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BLD2021-00721_05 Approved Stormwater
Washington Project Consultants, PLLC 212 S Rhododendron DR Port Townsend, WA 98368 Phone (360) 890-0752 STORMWATER MANAGEMENT REPORT Project: The Refuge – Addition of a Chapel MLA #14-0064 Location: 2275 Duckabush Road, Brinnon, WA Owner: The Refuge: Col. James A. Engren, Ret. Stormwater Supplement Report by: Marc A. Horton, PE Date: November 30,2021 Attachments: Attachment 1: Location Map Attachment 2: Site Plan Attachment 3: Stormwater Calculation Worksheet Attachment 4: Flow Chart – Figure 2.4.1 Attachment 5: Medium and Large Project Report (Worksheet A1) Attachment 6: Construction Pollution Prevention Plan (Worksheet B1) Attachment 7: Site BMP Options (Worksheet C) Attachment 8.: Large Project Worksheet (Worksheet L) Attachment 9: NRCS Soils Report Attachment 10: Hydraulic Model Report Attachment 11: Typical Bioretention Design Attachment 12: Operations and Maintenance of Bioretention Facilities Proposed Development: This report addresses stormwater management for addition of a Chapel at the existing facilities at The Refuge (Olympic Mountain Retreat and Conference Center) off Duckabush Road near Brinnon, WA. The location is provided as Attachment 1. The latest improvements at this facility were completed under MLA #14-0064 (application package April 2017). The addition of a Cabin #2 was completed under plans submitted in January 2021. Overall, several facilities were approved for construction, including: 4 Small Cabins A Cook Shed Waterworks Building Cabin #1 (2 BR) Cabin #2 (4 BR) 11/ 30/21 RECEIVED BY DCD 12/6/2021BLD2021-00721 Apr 07 2022 The Refuge – Chapel Page 2 of 4 The owner would now like to add a Chapel of 855 square feet (impervious coverage). All past improvements created 73,201 sf of impervious surface on the 17.8-acre site. The addition of the 855 sf Chapel and 4019 sf of walks and parking will increase this coverage to 79,080 sf (total of about 10% of the site). The location of the proposed new Chapel is shown on the site plan (Attachment 2) Regulatory Requirements: Several buildings were envisioned in the land use application MLA #14-0064. The majority of those were included in the approved Amended Phase I permit application (2017). Since 2017, Cabin #2 has been approved as a separate project application (January 2021). This proposal covers the Chapel which was also envisioned in MLA #14-0064. Because of its location, this project cannot reasonably connect with the existing stormwater collection and management system serving the main Refuge facility. This project will require a separate analysis and design of a separate system. The County uses a set of forms to address the regulatory requirements, and to help direct compliance with the Stormwater Management Manual of Western Washington (SWMMWW). The forms, and this report address the design compliance and construction and operational performance requirements. County forms begin with a Stormwater Calculation Worksheet. This was developed (Attachment 3) showing less than 35% total coverage, and defining the project as “new development”. Figure 2.4.1 from County forms) for new development was used to show that because of over 5,000 sf of new impervious surface, this project is a “Large” project” under the County’s system (Attachment 4). Large Projects need to meet all Minimum Requirements and are referred to Worksheet L for guidance on requirements. Additionally, Worksheets A1, B1 and C or equivalent are to be completed. A1 – Medium and Large Project Report is provided as Attachment 5 B1 – Stormwater Pollution Prevention Plan is provided as Attachment 6 C – BMP Options for Site is provided as Attachment 7 Because full dispersion is not considered feasible (flow paths would be in the stream buffer), and the parcel is greater than 5 acres, County Form L (Attachment 8) directs that this stormwater report and the site plan be developed by a licensed professional engineer. Existing Conditions: The drainage, soils, and general information for the 17.8 acres under MLA #14-0064 were described in the 2017 Amended Phase 1 Drainage & Erosion Control Report (2017 Report). For this site, NRCS soils mapping, and description are provided as Attachment 9. As previously described in the 2017 Report, these soils are a very gravelly loamy sand (Classified as GoC – Grove). Hydraulic conductivity of these soils is fairly high. NRCS reports the mid range conductivity between 13 to 43 inches per hour. As the site plan indicates, most of this site has in the past been cleared. Vegetation for the cleared areas is characteristic of volunteer grasses of the area. The remainder of the site is in forest / shrub typical of native vegetation for the area. RECEIVED BY DCD 12/6/2021 The Refuge – Chapel Page 3 of 4 The Chapel site is on a knoll, and an access currently exists to go from the roadway to the chapel site. The remainder of the site is fairly level (less than 5% slope), and sloping toward forested area and the stream to the west. The stream is not fish bearing. Design: Worksheet L required an assessment of the feasibility of full dispersion for this project. Since the slope of the site would require dispersion to the stream buffer, this option was rejected. Given the high infiltration potential of the soils, bioretention was selected as a treatment and management system for the Chapel and associated parking. The 2012 Western Washington Hydraulic Model was used to size biofiltration for this project. Proposed Stormwater Management: Because of the stream buffers and setbacks, the pond was designed as a non-overflow system using infiltration as the management technique. Dispersion would be preferred, but an area outside the buffer was not available. Soils for this site are very good for stormwater infiltration. The model was run with infiltration enabled at 13 inches per hour – the moderate rate reported by NRCS. A safety factor of 2 was used. Basin setup for the model was 0.18 acres and as follows: Predevelopment – 27% Forest / 73% Pasture – 100% Pervious Mitigated Scenario – 80% Impervious / 20% Pervious Pond sizing was established at: Bottom Length 22 ft Bottom Width 5 ft Bottom Area 110 sf Side Slopes 2:1 Overall Footprint (with side slopes) 17X34 ft Depth 3 ft Bottom Gravel Layer 0.5 ft Bottom Soil Layer 1.5 ft Freeboard 0.5 ft Riser Height 0.5 ft This facility provides estimated infiltration of 99.85% of the anticipated flow during the modeling period. The result as a PASS on all flow levels for the mitigated scenario and met LID performance standards. Model results are provided as Attachment 10. A typical Bioretention Design is provided as Attachment 11. Minimum Requirements 6-9 are not are not addressed specifically by the County system. They are addressed in this plan as follows: RECEIVED BY DCD 12/6/2021 The Refuge – Chapel Page 4 of 4 MR6 – Runoff Treatment: Met though the use of a bioretention system with meeting water quality requirements. MR7 – Flow Control: The designed system meets stream protection standards at the LID level. MR8 – Wetland Protection: Not applicable with this project. MR9 – Operations & Maintenance: Maintenance of a bioretention facility is covered explicitly in the SWMMWW. They are expected to be followed by the owner after construction, and are provided as Appendix 12. Site Plan Options: The final site plan including stormwater features can be adjusted to the design engineer’s preference as long as the critical pond design features such as bottom square footage, depth, and side slopes, etc. remain consistent with the overall model design parameters above. The current site plan is provided as Attachment 2. RECEIVED BY DCD 12/6/2021 Pr o j e c t L o c a t i o n RECEIVED BY DCD 12/6/2021 5 7 5 5 5 216 1 5 7 2 2 6 2 3 5 5 7 6 6 0 5 5 5 0 