Document Redmond_doc_e5077cc2d9

Stormwater Management Report Conditional Use Permit Emerald Heights Independent/Assisted Living Buildings 10901 176th Circle NE, Redmond, WA 98052 June 1, 2018 PREPARED BY: Bart Balko, P.E. COUGHLIN PORTER LUNDEEN 801 Second Avenue, Suite 900 Seattle, WA 98104 P [PHONE REDACTED] ---PAGE BREAK--- i Table of Contents Page I. PROJECT OVERVIEW 1 General Description 1 Existing Conditions 1 Proposed Conditions 1 II. DRAINAGE ANALYSIS 2 Upstream Analysis 2 Analysis 3 III. PROPOSED DRAINAGE SYSTEM 3 Flow 3 Table 1.1: Existing Land Cover 4 Table 1.2: Proposed Development Land Cover 4 Table 1.3: Existing and Proposed Conditions Right-of-Way 5 Table 1.4: Existing and Proposed Condition Peak Flows Vault 1 5 Table 1.5: Existing and Proposed Condition Peak Flows Vault 2 5 Table 2.1: Existing Land Cover 6 Table 2.2: Proposed Development Land Cover 6 Table 2.3: Existing and Proposed Condition Peak Flows 7 Water Quality Treatment 7 IV. DISCUSSION OF MINIMUM REQUIREMENTS 8 MR Preparation of Stormwater Site Plans 8 MR Construction Stormwater Pollution Prevention Plan 8 MR Source Control of Pollution 9 MR Preservation of Natural Drainage Systems and Outfalls 9 MR On-Site Stormwater Management 9 MR Runoff Treatment 9 MR Flow Control 9 MR Wetlands Protection 10 MR Operation and Maintenance 10 V. TEMPORARY EROSION AND SEDIMENT CONTROL 11 VI. LOW IMPACT DEVELOPMENT 12 APPENDIX A.1: FIGURES 15 Figure 1 – Vicinity Map Figure 2 – Wellhead Protection Map Figure 3 – Existing Conditions Figure 4A – Proposed Conditions Figure 4E – Right-of-Way Conditions Figure 4F – Right-of-Way Conditions Figure 5 – Proposed TDA Area Swap Figure 6 – Campus Basin Figure 7A – Flow Chart for Determining LID MR #5 Requirements TDA 1 Figure 7B – Flow Chart for Determining LID MR #5 Requirements TDA 2 Figure 7C – Stormwater Notebook Figure 3.2 (MR Flow Chart) Figure 7D – Flow Chart for Determining LID MR #5 Requirements Figure 8 – Conveyance Map Figure 9A – Flow Chart for Determining Minimum Requirements TDA 1 Figure 9B – Flow Chart for Determining Minimum Requirements TDA 2 Figure 9C – Flow Chart for Determining Minimum Requirements ROW ---PAGE BREAK--- ii Table of Contents Page APPENDIX A.2: FIGURES 35 Figure 1 – Vicinity Map Figure 2 – COR Standard Maps Figure 3 – Wellhead Protection Map Figure 4 – Existing Conditions Figure 5 – Proposed Conditions Figure 6 – 100-Year Flow Figure 7a – Campus Basin & Conveyance System Figure 7b Conveyance Figure 8a – Stormwater Notebook Figure 3.2 (MR Flow Chart) Figure 8b – Flow Chart for Determining LID MR #5 Requirements Figure 9 –LID Site Plan APPENDIX B.1: ENGINEERING CALCULATIONS 53 MGS Flood Report Vault 1 MGS Flood Report Vault 2 APPENDIX B.2: ENGINEERING CALCULATIONS 64 MGS Flood Report APPENDIX C: CONVEYANCE ANALYSIS 70 APPENDIX D: GEOTECHNICAL REPORT 71 APPENDIX E: OPERATIONS AND MAINTANENCE MANUAL 72 ---PAGE BREAK--- I. PROJECT OVERVIEW General Description Emerald Heights first opened its doors in Redmond in 1992. A major additions and renovations project occurred in 2002 creating additional living units and expanding service facilities. Currently, Emerald Heights is in the process of a multi-phase additions and renovations project, the first of which was completed in 2012. The first phase of construction included the construction of a new fitness center, clinic connection, and multiple parking areas around the site. Phase 1 construction also included the expansion of an existing detention pond, first constructed as a part of the 2002 expansion, to mitigate the addition of impervious surfaces. The second phase of construction included the addition of a multi-purpose facility, new parking areas, the New Courtyard Building, and a multi-story residential building with below grade parking. The following is a summary of phases of work that is referenced in this report; o 2002 Improvements o Fitness Center (includes parking in various locations around the site) o Multi-purpose Building (Includes parking south of the main building) o Trailside Building (Residential building with below grade parking) o New Courtyard Building (current phase of development) – subject of this Stormwater Report o New Assisted Living Building (current phase of development) – subject of this Stormwater Report The current phases of construction, for which this drainage report is written, includes the addition of the residential buildings known as the New Courtyard Building and the New Assisted Living Building. These projects are classified as Large Projects by the City of Redmond Stormwater Technical Notebook and will trigger Minimum Requirements #1-9. This will be described further in Section IV. Existing Conditions The Emerald Heights Redmond Campus site is located adjacent to mostly residential properties and is directly north of Redmond High School. The site address is 10901 176th Circle NE, Redmond, WA 98052. The parcel numbers are [PHONE REDACTED] and [PHONE REDACTED]. The existing site is 37.8 acres and consists of five separate drainage basins (See Figure 6 – Campus Basin in Appendix A.1, A.2). Courtyard Building The New Courtyard Building project site is located at the southern edge of the parcel adjacent to 179th Avenue NE. Currently this area consists of a mix of covered and uncovered parking as well as landscaping and native vegetation. A nature trail exists south of the parking lot, which will be included in the final design of the Courtyard Building. Work for the Courtyard Building project will occur in Drainage Basin 3 and 5, with the majority of the work occurring in Basin 3. Assisted Living Building The New Assisted Living Building project site is located at the east end of the parcel adjacent to 179th Avenue NE. Currently this area consists of a mix of covered and uncovered parking as well as landscaping and native vegetation. A nature trail exists east of the parking lot, which will be included in the final design of the New Assisted Living Building. Work for the Assisted Living Building project will occur in Drainage Basin 4. Proposed Conditions Courtyard Building The proposed building consists of one and two levels of below grade parking and two, 3-stories above grade structures composed of residential units. Site development associated with the project will include grading, paving, site access, on-site stormwater management, and utility construction. The purpose of this stormwater 1 ---PAGE BREAK--- report is to provide an understanding of existing and proposed site conditions, as well as to outline the proposed drainage system. Figure 3.2 Flow Chart for determining Requirements for New Development (located in Appendix A.1) of the City of Redmond 2017 Stormwater Technical Notebook indicates that this project is required to comply with the modified minimum requirements #1-9 of the Stormwater Technical Notebook. As such, flow control and water quality treatment were evaluated for the portion of this project in Basin 3 (hereby referred to as Threshold Discharge Area 1 or TDA Flow control and water quality treatment are not required for the portion of this project in Basin 5 (hereby referred to as Threshold Discharge Area 2 or TDA as this area of the project encompasses less than 5,000 square-feet. An area swap between TDA 1 and TDA 2 will be implemented. This will be discussed further in Section III and can also be seen in detail in Appendix A.1 Figure 5 – Proposed Conditions: Area Swap. Assisted Living Building The proposed building consists of 1-level of below grade parking and 3-stories of above grade structure composed of residential units. Site development associated with the project will include grading, paving, site access, on-site stormwater management, and utility coordination (including a fire plan). The purpose of this stormwater report is to provide an understanding of existing and proposed site conditions, as well as to outline the proposed drainage system. Figure 3.2 Flow Chart for determining Requirements for New Development (located in Appendix A.2) of the City of Redmond 2012 Stormwater Technical Notebook indicates that this project is required to comply with the modified minimum requirements #1-9 of the Stormwater Technical Notebook. As such, flow control and water quality treatment were evaluated for this project. Courtyard Building/Assisted Living Building Additionally, 300 linear feet of right-of-way improvements will be constructed for each project for a total of 600 linear feet. These improvements will include installing a landscaped strip adjacent to the roadway, constructing a concrete sidewalk, and replacing the existing ditch with a series of storm pipes and catch basins. The right- of-way improvements are considered bypass area of each project as discussed further in Section III. The right- of-way improvements can be seen in Figure 4E: Right-of-Way Conditions, located in Appendix A.1. II. DRAINAGE ANALYSIS Upstream Analysis Courtyard Building The proposed site will match the existing grade at the project limits as to not alter flow paths or drainage basins. There are no significant upstream areas that drain onto the project site. The adjacent “Trailside” building to the west has an existing fire lane which runs north-south between the buildings is at a higher elevation and will require a new catch basin to collect runoff. This upstream area will be considered area swap for uncaptured disturbed area and will be detained in Vault 1, see Proposed Drainage System section below. Assisted Living Building The proposed site will match the existing grade at the project limits as to not alter flow paths or drainage basins. However, the proposed location of the detention vault and building replace an existing stormwater dispersion trench; the site will receive some fairly non-significant flows from the previously dispersed area but they will be accounted for in the stormwater detention vault design. 2 ---PAGE BREAK--- Analysis Courtyard Building The proposed project will discharge to two different discharge points. The TDA 1 storm system discharges to an existing detention pond. Stormwater detained by the existing detention pond discharges to the existing 12- inch public storm main along NE 110th Way. The public storm system flows via a piped drainage system through residential neighborhoods to its outfall into Tylers Creek. TDA 2 sheet flows to a dispersion trench and then flows to the existing public system along 176th Ave NE. This leads to NE 108th Way and eventually discharges to Tylers Creek more than ¼ mile south of the TDA 1 discharge area. Tylers Creek drains to the south east and eventually drains to Bear Creek. Bear Creek drains to the south, eventually joining the Sammamish River near the 520 Bridge crossing south of downtown Redmond. Please see Figure 8 – Conveyance Map in Appendix A.1. Assisted Living Building The proposed site will discharge to the private storm outfall to the public storm system within the 179th Avenue NE Right-of-Way. The public storm system flows via a piped drainage system through residential neighborhoods to its outfall into Tylers Creek. Tylers Creek drains to the south east and eventually drains to Bear Creek. Beer Creek drains to the south, eventually joining the Sammamish River near the 520 Bridge crossing south of downtown Redmond. See Figure 7a and 7b – Campus Basin and Conveyance Map & Conveyance in Appendix A.2. III. PROPOSED DRAINAGE SYSTEM Flow Control Courtyard Building The proposed development requires flow control for TDA 1 based on criteria set forth in the 2017 City of Redmond Stormwater Technical Notebook; Flow control facilities are required for “projects in which the total effective impervious surfaces is 10,000 square feet or more in a threshold discharge area.” Flow control is not required for TDA 2, as there are less than 10,000 square feet of impervious surfaces. Because of this, the TDA 2 area will not be draining to the vaults but will instead be routed to a 21-foot dispersion trench in the southeast corner of the site. This dispersion trench disperses 1,443 square feet of impervious area. This section outlines the system used to achieve compliance with the 2014 minimum requirements as adapted by the City of Redmond. Flow control on-site in TDA 1 will be achieved through two concrete detention vaults located at the north edge of the building. The proposed vaults provide 25,590 cubic feet of live storage for runoff collected from the roof and surrounding landscape/hardscape. The graphic for the contributing area to the detention vaults and to the dispersion trench can be found in Figure 4A – Proposed Conditions of Appendix A.1. There are two bypass areas that will also be included in TDA 1. The right-of-way improvements and portions of the site that can be seen in Figure 4F/4E – ROW Conditions of Appendix A.1. The right-of-way improvements and all on-site bypass areas have been included in the MGS Flood calculations for Vault 1. See Table 1.2 below for a breakdown of the land cover areas. An area swap will be taking place between Basin 3 and Basin 5 (TDA 1 and TDA 7,518 square-feet of area from the original Basin 5 will now be draining to Vault 2 in Basin 3 and 7,485 square-feet of area to the southwest of the site that originally drained to Basin 3 is now draining to the dispersion trench in Basin 5. This area swap can be seen in greater detail in Figure 5 - Proposed Conditions: Area Swap of Appendix A.1. 