRON WE MAKE IT EASY `oro JACKSONVILLE MIAMI ARCADIA LAKELAND ATLANTA 2885 ST. CLAIR STREET 11321 NW 138TH ST 3144 HIGHWAY 17 NE 1030 AIRPORT RD 1436 MUNICIPAL PKWY JACKSONVILLE, FL 32254 MEDLEY, FL 33178 ARCADIA, FL 34266 LAKELAND, FL 33811 DOUGLASVILLE, GA 30134 (904) 359-5900 (305) 825-9000 (863) 491-0990 (863) 603-0995 (404) 968-8280 Table V-A.S: Maintenance Standards - Catch Basins Maintenance Defect Conditions When Maintenance is Needed Results Expected When Maintenance is per - Component formed Trash or debris which is located immediately in front of the catch basin opening or is blocking inletting capacity of the basin by more than 10%. No Trash or debris located immediately in front of Trash or debris (in the basin) that exceeds 60 percent of the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the catch basin or on grate opening. basin, but in no case less than a minimum of six inches clearance from the debris surface to the invert of the lowest pipe. No trash or debris in the catch basin. Trash & Debris Trash or debris in an inlet or outlet pipe blocking more than 1/3 of its height. Y P�P 9 9 Inlet and outlet pipes free of trash or debris. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within the catch basin. Sediment (in the basin) that exceeds 60 percent of the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the Sediment basin, but in no case less than a minimum of 6 inches clearance from the sediment surface to the invert of the lowest pipe. No sediment in the catch basin General Structure Damage to To slab has holes lar er than 2 square inches or cracks widerthan 1/4 inch. Intent is to make sure no material is running into basin p 9 q ( 9 )� Top slab is free of holes and cracks. Frame and/or Top Slab Frame not sitting flush on top slab, i.e., separation of more than 3/4 inch of the frame from the top slab. Frame not securely attached Frame is sitting flush on the riser rings or top slab and firmly attached. Fractures or Cracks in Maintenance person judges that structure is unsound. Basin replaced or repaired to design standards. Basin Walls/ Bottom Grout fillet has separated or cracked wider than 1/2 inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering Pipe is regrouted and secure at basin wall. catch basin through cracks. Settlement/ Mis- alignment If failure of basin has created a safety, function, or design problem. Basin replaced or repaired to design standards. Vegetation growing across and blocking more than 10% of the basin opening. No vegetation blocking opening to basin. Vegetation Vegetation growing in inlet/outlet pipe joints that is more than six inches tall and less than six inches apart. No vegetation or root growth present. Contamination and Pol- See Table V-A.1: Maintenance Standards - Detention Ponds No pollution present. lution Cover Not in Place Cover is missing or only partially in place. Any open catch basin requires maintenance. Cover/grate is in place, meets design standards, and is secured Catch Basin Locking Mechanism Not Working Mechanism cannot be opened by one maintenance person with propertools. Bolts into frame have less than 1/2 inch of thread. Mechanism opens with proper tools. Cover Cover Difficult to One maintenance person cannot remove lid after applying normal lifting pressure. Cover can be removed by one maintenance per - Remove (Intent is keep cover from sealing off access to maintenance.) son. Ladder Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, not securely attached to basin wall, misalignment, rust, cracks, or sharp edges. Ladder meets design standards and allows main- tenance person safe access. Grate opening Unsafe Grate with opening wider than 7/8 inch. Grate opening meets design standards. Metal Grates Trash and Debris Trash and debris that is blocking more than 20% of grate surface inletting capacity. Grate free of trash and debris. (If Applicable) Grate is in place, meets the design standards, and Damaged or Missing. Grate missing or broken member(s) of the grate. is installed and aligned with the flow path. 2019 Stormwater Management Manual for Western Washington Volume V - Appendix A - Page 1009 Table V-A.6. Maintenance Standards Debris Barriers (e.g., Trash Raeks�- Maintenanc nts Defect Condition When Maintenance is Needed Results Expected When Mainte. erformed General Trash and Debris rash or debris that is plugging more than 20% of the openings in the barri r c eared to design flow capacity. Bars are bent out o s han 3 iri, is Bars in place with no bends more than 3/4 inch. Damaged/ Missing Bars. Bars are fil re barrier missing. Bars in place according to design. Metal Bars are loose and rust is causing 50% deterioration to any part of barrier. a