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 0 3 0 3 0 0 0 3 5 0 5 5 5 5 5 5 5 0 50 0 0 0 0 5 0 0 0 0 0 5 0 0 5 5 5 1 6 3 1 5 2 5 1 2 5 1 2 5 1 7 5 1 75 1 75 1 7 5 1 5 8 6 1 3 1 7 1 5 7 2 2 67 3 6 7 5 1 5 9 1 1 6 1 2+ 3 2 9 5 3 2 5 1 8* 7 7 3 2 1 1 3 3 5 2 2 7 2 1 8 1 5 5 2 8 1 8 1 1 2 5 7 3 5 1 3 5 2 3 5 7 1 3 2 5 2 0 7 5 6 8 5 9 0 2 1 8 0 1 7 6 1 2 7 8 7 7 3 2 8 9 5 7 1 2 2 1 5 7 7 1 2 5 2 5 9 2 3 9 0 1 7 2 5 7 2 1 3 7 6 2 7 5 6 1 7 2 5 2 5 2 5 6 6 5 5 5 1 6 3 6 1 2 1 8 2 8 6 7 5 7 5 8 1 0 7 5 1 6 3 6 1 2 1 2 1 5 7 5 7 5 8 1 0 7 5 7 5 1 2 1 7 2 8 5 2 2 7 1 7 5 9 1 2 1 7 2 8 5 2 2 7 1 7 5 9 8 7 7 3 2 1 2 5 3316 75851121 310 6731 1R6537217 6, 7 3 1 7 1 2 9 6+ 7 2 7KH5HIXJH 2OPSLF0RXQWDLQ5HWUHDWRQIHUHQFH HQWHU DPHV5REELHGJUHQ 32R XFNDEXVK5RDG ULQQRQ MLPHGJUHQJPDLOFRP 3 5 3 5 2 5 6 2 1 6 7 1 7 8 5 6 7 1 6 7 2 1 1 7 2 1 6 3 1 2 5 7 5 1 6 7 0 5 6 2 1 2 8 1 7 6 1 7 2 1 1 3 2 5 7 2 1 2 6 F D O H 6 7 1 6 6 2 1 5 2 1 5 5 2 8 1 6 7 1 6 3 1 6 3 1 6 3 2 1 1 1 2 1 6 6 7 3 6 2 1 5 0 3 2 1 1 1 2 1 3 5 1 5 5 5 3 5 6 3 6 3 2 1 3 2 1 1 7 8 5 1 5 2 8 1 5 9 6 8 5 3 7 5 6 6+ 7 3 9 6( 5 6 6+ 7 66 2 A tt a c h m e n t 2 RECEIVED BY DCD 12/6/2021 stormwater calc worksheet QR code – REV. 5/31/2019 page 1 of 2 DEPARTMENT OF COMMUNITY DEVELOPMENT 621 Sheridan Street, Port Townsend, WA 98368 Tel: 360.379.4450 | Fax: 360.379.4451 Web: www.co.jefferson.wa.us/communitydevelopment E-mail: dcd@co.jefferson.wa.us STORMWATER CALCULATION WORKSHEET PARCEL # PROJECT/APPLICANT NAME: DETERMINING STORMWATER MANAGEMENT REQUIREMENTS: This stormwater calculation worksheet should be completed first to classify the proposal as “small,” “medium,” or “large.” The size determines whether a Stormwater Site Plan is required in conjunction with a stand-alone stormwater management permit application, building permit application, or other land use approval application that involves stormwater review. The basic information will also be helpful for completing a Stormwater Site Plan, if required. Land-disturbing activity is any activity that results in movement of earth, or a change in the existing soil cover (both vegetative and non-vegetative) and/or the existing soil topography. Land disturbing activities include, but are not limited to clearing, grading, filling, excavation, and compaction associated with stabilization of structures and road construction. Native vegetation is vegetation comprised of plant species, other than noxious weeds, which reasonably could have been expected to naturally occur on the site. Examples include species such as Douglas fir, western hemlock, western red cedar, alder, big-leaf maple, and vine maple; shrubs such as willow, elderberry, salmonberry, and salal; herbaceous plants such as sword fern, foam flower, and fireweed. LAND DISTURBING ACTIVITY, CONVERSION OF NATIVE VEGETATION, AND VOLUME OF CUT/FILL Calculate the total area to be cleared, graded, filled, Answer the following two questions related to excavated, and/or compacted for proposed development conversion of native vegetation: project. Include in this calculation the area to be cleared for: Does the project convert ¾ acres or more of Construction site for structures _________________ sq/ft native vegetation to lawn or landscaped areas? Drainfield, septic tank, etc. ____________________ sq/ft Circle: Yes No Well, utilities, etc. ___________________________ sq/ft Does the project convert 2 ½ acres or more of native vegetation to pasture? Driveway, parking, roads, etc. ___________________sq/ft Circle: Yes No Lawn, landscaping, etc. ______________________ sq/ft Other compacted surface, etc. _________________ sq/ft Indicate Total Volumes of Proposed: Includes BMP T5.13 Fill Volume) Temporary construction area ______________ sq/ft Total Land Disturbance ____________________ sq/ft Cut __________ Fill __________ (cu/yd) PARCEL SIZE (I.E., SITE) Size of parcel _________ acres An acre contains 43,560 square feet. Multiply the acreage by this figure. Size of parcel in square feet _________________ sq/ft Scan the QR code to access the digital form The Refuge / Chapel Addition Attachment 3 MLA14 - 00064 17.8 774,906 1200 4600 1000 6800 50 50 RECEIVED BY DCD 12/6/2021 stormwater calc worksheet QR code – REV. 5/31/2019 page 2 of 2 Applicants for “small” projects must comply only with Minimum Requirement #2—Construction Stormwater Pollution Prevention. Please submit the Small Project Certification (Worksheet “s). The proponent is responsible for employing the 12 Elements to control erosion and prevent sediment and other pollutants from leaving the site during the construction phase of the project. Pick up the Construction Stormwater Pollution Prevention (SWPPP) Best Management Practices (BMPs) Fact Sheet. Applicants for “medium” projects—those that must meet only Minimum Requirements #1 through #5 must submit Worksheet A1 and B1, a stormwater site plan and a construction stormwater pollution prevention site plan (See Reference A1A and B1A for guidance).). Large” projects—those that must meet all 9 Minimum Requirements— must submit Worksheet A1 and B1, a stormwater site plan and a construction stormwater pollution prevention site plan (See Reference A1A and B1A for guidance). Large projects also may require engineering. See Worksheet L to determine additional large project requirements. APPLICANT SIGNATURE By signing the Stormwater Calculation Worksheet, I as the applicant/owner attest that the information provided herein is true and correct to the best of my knowledge. I also certify that this application is being made with the full knowledge and consent of all owners of the affected property. LANDOWNER OR AUTHORIZED REPRESENTATIVE SIGNATURE) (DATE) STORMWATER CALCULATIONS – IMPERVIOUS SURFACE Impervious surface is a hard surface that either prevents or slows the entry of water into the soil as under natural conditions prior to development. A hard surface area which causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include, but are not limited to roof tops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials, and oiled, macadam or other surfaces which similarly impede the natural infiltration of stormwater. NEW EXISTING Structures (all roof area) _________________sq/ft Structures (all roof area) _________________sq/ft Sidewalks _________________sq/ft Sidewalks _________________sq/ft Patios _________________sq/ft Patios _________________sq/ft Solid Decks _________________sq/ft Solid Decks _________________sq/ft without infiltration below) (without infiltration below) Driveway, parking, roads, etc _______________sq/ft Driveway, parking, roads, etc _______________sq/ft Other _________________sq/ft Other _________________sq/ft Total New _________________sq/ft Total Existing _________________sq/ft TOTAL NEW + TOTAL EXISTING* _________________sq/ft *This amount will be used to check total lot coverage. DEVELOPMENT v. REDEVELOPMENT Divide the total existing impervious surface above by the size of the parcel and convert to a percentage. ____________% Does the site have > 35% or more existing impervious surface? The proposal is considered new development. Answer questions in Figure 2.4.1 Flow Chart for New Development to determine project size (next page). The proposal is considered redevelopment Answer questions in Figure 2.4.2. Flow Chart for Redevelopment to determine project size (next page). yes no Pond 833 1027 4019 5879 14,078 412 57,395 1,146 73,031 79,080 9.4% RECEIVED BY DCD 12/6/2021 5IJT JT B MBSHF QSPKFDU BSHF QSPKFDUT SFGFS UP 8PSLTIFFU GPS TVCNJUUBM SFRVJSFNFOUT U B NJOJNVN BMM MBSHF 1SPKFDU NVTU TVCNJU 8PSLTIFFU BOE PS FRVJWBMFOU 5IJT JT B NFEJVN QSPKFDU 4VCNJU 8PSLTIFFU BOE PS FRVJWBMFOU PNQMFUF 4NBMM 1SPKFDU FSUJGJDBUJPO 8PSLTIFFU 1SPKFDU NVTU GPMMPX POTUSVDUJPO 1PMMVUJPO 1SFWFOUJPO BDU 4IFFU JHVSF MPX IBSU GPS FX FWFMPQNFOU Attachment 4 RECEIVED BY DCD 12/6/2021 Worksheet A1 Medium & Large