3 ---PAGE BREAK--- TABLE 1.1: EXISTING LAND COVER Land Cover TDA 1 Existing TDA 2 Existing Totals Non-Pollution Generating Impervious Surface (NPGIS) 1,720 SF (0.040 acres) 0 1,720 SF (0.040 acres) Pollution Generating Impervious Surface (PGIS) 19,565 SF (0.449 acres) 0 19,565 SF (0.449 acres) Pervious Surfaces 20,645 SF (0.474 acres) 16,490 SF (0.379 acres) 37,135 SF (0.853 acres) Total Area 41,930 SF (0.963 acres) 16,490 SF (0.379 acres) 58,420 SF (1.341 acres) TABLE 1.2: PROPOSED DEVELOPMENT LAND COVER Land Cover Vault 1 Proposed Vault 2 Proposed TDA 2 TOTAL Proposed Non-Pollution Generating Impervious Surface (NPGIS) 12,108 SF (0.278 acres) 18,229 SF (0.419 acres) 1,443 SF (0.033 acres) 31,780 SF (0.730 acres) Pollution Generating Impervious Surface (PGIS) 3 1,682 SF (0.039 acres) 2,706 SF (0.062 acres) 0 4,388 SF (0.101 acres) Pervious Surfaces 2,155 SF (0.050 acres) 1,303 SF (0.030 acres) 12,305 SF (0.283 acres) 15,763 SF (0.362 acres) Total Area (without bypass) 15,945 SF (0.366 acres) 22,238 SF (0.511 acres) 13,748 SF (0.316 acres) 51,931 SF (1.192 acres) Vegetated Roof 1 0 3,015 SF (0.069 acres) 0 3,015 SF (0.069 acres) NPGIS Bypass2 1,685 SF (0.039 acres) 0 342 SF (0.008 acres) 2,027 SF (0.047 acres) PGIS Bypass2 630 (0.015 acres) 0 0 630 SF (0.015 acres) Landscape Bypass2 1,045 (0.024 acres) 0 1,280 SF (0.029 acres) 2,325 SF (0.053 acres) 1Vegetated roof area is included in the total “Non-Pollution Generating Impervious Surface (NPGIS)” area. 2All TDA 1 and Right-of-Way bypass is included in Vault 1 calculations. 3 PGIS to Vault 1 includes 1,682 SF of off-site area 4 ---PAGE BREAK--- TABLE 1.3: EXISTING AND PROPOSED CONDITIONS RIGHT-OF-WAY Land Cover Existing Proposed Non-Pollution Generating Impervious Surface (NPGIS) 3,225 SF (0.074 acres) 3,290 SF (0.076 acres) Pervious Surfaces 2,485 SF (0.057 acres) 2,420 SF (0.055 acres) Total Area 5,710 SF (0.131 acres) 5,710 SF (0.131 acres) The right-of-way areas do not trigger water quality, but the areas will be included for the flow control calculations of Vault 1 as mentioned previously. The proposed detention vault systems within TDA 1 shall match flow durations from forested conditions between 50% of the 2-year storm event through the full 50-year storm event, according to 2014 as adapted by the City of Redmond. This will include the bypass areas from the right-of-way and on-site. As mentioned previously, flow control is not required for TDA 2. The peak flows of pre-existing (forested) and proposed conditions, calculated in MGS Flood, are: TABLE 1.4: EXISTING AND PROPOSED CONDITION PEAK FLOWS VAULT 1 Pre-existing Runoff Vault 1 Post-development Runoff Vault 1 Net Reduction Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) Discharge (cfs) 2-Year 0.009 2-Year 0.010 -0.001 10-Year 0.019 10-Year 0.014 0.005 100-Year 0.035 100-Year 0.019 0.016 TABLE 1.5: EXISTING AND PROPOSED CONDITION PEAK FLOWS VAULT 2 Pre-existing Runoff Vault 1 Post-development Runoff Vault 1 Net Reduction Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) Discharge (cfs) 2-Year 0.012 2-Year 0.011 0.001 10-Year 0.026 10-Year 0.021 0.005 100-Year 0.049 100-Year 0.029 0.020 The complete MGS Flood reports for each vault can be found in Appendix B.1: Engineering Calculations. 5 ---PAGE BREAK--- Assisted Living Building The proposed development requires flow control based on criteria set forth in the 2012 City of Redmond Stormwater Technical Notebook; Flow control facilities are required for “projects in which the total effective impervious surfaces is 10,000 square feet or more in a threshold discharge area.” This section outlines the system used to achieve compliance with the 2014 minimum requirements as adapted by the City of Redmond. Flow control on-site will be achieved through a concrete detention vault located at the south side of the building. The proposed vault provides 15,000 cubic feet of live storage for runoff collected from the roof and surrounding landscape/hardscape. The graphic for the contributing area to the detention vault can be found in Figure 5 – Proposed Conditions of Appendix A.2. See Table 2.2 below for a breakdown of the land cover areas. TABLE 2.1: EXISTING LAND COVER Land Cover Existing Area Non-Pollution Generating Impervious Surface (NPGIS) 7,230 SF (0.16 ac) Pollution Generating Impervious Surface (PGIS) 2,950 SF (0.07 ac) Pervious Surfaces 28,020 SF (0.64 ac) Upstream Impervious Surface 1,980 SF (0.05 ac) Total Area 40,180 SF (0.92 ac) TABLE 2.2: PROPOSED DEVELOPMENT LAND COVER Land Cover Existing Area Non-Pollution Generating Impervious Surface (NPGIS) 21,800 SF (0.50 ac) Pollution Generating Impervious Surface (PGIS) 3,430 SF (0.08 ac) Pervious Surfaces 12,970 SF (0.29 ac) Upstream Impervious Surface 1,980 SF (0.05 ac) Total Area 40,180 SF (0.92 ac) Vegetated Roof1 1,540 SF (0.04 ac) 1Vegetated roof area is included in the total “Non-Pollution Generating Impervious Surface (NPGIS)” area. The proposed system shall match flow durations from forested conditions between 50% of the 2-year storm event through the full 50-year storm event, according to 2014 as adapted by the City of Redmond. 6 ---PAGE BREAK--- The peak flows of pre-existing (forested) and proposed conditions, calculated in MGS Flood, are: TABLE 2.3: EXISTING AND PROPOSED CONDITION PEAK FLOWS Pre-existing Runoff Post-development Runoff Net Reduction Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) Discharge (cfs) 2-Year 0.020 2-Year 0.017 0.003 10-Year 0.042 10-Year 0.037 0.005 100-Year 0.078 100-Year 0.049 0.029 The complete MGS Flood report can be found in Appendix B.2: Engineering Calculations. Water Quality Treatment Courtyard Building The proposed development does not require water quality based on criteria set forth in the 2012 City of Redmond Stormwater Technical Notebook; Water quality facilities are required for “projects in which the total of pollution generating impervious surface (PGIS) is 5,000 square feet or more in a threshold discharge area of the project.” The proposed development will decrease the amount of PGIS by 14,547 square feet. New PGIS area equals 3,336 SF, refer to Table 1.2. Assisted Living Building The proposed development does not require water quality based on criteria set forth in the 2012 City of Redmond Stormwater Technical Notebook; Water quality facilities are required for “projects in which the total of pollution generating impervious surface (PGIS) is 5,000 square feet or more in a threshold discharge area of the project.” Though water quality is not required per City of Redmond requirements, a wet vault is proposed in order to reduce the potential sediment carried in the stormwater runoff from accumulating in structures. The wet vault supplies an average of 2.04 feet of water quality depth to supply a total of 5,140 cubic feet of water quality volume. MGS Flood was utilized to calculate the required water quality volume to treat 91 percent of the entire runoff volume over a multi-decade period of record. The water quality design storm volume was calculated to equal 2,750 cubic feet, and therefore the proposed wet vault provides sufficient volume. 7 ---PAGE BREAK--- IV. DISCUSSION OF MINIMUM REQUIREMENTS Courtyard Building All Minimum Requirements are required for TDA 1, and only Minimum Requirements 1 and 2 are required for TDA 2. Please refer to Appendix A.1 Figure 9A and 9B – Flow Chart for Determining Minimum Requirements. Assisted Living Building All Minimum Requirements are required for the project. Please refer to Appendix A.2 Figure 8A and 8B – Flow Chart for Determining Minimum Requirements. MR Preparation of Stormwater Site Plans Stormwater plans and reports that address each of the applicable minimum requirements will be prepared by a licensed civil engineer in accordance with City Requirements. MR Construction Stormwater Pollution Prevention Plan A will be provided at a later date and a CESCL will be appointed by the contractor. a. Element 1: Preserve Vegetation/Mark Clearing Limits i. Clearing Limits are noted on plans and will be implemented prior to any offsite impacts or damage due to construction. Existing vegetation will be protected and retained to the maximum extent feasible. b. Element 2: Establish Construction Access i. The Contractor, per the plans, shall implement necessary BMP measures to ensure sediment does not leave site onto streets or adjacent properties. c. Element 3: Control Flow Rates i. Project construction shall implement sediment ponds and/or baker tanks in accordance with City standards. d. Element 4: Install Sediment Controls i. Project construction shall implement sediment ponds and/or baker tanks in accordance with City standards. A will be provided at a later date and a CESCL will be appointed by the contractor. e. Element 5: Stabilize Soils i. Soils shall be stabilized through a series of BMPs for any period of more than 7 days in dry weather or 2 days in wet weather. f. Element 6: Protect Slopes i. All slopes will incorporate the applicable BMPs per the plans including straw mulch, plastic sheeting, and hydroseed. g. Element 7: Protect Drain Inlets i. Existing drains shall be protected where applicable through the project site. h. Element 8: Stabilize Channels and Outlets i. Channels and outlets shall be protected and stabilized where applicable through the project site. i. Element 9: Control Pollutants i. BMPs shall be implemented to prevent or treat contamination of stormwater runoff by pH modifying sources. In addition, all waste materials from the site will be removed in a manner that does not cause contamination of stormwater. j. Element 10: Control De-Watering 8 ---PAGE BREAK--- i. De-watering is not expected to be implemented for either project due to low groundwater, however, some seepage into excavation is anticipated. Temporary pumps will be implemented as necessary during construction. k. Element 11: Maintain BMPs i. BMPs listed in the shall be maintained as needed through each project. As portions of each project get completed, portions of the established BMPs shall be adjusted to other areas of the project site until their completion. l. Element 12: Manage the Project i. Proposed erosion and sediment control measures will be implemented throughout construction as needed. MR Source Control of Pollution Stormwater will be prevented from coming in contact with pollutants through a series of BMPs listed within the A will be provided at a later date and a CESCL will be appointed by the contractor. MR Preservation of Natural Drainage Systems and Outfalls receiving waters will not be adversely affected by the construction or completion of these projects. No new drainage patterns offsite are expected with these projects. The projects are conveying water to the same private storm system as the existing condition. MR On-Site Stormwater Management Projects shall employ On-site Stormwater Management BMPs to infiltrate, disperse, and retain stormwater runoff onsite to the maximum extent feasible without causing flooding or erosion impacts during construction. Finished conditions for the site will meet the requirements set forth in #6-9. See Section “VI Low Impact Development” for implementation of stormwater BMPs. MR Runoff Treatment Courtyard Building On-site constructed water quality measures are not required for this project. The project proposes less than 5,000 square feet of PGIS within the project line therefore no water quality facilities are required. Assisted Living Building On-site constructed water quality measures are not required for this project. The project proposes less than 5,000 square feet of PGIS within the project line therefore no water quality facilities are required. However, in order to reduce future maintenance for structures from the detention vault, 5,140 cubit feet of water quality storage is being proposed as a wet vault. Projects located in Well Protection Zone III are subject to additional water quality requirements, however the project is not proposing to surface discharge PGIS nor infiltrate and therefore the project is not required to implement additional water quality measures. MR Flow Control Courtyard Building On-site constructed flow control measures are required for TDA 1 of this project. The project is proposing more than 10,000 square feet of effective impervious surfaces within TDA 1; therefore, two concrete detention vaults are proposed to meet flow control requirements. The project is proposing less than 10,000 square feet of effective impervious surfaces within TDA 2, so TDA 2 is not required to meet flow control requirements. 