d or repaired to design standards. Inlet/Outlet Pipe Debris barrier missing or not attached to pipe Barrier firmly attached to pipe Table V-A.7: Maintenance Standards - Energy Dissipators Maintenance Com- Defect Conditions When Maintenance is Needed Results Expected When Maintenance is ponents Performed External: Rock Pad Missing or Moved Rock Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil. Rock pad replaced to design standards. Erosion Soil erosion in or adjacent to rock pad. Rock pad replaced to design standards. Pipe Plugged with Sediment Accumulated sediment that exceeds 20% of the design depth. Pipe cleaned/flushed so that it matches design. Not Discharging Water Properly Visual evidence of water discharging at concentrated points along trench (normal condition is a "sheet flow" of water along trench). Trench redesigned or rebuilt to standards. Intent is to prevent erosion damage. Dispersion Trench Perforations Plugged. 99 Over 1/2 of perforations in pipe are plugged with debris and sediment. p p p p g9 Perforated pipe cleaned or replaced. p�p p Water Flows Out Top of "Distributor" Maintenance person observes or receives credible report of waterflowing out during any storm less than the design storm or its causing Facility rebuilt or redesigned to standards. Catch Basin. or appears likely to cause damage. Receiving Area Over -Saturated Water in receiving area is causing or has potential of causing landslide problems. No danger of landslides. I nternal: Worn or Damaged Post, Baffles, Side Structure dissipating flow deteriorates to 1/2 of original size or any concentrated worn spot exceeding one square foot which would Structure replaced to design standards. Manhole/Chamber of Chamber make structure unsound. Other Defects See Table V-A.5: Maintenance Standards - Catch Basins See Table V-A.S: Maintenance Standards - Catch Basins Maintenance ct or Prob- Condition When Maintenance is Needed Recommended Maintenance to Correct Problem Component lem Sediment Accu- Remove sediment deposits on grass treatment area of t hen finished, swale should be level from side to side and drain freely mutation on Sediment depth exceeds 2 inches. utlet. There should be no n ing water once inflow has ceased. Grass General Standing Water When water stands in the swale between storms and do ny of the following may apply: removes ash blockages, improve grade from head to foot of swale, remove clogged check dams, drain freely. add underdrains or convert to a wet biofiltration =wale. Flows er uneven or clogged so that flows are not uniformly Level the spreader and clean so that flows are spread evenly over entire swale width. distributed through entire swale width. 2019 Stormwater Management Manual for Western Washington Volume V - Appendix A - Page 1010 Recommended Frequency a Maintenance Com- Inspection Condition when Maintenance is Needed (Stand- ponent Routine Main- ards) Action Needed (Procedures) vegetation man- protocols) agement Note that the inspection and routine maintenance frequencies listed above are recommended by Ecology. They do se ce the municipal stormwater permit requirements for inspection frequency required of municipal stormwater per- mittees for "stormwater treatment and flow control BMPs/facilities". a Frequency: A = Annually; B = Biannually (twice per year); M = Monthl - east one visit should occur during the wet season (for debris/clog related maintenance, ction/maintenance visit should occur in the early fall, after deciduous trees have lost their leaves); S = Perform inspections of r storm events (24-hour storm event with a 10-year or greater recurrence interval). IPM -Integrated Pestt Mana e ISA - I ociety of Arboriculture Table V-A.22: Maintenance Standards - Permeable Pavement Recommended Frequency a Condition when Maintenance is Needed Component (Standards) Action Needed (Procedures) Inspection Routine Maintenance Surface/Wearing Course • Clean deposited soil or other materials from permeable pavement or other adjacent surfacing Permeable Pave- A S Runoff from adjacent pervious areas deposits • Check if surface elevation of planted area is too high, or slopes towards pavement, and can be regraded (prior ments, all soil, mulch or sediment on paving to regrading, protect permeable pavement by covering with temporary plastic and secure covering in place) • Mulch and/or plant all exposed soils that may erode to pavement surface Clean surface debris from pavement surface using one or a combination of the following methods: • Remove sediment, debris, trash, vegetation, and other debris deposited onto pavement (rakes and leaf blowers can be used for removing leaves) • Vacuum/sweep permeable paving installation using: A or B None (routine maintenance) Walk -behind vacuum (sidewalks) • High efficiency regenerative air or vacuum sweeper (roadways, parking lots) • ShopVac or brush brooms (small areas) Porous asphalt or per- • Hand held pressure washer or power washerwith rotating brushes Follow equipment manufacturer guidelines vious concrete for when equipment is most effective for cleaning permeable pavement. Dry weather is more effective for some equipment. • Review the overall performance of the facility (note that small clogged areas may not reduce overall per- formance of facility) Surface is clogged: Ponding on surface or water • Test the surface infiltration rate using ASTM C1701 as a corrective maintenance indicator. Perform one test Ab flows off the permeable pavement surface dur- per installation, up to 2,500 square feet. Perform an additional test for each additional 2,500 square feet up to ing a rain event (does not infiltrate) 15,000 square feet total. Above 15,000 square feet, add one test for every 10,000 square feet. • If the results indicate an infiltration rate of 10 inches per hour or less, then perform corrective maintenance to restore permeability. To clean clogged pavement surfaces, use one or combination of the following methods: 2019 Stormwater Management Manual for Western Washington Volume V - Appendix A - Page 1025 Table V-A.22: Maintenance Standards - Permeable Pavement (continued) Recommended Frequency a Condition when Maintenance is Needed Component (Standards) Action Needed (Procedures) Inspection Routine Maintenance • Combined pressure wash and vacuum system calibrated to not dislodge wearing course aggregate. • Hand held pressure washer or power washer with rotating brushes • Pure vacuum sweepers Note: If the annual/biannual routine maintenance standard to clean the pavement surface is conducted using equipment from the list above, corrective maintenance may not be needed. • Assess the overall performance of the pavement system during a rain event. If water runs off the pavement and/or there is ponding then see above. A Sediment present at the surface of the pave - ment • Determine source of sediment loading and evaluate whether or not the source can be reduced/eliminated. If the source cannot be addressed, consider increasing frequency of routine cleaning (e.g., twice per year instead of once per year). • Sidewalks: Use a stiff broom to remove moss in the summer when it is dry Summer Moss growth inhibits infiltration or poses slip safety hazard • Parking lots and roadways: Pressure wash, vacuum sweep, or use a combination of the two for cleaning moss from pavement surface. May require stiff broom or power brush in areas of heavy moss. • Fill potholes or small cracks with patching mixes • Large cracks and settlement may require cutting and replacing the pavement section. Replace in -kind where A Major cracks or trip hazards and concrete feasible. Replacing porous asphalt with conventional asphalt is acceptable if it is a small percentage of the spalling and raveling total facility area and does not impact the overall facility function. • Take appropriate precautions during pavement repair and replacement efforts to prevent clogging of adjacent porous materials Clean pavement surface using one or a combination of the following methods: • Remove sediment, debris, trash, vegetation, and other debris deposited onto pavement (rakes and leaf blowers can be used for removing leaves) • Vacuum/sweep permeable paving installation using: A or B None (routine maintenance) o Walk -behind vacuum (sidewalks) o High efficiency regenerative air orvacuum sweeper (roadways, parking lots) Interlocking concrete o ShopVac or brush brooms (small areas) paver blocks and Note: Vacuum settings may have to be adjusted to prevent excess uptake of aggregate from paver openings aggregate pavers orjoints. Vacuum surface openings in dry weather to remove dry, encrusted sediment. • Review the overall performance of the facility (note that small clogged areas may not reduce overall per- formance of facility) Surface is clogged: Ponding on surface or water • Test the surface infiltration rate using ASTM C 1701 as a corrective maintenance indicator. Perform one test Ab flows off the permeable pavement surface dur- per installation, up to 2,500 square feet. Perform an additional test for each additional 2,500 square feet up to ing a rain event (does not infiltrate) 15,000 square feet total. Above 15,000 square feet, add one test for every 10,000 square feet. • If the results indicate an infiltration rate of 10 inches per hour or less, then perform corrective maintenance to restore permeability. 