Project Report Ž Ž Z Ž Z Z E Ž Ž D W DW Ž Z Ž Ž Ž Ž D Z WŽ Ž Ž W Ž ŽŽ ŽŽ Ž ŽŽ Ž Ž Ž structures roads ŽŽ ŽŽ ŽŽ Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž ZŽt ZKt Complete the following:D Z ŽŽ Ž WŽŽ WŽ W tWWW tWWW Ž Ž Ž ŽŽ Ž Ž d Ž Ž ŽŽ Ž Ž Ž Ž Ž Ž ŽŽ DW Ž Ž Z Z E Ž ŽŽ DW Ž D Ž tWWW tKZ<^,d Ž Ž D Z Ž ŽŽ Ž WŽŽ Ž ŽŽ d Ž Ž ŽŽ Ž Ž Ž Ž Ž Ž Ž ŽŽ DW ŽŽ Ž ŽŽ Ž Ž Ž Ž ŽŽ DW t Ž Ž ŽŽ DW d Ž Ž Z Z Ž Ž ŽŽ Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž ŽŽ DW Ž Ž Ž Ž sŽ s Ž Ž D D Ž t tŽ tDDtt Ž Ž Attachment 5 RECEIVED BY DCD 12/6/2021 Worksheet A1 Medium & Large Project Report Ž Ž Ž ŽŽ Ž Ž Ž Ž DZ D Z Ž ŽŽ Ž WŽŽ Ž Ž D Ž Z Z Ž ŽŽ Ž Ž Ž Ž Ž Ž DZ Ž Ž Ž Ž Ž D Ž Ž Z sŽ s Ž tDDtt DZ Ž Ž ŽŽ Ž D Ž Ž Z sŽ s Ž tDDtt ŽŽ Ž ŽŽ DW Ž Ž ŽŽ Ž Ž ŽŽ RECEIVED BY DCD 12/6/2021 Worksheet A1 Medium & Large Project Report D Z WŽ Ž E Ž Ž Ž Ž ŽŽ Ž ŽŽ Ž Ž ŽŽ Ž Ž ŽŽ Ž Ž Ž ŽŽ Ž Ž ŽŽ EKd Ž Ž d sŽ s Ž tDDtt Ž Ž Ž ŽŽ Ž ŽŽ ŽŽ Ž Ž Ž Ž d Ž Ž Ž Ž Ž ŽŽ Ž Ž Ž Ž Ž ŽŽ Ž Ž Ž Ž Ž Ž Ž Ž d Ž Ž Ž Ž EKd d Ž Ž W Ž Ž Ž Ž Ž Ž Ž Ž Ž d Ž Ž Ž Ž Ž ŽŽ Ž Ž Ž Ž Ž ŽŽ Ž Ž Ž Ž Ž Ž DW h&&Z KE Ž Ž Ž Ž Ž Ž d Ž Ž Ž Ž Ž Ž Ž Engineering Ž Ž ŽŽ Ž Ž Ž Ž RECEIVED BY DCD 12/6/ Worksheet A1 Medium & Large Project Report Ž D Ž Ž Z Ž tŽ Ž LIST #1 Ž D Z K Ž D K Ž Ž Ž ŽŽ Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž dŽ Ž Ž Ž Ž Ž Ž d Ž Ž Ž tKZ<^,d Ž ZŽ Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž D Ž Ž Ž Ž Ž WZK Ž W Ž LIST #1 D WŽ Ž Ž Ž Z Ž Ž Z WZK Ž W Ž LIST #3 RECEIVED BY DCD 12/6/2021 Worksheet A1 Medium & Large Project Report D Ž Ž Ž Ž Ž Ž Ž WŽ ŽŽ Ž Y Ž DW d D Ž Ž Ž Roof Ž DW d KZ ŽŽ Ž DW d Z Z'WZK:d^EEKd h^DW d ŽŽ Ž DW d WŽ K ŽŽ DW d DW Ž tKZ<^,d dKW KDW>d E h D/d tKZ<^, d EK Kd,Z E&KZD d/KE Z Yh/Z d d,/^d/D D Ž Ž Ž Other Hard Surface areas Ž DW d W W DW d KZ Z Z'WZK:d^EEKd h^ DW d D Z K Ž D Ž LIST # 1 Ž Ž Ž Ž E^dZh d/KE^ŽŽ Ž Ž Each Category Ž Ž Ž Ž Ž Ž d Ž Ž Ž h tKZ<^,d Ž DW Ž Ž Ž Ž Ž tKZ<^,d Ž Ž Ž Ž Ž Ž Ž ZŽŽ Ž K Ž Ž Ž Ž Ž Ž Ž DW d KZ Ž Ž Ž DW d Ž tKZ<^,d dKW KDW>d E h D/d tKZ<^,d EK Kd,Z E& KZD d/KE Z Yh/Z d d,/^d/D RECEIVED BY DCD 12/6/2021 Worksheet B1 ŽŽ WŽŽ D WŽ tWWW Ž WŽŽ WŽ W Ž ŽŽ Ž Ž Ž Ž ŽŽ Z Ž Z Z E Ž Ž ŽŽ D W DW Ž d ŽŽ Ž Ž Ž ŽŽ ŽŽ Ž Ž Ž Ž Ž Ž Ž Ž Z Ž Ž Ž Ž W sŽ D d Ž Ž Ž Ž Ž Ž Ž Choose any of the following that apply:d Ž Ž Ž Ž ZŽŽ Ž Ž ZŽ Ž Ž Ž DW Ž Ž Ž d Ž Ž Ž Ž ŽŽ Ž Ž Ž Ž Ž tWWW s Ž Ž Ž Ž Ž ŽŽ Ž Ž Ž ŽŽ DW^ Ž Ž C101 Preserving Natural Vegetation C102 Buffer Zones C103 High Visibility Fence Ž Ž Ž Ž ŽŽ Ž Ž ŽŽ Ž Ž Ž Ž Ž Ž DW d WŽ ŽŽ Ž Y ŽŽ d Ž Ž Ž Ž ŽŽ Ž Ž Ž Ž Choose one of the following:d Ž ŽŽ Ž ŽŽ Ž Ž Ž Ž Ž ŽŽ Ž ŽŽ Ž Ž ŽŽ Ž Ž tWWW Ž Ž ŽŽ Ž ŽŽ DW^Ž Ž C105 Stabilized Construction Entrance / Exit C106 Wheel Wash C107 Construction Road / Parking Area Stabilization Attachment 6 RECEIVED BYDCD12/6/2021 Worksheet B1 ŽŽ WŽŽ D WŽ tWWW Ž WŽŽ WŽ W ŽŽ Ž Z d Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž ŽŽ This element does not apply to my project because (check any that apply): Ž Ž d Ž Ž Ž d Ž Ž Ž Ž Ž D ŽŽ DW ŽŽ Ž Ž tWWW W ŽŽ DW^Ž Ž C233 Silt FenceC231BrushBarrierC234 Vegetated Strip C232 Gravel Filter Berm C235 Wattles ŽŽ d Ž Ž Ž Ž ŽŽ DW Ž Select one of the two statements applicable to the project.d Ž Ž Ž Ž Ž Ž tWWW W Ž Ž ŽŽ ŽŽ Ž Ž EŽ Ž Ž Ž Ž Ž Ž D Ž Ž Ž Ž KŽ Ž K Ž Ž Ž Ž d Ž Ž Ž Ž Ž Ž ŽŽ ŽŽ DW Select one of the three statements applicable to the project.D Ž ŽŽ This element does not apply to my project because:D Ž DW Ž Ž DW Ž Ž RECEIVED BY DCD 12/6/2021 Worksheet B1 ŽŽ WŽŽ D WŽ tWWW Ž WŽŽ WŽ W Ž C120 Temporary & Permanent Seeding C123 Plastic CoveringC121MulchingC124 SoddingC122Nets & Blankets C125 Topsoil / Composting C131 Gradient Terraces C140 Dust Control C235 Wattles WŽ Ž d Ž Ž Ž Ž Ž Ž ŽŽ Select one of the two statements applicable to the project.EŽ Ž Ž Ž Ž ŽŽ Ž ŽŽ Ž Ž Ž ŽŽ Ž ŽŽ dŽ Ž Ž Ž Ž ŽŽ d Ž Ž Ž D ŽŽ Ž Ž Ž Ž ŽŽ ŽŽ Ž ŽŽ DW C120 Temporary & Permanent Seeding C204 Pipe Slope Drains C205 Subsurface Drains C206 Level Spreader C207 Check Dams C208 Triangular Silt Dike Geotextile- Encased Check Dam) Ž Ž Ž Ž Ž Ž tWWW W Ž ŽŽ ŽŽ DW^Ž Ž C220 Storm Drain Inlet Protection d Ž Ž Ž Ž Ž d Ž Ž Ž WŽ W d Ž Ž Ž Ž Ž ŽŽ Ž Ž Ž Ž Ž Ž Ž Select one of the three statements applicable to the project.RECEIVED BY DCD 12/6/2021 Worksheet B1 ŽŽ WŽŽ D WŽ tWWW Ž WŽŽ WŽ W Ž Ž ŽŽ Ž Ž ŽŽ DW^Ž Ž C202 Channel Lining C207 Check Dams C235 WattlesC209OutletProtection Ž K d Ž Ž Ž Ž Ž Ž Ž ŽŽ Ž Ž Ž Ž Select one of the three statements applicable to the project.ŽŽ Ž EŽ Ž Ž Ž Ž Ž d Ž Ž ŽŽ Ž Ž Ž Ž C151 Concrete Handling C152 Sawcutting and Surfacing Pollution Prevention C153 Material Delivery, Storage, and Containment C154 Concrete Washout Area Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž ŽŽ Ž Ž ŽŽ DW ŽŽ DW^Ž Ž ŽŽ WŽ This element does not apply to my project because (circle any that apply - /Ž d Ž Ž Ž DW Ž Ž Ž Ž Ž Ž d Ž Ž Ž d Ž Ž d Ž Ž Ž d Ž Ž Ž d Ž Ž Ž d Ž Ž RECEIVED BY DCD 12/6/2021 Worksheet B1 ŽŽ WŽŽ D WŽ tWWW Ž WŽŽ WŽ W C203 Water Bars C236 Vegetated Filtration C206 Level Spreader ŽŽ EŽ Ž Ž ŽŽ DW^Ž Ž Ž Select one of the two statements applicable to the project.d Ž Ž Ž Ž Ž Ž Ž Ž Ž Ž Describe the steps you will take: D WŽ d tWWW Ž Ž ŽŽ ŽŽ DW ŽŽ D ŽŽ ŽŽ Ž Ž Ž Ž DW ŽŽ DW Ž Ž D DW Ž Ž D D W D W Ž DW ŽŽ Ž Ž Ž Ž Ž Ž Ž Ž d Ž Ž Ž Ž ŽŽ ŽŽ DW Ž Ž Ž d Ž Ž Ž Ž Ž Ž Ž Ž tWWW Ž ŽŽ Ž DW Ž Ž Ž Ž Ž Ž ŽŽ Ž RECEIVED BY DCD 12/6/2021 Worksheet B1 ŽŽ WŽŽ D WŽ tWWW Ž WŽŽ WŽ W C102 Buffer Zone C103 High Visibility Fence C233 Silt Fence C231 Brush Barrier C234 Vegetated Strip Ž Z WŽ Ž Ž DW Ž d Ž Ž Ž Ž Ž DW Ž Ž ŽŽ ŽŽ d Ž DW Ž Ž Ž ŽŽ Ž Ž ŽŽ ŽŽ Ž Ž Ž Ž Ž ŽŽ ŽŽ Ž Ž Ž Ž Ž DŽ Ž Ž Ž DW ŽŽ Ž Ž DW Ž ŽŽ ŽŽ Ž DW Ž h ŽŽ Ž ŽŽ DW Ž Ž Ž Ž ŽŽ Ž ŽŽ Ž ŽŽ ŽŽ DW^Ž Ž K RECEIVED BY DCD 12/6/2021 Co m p l e t e c o n s t r u c t i o n s t o r m w a t e r c o n t r o l B M P d e t a i l s a r e f o u n d in V o l u m e I I o f t h e D O E S t o r m w a t e r M a n a g e m e n t M a n u a l RE F E R E N C E B 1 A C o n s t r u c t i o n B M P O p t i o n s Si t e p l a n l o o k i n g t o o c r o w d e d U s e t h e l e t t e r s on t h i s p a g e a s r e f e r e n c e i n s t e a d o f d r a w i n g th e B M P B e s u r e t o i n d i c a t e l o c a t i o n s i z i n g i f ap p l i c a b l e u s e t h e p r o p e r s y m b o l i n d i c a t e d on e a c h B M P RECEIVED BY DCD 12/6/2021 RECEIVED BY DCD 12/6/2021 1 Worksheet C What’s the best option for your site? Roofs BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Lawn and Landscaped Areas BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Minimum Requirement #5 (On-Site Stormwater Management) The following tables summarize the criteria that can be used to justify why you cannot use various stormwater management best management practices (BMPs) for consideration for Minimum Requirement #5. This information is also included under the detailed descriptions of each BMP in the Department of Ecology’s Stormwater Management Manual for Western Washington (SWMMWW [2014]). Where any inconsistencies or lack of clarity exists, the requirements in the main text of the SWMMWW shall be applied. HOW TO USE: Evaluate the feasibility of the BMPs in priority order based on Worksheet A1 page 5 (List #1) or 6 (List #3) or Worksheet L for Large Projects (List #2). Only one criterion needs to be selected for a BMP before evaluating the next BMP on the list. Full Dispersion BMP T5.30, SWMMWW Volume V, Section 5.3 A 65 to 10 ratio of forested or native vegetation area to impervious area cannot be achieved. PLQLPXP IRUHVWHG RU QDWLYH YHJHWDWLRQ ÀRZSDWK OHQJWK RI IHHW IHHW IRU VKHHW ÀRZ IURP D QRQ QDWLYH SHUYLRXV surface) and protected by easement cannot be achieved. Siting and design criteria cannot be achieved on site. There is an alternatie septic system on this lot or an adjacent ORW PRXQG VDQG OWHU SUHVVXUH GLVWULEXWLRQ OHQGRQ DHURELF treatment unit). Therefore, there is not at least 3 feet or PRUH RI SHUPHDEOH VRLO IURP WKH SURSRVHG QDO JUDGH WR WKH seasonal high groundwater table or other impermeable