9 ---PAGE BREAK--- Assisted Living Building On-site constructed flow control measures are required for this project. The project is proposing more than 10,000 square feet of effective impervious service therefore a concrete detention vault is proposed to meet flow control requirements. MR Wetlands Protection Stormwater from this site does not discharge into a wetland and therefore wetlands protection is not required as per section 2.5.8 of the City of Redmond Clearing, Grading, and Stormwater Management Technical Notebook. MR Operation and Maintenance An operation and maintenance manual that is consistent with the provision in Volume V of the City’s Stormwater Technical Notebook shall be provided for all proposed stormwater facilities and BMPs. The Operation and Maintenance Manual will be provided in Appendix E in later editions of this report during the CCR process. 10 ---PAGE BREAK--- V. TEMPORARY EROSION AND SEDIMENT CONTROL Erosion control systems will be implemented throughout the construction process until the site is stabilized. All temporary erosion and sedimentation control requirements will comply with Chapter 15.24 of the Redmond Municipal Code and the Department of Ecology (DOE) Best Management Practices (BMPs). Best Management Practices are defined as physical, structural and/or managerial practices, that when used singly or in combination, prevent or reduce pollution of storm water runoff caused by construction activities. The Dry Season Temporary Erosion and Sedimentation Control plan for the proposed site has been designed to protect off-site properties as well as to prevent sediment-laden water from entering the public storm system. A “wet weather plan” will be developed prior to construction in the rainy season. 11 ---PAGE BREAK--- VI. LOW IMPACT DEVELOPMENT Low impact development (LID) on the project site was assessed to meet the minimum requirements set forth in Sections 8.7.4 and 8.7.5 of the 2012 Stormwater Technical Notebook. This project is required to evaluate the feasibility of BMPs in List #2 of the 2014 but is not required to meet the LID Performance Standard (See Appendix A.1 Figure 9C Flow Chart for Determining LID MR #5 Requirements and Appendix A.2 1 Figure 8B Flow Chart for Determining LID MR #5 Requirements). The following LID BMP’s were considered to implement On-Site Stormwater Management and to meet LID Performance Standards: Courtyard Building Post-Construction Soil Quality and Depth: Post-Construction soil quality and depth will be implemented for the entire 17,688 square feet of the proposed landscaped areas within TDA 1 and TDA 2. Full Dispersion: The available native vegetation flow path length at a less than 3:1 slope is less than 100 feet; therefore, full dispersion has been deemed infeasible for the project. Downspout Full Infiltration: Downspout full infiltration has been deemed infeasible for the project because the site does not meet minimum setback requirements, the site does not consist of outwash or loam soils, and the native soils do not meet minimum required infiltration rates. Bioretention Cells, Swales, and Planter Boxes: Bioretention has been deemed infeasible for on-site stormwater management because infiltration was deemed infeasible for the project: bioretention may be used with underdrains when the native soil infiltration rates are less than 0.30 inches/hour, however in order to receive credit for on-site stormwater management underdrains must not be used. Downspout Dispersion Systems: Downspout dispersion systems have been deemed infeasible because it does not meet minimum required vegetated flow path and minimum required setbacks from the property line and structures. Perforated Stub-Out Connections: Roof area routed through a downspout dispersion system could not be routed to the detention vault via gravity flow in all cases. Permeable Pavements: Permeable pavements have been deemed infeasible for on-site stormwater management because the native soil infiltration rate is less than 0.30 inches/hour; permeable pavements may be used with underdrains when the native soil infiltration rates are less than 0.30 inches/hour, however in order to receive credit for on-site stormwater management underdrains must not be used. Sheet Flow Dispersion: Sheet flow dispersion has been deemed infeasible because the on-site impervious surfaces either 1) do not have a vegetated surface directly adjacent or 2) are concentrated flows. Concentrated Flow Dispersion: Due to site constraints concentrated flows would not maintain the minimum vegetated flow of at least 50 feet between the discharge point and the property line. Tree Retention and Tree Planting: The project proposes to retain 7 trees on site and to plant 67 trees. Of the 74 total trees 3 existing evergreens, 5 new deciduous, and 9 new evergreen trees will be used for onsite stormwater management. The trees used for onsite stormwater management fulfill the requirements of size and proximity to ground level impervious surface. The new and retained trees mitigate a total of 850 square feet (0.02 acres) of impervious area. Vegetated Roofs: The project proposed 2,945 square-feet of vegetated roof with more than 8 inches of soil. Vegetated roof used for onsite stormwater management can be modelled as 50% impervious and 50% pervious area, as stated in the 2014 12 ---PAGE BREAK--- Assisted Living Building Post-Construction Soil Quality and Depth: Post-Construction soil quality and depth will be implemented for the entire 11,290 square feet of the proposed landscaped area. Full Dispersion: The available native vegetation flow path length at a less than 3:1 slope is less than 100 feet, therefore full dispersion has been deemed infeasible for the project. Downspout Full Infiltration: Downspout full infiltration has been deemed infeasible for the project because the site does not meet minimum setback requirements, the site does not consist of outwash or loam soils, and the native soils do not meet minimum required infiltration rates. Bioretention Cells, Swales, and Planter Boxes: Bioretention has been deemed infeasible for on-site stormwater management because infiltration was deemed infeasible for the project: bioretention may be used with underdrains when the native soil infiltration rates are less than 0.30 inches/hour, however in order to receive credit for on-site stormwater management underdrains must not be used. Downspout Dispersion Systems: Downspout dispersion systems have been deemed infeasible because it does not meet minimum required vegetated flow path and minimum required setbacks from the property line and structures. Perforated Stub-Out Connections: The roof is internally drained and no downspouts are proposed for the project. Additionally, roof area routed through a downspout dispersion system could not be routed to the detention vault via gravity flow. Permeable Pavements: Permeable has been deemed infeasible for on-site stormwater management because the native soil infiltration rate is less than 0.30 inches/hour; permeable pavements may be used with underdrains when the native soil infiltration rates are less than 0.30 inches/hour, however in order to receive credit for on-site stormwater management underdrains must not be used. Sheet Flow Dispersion: Sheet flow dispersion has been deemed infeasible because the impervious surfaces onsite either 1) do not have a vegetated surface directly adjacent or 2) are concentrated flows. Concentrated Flow Dispersion: Due to site constraints concentrated flows would not maintain the minimum vegetated flow of at least 50 feet between the discharge point and the property line or the adjacent existing detention pond. Tree Retention and Tree Planting: The project proposes to retain 7 trees on site and to plant 93 trees. Of the 100 total trees 3 existing evergreens, 7 new deciduous, and 7 new evergreen trees will be used for onsite stormwater management. The trees used for onsite stormwater management fulfill the requirements of size and proximity to ground level impervious surface. The new and retained trees mitigate a total of 790 square feet (0.02 acres) of impervious area. Vegetated Roofs: The project proposed 1,540 square feet of vegetated roof with more than 8 inches of soil. Vegetated roof used for onsite stormwater management can be modelled as 50% impervious and 50% pervious area, as stated in the 2014 Due to site constraints and infeasibility criteria provided above the project is proposing to provide Onsite Stormwater Management and LID to the maximum extent feasible. 13 ---PAGE BREAK--- The following are the responses to the site assessment minimum requirements as noted in Section 8.7.5: 1. A survey prepared by a registered land surveyor showing existing public and private development, including utility infrastructure, on and adjacent to the site, major and minor hydrologic features, including seeps, springs, closed depression areas, drainage swales, and 2 foot contours up to 10 percent slope and 5 foot contours for slopes above 10 percent. Spot elevations shall be at 25 foot intervals. A survey has been prepared by a registered land surveyor meeting the required criteria. 2. Location of all existing lot lines, lease areas and easements. A survey has been prepared by a registered land surveyor meeting the required criteria. 3. A soils report prepared by a licensed geotechnical engineer or licensed engineering geologist. The report shall identify: a. Underlying soils on the site utilizing soil pits and soil grain analysis to assess infiltration capability on site. The frequency and distribution of test pits shall be adequate to direct placement of the roads and structures away from soils that can most effectively infiltrate stormwater; b. Percolation tests if appropriate or requested by the Stormwater Engineer; c. Topographic and geologic features that may act as natural stormwater storage or conveyance and underlying soils that provide opportunities for storage and partial infiltration; d. Depth to wet season high groundwater; e. Geologic hazard areas and associated buffer requirements as defined in RZC 21.64.060; f. Distance from site boundaries to any areas within 200 feet of the site identified as landslide hazard areas or having a slope of 40 percent or steeper with a vertical relief of 10 feet or more; [Note: The City may require the applicant to expand the 200 feet to encompass a larger area if there are concerns for geological hazards.] g. Identification of Wellhead Protection Zone(s); and h. For previously cleared or graded sites, analysis of topsoil according to the soil i. requirements in the City of Redmond Standard Specifications, Section 9.14.1. A geotechnical report has been prepared by a licensed geotechnical engineer meeting the required criteria (see Appendix D, Geotechnical Report), which includes a letter describing the infiltration testing done on-site. As an added clarification to the submitted documents the project Geotechnical Engineer, Jeffrey Laub, has confirmed that it is his professional opinion that infiltration is infeasible onsite due to the presence of very dense glacially consolidated lodgment till soils. In addition to the limited infiltration on-site there is not any location to install an infiltration facility due to City of Redmond setback requirements; see Appendix A.2 Figure 9 - LID Site Plan for addition information. Also, a topographic survey has been prepared by a licensed surveyor to meet the required criteria. 4. A survey of existing native vegetation cover and wildlife habitat by a qualified biologist identifying any forest areas on the site, species and condition of ground cover and shrub layer, and tree species, seral stage, and canopy cover. A survey has been prepared by a registered land surveyor meeting the required criteria. 5. A streams, wetland, and water body survey and classification report by a qualified biologist showing wetland and buffer boundaries consistent with the requirements of RZC 21.64.030 and Critical Areas Reporting Requirements (RZC Appendix A survey has been prepared by a registered land surveyor meeting the required criteria. 6. Flood hazard areas on or adjacent to the site. A survey has been prepared by a registered land surveyor. There are no flood hazards on or adjacent to the site. 7. A preliminary drainage report providing analysis of the existing site hydrologic conditions on the site and recommendations for type, location, and restrictions on LID BMPs. See Appendix B.1 and B.2, Drainage Calculations, for a hydrologic analysis of the project site. 8. Other studies as deemed necessary by the Stormwater Engineer. No other documents have been identified as being necessary for LID assessment. 