2019 Stormwater Management Manual for Western Washington Volume V - Appendix A - Page 1026 Table V-A.22: Maintenance Standards - Permeable Pavement (continued) Recommended Frequency a Condition when Maintenance is Needed Component (Standards) Action Needed (Procedures) Inspection Routine Maintenance • Clogging is usually an issue in the upper 2 to 3 centimeters of aggregate. Remove the upper layer of encrusted sediment, and fines, and/or vegetation from openings and joints between the pavers by mechanical means and/or suction equipment (e.g., pure vacuum sweeper). • Replace aggregate in paver cells, joints, or openings per manufacturer's recommendations • Assess the overall performance of the pavement system during a rain event. If water runs off the pavement and/or there is ponding, then see above. A Sediment present at the surface of the pave - ment • Determine source of sediment loading and evaluate whether or not the source can be reduced/eliminated. If the source cannot be addressed, consider increasing frequency of routine cleaning (e.g., twice per year instead of once per year). • Sidewalks: Use a stiff broom to remove moss in the summer when it is dry Summer Moss growth inhibits infiltration or poses slip safety hazard • Parking lots and roadways: Vacuum sweep or stiff broom/power brush for cleaning moss from pavement sur- face A Paver block missing or damaged Remove individual damaged paver blocks by hand and replace or repair per manufacturer's recommendations A Loss of aggregate material between paver Refill per manufacturer's recommendations for interlocking paver sections blocks A Settlement of surface May require resetting • Remove sediment, debris, trash, vegetation, and other debris deposited onto pavement (rakes and leaf A or B None (routine maintenance) blowers can be used for removing leaves) • Follow equipment manufacturer guidelines for cleaning surface. Aggregate is clogged: Ponding on surface or • Use vacuum truck to remove and replace top course aggregate Ab water flows off the permeable pavement surface during a rain event (does not infiltrate) 0Replace aggregate in paving grid per manufacturer's recommendations • Remove pins, pry up grid segments, and replace gravel Open -celled paving A Paving grid missing or damaged • Replace grid segments where three or more adjacent rings are broken or damaged grid with gravel • Follow manufacturer guidelines for repairing surface. A Settlement of surface May require resetting A Loss of aggregate material in paving grid Replenish aggregate material by spreading gravel with a rake (gravel level should be maintained at the same level as the plastic rings or no more than 1/4 inch above the top of rings). See manufacturer's recommendations. • Manually remove weeds A Weeds present • Presence of weeds may indicate that too many fines are present (refer to Actions Needed under "Aggregate is clogged" to address this issue) • Remove sediment, debris, trash, vegetation, and other debris deposited onto pavement (rakes and leaf Open -celled paving A or B None (routine maintenance) blowers can be used for removing leaves) grid with grass • Follow equipment manufacturer guidelines for cleaning surface. 2019 Stormwater Management Manual for Western Washington Volume V - Appendix A - Page 1027 Table V-A.22: Maintenance Standards - Permeable Pavement (continued) Recommended Frequency a Condition when Maintenance is Needed Component (Standards) Action Needed (Procedures) Inspection Routine Maintenance Aggregate is clogged: Ponding on surface or Ab water flows off the permeable pavement surface Rehabilitate per manufacturer's recommendations. during a rain event (does not infiltrate) • Remove pins, pry up grid segments, and replace grass A Paving grid missing or damaged • Replace grid segments where three or more adjacent rings are broken or damaged • Follow manufacturer guidelines for repairing surface. A Settlement of surface May require resetting • Restore growing medium, reseed or plant, aerate, and/or amend vegetated area as needed A Poor grass coverage in paving grid • Traffic loading may be inhibiting grass growth; reconsider traffic loading if feasible As needed None (routine maintenance) Use a mulch mower to mow grass • Sprinkle a thin layer of compost on top of grass surface (1/2" top dressing) and sweep it in A None (routine maintenance) • Do not use fertilizer • Manually remove weeds A Weeds present • Mow, torch, or inoculate and replace with preferred vegetation Inlets/Outlets/Pipes Inlet/outlet A Pipe is damaged Repair/replace pipe A Pipe is clogged Remove roots or debris Clean orifice at least bian- Plant roots, sediment or debris reducing caps- • Jet clean or rota cut debris/roots from underdrain s rotary ( ) Underdrain pipe p p Clean pipe as needed