layer. There is not at least 1 foot or more of permeable soil from WKH SURSRVHG ERWWRP RI WKH LQ¿OWUDWLRQ V\VWHP WR WKH VHDVRQDO high groundwater table or other impermeable layer. Downspout Full Q¿OWUDWLRQ BMP T5.10A, SWMMWW Volume III, Section 3.1.1 Post-construction Soil Quality and Depth BMP T5.13 SWMMWW Volume V, Section 5.3) Lawn and landscape area is on till slopes greater than 33 percent. Siting and design criteria cannot be achieved on site. List #1, #2 and #3 List #1 and #2 List #1, #2 and #3 None of the above boxes are checked. This is the BMP that must be used for lawn and landscaped areas. On Worksheet A1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. None of the above boxes are checked. This is the BMP that must be used for roofs. On Worksheet A1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. Attachment 7RECEIVEDBYDCD12/6/2021 2 Worksheet C What’s the best option for your site? Roofs (cont.) BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Where professional geotechnical evaluation recommends LQ¿OWUDWLRQ QRW EH XVHG GXH WR UHDVRQDEOH FRQFHUQV DERXW HURVLRQ VORSH IDLOXUH RU GRZQ JUDGLHQW ÀRRGLQJ Within an area whose ground water drains into an erosion hazard, or landslide hazard area. Where the only area available for siting would threaten the VDIHW\RU UHOLDELOLW\RI SUH H[LVWLQJ XQGHUJURXQG XWLOLWLHV SUH H[LVWLQJ XQGHUJURXQG VWRUDJH WDQNV SUH H[LVWLQJ VWUXFWXUHV RU SUH H[LVWLQJ URDG RU SDUNLQJ ORW VXUIDFHV Where the only area available for siting does not allow for D VDIH RYHUÀRZ SDWKZD\WR VWRUPZDWHU GUDLQDJH V\VWHP RU private storm sewer system. Where there is a lack of usable space for bioretention areas DW UH GHYHORSPHQW VLWHV RU ZKHUH WKHUH LV LQVX FLHQW VSDFH ZLWKLQ WKH H[LVWLQJ SXEOLF ULJKW RI ZD\RQ SXEOLF URDG SURMHFWV Note: Criteria with setback distances are as measured from the bottom edge of the bioretention soil mix.Citation of any of the following infeasibility criteria must be EDVHG RQ DQ HYDOXDWLRQ RI VLWH VSHFL¿F FRQGLWLRQV DQG D ZULWWHQ recommendation from an appropriate licensed professional (e. g., engineer, geologist, hydrogeologist):KHUH LQ¿OWUDWLQJ ZDWHU ZRXOG WKUHDWHQ VKRUHOLQH VWUXFWXUHV such as bulkheads.KHUH LQ¿OWUDWLQJ ZDWHU ZRXOG WKUHDWHQ H[LVWLQJ EHORZ JUDGH basements.Bioretention or Rain Gardens BMP T7.30 or T5. 14A SWMMWW Volume V, Section 7. 4 List #1 ( both)and List # 2 bioretention only)Downspout Full Q¿ OWUDWLRQ cont.)BMP T5. 10A, SWMMWW Volume Slopes steeper than 25% or less than 200’ from slope steeper than 40%.Siting and design criteria cannot be achieved on site.None of the above boxes are checked. This is the BMP that must be used for roofs. On Worksheet A1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. Design (bioretention) will handle roof drainage.RECEIVED BY DCD 12/6/ 3 Worksheet C What’s the best option for your site? Roofs (cont.) BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Bioretention or Rain Gardens cont.) BMP T7.30 or T5.14A SWMMWW Volume V, Section 7.4 Where land for bioretention is within an erosion hazard, or ODQGVOLGH KD]DUG DUHD DV GH¿QHG E\3$0& Where the site cannot be reasonably designed to locate bioretention areas on slopes less than 8 percent. Within 50 feet from the top of slopes that are greater than 20 percent and over 10 feet of vertical relief. For properties with known soil or groundwater contamination typically federal Superfund sites or state cleanup sites under the Model Toxics Control Act [MTCA]): Within 100 feet of an area known to have deep soil contamination. KHUH JURXQGZDWHU PRGHOLQJ LQGLFDWHV LQ¿OWUDWLRQ will likely increase or change the direction of the migration of pollutants in the groundwater. Wherever surface soils have been found to be contaminated unless those soils are removed within KRUL]RQWDO IHHW IURP WKH LQ¿OWUDWLRQ DUHD LWKLQ IHHW RI D FORVHG RU DFWLYH ODQG¿OO Within 10 feet of an underground storage tank and connecting underground pipes when the capacity of the tank and pipe system is 1,100 gallons or less. As used in these criteria, an underground storage tank means any tank used to store petroleum products, chemicals, or liquid hazardous wastes of which 10 percent or more of the storage volume including volume in the connecting piping system) is beneath the ground surface. Within 100 feet of an underground storage tank and connecting underground pipes when the capacity of the tank and pipe system is greater than 1,100 gallons. The following criteria can be cited as reasons for infeasibility ZLWKRXW IXUWKHU MXVWL¿FDWLRQ WKRXJK VRPH UHTXLUH SURIHVVLRQDO services to make the observation): Within setback provided for BMP T7.30 (SWMMWW Volume V, Section 7.4) Where they are not compatible with surrounding drainage system as determined by the county (e.g., project drains to an existing stormwater collection system whose elevation or location precludes connection to a properly functioning bioretention area). RECEIVED BY DCD 12/6/2021 4 Worksheet C What’s the best option for your site? Roofs (cont.) BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed KHUH HOG WHVWLQJ LQGLFDWHV SRWHQWLDO ELRUHWHQWLRQ UDLQ garden sites have a measured (a.k.a., initial) native soil saturated hydraulic conductivity less than 0.30 inches per KRXU VPDOO VFDOH RU ODUJH VFDOH 3,7 LQ DFFRUGDQFH ZLWK SWMMWW Volume III, Section 3.3.6 (or an alternative VPDOO VFDOH WHVW VSHFL¿HG E\WKH ORFDO JRYHUQPHQW VKDOO be used to demonstrate infeasibility of bioretention areas. I WKH PHDVXUHG QDWLYH VRLO LQ¿OWUDWLRQ UDWH LV OHVV WKDQ LQ KRXU ELRUHWHQWLRQ UDLQ JDUGHQ 03V DUH QRW UHTXLUHG to be evaluated as an option in List #1 or List #2. In these slow draining soils, a bioretention area with an underdrain PD\EH XVHG WR WUHDW SROOXWLRQ JHQHUDWLQJ VXUIDFHV WR KHOS PHHW 0LQLPXP 5HTXLUHPHQW 5XQR 7UHDWPHQW I WKH underdrain is elevated within a base course of gravel, it will DOVR SURYLGH VRPH PRGHVW ÀRZ UHGXFWLRQ EHQH¿W WKDW ZLOO KHOS achieve Minimum Requirement #7. Where the minimum vertical separation of 3 feet to the seasonal high groundwater elevation or other impermeable layer would not be achieved below bioretention that would serve a drainage area that exceeds the following thresholds and cannot reasonably be broken down into amounts smaller than indicated): R VTXDUH IHHW RI SROOXWLRQ JHQHUDWLQJ LPSHUYLRXV VXUIDFH 3*,6 o 10,000 square feet of impervious area o 0.75 acres of lawn and landscape. Any area where these facilities are prohibited by an approved cleanup plan under the state MTCA or Federal Superfund Law, or an environmental covenant under Chapter 64.70 RCW. Within 100 feet of a drinking water well, or a spring used for drinking water supply. Bioretention or Rain Gardens cont.) Where the minimum vertical separation of 1 foot to the seasonal high groundwater or other impermeable layer would not be achieved below bioretention that would serve a drainage area less than the above thresholds RECEIVED BY DCD 12/6/2021 5 Worksheet C What’s the best option for your site? Roofs (cont.) BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Perforated Stub-Out Connections BMP T5.10C SWMMWW Volume III, Section 3.1.3 For sites with septic systems, the only location available for WKH SHUIRUDWHG SRUWLRQ RI WKH SLSH LV ORFDWHG XS JUDGLHQW RI WKH GUDLQ¿HOG SULPDU\DQG UHVHUYH DUHDV 7KLV UHTXLUHPHQW FDQ EH ZDLYHG LI VLWH WRSRJUDSK\ZLOO FOHDUO\SURKLELW ÀRZV IURP LQWHUVHFWLQJ WKH GUDLQ¿HOG RU ZKHUH VLWH FRQGLWLRQV VRLO permeability, distance between systems, etc.) indicate that this is unnecessary. 7KHUH LV D PRXQG VDQG¿OWHU OHQGHQ RU DHURELF WUHDWPHQW device on this or an adjacent lot. Therefore, there is not at OHDVW IRRW RI SHUPHDEOH VRLO IURP WKH SURSRVHG ERWWRP QDO JUDGH RI WKH SHUIRUDWHG VWXE RXW FRQQHFWLRQ WUHQFK WR WKH highest estimated groundwater table or other impermeable layer. 