14 ---PAGE BREAK--- APPENDIX A.1: FIGURES Figure 1 – Vicinity Map Figure 2 – Wellhead Protection Map Figure 3 – Existing Conditions Figure 4A – Proposed Conditions Figure 4E – Right-of-Way Conditions Figure 4F – Right-of-Way Conditions Figure 5 – Proposed TDA Area Swap Figure 6 – Campus Basin Figure 7A – Flow Chart for Determining LID MR #5 Requirements TDA 1 Figure 7B – Flow Chart for Determining LID MR #5 Requirements TDA 2 Figure 7C – Stormwater Notebook Figure 3.2 (MR Flow Chart) Figure 7D – Flow Chart for Determining LID MR #5 Requirements ROW Figure 8 – Conveyance Map Figure 9A – Flow Chart for Determining Minimum Requirements TDA 1 Figure 9B – Flow Chart for Determining Minimum Requirements TDA 2 Figure 9C – Flow Chart for Determining Minimum Requirements ROW 15 ---PAGE BREAK--- EH: Independent Living Building C160134-01 Rice Fergus Miller 01-04-2018 BLH BSB Project Site 801 Second Avenue, Seattle, WA 98104 Figure 1 - Vicinity Map NTS Emerald Heights Redmond Campus 16 ---PAGE BREAK--- Figure 2 - Wellhead Protection Map Not to Scale EH: Independent Living Building C160134-01 Rice Fergus Miller 01-04-2018 BLH BSB Project Site 17 ---PAGE BREAK--- 176TH CIRCLE NE 1"=40' TDA 2 Site Boundary Pervious TDA 1 NPGIS TDA 1 PGIS TDA 1 Pervious TDA 2 Legend 20,645 SF 1,720 SF 19,565 SF 16,490 SF Total Area = 58,420 SF (1.317 acres) TDA 1 TDA 1 is a portion of Basin 3, and TDA 2 is a portion of Basin 5. See Figure 5. Proposed Building Outlines 18 Emerald Heights - Courtyard Independent Living C160134-01 06-01-2018 Figure 3 Existing Conditions ---PAGE BREAK--- 176TH CIRCLE NE Figure 4A OVERALL PROPOSED CONDITIONS 1" = 40' Dispersion Trench Vault 2 Bypass area modeled with Vault 1 in MGS Flood TDA 1 is a portion of Basin 3, and TDA 2 is a portion of Basin 5. See Figure 5. Vault 1 Site Boundary Green Roof TDA 1 Landscape Bypass Landscape TDA 1 Landscape TDA 2 Landscape TDA 2 Bypass Off-Site Landscape Area Swap Off-Site NPGIS Area Swap NPGIS Bypass NPGIS TDA 1 NPGIS TDA 2 NPGIS TDA 2 Bypass Off-Site PGIS to Vault 1 PGIS Bypass PGIS TDA 1 Roof TDA 1 Legend 3,015 SF 1,045 SF 2,528 SF 12,305 SF 1,280 SF 930 SF 73 SF 1,685 SF 4,516 SF 1,443 SF 342 SF 1,682 SF 630 SF 2,706 SF 24,240 SF Total Area = 58,420 SF (1.317 acres) See Figures 4B, 4C, 4D, and 4E for breakdowns of Vault 1, Vault 2, TDA 2, and ROW. See Figure 5 for a breakdown of Area Swap. Off-site area to Vault 1: Area Swap Total On-Site Area = 55,735 SF (1.280 acres) 19 Emerald Heights - Courtyard Independent Living C160134-01 06-01-2018 ---PAGE BREAK--- 51+00 52+00 53+00 51+50 52+50 53+50 *All ROW Landscape area and all but 0.011 acres of ROW NPGIS area is being modeled as Vault 1 Bypass. 0.011 acres of ROW NPGIS area is being modeled as Vault 2 Bypass. Existing Proposed Pervious NPGIS Legend 1,045 SF 1,600 SF Total Area* = 2,645 SF 1" = 30' Pervious NPGIS Legend 1,125 SF 1,520 SF Total Area = 2,645 SF 20 Emerald Heights - Independent Living Courtyard Building C160134-01 06-01-2018 Figure 4E Right-Of-Way Conditions ---PAGE BREAK--- 54+00 55+00 56+00 54+50 55+50 56+50 Existing Proposed Pervious NPGIS Legend 1,375 SF 1,690 SF Total Area = 3,065 SF 1" = 30' Pervious NPGIS Legend 1,360 SF 1,705 SF Total Area = 3,065 SF 21 Emerald Heights - Independent Living Courtyard Building C160134-01 06-01-2018 Figure 5B Right-Of-Way Conditions ---PAGE BREAK--- 22 Emerald Heights - Courtyard Independent Living C160134-01 05-14-2018 FIGURE 5 PROPOSED CONDITIONS: AREA SWAP 176TH CIRCLE NE Site Boundary TDA 2 Boundary Roof TDA 1 (Area Swap) Green Roof TDA 1 (Area Swap) Landscape TDA 2 Bypass (Area Swap) Landscape TDA 2 (Area Swap) NPGIS TDA 1 Bypass (Area Swap) NPGIS TDA 1 (Area Swap) NPGIS TDA 2 (Area Swap) PGIS TDA 1 Bypass (Area Swap) Landscape TDA 2 Landscape TDA 2 Bypass NPGIS TDA 2 NPGIS TDA 2 Bypass Legend Total Area Swapped = 16,195 SF 7,376 SF 154 SF 468 SF 6,390 SF 283 SF 65 SF 1,094 SF 365 SF 18,225 SF 2,559 SF 1,793 SF 684 SF 1" = 40' ---PAGE BREAK--- LUNDEEN PORTER COUGHLIN Basin 2 3.2 ac Basin 3 6.7 ac Pond 3 Pond 1 Tributary Basin Pond 2 Basin 4 1.7 ac Basin 1 25.3 ac Flow Splitter Pond 1 Figure 5 - Campus Basin Conveyance Pipe Bypass flows to existing Pond 3 Proposed Courtyard Building Basin 5 0.9 ac Connection to existing private storm system 23 ---PAGE BREAK--- No, the project triggered only MR #2 No, the project triggered MRs #1 - No, the project is outside the UGA. No, project developer chose List No, project developer chose List Flow Chart for Determining LID MR #5 Requirements Did the project developer choose to meet the LID Performance Standard? Does the project discharge to Flow Control Exempt Waters (per Minimum Requirement (MR) Yes Does the project trigger only MRs #1 - (Per Figure 3.2 or Figure 3.3 in Appendix 1 of the 2013-2018 WWA Phase II Permit & Phase I Permit.) No Yes Did the project developer choose to meet the LID Performance Standard? Yes REQUIRED: Meet the LID Performance Standard through the use of any BMP(s) in the 2012 or the LID Technical Guidance Manual for Puget Sound except for Rain Gardens (the use of Bioretention is acceptable). REQUIRED for Projects Triggering MR Apply BMP T5.13 Post-Construction Soil Quality and Depth. NOT REQUIRED: Applying the BMPs in List #1 or List REQUIRED: For each surface, consider the BMPs in the order listed in List #1 for that type of surface. Use the first BMP that is considered feasible. NOT REQUIRED: Achievement of the LID Performance Standard. REQUIRED: For each surface, consider the BMPs in the order listed in List #2 for that type of surface. Use the first BMP that is considered feasible. NOT REQUIRED: Achievement of the LID Performance Standard. Is the project inside the UGA? Yes Is the project on a parcel of 5 acres or larger? REQUIRED: Meet the LID Performance Standard through the use of any BMP(s) in the 2012 or the LID Technical Guidance Manual for Puget Sound except for Rain Gardens (the use of Bioretention is acceptable). If the project can’t meet the LID Performance Standard, it must be redesigned to meet the LID performance standard or an exception / variance must be approved. REQUIRED: Apply BMP T5.13 Post- Construction Soil Quality and Depth. NOT REQUIRED: Applying the BMPs in List #1 or List No Yes Yes No additional requirements *Recommended by Ecology for projects triggering MR #1-5. REQUIRED: Implement the following BMPs where feasible: o BMP T5.13: Post-Construction Soil Quality and Depth o BMP T5.10A, B, or C: Downspout Full Infiltration, Downspout Dispersion Systems, or Perforated Stub-out Connections o BMP T5.11 or T5.12: Concentrated Flow Dispersion or Sheet Flow Dispersion NOT REQUIRED: Achievement of the LID Performance Standard. Applying the other BMPs in List #1 or List Refer to your Municipal Stormwater Permit, 2012 Stormwater Management Manual for Western Washington, and/or your local jurisdiction for more information about these requirements and other requirements. Revised 3/11/13 24 ---PAGE BREAK--- No, the project triggered only MR #2 No, the project triggered MRs #1 - No, the project is outside the UGA. No, project developer chose List No, project developer chose List Flow Chart for Determining LID MR #5 Requirements Did the project developer choose to meet the LID Performance Standard? Does the project discharge to Flow Control Exempt Waters (per Minimum Requirement (MR) Yes Does the project trigger only MRs #1 - (Per Figure 3.2 or Figure 3.3 in Appendix 1 of the 2013-2018 WWA Phase II Permit & Phase I Permit.) No Yes Did the project developer choose to meet the LID Performance Standard? Yes REQUIRED: Meet the LID Performance Standard through the use of any BMP(s) in the 2012 or the LID Technical Guidance Manual for Puget Sound except for Rain Gardens (the use of Bioretention is acceptable). REQUIRED for Projects Triggering MR Apply BMP T5.13 Post-Construction Soil Quality and Depth. NOT REQUIRED: Applying the BMPs in List #1 or List REQUIRED: For each surface, consider the BMPs in the order listed in List #1 for that type of surface. Use the first BMP that is considered feasible. NOT REQUIRED: Achievement of the LID Performance Standard. REQUIRED: For each surface, consider the BMPs in the order listed in List #2 for that type of surface. Use the first BMP that is considered feasible. NOT REQUIRED: Achievement of the LID Performance Standard. Is the project inside the UGA? Yes Is the project on a parcel of 5 acres or larger? REQUIRED: Meet the LID Performance Standard through the use of any BMP(s) in the 2012 or the LID Technical Guidance Manual for Puget Sound except for Rain Gardens (the use of Bioretention is acceptable). If the project can’t meet the LID Performance Standard, it must be redesigned to meet the LID performance standard or an exception / variance must be approved. REQUIRED: Apply BMP T5.13 Post- Construction Soil Quality and Depth. NOT REQUIRED: Applying the BMPs in List #1 or List No Yes Yes No additional requirements *Recommended by Ecology for projects triggering MR #1-5. REQUIRED: Implement the following BMPs where feasible: o BMP T5.13: Post-Construction Soil Quality and Depth o BMP T5.10A, B, or C: Downspout Full Infiltration, Downspout Dispersion Systems, or Perforated Stub-out Connections o BMP T5.11 or T5.12: Concentrated Flow Dispersion or Sheet Flow Dispersion NOT REQUIRED: Achievement of the LID Performance Standard. Applying the other BMPs in List #1 or List Refer to your Municipal Stormwater Permit, 2012 Stormwater Management Manual for Western Washington, and/or your local jurisdiction for more information about these requirements and other requirements. Revised 3/11/13 25 ---PAGE BREAK--- List #1 & List For each surface, consider the BMP’s in the order listed for that type of surface. Use the first BMP that is considered feasible. BMPs List #1 (Project triggers Minimum Requirements #1-5) List #2 (Project triggers Minimum Requirements #1-9) Lawn & Landscaped Areas: • Post-Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the • Post-Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the Roofs: 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the or Downspout Full Infiltration Systems in accordance with BMP T5.10A in Section 3.1.1 of Volume III of the 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the or Downspout Full Infiltration Systems in accordance with BMP T5.10A in Section 3.1.1 of Volume III of the 2. Rain Gardens in accordance with the “Rain Garden Handbook for Western Washington,” or Bioretention in accordance with Chapter 7 of Volume V of the The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5% of the area draining to it. 2. Bioretention (See Chapter 7 of Volume V of the facilities that have a minimum horizontally projected surface area below the overflow which is at least 5% of the of the total surface area draining to it 3. Downspout Dispersion Systems in accordance with BMP T5.10B in Section 3.1.2 of Volume III of the 3. Downspout Dispersion Systems in accordance with BMP T5.10B in Section 3.1.2 of Volume III of the 4. Perforated Stub-out Connections in accordance with BMP T5.10C in Section 3.1.3 of Volume III of the 4. Perforated Stub-out Connections in accordance with BMP T5.10C in Section 3.1.3 of Volume III of the Other Hard Surfaces: 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the 2. Permeable pavement1 in accordance with BMP T5.15 in Chapter 5 of Volume V of the or Rain Gardens in accordance with the “Rain Garden Handbook for Western Washington,” or Bioretention in accordance with Chapter 7 of Volume V of the The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5% of the area draining to it. 2. Permeable pavement1 in accordance with BMP T5.15 in Chapter 5 of Volume V of the 3. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow Dispersion in accordance with BMP T5.11 in Chapter 5 of Volume V of the 3. Bioretention (See Chapter 7, Volume V of the facilities that have a minimum horizontally projected surface area below the overflow which is at least 5% of the of the total surface area draining to it. 4. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow Dispersion in accordance with BMP T5.11 in Chapter 5 of Volume V of the 1 This is not a requirement to pave these surfaces. Where pavement is proposed, it must be permeable to the extent feasible unless full dispersion is employed. Refer to your Municipal Stormwater Permit, 2012 Stormwater Management Manual for Western Washington, and/or your local jurisdiction for more information about these requirements and other requirements. 