p p nually (may need more fre- quent cleaning during wet cityof underdrain ma cause prolonged draw- (may p g If underdrains are equipped with a flow restrictor (e.g., orifice) to attenuate flows, the orifice must be cleaned season) down period) regularly Clean orifice at least bian- • Jet clean or rotary cut debris/roots from under-drain(s) Raised subsurface overflow pipe Clean as needed pipe nually (may need more fre- quent cleaning during wet Plant roots, sediment or debris reducing capa- city of underdrain If underdrains are equipped with a flow restrictor (e.g., orifice) to attenuate flows, the orifice must be cleaned season) regularly Outlet structure A, S Sediment, vegetation, or debris reducing capa- • Clear the blockage cityof outlet structure Identify the source of the blockage and take actions to prevent future blockages Overflow g Native soil is exposed or other signs of erosion Repair erosion and stabilize surface damage are present at discharge point Aggregate Storage Reservoir Water remains in the storage aggregate longer If immediate cause of extended ponding is not identified, schedule investigation of subsurface materials or other Observation port A, S than anticipated by design after the end of a potential causes of system failure. storm 2019 Stormwater Management Manual for Western Washington Volume V - Appendix A - Page 1028 Table V-A.22: Maintenance Standards - Permeable Pavement (continued) Recommended Frequency a Condition when Maintenance is Needed Component (Standards) Action Needed (Procedures) Inspection Routine Maintenance Vegetation Vegetation related fallout clogs or will potentially • Sweep leaf litter and sediment to prevent surface clogging and ponding Adjacent large As needed clog voids . Prevent large root systems from damaging subsurface structural components shrubs or trees Once in May and Once in Y Vegetation growing beyond facility edge onto 9 g 9 Y Y g Edging and trimming of planted areas to control roundcovers and shrubs from overreaching the sidewalks, paths and g g 9 p 9 g September sidewalks, paths, and street edge street edge improves appearance and reduces clogging of permeable pavements by leaf litter, mulch and soil. Leaves, needles, and o In fall (October tDecember) after leaf drop to11 times, Accumulation of organic debris and leaf litter Use leaf blower or vacuum to blow or remove leaves, evergreen needles, and debris (i.e., flowers, blossoms) off of organic debris depending on canopy cover) and away from permeable pavement Note that the inspection and routine maintenance frequencies listed above are recommended by Ecology. They do not supersede or replace the municipal stormwater permit requirements for inspection frequency required of municipal stormwater per- mittees for "stormwater treatment and flow control BMPs/facilities". a Frequency: A= Annually; B= Biannually (twice per year); S = Perform inspections after major storm events (24-hour storm event with a 10-year or greater recurrence interval). b Inspection should occur during storm event. Activity Objective Schedule Notes Structural and Dr " e Components Clear inlet pipes: Remove soil subs vegetation or other debris. Maintain free drain- age of inlet pipes. Twice annually. Inspect drain pipe: Check for cracks settling and prop nment, Maintain free drain - and correct and re -compact soils orfill material surrounding pipe, i e of inlet pipes. Twice annually. necessary. Inspect fire ventilation points for proper operation Fire and safety. Twice annually. Maintain egress and ingress: Clear routes of obstructions and main - Fire and safety. Twice ann tr tained to design standards. arden design should provide drainage rates that do not allow pooling of waterfor periods that promote insect larvae Insects: (see note) develop m f standing water is present for extended periods correct drainage problem. Chemical sprays should not be used. Prevent release of contaminants: Identify activities (mechanical During construction of systems maintenance, pet access, etc.) that can potentially release Wat ity pro- roof and then as determ- Any cause of pollutant release should be corre s soon as identified and the pollutant removed. pollutants to the roof garden and establish agreements to prevent ection. fined by inspection. release. Vegetation and Growth Medium Promote selected Invasive or nuisance s: Remove mand without herb- plant growth and sur- Twice annually.anually. At a minimum, schedule weeding with inspections to coincide with important horticultural cycles rior to major weed icide applicat' vival, maintain aes- varieties dispersing seeds). thetics. 2019 Stormwater Management Manual for Western Washington Volume V - Appendix - Page 1029