7KH RQO\ORFDWLRQ DYDLODEOH IRU WKH SHUIRUDWHG VWXE RXW connection is under impervious or heavily compacted soils. The only location available is on or above slopes greater than 20% Siting and design criteria cannot be achieved on site. RU VSODVK EORFNV D YHJHWDWHG ÀRZSDWK DW OHDVW IHHW LQ length from the downspout to the downstream property line, structure, stream, wetland, slope over 15 percent, or other impervious surface is not feasible. RU WUHQFKHV D YHJHWDWHG ÀRZSDWK RI DW OHDVW IHHW LQ between the outlet of the trench and any property line, structure, stream, wetland, or impervious surface is not IHDVLEOH YHJHWDWHG ÀRZSDWK RI DW OHDVW IHHW EHWZHHQ WKH outlet of the trench and any slope steeper than 15 percent is not feasible. Siting and design criteria cannot be achieved on site. Downspout Dispersion Systems BMP T5.10B SWMMWW Volume III, Section 3.1.2 List #1, #2 and #3 List #1, #2 and #3 LWKLQ IHHW RI VPDOO RQ VLWH VHZDJH GLVSRVDO GUDLQ¿HOG including reserve areas, and grey water reuse systems. For VHWEDFNV IURP D ODUJH RQ VLWH VHZDJH GLVSRVDO V\VWHP VHH KDSWHU None of the above boxes are checked. This is the BMP that must be used for roofs. On Worksheet A1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. None of the above boxes are checked. This is the BMP that must be used for roofs. On Worksheet A1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. None of the above boxes are checked. This is the BMP that must be used for roofs. On Worksheet A1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. RECEIVED BY DCD 12/6/2021 6 Worksheet C What’s the best option for your site? Other Hard Surfaces BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Where professional geotechnical evaluation recommends LQ¿OWUDWLRQ QRW EH XVHG GXH WR UHDVRQDEOH FRQFHUQV DERXW HURVLRQ VORSH IDLOXUH RU GRZQJUDGLHQW ÀRRGLQJ Within an area whose ground water drains into an erosion hazard, or landslide hazard area. KHUH LQ¿OWUDWLQJ DQG SRQGHG ZDWHU EHORZ WKH QHZ SHUPHDEOH pavement area would compromise adjacent impervious pavements. KHUH LQ¿OWUDWLQJ ZDWHU EHORZ D QHZ SHUPHDEOH SDYHPHQW area would threaten existing below grade basements. KHUH LQ¿OWUDWLQJ ZDWHU ZRXOG WKUHDWHQ VKRUHOLQH VWUXFWXUHV such as bulkheads. Down slope of steep, erosion prone areas that are likely to deliver sediment to the area of pervious pavement. KHUH OO VRLOV DUH XVHG WKDW FDQ EHFRPH XQVWDEOH ZKHQ saturated. Excessively steep slopes where water within the aggregate base layer or at the subgrade surface cannot be controlled by detention structures and may cause erosion and structural IDLOXUH RU ZKHUH VXUIDFH UXQR YHORFLWLHV PD\SUHFOXGH DGHTXDWH LQ¿OWUDWLRQ DW WKH SDYHPHQW VXUIDFH Citation of any of the following infeasibility criteria must be EDVHG RQ DQ HYDOXDWLRQ RI VLWH VSHFL¿F FRQGLWLRQV DQG D ZULWWHQ recommendation from an appropriate licensed professional (e.g., engineer, geologist, hydrogeologist): Permeable Pavement BMP T5.15, SWMMWW Volume V, Section 5.3 List #1 and #2 Full Dispersion BMP T5.30 SWMMWW Volume V, Section 5.3 A 65 to 10 ratio of forested or native vegetation area to impervious area cannot be achieved. PLQLPXP IRUHVWHG RU QDWLYH YHJHWDWLRQ ÀRZSDWK OHQJWK RI IHHW IHHW IRU VKHHW ÀRZ IURP D QRQ QDWLYH SHUYLRXV surface) cannot be achieved. Siting and design criteria cannot be achieved on site. List #1 and #2 None of the above boxes are checked. This is the BMP that must be used for hard surfaces. On Worksheet A1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. Note that Raingardens may be used in lieu of permeable pavement if subject to List #1. Bioretention Used RECEIVED BY DCD 12/6/2021 7 Worksheet C What’s the best option for your site? Other Hard Surfaces (cont.) BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Permeable Pavement cont.) BMP T5.15, SWMMWW Vol ume V, Section 5.3 Within an area designated as an erosion hazard, or landslide hazard. Within 50 feet from the top of slopes that are greater than 20 percent. For properties with known soil or groundwater contamination (typically federal Superfund sites or state cleanup sites under MTCA): Within 100 feet of an area known to have deep soil contamination. KHUH JURXQGZDWHU PRGHOLQJ LQGLFDWHV LQ¿OWUDWLRQ will likely increase or change the direction of the migration of pollutants in the groundwater. Wherever surface soils have been found to be contaminated unless those soils are removed ZLWKLQ KRUL]RQWDO IHHW IURP WKH LQ¿OWUDWLRQ DUHD Any area where these facilities are prohibited by an approved cleanup plan under the state MTCA or Federal Superfund Law, or an environmental covenant under Chapter 64.70 RCW. LWKLQ IHHW RI D FORVHG RU DFWLYH ODQG¿OO Within 100 feet of a drinking water well, or a spring used IRU GULQNLQJ ZDWHU VXSSO\LI WKH SDYHPHQW LV D SROOXWLRQ generating surface. The following criteria can be cited as reasons for infeasibility without IXUWKHU MXVWL¿FDWLRQ WKRXJK VRPH UHTXLUH SURIHVVLRQDO VHUYLFHV WR make the observation): KHUH SHUPHDEOH SDYHPHQWV FDQQRW SURYLGH VX FLHQW strength to support heavy loads at industrial facilities such as ports.Where installation of permeable pavement would threaten WKH VDIHW\RU UHOLDELOLW\RI SUH H[LVWLQJ XQGHUJURXQG XWLOLWLHV SHU H[LVWLQJ XQGHUJURXQG VWRUDJH WDQNV RU SUH H[LVWLQJ URDG subgrades.Note that Raingardens may be used in lieu of permeable pavement if subject to List # 1. RECEIVED BY DCD 12/6/ 8 Worksheet C What’s the best option for your site? LWKLQ IHHW RI D VPDOO RQ VLWH VHZDJH GLVSRVDO GUDLQ¿HOG including reserve areas, and grey water reuse systems. For VHWEDFNV IURP D ODUJH RQ VLWH VHZDJH GLVSRVDO V\VWHP VHH KDSWHU Within 10 feet of any underground storage tank and connecting underground pipes, regardless of tank size. As used in these criteria, an underground storage tank means any tank used to store petroleum products, chemicals, or liquid hazardous wastes of which 10 percent or more of the storage volume (including volume in the connecting piping system) is beneath the ground surface. W PXOWL OHYHO SDUNLQJ JDUDJHV DQG RYHU FXOYHUWV DQG bridges. Where the site design cannot avoid putting pavement LQ DUHDV OLNHO\WR KDYH ORQJ WHUP H[FHVVLYH VHGLPHQW deposition after construction (e.g., construction and landscaping material yards). Where the site cannot reasonably be designed to have a porous asphalt surface at less than 5 percent slope, or a pervious concrete surface at less than 10 percent slope, or a permeable interlocking concrete pavement surface (where DSSURSULDWH DW OHVV WKDQ SHUFHQW VORSH ULG V\VWHPV upper slope limit can range from 6 to 12 percent; check with manufacturer and local supplier. KHUH WKH VXEJUDGH VRLOV EHORZ D SROOXWLRQ JHQHUDWLQJ permeable pavement (e.g., road or parking lot) do not meet the soil suitability criteria for providing treatment. See soil suitability criteria for treatment in the SWMMWW Volume III, Section 3.3.7. Note: In these instances, the FRXQW\PD\DSSURYH LQVWDOODWLRQ RI D LQFK VDQG OWHU OD\HU PHHWLQJ FRXQW\VSHFL¿FDWLRQV IRU WUHDWPHQW DV D FRQGLWLRQ RI construction. KHUH XQGHUO\LQJ VRLOV DUH XQVXLWDEOH IRU VXSSRUWLQJ WUD F loads when saturated. Soils meeting a California Bearing Ratio of 5 percent are considered suitable for residential access roads.Where replacing existing impervious surfaces unless the H[LVWLQJ VXUIDFH LV D QRQ SROOXWLRQ JHQHUDWLQJ VXUIDFH RYHU an outwash soil with a saturated hydraulic conductivity of 4 inches per hour or greater.Other Hard Surfaces ( cont.)BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Permeable Pavement cont.)BMP T5. 15, SWMMWW Volume V, Section 5. 