26 ---PAGE BREAK--- No, the project triggered only MR #2 No, the project triggered MRs #1 - No, the project is outside the UGA. No, project developer chose List No, project developer chose List Flow Chart for Determining LID MR #5 Requirements Did the project developer choose to meet the LID Performance Standard? Does the project discharge to Flow Control Exempt Waters (per Minimum Requirement (MR) Yes Does the project trigger only MRs #1 - (Per Figure 3.2 or Figure 3.3 in Appendix 1 of the 2013-2018 WWA Phase II Permit & Phase I Permit.) No Yes Did the project developer choose to meet the LID Performance Standard? Yes REQUIRED: Meet the LID Performance Standard through the use of any BMP(s) in the 2012 or the LID Technical Guidance Manual for Puget Sound except for Rain Gardens (the use of Bioretention is acceptable). REQUIRED for Projects Triggering MR Apply BMP T5.13 Post-Construction Soil Quality and Depth. NOT REQUIRED: Applying the BMPs in List #1 or List REQUIRED: For each surface, consider the BMPs in the order listed in List #1 for that type of surface. Use the first BMP that is considered feasible. NOT REQUIRED: Achievement of the LID Performance Standard. REQUIRED: For each surface, consider the BMPs in the order listed in List #2 for that type of surface. Use the first BMP that is considered feasible. NOT REQUIRED: Achievement of the LID Performance Standard. Is the project inside the UGA? Yes Is the project on a parcel of 5 acres or larger? REQUIRED: Meet the LID Performance Standard through the use of any BMP(s) in the 2012 or the LID Technical Guidance Manual for Puget Sound except for Rain Gardens (the use of Bioretention is acceptable). If the project can’t meet the LID Performance Standard, it must be redesigned to meet the LID performance standard or an exception / variance must be approved. REQUIRED: Apply BMP T5.13 Post- Construction Soil Quality and Depth. NOT REQUIRED: Applying the BMPs in List #1 or List No Yes Yes No additional requirements *Recommended by Ecology for projects triggering MR #1-5. REQUIRED: Implement the following BMPs where feasible: o BMP T5.13: Post-Construction Soil Quality and Depth o BMP T5.10A, B, or C: Downspout Full Infiltration, Downspout Dispersion Systems, or Perforated Stub-out Connections o BMP T5.11 or T5.12: Concentrated Flow Dispersion or Sheet Flow Dispersion NOT REQUIRED: Achievement of the LID Performance Standard. Applying the other BMPs in List #1 or List Refer to your Municipal Stormwater Permit, 2012 Stormwater Management Manual for Western Washington, and/or your local jurisdiction for more information about these requirements and other requirements. Revised 3/11/13 27 ---PAGE BREAK--- List #1 & List For each surface, consider the BMP’s in the order listed for that type of surface. Use the first BMP that is considered feasible. BMPs List #1 (Project triggers Minimum Requirements #1-5) List #2 (Project triggers Minimum Requirements #1-9) Lawn & Landscaped Areas: • Post-Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the • Post-Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the Roofs: 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the or Downspout Full Infiltration Systems in accordance with BMP T5.10A in Section 3.1.1 of Volume III of the 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the or Downspout Full Infiltration Systems in accordance with BMP T5.10A in Section 3.1.1 of Volume III of the 2. Rain Gardens in accordance with the “Rain Garden Handbook for Western Washington,” or Bioretention in accordance with Chapter 7 of Volume V of the The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5% of the area draining to it. 2. Bioretention (See Chapter 7 of Volume V of the facilities that have a minimum horizontally projected surface area below the overflow which is at least 5% of the of the total surface area draining to it 3. Downspout Dispersion Systems in accordance with BMP T5.10B in Section 3.1.2 of Volume III of the 3. Downspout Dispersion Systems in accordance with BMP T5.10B in Section 3.1.2 of Volume III of the 4. Perforated Stub-out Connections in accordance with BMP T5.10C in Section 3.1.3 of Volume III of the 4. Perforated Stub-out Connections in accordance with BMP T5.10C in Section 3.1.3 of Volume III of the Other Hard Surfaces: 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the 2. Permeable pavement1 in accordance with BMP T5.15 in Chapter 5 of Volume V of the or Rain Gardens in accordance with the “Rain Garden Handbook for Western Washington,” or Bioretention in accordance with Chapter 7 of Volume V of the The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5% of the area draining to it. 2. Permeable pavement1 in accordance with BMP T5.15 in Chapter 5 of Volume V of the 3. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow Dispersion in accordance with BMP T5.11 in Chapter 5 of Volume V of the 3. Bioretention (See Chapter 7, Volume V of the facilities that have a minimum horizontally projected surface area below the overflow which is at least 5% of the of the total surface area draining to it. 4. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow Dispersion in accordance with BMP T5.11 in Chapter 5 of Volume V of the 1 This is not a requirement to pave these surfaces. Where pavement is proposed, it must be permeable to the extent feasible unless full dispersion is employed. Refer to your Municipal Stormwater Permit, 2012 Stormwater Management Manual for Western Washington, and/or your local jurisdiction for more information about these requirements and other requirements. 28 ---PAGE BREAK--- 176th AVE NE NE 111th ST 176th CIR NE 178th PL NE NE 108th WAY NE 109th ST 183rd AVE NE NE 110th WAY 181st AVE NE NE 109th CT 179th CT NE 182nd AVE NE 177th CT NE NE 110th ST NE 112th WAY 180th PL NE 180th CT NE NE 108th CT 183rd PL NE 184th PL NE 178th CT NE 182nd PL NE NE 107th ST NE 107th CT NE 110th WAY NE 111th ST 177th CT NE Esri, HERE, DeLorme, MapmyIndia, © OpenStreetMap contributors, and the GIS user community, Source: Esri, DigitalGlobe, GeoEye, Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community Legend Pond Stream Centerline swPipe swVault Emerald Heights, Redmond, WA Data from City of Redmond ° 1 " = 200 ' Date: 2/23/2017 TDA 2 CONNECTION TO PUBLIC SYSTEM ROUTED THROUGH DETENTION VAULT DISCHARGE TO TYLERS CREEK DISCHARGE TO BEAR CREAK ROUTED IN PUBLIC PIPED SYSTEM ROUTED IN PUBLIC PIPED SYSTEM Figure 7: Conveyance Scale: 1'=200' TDA 1 CONNECTION TO PUBLIC SYSTEM 29 ---PAGE BREAK--- D E P A R T M E N T O F ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure I-2.4.1 Flow Chart for Determining Requirements for New Development Revised June 2015 Does the site have 35% or more of existing impervious coverage? Does the project result in 5,000 square feet, or greater, of new plus replaced hard surface area? All Minimum Requirements apply to the new and replaced hard surfaces and converted vegetation areas. Does the project convert 3 4 acres or more of vegetation to lawn or landscaped areas, or convert 2.5 acres or more of native vegetation to pasture? Minimum Requirements #1 through #5 apply to the new and replaced hard surfaces and the land disturbed. See Redevelopment Minimum Requirements and Flow Chart (Figure I-2.4.2). Does the project result in 2,000 square feet, or greater, of new plus replaced hard surface area? Does the project have land disturbing activities of 7,000 square feet or greater? Minimum Requirement #2 applies. Start Here Yes No No No No No Yes Yes Yes Yes 30 ---PAGE BREAK--- D E P A R T M E N T O F ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure I-2.4.2 Flow Chart for Determining Requirements for Redevelopment Revised June 2015 Does the project result in 2,000 square feet, or more, of new plus replaced hard surface area? OR Does the land disturbing activity total 7,000 square feet or greater? Minimum Requirement #2 applies. Minimum Requirements #1 through #5 apply to the new and replaced hard surfaces and the land disturbed. Does the project add 5,000 square feet or more of new hard surfaces? OR Convert 3 4 acres or more of vegetation to lawn or landscaped areas? OR Convert 2.5 acres or more of native vegetation to pasture? All Minimum Requirements apply to the new hard surfaces and the converted vegetation areas. Is this a road related project? Does the project add 5,000 square feet or more of new hard surfaces? Do the new hard surfaces add 50% or more to the existing hard surfaces within the project limits? Is the total of new plus replaced hard surfaces 5,000 square feet or more, AND does the value of the proposed improvements - including interior improvements - exceed 50% of the assessed value (or replacement value) of the existing site improvements? No additional requirements. All Minimum Requirements apply to the new and replaced hard surfaces and converted vegetation areas. Yes No Next Question Yes No Next Question Yes No No Yes No No Yes Yes 31 ---PAGE BREAK--- D E P A R T M E N T O F ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure I-2.4.1 Flow Chart for Determining Requirements for New Development Revised June 2015 Does the site have 35% or more of existing impervious coverage? Does the project result in 5,000 square feet, or greater, of new plus replaced hard surface area? All Minimum Requirements apply to the new and replaced hard surfaces and converted vegetation areas. Does the project convert 3 4 acres or more of vegetation to lawn or landscaped areas, or convert 2.5 acres or more of native vegetation to pasture? Minimum Requirements #1 through #5 apply to the new and replaced hard surfaces and the land disturbed. See Redevelopment Minimum Requirements and Flow Chart (Figure I-2.4.2). Does the project result in 2,000 square feet, or greater, of new plus replaced hard surface area? Does the project have land disturbing activities of 7,000 square feet or greater? Minimum Requirement #2 applies. Start Here Yes No No No No No Yes Yes Yes Yes 32 ---PAGE BREAK--- D E P A R T M E N T O F ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure I-2.4.1 Flow Chart for Determining Requirements for New Development Revised June 2015 Does the site have 35% or more of existing impervious coverage? Does the project result in 5,000 square feet, or greater, of new plus replaced hard surface area? All Minimum Requirements apply to the new and replaced hard surfaces and converted vegetation areas. Does the project convert 3 4 acres or more of vegetation to lawn or landscaped areas, or convert 2.5 acres or more of native vegetation to pasture? Minimum Requirements #1 through #5 apply to the new and replaced hard surfaces and the land disturbed. See Redevelopment Minimum Requirements and Flow Chart (Figure I-2.4.2). Does the project result in 2,000 square feet, or greater, of new plus replaced hard surface area? Does the project have land disturbing activities of 7,000 square feet or greater? Minimum Requirement #2 applies. Start Here Yes No No No No No Yes Yes Yes Yes 33 ---PAGE BREAK--- D E P A R T M E N T O F ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure I-2.4.2 Flow Chart for Determining Requirements for Redevelopment Revised June 2015 Does the project result in 2,000 square feet, or more, of new plus replaced hard surface area? OR Does the land disturbing activity total 7,000 square feet or greater? Minimum Requirement #2 applies. Minimum Requirements #1 through #5 apply to the new and replaced hard surfaces and the land disturbed. Does the project add 5,000 square feet or more of new hard surfaces? OR Convert 3 4 acres or more of vegetation to lawn or landscaped areas? OR Convert 2.5 acres or more of native vegetation to pasture? All Minimum Requirements apply to the new hard surfaces and the converted vegetation areas. Is this a road related project? Does the project add 5,000 square feet or more of new hard surfaces? Do the new hard surfaces add 50% or more to the existing hard surfaces within the project limits? Is the total of new plus replaced hard surfaces 5,000 square feet or more, AND does the value of the proposed improvements - including interior improvements - exceed 50% of the assessed value (or replacement value) of the existing site improvements? No additional requirements. All Minimum Requirements apply to the new and replaced hard surfaces and converted vegetation areas. Yes No Next Question Yes No Next Question Yes No No Yes No No Yes Yes 34 ---PAGE BREAK--- APPENDIX A.2: FIGURES Figure 1 – Vicinity Map Figure 2 – COR Standard Maps Figure 3 – Wellhead Protection Map Figure 4 – Existing Conditions Figure 5 – Proposed Conditions Figure 6 – 100-Year Flow Figure 7a – Campus Basin & Conveyance System Figure 7b Conveyance Figure 8a – Stormwater Notebook Figure 3.2 (MR Flow Chart) Figure 8b – Flow Chart for Determining LID MR #5 Requirements Figure 9 –LID Site Plan 35 ---PAGE BREAK--- 36 EH: Assisted Living Building C150030-02 Rice Fergus Miller 06/09/2016 IDS BSB Project Site 801 Second Avenue, Seattle, WA 98104 Figure 1 - Vicinity Map NTS Emerald Heights Redmond Campus ---PAGE BREAK--- SE Redmond Grass Lawn Spiritbrook Viewpoint Open Space Viewpoint Idylwood Beach Cascade View Westside Bridle Crest Trail Site Redmond West Wetlands Luke McRedmond Landing Edge Skate Park ORSCC Anderson OFH Bear Creek Reservoir Jonathan Hartman Sixty Acres (King County) Marymoor (King County) Juel Farrel- McWhirter Conrad Olson Farm Bear and Evans Creek Greenway Arthur Johnson Meadow NE Redmond Sammamish Valley Willows Creek Scotts Pond Sunset Gardens Municipal Campus Perrigo Nike Perrigo Heights L a k e L a k e S a m m a m i s h S a m m a m i s h U V 520 U V 520 188th AVE NE NE 124th ST AVON DALE WY CLEVEL A ND S T NE 24th ST NE 40th ST 166th AVE NE 156th AVE NE 172nd AVE NE 160th AVE NE NE 116th ST NE 80th ST NE 80th ST NE 104th ST NE 20th ST 164th AVE NE 132nd AVE NE NE 79th ST NE 76th ST 1 6 2nd AVE NE 154th PL NE 154 t h AVE NE NE 111th ST NE 90th ST E LK S AMMA MISH PKW Y 152nd AVE NE 185th AVE NE 180th AVE NE NE 128th ST UNION HILL RD B E A R C REE K P K WY NE 60th ST 154th AVE NE NE 124th WY NE 36t h ST 178th PL NE 132nd AVE NE NE 116th ST O LD R ED M O ND RD W L K SAMMAM I SH P K WY RED-WOOD RD 148th AVE NE BEL-RED RD 171st AV E N E WILL O WS RD 180th AVE NE 140th AVE NE 161st AVE NE 1 6 0 t h A V E NE NE 100th ST AVONDALE RD NE 85th ST NE 83rd ST 172nd AVE NE REDMOND WY 148th AVE NE NE 75th ST NE 5 1st ST 150th AVE NE REDMOND WY AVONDA L E RD 50 100 400 450 350 150 250 300 200 350 250 300 150 200 150 100 300 450 50 400 200 50 50 50 50 250 150 100 150 50 100 100 100 200 350 100 250 300 300 300 350 200 350 300 250 150 100 300 100 450 50 250 350 300 250 300 150 250 400 350 200 50 50 150 50 300 100 400 150 250 150 300 200 50 100 50 50 350 200 150 200 300 200 250 150 400 250 450 50 300 300 50 300 150 300 400 50 50 250 300 200 350 250 100 50 100 50 300 100 Erosion Hazard Areas Critical Areas Map City of Redmond, Washington Ü 0 0.5 1 Miles Disclaimer: This map is created and maintained by GIS Services Group,Finance and Information Services, City of Redmond, Washington, for reference purposes only. The City makes no guarantee as to the accuracy of the features shown on this map. File Name:\\redmond.man\fs\GISUser\GIS\GISServicesProject\GISServices\RedmondGovWebsite\03GIS\ErosionHazardAreas_11x17.mxd Effective: 05/28/2005 Note: This map shall be used as a general guide. It represents approximate locations. Consult the Critical Areas Ordinance (CAO) for reporting requirements. In the event there is a conflict between the map and the criteria or standards of the CAO, the criteria shall prevail. Data Source: SCS Soil Survey Contour Erosion Hazard Area City Limit Water Park and Open Space 17 of 189 37 Figure 2A - Erosion Hazard Areas Project Site ---PAGE BREAK--- SE Redmond Grass Lawn Spiritbrook Viewpoint Open Space Viewpoint Idylwood Beach Cascade View Westside Bridle Crest Trail Site Redmond West Wetlands Luke McRedmond Landing Edge Skate Park ORSCC Anderson OFH Bear Creek Reservoir Jonathan Hartman Sixty Acres (King County) Marymoor (King County) Juel Farrel- McWhirter Conrad Olson Farm Bear and Evans Creek Greenway Arthur Johnson Meadow NE Redmond Sammamish Valley Willows Creek Scotts Pond Sunset Gardens Municipal Campus Perrigo Nike Perrigo Heights L a k e L a k e S a m m a m i s h S a m m a m i s h U V 520 U V 520 188th AVE NE NE 124th ST AVON DALE WY CLEVEL A ND S T NE 24th ST NE 40th ST 166th AVE NE 156th AVE NE 172nd AVE NE 160th AVE NE NE 116th ST NE 80th ST NE 80th ST NE 104th ST NE 20th ST 164th AVE NE 132nd AVE NE NE 79th ST NE 76th ST 1 6 2nd AVE NE 154th PL NE 154 t h AVE NE NE 111th ST NE 90th ST E LK S AMMA MISH PKW Y 152nd AVE NE 185th AVE NE 180th AVE NE NE 128th ST UNION HILL RD B E A R C REE K P K WY NE 60th ST 154th AVE NE NE 124th WY NE 36t h ST 178th PL NE 132nd AVE NE NE 116th ST O LD R ED M O ND RD W L K SAMMAM I SH P K WY RED-WOOD RD 148th AVE NE BEL-RED RD 171st AV E N E WILL O WS RD 180th AVE NE 140th AVE NE 161st AVE NE 1 6 0 t h A V E NE NE 100th ST AVONDALE RD NE 85th ST NE 83rd ST 172nd AVE NE REDMOND WY 148th AVE NE NE 75th ST NE 5 1st ST 150th AVE NE REDMOND WY AVONDA L E RD Frequently Flooded Areas City of Redmond, Washington Effective: 05/28/2005 Ü 0 0.5 1 Miles Disclaimer: This map is created and maintained by GIS Services Group,Finance and Information Services, City of Redmond, Washington, for reference purposes only. The City makes no guarantee as to the accuracy of the features shown on this map. File Critical Areas Map Data Source: FEMA Flood Insurance Rate Maps Note: This map shall be used as a general guide. It represents approximate locations. Consult the Critical Areas Ordinance (CAO) for reporting requirements. In the event there is a conflict between the map and the criteria or standards of the CAO, the criteria shall prevail. FEMA Floodway City Limit 100 Year Floodplain Park and Open Space Water 18 of 189 38 Figure 2B - Frequently Flooded Areas Project Site ---PAGE BREAK--- SE Redmond Grass Lawn Spiritbrook Viewpoint Open Space Viewpoint Idylwood Beach Cascade View Westside Bridle Crest Trail Site Redmond West Wetlands Luke McRedmond Landing Edge Skate Park ORSCC Anderson OFH Bear Creek Reservoir Jonathan Hartman Sixty Acres (King County) Marymoor (King County) Juel Farrel- McWhirter Conrad Olson Farm Bear and Evans Creek Greenway Arthur Johnson Meadow NE Redmond Sammamish Valley Willows Creek Scotts Pond Sunset Gardens Municipal Campus Perrigo Nike Perrigo Heights L a k e L a k e S a m m a m i s h S a m m a m i s h U V 520 U V 520 188th AVE NE NE 124th ST AVON DALE WY CLEVEL A ND S T NE 24th ST NE 40th ST 166th AVE NE 156th AVE NE 172nd AVE NE 160th AVE NE NE 116th ST NE 80th ST NE 80th ST NE 104th ST NE 20th ST 164th AVE NE 132nd AVE NE NE 79th ST NE 76th ST 1 6 2nd AVE NE 154th PL NE 154 t h AVE NE NE 111th ST NE 90th ST E LK S AMMA MISH PKW Y 152nd AVE NE 185th AVE NE 180th AVE NE NE 128th ST UNION HILL RD B E A R C REE K P K WY NE 60th ST 154th AVE NE NE 124th WY NE 36t h ST 178th PL NE 132nd AVE NE NE 116th ST O LD R ED M O ND RD W L K SAMMAM I SH P K WY RED-WOOD RD 148th AVE NE BEL-RED RD 171st AV E N E WILL O WS RD 180th AVE NE 140th AVE NE 161st AVE NE 1 6 0 t h A V E NE NE 100th ST AVONDALE RD NE 85th ST NE 83rd ST 172nd AVE NE REDMOND WY 148th AVE NE NE 75th ST NE 5 1st ST 150th AVE NE REDMOND WY AVONDA L E RD 50 100 400 450 350 150 250 300 200 350 250 300 150 200 150 100 300 450 50 400 200 50 50 50 50 250 150 100 150 50 100 100 100 200 350 100 250 300 300 300 350 200 350 300 250 150 100 300 100 450 50 250 350 300 250 300 150 250 400 350 200 50 50 150 50 300 100 400 150 250 150 300 200 50 100 50 50 350 200 150 200 300 200 250 150 400 250 450 50 300 300 50 300 150 300 400 50 50 250 300 200 350 250 100 50 100 50 300 100 Landslide Hazard Areas Critical Areas Map City of Redmond, Washington Ü 0 0.5 1 Miles Disclaimer: This map is created and maintained by GIS Services Group,Finance and Information Services, City of Redmond, Washington, for reference purposes only. The City makes no guarantee as to the accuracy of the features shown on this map. File Name:File Name:\\redmond.man\fs\GISUser\GIS\GISServicesProject\GISServices\RedmondGovWebsite\03GIS\LandslideHazardAreas_11x17.mxd Landslide Hazard Area Contour City Limit Park and Open Space Water Effective: 05/28/2005 Note: This map shall be used as a general guide. It represents approximate locations. Consult the Critical Areas Ordinance (CAO) for reporting requirements. In the event there is a conflict between the map and the criteria or standards of the CAO, the criteria shall prevail. Data Source: USGS Topographic Maps USGS Geologic Maps 19 of 189 39 Figure 2C - Landslide Hazard Areas Project Site ---PAGE BREAK--- SE Redmond Grass Lawn Spiritbrook Viewpoint Open Space Viewpoint Idylwood Beach Cascade View Westside Bridle Crest Trail Site Redmond West Wetlands Luke McRedmond Landing Edge Skate Park ORSCC Anderson OFH Bear Creek Reservoir Jonathan Hartman Sixty Acres (King County) Marymoor (King County) Juel Farrel- McWhirter Conrad Olson Farm Bear and Evans Creek Greenway Arthur Johnson Meadow NE Redmond Sammamish Valley Willows Creek Scotts Pond Sunset Gardens Municipal Campus Perrigo Nike Perrigo Heights L a k e L a k e S a m m a m i s h S a m m a m i s h U V 520 U V 520 188th AVE NE NE 124th ST AVON DALE WY CLEVEL A ND S T NE 24th ST NE 40th ST 166th AVE NE 156th AVE NE 172nd AVE NE 160th AVE NE NE 116th ST NE 80th ST NE 80th ST NE 104th ST NE 20th ST 164th AVE NE 132nd AVE NE NE 79th ST NE 76th ST 1 6 2nd AVE NE 154th PL NE 154 t h AVE NE NE 111th ST NE 90th ST E LK S AMMA MISH PKW Y 152nd AVE NE 185th AVE NE 180th AVE NE NE 128th ST UNION HILL RD B E A R C REE K P K WY NE 60th ST 154th AVE NE NE 124th WY NE 36t h ST 178th PL NE 132nd AVE NE NE 116th ST O LD R ED M O ND RD W L K SAMMAM I SH P K WY RED-WOOD RD 148th AVE NE BEL-RED RD 171st AV E N E WILL O WS RD 180th AVE NE 140th AVE NE 161st AVE NE 1 6 0 t h A V E NE NE 100th ST AVONDALE RD NE 85th ST NE 83rd ST 172nd AVE NE REDMOND WY 148th AVE NE NE 75th ST NE 5 1st ST 150th AVE NE REDMOND WY AVONDA L E RD Seismic Hazard Areas Critical Areas Map City of Redmond, Washington Ü 0 0.5 1 Miles Disclaimer: This map is created and maintained by GIS Services Group,Finance and Information Services, City of Redmond, Washington, for reference purposes only. The City makes no guarantee as to the accuracy of the features shown on this map. File Name:\\redmond.man\fs\GISUser\GIS\GISServicesProject\GISServices\RedmondGovWebsite\03GIS\SeismicHazardAreas_11x17.mxd Effective: 05/28/2005 Data Source: USGS Geologic Maps Note: This map shall be used as a general guide. It represents approximate locations. Consult the Critical Areas Ordinance (CAO) for reporting requirements. In the event there is a conflict between the map and the criteria or standards of the CAO, the criteria shall prevail. Seismic Hazard Area City Limit Park and Open Space Water 20 of 189 40 Figure 2D - Seismic Hazard Areas Project Site ---PAGE BREAK--- 21 of 189 41 Figure 2E - Stream Classification Project Site ---PAGE BREAK--- SE Redmond Grass Lawn Spiritbrook Viewpoint Open Space Viewpoint Idylwood Beach Cascade View Westside Bridle Crest Trail Site Redmond West Wetlands Luke McRedmond Landing Edge Skate Park ORSCC Anderson OFH Bear Creek Reservoir Jonathan Hartman Sixty Acres (King County) Marymoor (King County) Juel Farrel- McWhirter Conrad Olson Farm Bear and Evans Creek Greenway Arthur Johnson Meadow NE Redmond Sammamish Valley Willows Creek Scotts Pond Sunset Gardens Municipal Campus Perrigo Nike Perrigo Heights L a k e L a k e S a m m a m i s h S a m m a m i s h U V 520 U V 520 188th AVE NE NE 124th ST AVON DALE WY CLEVEL A ND S T NE 24th ST NE 40th ST 166th AVE NE 156th AVE NE 172nd AVE NE 160th AVE NE NE 116th ST NE 80th ST NE 80th ST NE 104th ST NE 20th ST 164th AVE NE 132nd AVE NE NE 79th ST NE 76th ST 1 6 2nd AVE NE 154th PL NE 154 t h AVE NE NE 111th ST NE 90th ST E LK S AMMA MISH PKW Y 152nd AVE NE 185th AVE NE 180th AVE NE NE 128th ST UNION HILL RD B E A R C REE K P K WY NE 60th ST 154th AVE NE NE 124th WY NE 36t h ST 178th PL NE 132nd AVE NE NE 116th ST O LD R ED M O ND RD W L K SAMMAM I SH P K WY RED-WOOD RD 148th AVE NE BEL-RED RD 171st AV E N E WILL O WS RD 180th AVE NE 140th AVE NE 161st AVE NE 1 6 0 t h A V E NE NE 100th ST AVONDALE RD NE 85th ST NE 83rd ST 172nd AVE NE REDMOND WY 148th AVE NE NE 75th ST NE 5 1st ST 150th AVE NE REDMOND WY AVONDA L E RD Wetlands Critical Areas Map City of Redmond, Washington Ü 0 0.5 1 Miles Disclaimer: This map is created and maintained by GIS Services Group,Finance and Information Services, City of Redmond, Washington, for reference purposes only. The City makes no guarantee as to the accuracy of the features shown on this map. File Name:\\redmond.man\fs\GISUser\GIS\GISServicesProject\GISServices\RedmondGovWebsite\03GIS\Wetlands_11x17.mxd Wetland Mixed Wetland/Upland City Limit Park and Open Space Water Effective: 05/28/2005 Data Source: USGS National Wetland Inventory Aerial Photo Interpretation SCS Soil Survey City of Redmond Note: This map shall be used as a general guide. It represents approximate locations. Consult the Critical Areas Ordinance (CAO) for reporting requirements. In the event there is a conflict between the map and the criteria or standards of the CAO, the criteria shall prevail. 