3 Note that Raingardens may be used in lieu of permeable pavement if subject to List # 1. RECEIVED BY DCD 12/6/ 9 Worksheet C What’s the best option for your site? KHUH DSSURSULDWH HOG WHVWLQJ LQGLFDWHV VRLOV KDYH D measured (a.k.a., initial) subgrade soil saturated hydraulic FRQGXFWLYLW\OHVV WKDQ LQFKHV SHU KRXU 2QO\VPDOO VFDOH 3,7 RU ODUJH VFDOH 3,7 PHWKRGV LQ DFFRUGDQFH ZLWK SWMMWW Volume III, Section 3.3.6 (or an alternative small VFDOH WHVW VSHFL¿HG E\WKH ORFDO JRYHUQPHQW VKDOO EH XVHG WR evaluate infeasibility of permeable pavement areas. (Note: In these instances, unless other infeasibility restrictions apply, roads and parking lots may be built with an underdrain, SUHIHUDEO\HOHYDWHG ZLWKLQ WKH EDVH FRXUVH LI ÀRZ FRQWURO EHQH¿WV DUH GHVLUHG 5RDGV WKDW UHFHLYH PRUH WKDQ YHU\ORZ WUD F YROXPHV DQG DUHDV KDYLQJ PRUH WKDQ YHU\ORZ WUXFN WUD F 5RDGV ZLWK D SURMHFWHG DYHUDJH GDLO\WUD F YROXPH RI YHKLFOHV or less are very low volume roads (AASHTO 2001) (U.S. Department of Transportation, 2013). Areas with very low WUXFN WUD F YROXPHV DUH URDGV DQG RWKHU DUHDV QRW VXEMHFW WR WKURXJK WUXFN WUD F EXW PD\UHFHLYH XS WR ZHHNO\XVH E\utility trucks (e.g., garbage, recycling), daily school bus use, DQG PXOWLSOH GDLO\XVH E\SLFN XS WUXFNV PDLO SDUFHO GHOLYHU\trucks, and maintenance vehicles. Note: This infeasibility FULWHULRQ GRHV QRW H[WHQG WR VLGHZDONV DQG RWKHU QRQ WUD F bearing surfaces associated with the collector or arterial.W VLWHV GH¿QHG DV KLJK XVH VLWHV´UHIHU WR WKH ORVVDU\LQ the SWMMWW Volume I).Q DUHDV ZLWK LQGXVWULDO DFWLYLW\´DV LGHQWL¿HG LQ 5 122.26(b)(14).Where the risk of concentrated pollutant spills is more likely such as gas stations, truck stops, and industrial chemical storage sites.Where routine, heavy applications of sand occur in frequent snow zones to maintain traction during weeks of snow and ice accumulation.Where the seasonal high groundwater or an underlying LPSHUPHDEOH ORZ SHUPHDEOH OD\HU ZRXOG FUHDWH VDWXUDWHG conditions within 1 foot of the bottom of the lowest gravel base course. Other Hard Surfaces (cont.)BMP and Applicable Lists Reason why the BMP will not work on site. Additional Comments If needed Permeable Pavement cont.) BMP T5.15, SWMMWW Volume V, Section 5.3 None of the above boxes are checked. This is the BMP that must be used for hard surfaces. On Worksheet A1, indicate that this will be the BMP used. (List #1 may use Raingardens in lieu of Permeable Pavement). CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. Note that Raingardens may be used in lieu of permeable pavement if subject to List #1. 10 Worksheet C What’s the best option for your site? Other Hard Surfaces (cont.) BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Where professional geotechnical evaluation recommends LQ¿OWUDWLRQ QRW EH XVHG GXH WR UHDVRQDEOH FRQFHUQV DERXW HURVLRQ VORSH IDLOXUH RU GRZQ JUDGLHQW ÀRRGLQJ Within an area whose ground water drains into an erosion hazard, or landslide hazard area. Where the only area available for siting would threaten the VDIHW\RU UHOLDELOLW\RI SUH H[LVWLQJ XQGHUJURXQG XWLOLWLHV SUH H[LVWLQJ XQGHUJURXQG VWRUDJH WDQNV SUH H[LVWLQJ VWUXFWXUHV RU SUH H[LVWLQJ URDG RU SDUNLQJ ORW VXUIDFHV Where the only area available for siting does not allow for D VDIH RYHUÀRZ SDWKZD\WR VWRUPZDWHU GUDLQDJH V\VWHP RU private storm sewer system. Where there is a lack of usable space for bioretention areas DW UH GHYHORSPHQW VLWHV RU ZKHUH WKHUH LV LQVX FLHQW VSDFH ZLWKLQ WKH H[LVWLQJ SXEOLF ULJKW RI ZD\RQ SXEOLF URDG SURMHFWV Note: Criteria with setback distances are as measured from the bottom edge of the bioretention soil mix.Citation of any of the following infeasibility criteria must be EDVHG RQ DQ HYDOXDWLRQ RI VLWH VSHFL¿F FRQGLWLRQV DQG D ZULWWHQ recommendation from an appropriate licensed professional (e. g., engineer, geologist, hydrogeologist):KHUH LQ¿OWUDWLQJ ZDWHU ZRXOG WKUHDWHQ VKRUHOLQH VWUXFWXUHV such as bulkheads.KHUH LQ¿OWUDWLQJ ZDWHU ZRXOG WKUHDWHQ H[LVWLQJ EHORZ JUDGH basements.The following criteria can be cited as reasons for infeasibility ZLWKRXW IXUWKHU MXVWL¿FDWLRQ WKRXJK VRPH UHTXLUH SURIHVVLRQDO services to make the observation):Within setback provided for BMP T7.30 (SWMMWW Volume V, Section 7. 4)Where they are not compatible with surrounding drainage system as determined by the county (e.g., project drains to an existing stormwater collection system whose elevation or location precludes connection to a properly functioning bioretention area).Bioretention or Rain Gardens BMP T7. 30, SWMMWW Volume V, Section 7. 4 List #1 ( both)and List # 2 bioretention only)RECEIVED BY DCD 12/6/ 11 Worksheet C What’s the best option for your site? Other Hard Surfaces (cont.) BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Bioretention or Rain Gardens cont.) BMP T7.30, SWMMWW Volume V, Section 7.4 Where land for bioretention is within an erosion hazard, or ODQGVOLGH KD]DUG DUHD DV GH¿QHG E\3$0& Where the site cannot be reasonably designed to locate bioretention areas on slopes less than 8 percent. Within 50 feet from the top of slopes that are greater than 20 percent and over 10 feet of vertical relief. For properties with known soil or groundwater contamination typically federal Superfund sites or state cleanup sites under the Model Toxics Control Act [MTCA]): Within 100 feet of an area known to have deep soil contamination. KHUH JURXQGZDWHU PRGHOLQJ LQGLFDWHV LQ¿OWUDWLRQ will likely increase or change the direction of the migration of pollutants in the groundwater. Wherever surface soils have been found to be contaminated unless those soils are removed within KRUL]RQWDO IHHW IURP WKH LQ¿OWUDWLRQ DUHD LWKLQ IHHW RI D FORVHG RU DFWLYH ODQG¿OO Within 10 feet of an underground storage tank and connecting underground pipes when the capacity of the tank and pipe system is 1,100 gallons or less. As used in these criteria, an underground storage tank means any tank used to store petroleum products, chemicals, or liquid hazardous wastes of which 10 percent or more of the storage volume including volume in the connecting piping system) is beneath the ground surface. Within 100 feet of an underground storage tank and connecting underground pipes when the capacity of the tank and pipe system is greater than 1,100 gallons. Where the minimum vertical separation of 1 foot to the seasonal high groundwater or other impermeable layer would not be achieved below bioretention that would serve a drainage area less than the above thresholds RECEIVED BY DCD 12/6/2021 12 Worksheet C What’s the best option for your site? Other Hard Surfaces (cont.) BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed KHUH HOG WHVWLQJ LQGLFDWHV SRWHQWLDO ELRUHWHQWLRQ UDLQ garden sites have a measured (a.k.a., initial) native soil saturated hydraulic conductivity less than 0.30 inches per KRXU VPDOO VFDOH RU ODUJH VFDOH 3,7 LQ DFFRUGDQFH ZLWK SWMMWW Volume III, Section 3.3.6 (or an alternative VPDOO VFDOH WHVW VSHFL¿HG E\WKH ORFDO JRYHUQPHQW VKDOO be used to demonstrate infeasibility of bioretention areas. I WKH PHDVXUHG QDWLYH VRLO LQ¿OWUDWLRQ UDWH LV OHVV WKDQ LQ KRXU ELRUHWHQWLRQ UDLQ JDUGHQ 03V DUH QRW UHTXLUHG to be evaluated as an option in List #1 or List #2. In these slow draining soils, a bioretention area with an underdrain PD\EH XVHG WR WUHDW SROOXWLRQ JHQHUDWLQJ VXUIDFHV WR KHOS PHHW 0LQLPXP 5HTXLUHPHQW 5XQR 7UHDWPHQW I WKH underdrain is elevated within a base course of gravel, it will DOVR SURYLGH VRPH PRGHVW ÀRZ UHGXFWLRQ EHQH¿W WKDW ZLOO KHOS achieve Minimum Requirement #7. Where the minimum vertical separation of 3 feet to the seasonal high groundwater elevation or other impermeable layer would not be achieved below bioretention that would serve a drainage area that exceeds the following thresholds and cannot reasonably be broken down into amounts smaller than indicated): R VTXDUH IHHW RI SROOXWLRQ JHQHUDWLQJ LPSHUYLRXV VXUIDFH 3*,6 o 10,000 square feet of impervious area o 0.75 acres of lawn and landscape. Any area where these facilities are prohibited by an approved cleanup plan under the state MTCA or Federal Superfund Law, or an environmental covenant under Chapter 64.70 RCW. Within 100 feet of a drinking water well, or a spring used for