22 of 189 42 Figure 2F - Wetlands Project Site ---PAGE BREAK--- 43 Figure 3 - Wellhead Protection Map Not to Scale EH: Assisted Living Building C150030-02 Rice Fergus Miller 06/08/2017 IDS BSB Project Site ---PAGE BREAK--- 44 Figure 4 - Existing Conditions Scale:1"=40' EH: Assisted Living Building C150030-02 Rice Fergus Miller 05/30/2018 IDS BSB Impervious Area: 4,210 (0.097 ac) PGIS Area: 2,950 SF (0.068 ac) Gravel Path Area: 3,020 SF (0.069 ac) Pervious Area: 28,020 SF (0.643 ac) Upstream Impervious Area: 1,980 (0.045 ac) Total Area: 40,180 SF (0.922 ac) Project Limits Legend MGS Flood Existing Areas Till Forest: Impervious + PGIS + Gravel Path + Pervious+ Upstream Impervious Till Forest: 0.097 + 0.068 + 0.069 + 0.648 + 0.045 Till Forest: 0.927 acres Total Area: 0.927 acres Intercept Upstream impervious area from Lawn Bowling Field routed to Detention Vault ---PAGE BREAK--- 801 SECOND AVENUE, SUITE 900 SEATTLE, WA 98104 / P [PHONE REDACTED] / cplinc.com 2014 45 Impervious Bypass: 330 SF (0.008 ac) Pervious Bypass: 8,550 SF ( 0.196 ac) PGIS Bypass: 970 SF (0.022 ac) Impervious Roof: 16,130 SF (0.370 ac) Impervious Hardscape: 5,670 SF ( 0.130 ac) Pervious Landscape: 12,970 SF (0.298 ac) PGIS: 3,430 SF (0.079 ac) Upstream Impervious: 1,980 SF (0.045 ac) Total Area: 40,180 SF (0.922 ac) Project Limits Legend (Total) Legend (Bypass) MGS Flood Proposed Areas Impervious Bypass: Impervious Bypass + PGIS Bypass - BMPs 1 Impervious Bypass: 0.008 + 0.022 - 0.007 Total Impervious Bypass: 0.023 acres Till Grass Bypass: BMPs 1 Till Grass Bypass: 0.007 acres (3 EX Evergreen) Till Pasture Bypass: Pervious Bypass2 Till Pasture Bypass: 0.196 acres Impervious Area: Roof + Hardscape + Upstream + PGIS - Impervious Bypass - PGIS Bypass - BMPs1,3 Impervious Area: 0.370 + 0.130 + 0.045 + 0.079 - 0.008 - 0.022 - 0.030 Impervious Area: 0.564 acres Till Grass Area: BMPs1,3 Till Grass Area: 0.030 acres (7 Evergreen, 7 Deciduous + 50% Veg. Roof) Till Pasture Area: Pervious Landscape2 - Pervious Bypass2 Till Pasture Area: 0.102 acres Total Area: 0.922 acres See Figure 7 - LID Site Plan Legend (BMP) Connection to Private Storm System Connection to Public Storm System Stormwater Detention Vault 1Tree retention and tree planting mitigates impervious surface to be modeled as till grass per 2014 Volume V, Chapter 5, Section 3.1, BMP T5.16 Flow Control Credits. 2Post-Construction Soil Quality and Depth mitigates till grass surfaces to be modeled as till pasture per 2014 Volume V, Chapter 5, Section 3.1, BMP T5.13 Runoff Model Representation. 3Vegetated Roof mitigates impervious area to be modeled as 50% Impervious and 50% Pervious per 2014 Volume V, Chapter 5, Section 3.1, BMP T5.13 Runoff Model Representation. Intercept Upstream impervious area from Lawn Bowling Field routed to Detention Vault 47+00 47+25 47+50 47+75 48+00 48+25 48+50 48+75 49+00 49+25 49+50 49+75 50+00 EH: Assisted Living Building C150030-02 Rice Fergus Miller 05/30/2018 IDS BSB ---PAGE BREAK--- 46 Figure 6 - 100-Year Flow Scale:1"=40' EH: Assisted Living Building C150030-02 Rice Fergus Miller 06/07/2017 IDS BSB 10+00 PROPOSED BUILDING ---PAGE BREAK--- 47 801 SECOND AVENUE, SUITE 900 SEATTLE, WA 98104 / P [PHONE REDACTED] / cplinc.com 2014 Basin 2 3.2 ac Basin 3 6.7 ac Pond 3 Pond 1 Tributary Basin Pond 2 Basin 4 2.6 ac Basin 1 25.3 ac Flow Splitter Pond 1 Proposed AL Building Conveyance Pipe Connection to existing private storm system Bypass flows to existing Pond 3 EH: Assisted Living Building C150030-02 Rice Fergus Miller 06/08/2017 IDS BSB Figure 7a: Campus Basin & Conveyance Not to Scale ---PAGE BREAK--- 176th AVE NE NE 111th ST 176th CIR NE 178th PL NE NE 108th WAY NE 109th ST 183rd AVE NE NE 110th WAY 181st AVE NE NE 109th CT 179th CT NE 182nd AVE NE 177th CT NE NE 110th ST NE 112th WAY 180th PL NE 180th CT NE NE 108th CT 183rd PL NE 184th PL NE 178th CT NE 182nd PL NE NE 107th ST NE 107th CT NE 110th WAY NE 111th ST 177th CT NE Esri, HERE, DeLorme, MapmyIndia, © OpenStreetMap contributors, and the GIS user community, Source: Esri, DigitalGlobe, GeoEye, Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community Legend Pond Stream Centerline swPipe swVault Emerald Heights, Redmond, WA Data from City of Redmond ° 1 " = 200 ' Date: 2/23/2017 48 PROJECT DISCHARGE LOCATION TO PUBLIC SYSTEM ROUTED THROUGH DETENTION VAULT DISCHARGE TO TYLERS CREEK DISCHARGE TO BEAR CREAK ROUTED IN PUBLIC PIPED SYSTEM ROUTED IN PUBLIC PIPED SYSTEM Figure 7: Conveyance Scale: 1'=200' ---PAGE BREAK--- 49 ---PAGE BREAK--- No, the project triggered only MR #2 No, the project triggered MRs #1 - No, the project is outside the UGA. No, project developer chose List No, project developer chose List Flow Chart for Determining LID MR #5 Requirements Did the project developer choose to meet the LID Performance Standard? Does the project discharge to Flow Control Exempt Waters (per Minimum Requirement (MR) Yes Does the project trigger only MRs #1 - (Per Figure 3.2 or Figure 3.3 in Appendix 1 of the 2013-2018 WWA Phase II Permit & Phase I Permit.) No Yes Did the project developer choose to meet the LID Performance Standard? Yes REQUIRED: Meet the LID Performance Standard through the use of any BMP(s) in the 2012 or the LID Technical Guidance Manual for Puget Sound except for Rain Gardens (the use of Bioretention is acceptable). REQUIRED for Projects Triggering MR Apply BMP T5.13 Post-Construction Soil Quality and Depth. NOT REQUIRED: Applying the BMPs in List #1 or List REQUIRED: For each surface, consider the BMPs in the order listed in List #1 for that type of surface. Use the first BMP that is considered feasible. NOT REQUIRED: Achievement of the LID Performance Standard. REQUIRED: For each surface, consider the BMPs in the order listed in List #2 for that type of surface. Use the first BMP that is considered feasible. NOT REQUIRED: Achievement of the LID Performance Standard. Is the project inside the UGA? Yes Is the project on a parcel of 5 acres or larger? REQUIRED: Meet the LID Performance Standard through the use of any BMP(s) in the 2012 or the LID Technical Guidance Manual for Puget Sound except for Rain Gardens (the use of Bioretention is acceptable). If the project can’t meet the LID Performance Standard, it must be redesigned to meet the LID performance standard or an exception / variance must be approved. REQUIRED: Apply BMP T5.13 Post- Construction Soil Quality and Depth. NOT REQUIRED: Applying the BMPs in List #1 or List No Yes Yes No additional requirements *Recommended by Ecology for projects triggering MR #1-5. REQUIRED: Implement the following BMPs where feasible: o BMP T5.13: Post-Construction Soil Quality and Depth o BMP T5.10A, B, or C: Downspout Full Infiltration, Downspout Dispersion Systems, or Perforated Stub-out Connections o BMP T5.11 or T5.12: Concentrated Flow Dispersion or Sheet Flow Dispersion NOT REQUIRED: Achievement of the LID Performance Standard. Applying the other BMPs in List #1 or List Refer to your Municipal Stormwater Permit, 2012 Stormwater Management Manual for Western Washington, and/or your local jurisdiction for more information about these requirements and other requirements. Revised 3/11/13 50 ---PAGE BREAK--- List #1 & List For each surface, consider the BMP’s in the order listed for that type of surface. Use the first BMP that is considered feasible. BMPs List #1 (Project triggers Minimum Requirements #1-5) List #2 (Project triggers Minimum Requirements #1-9) Lawn & Landscaped Areas: • Post-Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the • Post-Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the Roofs: 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the or Downspout Full Infiltration Systems in accordance with BMP T5.10A in Section 3.1.1 of Volume III of the 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the or Downspout Full Infiltration Systems in accordance with BMP T5.10A in Section 3.1.1 of Volume III of the 2. Rain Gardens in accordance with the “Rain Garden Handbook for Western Washington,” or Bioretention in accordance with Chapter 7 of Volume V of the The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5% of the area draining to it. 2. Bioretention (See Chapter 7 of Volume V of the facilities that have a minimum horizontally projected surface area below the overflow which is at least 5% of the of the total surface area draining to it 3. Downspout Dispersion Systems in accordance with BMP T5.10B in Section 3.1.2 of Volume III of the 3. Downspout Dispersion Systems in accordance with BMP T5.10B in Section 3.1.2 of Volume III of the 4. Perforated Stub-out Connections in accordance with BMP T5.10C in Section 3.1.3 of Volume III of the 4. Perforated Stub-out Connections in accordance with BMP T5.10C in Section 3.1.3 of Volume III of the Other Hard Surfaces: 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the 1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the 2. Permeable pavement1 in accordance with BMP T5.15 in Chapter 5 of Volume V of the or Rain Gardens in accordance with the “Rain Garden Handbook for Western Washington,” or Bioretention in accordance with Chapter 7 of Volume V of the The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5% of the area draining to it. 2. Permeable pavement1 in accordance with BMP T5.15 in Chapter 5 of Volume V of the 3. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow Dispersion in accordance with BMP T5.11 in Chapter 5 of Volume V of the 3. Bioretention (See Chapter 7, Volume V of the facilities that have a minimum horizontally projected surface area below the overflow which is at least 5% of the of the total surface area draining to it. 4. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow Dispersion in accordance with BMP T5.11 in Chapter 5 of Volume V of the 1 This is not a requirement to pave these surfaces. Where pavement is proposed, it must be permeable to the extent feasible unless full dispersion is employed. Refer to your Municipal Stormwater Permit, 2012 Stormwater Management Manual for Western Washington, and/or your local jurisdiction for more information about these requirements and other requirements. 51 ---PAGE BREAK--- 52 Figure 9 - LID Site Plan Scale:1"=40' EH: Assisted Living Building C150030-02 Rice Fergus Miller 05/30/2018 IDS BSB LID Credit Planted Evergreen Tree (7 Trees) LID Credit Retained Evergreen Tree (3 Trees) LID Credit Planted Deciduous Tree (7 Trees) Post-Construction Soil Quality and Depth (12,970 SF) Vegetated Roof (1,540 SF) Legend Serbian Spruce Douglas Fir Hakuro Nishiki Willow Katsura Tree Maidenhair Tree Douglas Fir Autumn Blaze Maple Western Red Cedar Serbian Spruce Katsura Tree Autumn Blaze Maple Tall Slender Hinoki Cypress Autumn Blaze Maple EX 14" Fir to Remain EX Fir to Remain EX 12" Fir to Remain Notes: 1. All trees used for flow control credits conform to minimum requirements described in Section V-5.3.1 BMP T5.16: Tree Retention and Tree Planting of the 2014 Stormwater Management Manual for Western Washington. 2. See landscape planting plan for additional tree descriptions and information. 20' Down slope from Building 20' Down slope from Building 100' Up slope From Building EX Detention Pond Infiltration Setback Evaluation: City of Redmond 2012 Stormwater Technical Notebook minimum setback requirements for infiltration facilities include: 1. Minimum 20' down slope and 100' up slope of building foundations. 2. 10' from NGPE and property line. By maintaining the minimum setbacks above and not encroaching on the existing detention pond there is no location for an infiltration facility to be installed on-site. 10 ft 8 ft 8 ft 9 ft 12 ft 18 ft 18 ft 13 ft 2 ft 16 ft 1 ft 6 ft 7 ft 2 ft 10+00 ---PAGE BREAK--- APPENDIX B.1: ENGINEERING CALCULATIONS MGS Flood Report Vault 1 MGS Flood Report Vault 2 53 ---PAGE BREAK--- MGS FLOOD PROJECT REPORT Program Version: 4.43 Program License Number: 200610002 Project Simulation Performed on: 05/30/2018 10:46 AM Report Generation Date: 05/30/2018 10:46 AM Input File Name: Vault 1 Final 20180216.fld Project Name: Emerald Heights Courtyard Vault 1 Analysis Title: Comments: PRECIPITATION INPUT Computational Time Step (Minutes): 60 Extended Precipitation Time Series Selected Climatic Region Number: 0 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default Default HSPF Parameters Used (Not Modified by User) WATERSHED DEFINITION Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.420 0.420 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.420 0.420 PREDEVELOPED Number of Subbasins: 1 Subbasin : Subbasin 1 (Acres) Till Forest 0.420 Subbasin Total 0.420 54 ---PAGE BREAK--- POSTDEVELOPED Number of Subbasins: 2 Subbasin : Subbasin 1 (Acres) Till Pasture 0.050 Impervious 0.317 Subbasin Total 0.367 Subbasin : Subbasin 2 (Acres) Till Pasture 0.027 Impervious 0.026 Subbasin Total 0.053 LINK DATA PREDEVELOPED Number of Links: 1 Link Name: New Copy Lnk1 Link Type: Copy Link: None LINK DATA POSTDEVELOPED Number of Links: 2 Link Name: New Structure Lnk1 Link Type: Structure Link Name: New Copy Lnk2 Prismatic Pond Option Used Pond Floor Elevation (ft) : 100.00 Riser Crest Elevation (ft) : 108.50 Max Pond Elevation (ft) : 109.00 Storage Depth (ft) : 8.50 Pond Bottom Length (ft) : 96.0 Pond Bottom Width (ft) : 17.0 Pond Side Slopes (ft/ft) : L1= 0.00 L2= 0.00 W1= 0.00 W2= 0.00 Bottom Area (sq-ft) : 1632. Area at Riser Crest El (sq-ft) : 1,632. (acres) : 0.037 Volume at Riser Crest (cu-ft) : 13,872. 