drinking water supply. LWKLQ IHHW RI VPDOO RQ VLWH VHZDJH GLVSRVDO GUDLQ¿HOG including reserve areas, and grey water reuse systems. For VHWEDFNV IURP D ODUJH RQ VLWH VHZDJH GLVSRVDO V\VWHP VHH KDSWHU Bioretention or Rain Gardens cont.) BMP T7.30, SWMMWW Volume V, Section 7.4 None of the above boxes are checked. This is the BMP that must be used for hard surfaces. On Worksheet A1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. RECEIVED BY DCD 12/6/2021 13 Worksheet C What’s the best option for your site? Other Hard Surfaces (cont.) BMP and Applicable Lists Reason why the BMP will not work on site.Additional Comments If needed Sheet Flow Dispersion BMP T5.12, SWMMWW Volume V, Section 5.3 3RVLWLYH GUDLQDJH IRU VKHHW ÀRZ UXQR FDQQRW EH DFKLHYHG Area to be dispersed (e.g., driveway, patio) cannot be graded to have less than a 15 percent slope. RU ÀDW WR PRGHUDWHO\VORSHG DUHDV DW OHDVW D IRRW ZLGH YHJHWDWLRQ EX HU IRU GLVSHUVLRQ RI WKH DGMDFHQW IHHW RI contributing surface cannot be achieved. For variably sloped DUHDV DW OHDVW D IRRW YHJHWDWHG ÀRZSDWK EHWZHHQ EHUPV cannot be achieved.Siting and design criteria cannot be achieved on site. Concentrated Flow Dispersion BMP T5. 11, SWMMWW Volume V, Section 5. 3 PLQLPXP IRRW OHQJWK RI URFN SDG DQG IRRW ÀRZSDWK 25 D GLVSHUVLRQ WUHQFK DQG IRRW ÀRZSDWK IRU HYHU\sq. ft. of drainage area followed with applicable setbacks cannot be achieved.More than 700 sq. ft. drainage area drains to any dispersion device.Siting and design criteria cannot be achieved on site.List #1, # 2 and # 3 List #1, # 2 and # 3 None of the above boxes are checked. This is the BMP that must be used for hard surfaces. On Worksheet A1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. None of the above boxes are checked. This is the BMP that must be used for hard surfaces. On Worksheet A1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none, STOP. RECEIVED BY DCD 12/6/ Worksheet L Large Projects Large Projects subject to Minimum Requirements #1 9 must complete Worksheet A1 as applicable. Also complete Worksheet B1. No Further acon needed. Demonstrate full dispersion on site plan. Is the project on a parcel 5 acres or larger? Yes The proponent must submit a stormwater report and site plan prepared by a licensed engineer that complies with the 2012 Department of Ecology Stormwater Man- agement Manual for West- ern Washington as amended in 2014. The report prepared by the engineer must demonstrate compliance with the LID Performance Standard and all minimum requirements. no For each surface consider the BMPs in the order listed in List #1 page 5 in Worksheet A1, except, raingardens may not be used. This process is equiva- lent to List #2 in the 2012 Department of Ecology Stormwater Management Manual for Western Washington as amended in 2014. Is the project in the Urban Growth Area? Yes no Does the project meet feasibility criteria for full dispersion (see Worksheet C1)? Yes no Yesno Does the project discharge to a sub basin draining to salt water, Dosewallips River, or Hoh River? Use List #3 on Worksheet A1 page 6. No further acon is needed. 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6 D Q G 6 L O W O D 0 R L V W EX O N GH Q V L W 6D W X U D W H G K\ G U D X O L F FR Q G X F W L Y L W Y D L O D E O H ZD W H U FD S D F L W L Q H D U H[ W H Q V L E L O L W 2U J D Q L F PD W W H U U R V L R Q ID F W R U V L Q G HU R G L E L O L W JU R X S L Q G HU R G L E L O L W LQ G H Z I 7 Q 3 F W 3 F W 3 F W J F F P L F U R P V H F Q Q 3 F W 3 F W R U R Y H YH U J U D Y H O O OR D P V D Q G W R SH U F H Q W VO R S H V U R Y H D W D 6 R X U F H Q I R U P D W L R Q 6R L O 6 X U Y H U H D H I I H U V R Q R X Q W U H D D V K L Q J W R Q 6X U Y H U H D D W D 9 H U V L R Q 6 H S 3K V L F D O 6 R L O 3 U R S H U W L H V H I I H U V R Q R X Q W U H D D V K L Q J W R Q 1D W X U D O 5 H V R X U F H V R Q V H U Y D W L R Q 6 H U Y L F H H E 6 R L O 6 X U Y H 1D W L R Q D O R R S H U D W L Y H 6 R L O 6 X U Y H 3D J H R I RECEIVED BY DCD 12/6/2021 WWHM2012 PROJECT REPORT Attachment 10 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:29:25 AM Page 2 General Model Information Project Name: Refuge Chapel Site Name: Refuge Site Address: City: Report Date: 11/15/2021 Gage: Quilcene Data Start: 1948/10/01 Data End: 2009/09/30 Timestep: 15 Minute Precip Scale: 1.444 Version Date: 2018/10/10 Version: 4.2.16 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:29:25 AM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Pasture, Flat 0.05 C, Forest, Flat 0.13 Pervious Total 0.18 Impervious Land Use acre Impervious Total 0 Basin Total 0.18 Element Flows To: Surface Interflow Groundwater RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:29:25 AM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Pasture, Flat 0.03 Pervious Total 0.03 Impervious Land Use acre ROOF TOPS FLAT 0.02 PARKING FLAT 0.12 POND 0.01 Impervious Total 0.15 Basin Total 0.18 Element Flows To: Surface Interflow Groundwater Surface retention 1 Surface retention 1 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:29:25 AM Page 5 Routing Elements Predeveloped Routing RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:29:25 AM Page 6 Mitigated Routing Bioretention 1 Bottom Length: 22.00 ft. Bottom Width: 5.00 ft. Material thickness of first layer: 1.5 Material type for first layer: SMMWW 12 in/hr Material thickness of second layer: 0.5 Material type for second layer: GRAVEL Material thickness of third layer: 0 Material type for third layer: GRAVEL Infiltration On Infiltration rate: 13 Infiltration safety factor: 1 Wetted surface area On Total Volume Infiltrated (ac-ft.): 62.308 Total Volume Through Riser (ac-ft.): 0.093 Total Volume Through Facility (ac-ft.): 62.401 Percent Infiltrated: 99.85 Total Precip Applied to Facility: 2.038 Total Evap From Facility: 0.454 Underdrain not used Discharge Structure Riser Height: 0.5 ft. Riser Diameter: 12 in. Element Flows To: Outlet 1 Outlet 2 Bioretention Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.0090 0.0000 0.0000 0.0000 0.0330 0.0089 0.0000 0.0000 0.0000 0.0659 0.0087 0.0001 0.0000 0.0000 0.0989 0.0086 0.0001 0.0000 0.0000 0.1319 0.0085 0.0002 0.0000 0.0000 0.1648 0.0084 0.0002 0.0000 0.0000 0.1978 0.0082 0.0003 0.0000 0.0000 0.2308 0.0081 0.0003 0.0000 0.0001 0.2637 0.0080 0.0003 0.0000 0.0001 0.2967 0.0079 0.0004 0.0000 0.0002 0.3297 0.0077 0.0004 0.0000 0.0003 0.3626 0.0076 0.0005 0.0000 0.0004 0.3956 0.0075 0.0005 0.0000 0.0005 0.4286 0.0074 0.0006 0.0000 0.0007 0.4615 0.0072 0.0007 0.0000 0.0008 0.4945 0.0071 0.0007 0.0000 0.0010 0.5275 0.0070 0.0008 0.0000 0.0013 0.5604 0.0069 0.0008 0.0000 0.0015 0.5934 0.0068 0.0009 0.0000 0.0019 0.6264 0.0067 0.0010 0.0000 0.0022 0.6593 0.0065 0.0010 0.0000 0.0026 0.6923 0.0064 0.0011 0.0000 0.0030 0.7253 0.0063 0.0012 0.0000 0.0035 0.7582 0.0062 0.0012 0.0000 0.0041 0.7912 0.0061 0.0013 0.0000 0.0047 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:29:25 AM Page 7 0.8242 0.0060 0.0014 0.0000 0.0053 0.8571 0.0059 0.0014 0.0000 0.0061 0.8901 0.0058 0.0015 0.0000 0.0069 0.9231 0.0057 0.0016 0.0000 0.0077 0.9560 0.0055 0.0017 0.0000 0.0086 0.9890 0.0054 0.0018 0.0000 0.0096 1.0220 0.0053 0.0018 0.0000 0.0107 1.0549 0.0052 0.0019 0.0000 0.0119 1.0879 0.0051 0.0020 0.0000 0.0132 1.1209 0.0050 0.0021 0.0000 0.0145 1.1538 0.0049 0.0022 0.0000 0.0160 1.1868 0.0048 0.0023 0.0000 0.0167 1.2198 0.0047 0.0024 0.0000 0.0179 1.2527 0.0046 0.0024 0.0000 0.0196 1.2857 0.0045 0.0025 0.0000 0.0214 1.3187 0.0044 0.0026 0.0000 0.0233 1.3516 0.0043 0.0027 0.0000 0.0253 1.3846 0.0042 0.0028 0.0000 0.0275 1.4176 0.0041 0.0029 0.0000 0.0298 1.4505 0.0040 0.0030 0.0000 0.0322 1.4835 0.0039 0.0031 0.0000 0.0348 1.5165 0.0038 0.0032 0.0000 0.0375 1.5495 0.0037 0.0033 0.0000 0.0404 1.5824 0.0037 0.0034 0.0000 0.0434 1.6154 0.0036 0.0035 0.0000 0.0755 1.6484 0.0035 0.0036 0.0000 0.0767 