55 ---PAGE BREAK--- (ac-ft) : 0.318 Area at Max Elevation (sq-ft) : 1632. (acres) : 0.037 Vol at Max Elevation (cu-ft) : 15,014. (ac-ft) : 0.345 Massmann Infiltration Option Used Hydraulic Conductivity (in/hr) : 0.00 Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low Maintenance : Average or Better Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 18.00 Common Length (ft) : 0.000 Riser Crest Elevation : 108.50 ft Hydraulic Structure Geometry Number of Devices: 2 ---Device Number 1 Device Type : Circular Orifice Control Elevation (ft) : 100.00 Diameter (in) : 0.25 Orientation : Horizontal Elbow : No ---Device Number 2 Device Type : Circular Orifice Control Elevation (ft) : 106.00 Diameter (in) : 0.75 Orientation : Vertical Elbow : No Link Name: New Copy Lnk2 Link Type: Copy Link: None FREQUENCY AND DURATION PREDEVELOPED Number of Subbasins: 1 Number of Links: 1 POSTDEVELOPED Number of Subbasins: 2 Number of Links: 2 ***********Groundwater Recharge Summary 56 ---PAGE BREAK--- Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) Subbasin: Subbasin 1 72.823 Link: New Copy Lnk1 0.000 Total: 72.823 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) Subbasin: Subbasin 1 8.863 Subbasin: Subbasin 2 4.786 Link: New Structure Lnk1 Not Computed Link: New Copy Lnk2 0.000 Total: 13.648 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.461 ac-ft/year, Post Developed: 0.086 ac-ft/year Quality Facility Data PREDEVELOPED Number of Links: 1 Link: New Copy Lnk1 Infiltration/Filtration Inflow Volume (ac-ft): 37.74 Inflow Volume Including PPT-Evap (ac-ft): 37.74 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To System (ac-ft): 37.74 Secondary Outflow To System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% POSTDEVELOPED Number of Links: 2 Link: New Copy Lnk2 Infiltration/Filtration Inflow Volume (ac-ft): 162.60 Inflow Volume Including PPT-Evap (ac-ft): 162.60 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To System (ac-ft): 162.60 Secondary Outflow To System (ac-ft): 0.00 57 ---PAGE BREAK--- Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ***********Compliance Point Results Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Link: New Copy Lnk2 Point of Compliance Flow Frequency Data Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) 2-Year 8.917E-03 2-Year 9.853E-03 5-Year 1.522E-02 5-Year 1.252E-02 10-Year 1.894E-02 10-Year 1.463E-02 25-Year 2.443E-02 25-Year 1.720E-02 50-Year 2.942E-02 50-Year 1.818E-02 100-Year 3.531E-02 100-Year 1.862E-02 200-Year 4.775E-02 200-Year 2.224E-02 Record too Short to Compute Peak Discharge for These Recurrence Intervals Flow Duration Performance Excursion at Predeveloped 50%Q2 (Must be Less Than or Equal to -2.9% PASS Maximum Excursion from 50%Q2 to Q2 (Must be Less Than or Equal to -2.9% PASS Maximum Excursion from Q2 to Q50 (Must be less than 10%): -72.8% PASS Percent Excursion from Q2 to Q50 (Must be less than 50%): 0.0% PASS MEETS ALL FLOW DURATION DESIGN CRITERIA: PASS LID Duration Performance Excursion at Predeveloped 8%Q2 (Must be Less Than 450.8% FAIL Maximum Excursion from 8%Q2 to 50%Q2 (Must be Less Than 568.7% FAIL LID DURATION DESIGN CRITERIA: FAIL 58 ---PAGE BREAK--- MGS FLOOD PROJECT REPORT Program Version: 4.43 Program License Number: 200610002 Project Simulation Performed on: 05/30/2018 10:43 AM Report Generation Date: 05/30/2018 10:43 AM Input File Name: Vault 2 smaller 20180216.fld Project Name: Courtyard Vault 2 Analysis Title: 20170918 Comments: PRECIPITATION INPUT Computational Time Step (Minutes): 60 Extended Precipitation Time Series Selected Climatic Region Number: 0 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default Default HSPF Parameters Used (Not Modified by User) WATERSHED DEFINITION Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.586 0.586 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.586 0.586 PREDEVELOPED Number of Subbasins: 1 Subbasin : Subbasin 1 (Acres) Till Forest 0.586 Subbasin Total 0.586 59 ---PAGE BREAK--- POSTDEVELOPED Number of Subbasins: 2 Subbasin : Subbasin 1 (Acres) Till Pasture 0.065 Impervious 0.481 Subbasin Total 0.546 Subbasin : Subbasin 2 (Acres) Till Pasture 0.017 Impervious 0.023 Subbasin Total 0.040 LINK DATA PREDEVELOPED Number of Links: 1 Link Name: New Copy Lnk1 Link Type: Copy Link: None LINK DATA POSTDEVELOPED Number of Links: 2 Link Name: New Structure Lnk1 Link Type: Structure Link Name: New Copy Lnk2 Prismatic Pond Option Used Pond Floor Elevation (ft) : 100.00 Riser Crest Elevation (ft) : 106.51 Max Pond Elevation (ft) : 107.01 Storage Depth (ft) : 6.51 Pond Bottom Length (ft) : 72.0 Pond Bottom Width (ft) : 25.0 Pond Side Slopes (ft/ft) : L1= 0.00 L2= 0.00 W1= 0.00 W2= 0.00 Bottom Area (sq-ft) : 1800. Area at Riser Crest El (sq-ft) : 1,800. (acres) : 0.041 Volume at Riser Crest (cu-ft) : 11,718. 60 ---PAGE BREAK--- (ac-ft) : 0.269 Area at Max Elevation (sq-ft) : 1800. (acres) : 0.041 Vol at Max Elevation (cu-ft) : 12,978. (ac-ft) : 0.298 Massmann Infiltration Option Used Hydraulic Conductivity (in/hr) : 0.00 Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low Maintenance : Average or Better Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 106.51 ft Hydraulic Structure Geometry Number of Devices: 3 ---Device Number 1 Device Type : Circular Orifice Control Elevation (ft) : 100.00 Diameter (in) : 0.31 Orientation : Horizontal Elbow : No ---Device Number 2 Device Type : Circular Orifice Control Elevation (ft) : 104.25 Diameter (in) : 0.50 Orientation : Vertical Elbow : No ---Device Number 3 Device Type : Circular Orifice Control Elevation (ft) : 105.00 Diameter (in) : 0.50 Orientation : Horizontal Elbow : Yes Link Name: New Copy Lnk2 Link Type: Copy Link: None FREQUENCY AND DURATION PREDEVELOPED Number of Subbasins: 1 Number of Links: 1 61 ---PAGE BREAK--- POSTDEVELOPED Number of Subbasins: 2 Number of Links: 2 ***********Groundwater Recharge Summary Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) Subbasin: Subbasin 1 101.605 Link: New Copy Lnk1 0.000 Total: 101.605 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) Subbasin: Subbasin 1 11.521 Subbasin: Subbasin 2 3.013 Link: New Structure Lnk1 Not Computed Link: New Copy Lnk2 0.000 Total: 14.535 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.643 ac-ft/year, Post Developed: 0.092 ac-ft/year Quality Facility Data PREDEVELOPED Number of Links: 1 Link: New Copy Lnk1 Infiltration/Filtration Inflow Volume (ac-ft): 52.65 Inflow Volume Including PPT-Evap (ac-ft): 52.65 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To System (ac-ft): 52.65 Secondary Outflow To System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% POSTDEVELOPED Number of Links: 2 Link: New Copy Lnk2 62 ---PAGE BREAK--- Infiltration/Filtration Inflow Volume (ac-ft): 234.42 Inflow Volume Including PPT-Evap (ac-ft): 234.42 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To System (ac-ft): 234.42 Secondary Outflow To System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ***********Compliance Point Results Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Link: New Copy Lnk2 Point of Compliance Flow Frequency Data Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) 2-Year 1.244E-02 2-Year 1.058E-02 5-Year 2.123E-02 5-Year 1.479E-02 10-Year 2.642E-02 10-Year 2.116E-02 25-Year 3.409E-02 25-Year 2.488E-02 50-Year 4.105E-02 50-Year 2.779E-02 100-Year 4.927E-02 100-Year 2.829E-02 200-Year 6.663E-02 200-Year 2.863E-02 Record too Short to Compute Peak Discharge for These Recurrence Intervals Flow Duration Performance Excursion at Predeveloped 50%Q2 (Must be Less Than or Equal to -5.0% PASS Maximum Excursion from 50%Q2 to Q2 (Must be Less Than or Equal to -5.0% PASS Maximum Excursion from Q2 to Q50 (Must be less than 10%): 0.9% PASS Percent Excursion from Q2 to Q50 (Must be less than 50%): 1.3% PASS MEETS ALL FLOW DURATION DESIGN CRITERIA: PASS LID Duration Performance Excursion at Predeveloped 8%Q2 (Must be Less Than 438.0% FAIL Maximum Excursion from 8%Q2 to 50%Q2 (Must be Less Than 609.8% FAIL LID DURATION DESIGN CRITERIA: FAIL 63 ---PAGE BREAK--- APPENDIX B.2: ENGINEERING CALCULATIONS MGS Flood Report 64 ---PAGE BREAK--- MGS FLOOD PROJECT REPORT Program Version: 4.43 Program License Number: 200610002 Project Simulation Performed on: 05/30/2018 4:21 PM Report Generation Date: 05/30/2018 4:22 PM Input File Name: AL Building Detention.fld Project Name: Emerald Heights MR2 Analysis Title: Detention AL Bldg Comments: Created: IDS 2016.12.01 Updated: IDS 2018.05.30 PRECIPITATION INPUT Computational Time Step (Minutes): 60 Extended Precipitation Time Series Selected Climatic Region Number: 0 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default Default HSPF Parameters Used (Not Modified by User) WATERSHED DEFINITION Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.922 0.922 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.922 0.922 PREDEVELOPED Number of Subbasins: 1 Subbasin : Onsite (Acres) Till Forest 0.922 Subbasin Total 0.922 65 ---PAGE BREAK--- POSTDEVELOPED Number of Subbasins: 2 Subbasin : Subbasin 1 (Acres) Till Pasture 0.102 Till Grass 0.030 Impervious 0.564 Subbasin Total 0.696 Subbasin : Onsite Bypass (Acres) Till Pasture 0.196 Till Grass 0.007 Impervious 0.023 Subbasin Total 0.226 LINK DATA PREDEVELOPED Number of Links: 1 Link Name: Outfall Link Type: Copy Link: None LINK DATA POSTDEVELOPED Number of Links: 2 Link Name: Detention Vault Link Type: Structure Link Name: Outfall Prismatic Pond Option Used Pond Floor Elevation (ft) : 337.75 Riser Crest Elevation (ft) : 343.50 Max Pond Elevation (ft) : 344.00 Storage Depth (ft) : 5.75 Pond Bottom Length (ft) : 87.0 Pond Bottom Width (ft) : 30.0 Pond Side Slopes (ft/ft) : L1= 0.00 L2= 0.00 W1= 0.00 W2= 0.00 Bottom Area (sq-ft) : 2610. 66 ---PAGE BREAK--- Area at Riser Crest El (sq-ft) : 2,610. (acres) : 0.060 Volume at Riser Crest (cu-ft) : 15,008. (ac-ft) : 0.345 Area at Max Elevation (sq-ft) : 2610. (acres) : 0.060 Vol at Max Elevation (cu-ft) : 16,574. (ac-ft) : 0.380 Massmann Infiltration Option Used Hydraulic Conductivity (in/hr) : 0.00 Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low Maintenance : Average or Better Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 343.50 ft Hydraulic Structure Geometry Number of Devices: 2 ---Device Number 1 Device Type : Circular Orifice Control Elevation (ft) : 337.75 Diameter (in) : 0.38 Orientation : Horizontal Elbow : No ---Device Number 2 Device Type : Circular Orifice Control Elevation (ft) : 342.00 Diameter (in) : 0.87 Orientation : Horizontal Elbow : No Link Name: Outfall Link Type: Copy Link: None FREQUENCY AND DURATION PREDEVELOPED Number of Subbasins: 1 Number of Links: 1 POSTDEVELOPED Number of Subbasins: 2 Number of Links: 2 67 ---PAGE BREAK--- ***********Groundwater Recharge Summary Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) Subbasin: Onsite 159.863 Link: Outfall 0.000 Total: 159.863 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) Subbasin: Subbasin 1 21.767 Subbasin: Onsite Bypass 35.602 Link: Detention Vault Not Computed Link: Outfall 0.000 Total: 57.369 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 1.012 ac-ft/year, Post Developed: 0.363 ac-ft/year Quality Facility Data PREDEVELOPED Number of Links: 1 Link: Outfall Infiltration/Filtration Inflow Volume (ac-ft): 82.84 Inflow Volume Including PPT-Evap (ac-ft): 82.84 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To System (ac-ft): 82.84 Secondary Outflow To System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% POSTDEVELOPED Number of Links: 2 Link: Outfall Infiltration/Filtration Inflow Volume (ac-ft): 309.77 Inflow Volume Including PPT-Evap (ac-ft): 309.77 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% 68 ---PAGE BREAK--- Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To System (ac-ft): 309.77 Secondary Outflow To System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ***********Compliance Point Results Scenario Predeveloped Compliance Link: Outfall Scenario Postdeveloped Compliance Link: Outfall Point of Compliance Flow Frequency Data Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) 2-Year 1.958E-02 2-Year 1.682E-02 5-Year 3.341E-02 5-Year 2.628E-02 10-Year 4.157E-02 10-Year 3.676E-02 25-Year 5.364E-02 25-Year 4.412E-02 50-Year 6.458E-02 50-Year 4.517E-02 100-Year 7.752E-02 100-Year 4.839E-02 200-Year 0.105 200-Year 5.755E-02 Record too Short to Compute Peak Discharge for These Recurrence Intervals Flow Duration Performance Excursion at Predeveloped 50%Q2 (Must be Less Than or Equal to -10.6% PASS Maximum Excursion from 50%Q2 to Q2 (Must be Less Than or Equal to -10.6% PASS Maximum Excursion from Q2 to Q50 (Must be less than 10%): -16.0% PASS Percent Excursion from Q2 to Q50 (Must be less than 50%): 0.0% PASS MEETS ALL FLOW DURATION DESIGN CRITERIA: PASS 69 ---PAGE BREAK--- APPENDIX C: CONVEYANCE ANALYSIS Included in a later version of this report 70 ---PAGE BREAK--- APPENDIX D: GEOTECHNICAL REPORT Included in a later version of this report 71 ---PAGE BREAK--- APPENDIX E: OPERATIONS AND MAINTANENCE MANUAL Included in a later version of this report 72