1.6813 0.0034 0.0037 0.0000 0.0780 1.7143 0.0033 0.0039 0.0000 0.0792 1.7473 0.0032 0.0040 0.0000 0.0805 1.7802 0.0031 0.0041 0.0000 0.0817 1.8132 0.0030 0.0042 0.0000 0.0830 1.8462 0.0029 0.0043 0.0000 0.0842 1.8791 0.0029 0.0044 0.0000 0.0855 1.9121 0.0028 0.0045 0.0000 0.0868 1.9451 0.0027 0.0046 0.0000 0.0881 1.9780 0.0026 0.0048 0.0000 0.0894 2.0000 0.0025 0.0049 0.0000 0.0903 Bioretention Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)To Amended(cfs)Infilt(cfs) 2.0000 0.0090 0.0049 0.0000 0.0550 0.0017 2.0330 0.0091 0.0051 0.0000 0.0550 0.0034 2.0659 0.0092 0.0055 0.0000 0.0582 0.0052 2.0989 0.0093 0.0058 0.0000 0.0603 0.0069 2.1319 0.0095 0.0061 0.0000 0.0624 0.0087 2.1648 0.0096 0.0064 0.0000 0.0646 0.0104 2.1978 0.0097 0.0067 0.0000 0.0668 0.0122 2.2308 0.0099 0.0070 0.0000 0.0690 0.0140 2.2637 0.0100 0.0074 0.0000 0.0713 0.0158 2.2967 0.0102 0.0077 0.0000 0.0736 0.0176 2.3297 0.0103 0.0080 0.0000 0.0760 0.0194 2.3626 0.0104 0.0084 0.0000 0.0784 0.0212 2.3956 0.0106 0.0087 0.0000 0.0808 0.0231 2.4286 0.0107 0.0091 0.0000 0.0833 0.0249 2.4615 0.0109 0.0094 0.0000 0.0859 0.0268 2.4945 0.0110 0.0098 0.0000 0.0885 0.0286 2.5275 0.0111 0.0101 0.0483 0.0894 0.0305 2.5604 0.0113 0.0105 0.1574 0.0894 0.0324 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:29:25 AM Page 8 2.5934 0.0114 0.0109 0.3014 0.0894 0.0343 2.6264 0.0116 0.0113 0.4712 0.0894 0.0362 2.6593 0.0117 0.0116 0.6597 0.0894 0.0381 2.6923 0.0119 0.0120 0.8600 0.0894 0.0401 2.7253 0.0120 0.0124 1.0650 0.0894 0.0420 2.7582 0.0122 0.0128 1.2676 0.0894 0.0440 2.7912 0.0123 0.0132 1.4606 0.0894 0.0459 2.8242 0.0125 0.0136 1.6378 0.0894 0.0479 2.8571 0.0126 0.0141 1.7939 0.0894 0.0499 2.8901 0.0128 0.0145 1.9255 0.0894 0.0519 2.9231 0.0129 0.0149 2.0318 0.0894 0.0539 2.9560 0.0131 0.0153 2.1153 0.0894 0.0559 2.9890 0.0132 0.0158 2.1826 0.0894 0.0566 3.0000 0.0133 0.0159 2.2755 0.0894 0.0000 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:29:25 AM Page 9 Surface retention 1 Element Flows To: Outlet 1 Outlet 2 Bioretention 1 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:29:25 AM Page 10 Analysis Results POC 1 Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area: 0.18 Total Impervious Area: 0 Mitigated Landuse Totals for POC #1 Total Pervious Area: 0.03 Total Impervious Area: 0.15 Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.064371 5 year 0.106956 10 year 0.139468 25 year 0.185095 50 year 0.22223 100 year 0.261955 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.445642 5 year 1.111008 10 year 1.642058 25 year 2.341881 50 year 2.86176 100 year 3.357662 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.155 0.149 1950 0.044 0.000 1951 0.101 0.000 1952 0.063 0.000 1953 0.053 0.000 1954 0.114 0.012 1955 0.139 0.121 1956 0.394 0.320 1957 0.094 0.000 1958 0.143 0.000 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:03 AM Page 11 1959 0.093 0.027 1960 0.048 0.000 1961 0.166 0.023 1962 0.033 0.000 1963 0.065 0.000 1964 0.051 0.000 1965 0.016 0.000 1966 0.156 0.069 1967 0.084 0.008 1968 0.082 0.000 1969 0.052 0.000 1970 0.084 0.000 1971 0.099 0.059 1972 0.087 0.000 1973 0.043 0.000 1974 0.077 0.000 1975 0.063 0.000 1976 0.092 0.000 1977 0.042 0.000 1978 0.068 0.000 1979 0.049 0.000 1980 0.051 0.000 1981 0.046 0.000 1982 0.047 0.000 1983 0.078 0.105 1984 0.024 0.000 1985 0.021 0.000 1986 0.050 0.000 1987 0.073 0.000 1988 0.044 0.000 1989 0.026 0.000 1990 0.019 0.000 1991 0.063 0.022 1992 0.046 0.000 1993 0.031 0.000 1994 0.078 0.037 1995 0.051 0.000 1996 0.076 0.000 1997 0.051 0.000 1998 0.063 0.000 1999 0.102 0.080 2000 0.054 0.001 2001 0.017 0.073 2002 0.164 0.166 2003 0.138 0.108 2004 0.060 0.000 2005 0.083 0.081 2006 0.109 0.075 2007 0.093 0.144 2008 0.073 0.000 2009 0.034 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.3943 0.3196 2 0.1655 0.1664 3 0.1637 0.1488 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:03 AM Page 12 4 0.1558 0.1444 5 0.1545 0.1213 6 0.1426 0.1084 7 0.1390 0.1046 8 0.1384 0.0811 9 0.1141 0.0799 10 0.1094 0.0754 11 0.1022 0.0734 12 0.1006 0.0686 13 0.0987 0.0585 14 0.0938 0.0366 15 0.0934 0.0269 16 0.0929 0.0234 17 0.0916 0.0222 18 0.0874 0.0125 19 0.0840 0.0078 20 0.0838 0.0013 21 0.0829 0.0000 22 0.0821 0.0000 23 0.0778 0.0000 24 0.0776 0.0000 25 0.0772 0.0000 26 0.0761 0.0000 27 0.0734 0.0000 28 0.0730 0.0000 29 0.0684 0.0000 30 0.0648 0.0000 31 0.0634 0.0000 32 0.0629 0.0000 33 0.0628 0.0000 34 0.0627 0.0000 35 0.0596 0.0000 36 0.0537 0.0000 37 0.0529 0.0000 38 0.0522 0.0000 39 0.0514 0.0000 40 0.0512 0.0000 41 0.0508 0.0000 42 0.0507 0.0000 43 0.0501 0.0000 44 0.0493 0.0000 45 0.0483 0.0000 46 0.0468 0.0000 47 0.0459 0.0000 48 0.0458 0.0000 49 0.0443 0.0000 50 0.0443 0.0000 51 0.0428 0.0000 52 0.0419 0.0000 53 0.0336 0.0000 54 0.0334 0.0000 55 0.0311 0.0000 56 0.0261 0.0000 57 0.0236 0.0000 58 0.0210 0.0000 59 0.0188 0.0000 60 0.0173 0.0000 61 0.0160 0.0000 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:03 AM Page 13 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:03 AM Page 14 Duration Flows The Facility PASSED Flow(cfs) Predev Mit Percentage Pass/Fail 0.0322 547 50 9 Pass 0.0341 471 48 10 Pass 0.0360 413 46 11 Pass 0.0379 375 44 11 Pass 0.0399 343 42 12 Pass 0.0418 311 37 11 Pass 0.0437 272 35 12 Pass 0.0456 243 34 13 Pass 0.0475 218 34 15 Pass 0.0495 201 34 16 Pass 0.0514 182 30 16 Pass 0.0533 168 30 17 Pass 0.0552 160 29 18 Pass 0.0571 149 26 17 Pass 0.0591 137 24 17 Pass 0.0610 116 24 20 Pass 0.0629 107 23 21 Pass 0.0648 99 21 21 Pass 0.0667 94 21 22 Pass 0.0687 87 20 22 Pass 0.0706 82 19 23 Pass 0.0725 79 19 24 Pass 0.0744 72 17 23 Pass 0.0763 67 15 22 Pass 0.0783 59 15 25 Pass 0.0802 53 13 24 Pass 0.0821 47 11 23 Pass 0.0840 40 11 27 Pass 0.0859 38 11 28 Pass 0.0879 36 11 30 Pass 0.0898 36 10 27 Pass 0.0917 33 9 27 Pass 0.0936 30 9 30 Pass 0.0955 27 9 33 Pass 0.0975 27 8 29 Pass 0.0994 23 8 34 Pass 0.1013 22 8 36 Pass 0.1032 21 8 38 Pass 0.1051 19 7 36 Pass 0.1071 19 7 36 Pass 0.1090 17 6 35 Pass 0.1109 16 6 37 Pass 0.1128 14 6 42 Pass 0.1147 13 6 46 Pass 0.1166 12 6 50 Pass 0.1186 11 6 54 Pass 0.1205 10 6 60 Pass 0.1224 10 5 50 Pass 0.1243 10 5 50 Pass 0.1262 10 5 50 Pass 0.1282 10 5 50 Pass 0.1301 10 5 50 Pass 0.1320 10 5 50 Pass RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:03 AM Page 15 0.1339 10 5 50 Pass 0.1358 10 5 50 Pass 0.1378 10 5 50 Pass 0.1397 8 5 62 Pass 0.1416 8 5 62 Pass 0.1435 7 5 71 Pass 0.1454 7 4 57 Pass 0.1474 7 4 57 Pass 0.1493 7 3 42 Pass 0.1512 7 3 42 Pass 0.1531 7 3 42 Pass 0.1550 6 3 50 Pass 0.1570 5 3 60 Pass 0.1589 4 3 75 Pass 0.1608 4 3 75 Pass 0.1627 4 3 75 Pass 0.1646 3 3 100 Pass 0.1666 2 2 100 Pass 0.1685 2 2 100 Pass 0.1704 2 2 100 Pass 0.1723 2 2 100 Pass 0.1742 2 1 50 Pass 0.1762 2 1 50 Pass 0.1781 2 1 50 Pass 0.1800 2 1 50 Pass 0.1819 2 1 50 Pass 0.1838 2 1 50 Pass 0.1858 2 1 50 Pass 0.1877 2 1 50 Pass 0.1896 2 1 50 Pass 0.1915 2 1 50 Pass 0.1934 2 1 50 Pass 0.1954 2 1 50 Pass 0.1973 1 1 100 Pass 0.1992 1 1 100 Pass 0.2011 1 1 100 Pass 0.2030 1 1 100 Pass 0.2050 1 1 100 Pass 0.2069 1 1 100 Pass 0.2088 1 1 100 Pass 0.2107 1 1 100 Pass 0.2126 1 1 100 Pass 0.2146 1 1 100 Pass 0.2165 1 1 100 Pass 0.2184 1 1 100 Pass 0.2203 1 1 100 Pass 0.2222 1 1 100 Pass RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:03 AM Page 16 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:03 AM Page 17 LID Report RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:30 AM Page 18 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:30 AM Page 19 Appendix Predeveloped Schematic RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:31 AM Page 20 Mitigated Schematic RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 21 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES File> <Un#> <-----------File Name------------------------------>*** ID-> *** WDM 26 Refuge Chapel.wdm MESSU 25 PreRefuge Chapel.MES 27 PreRefuge Chapel.L61 28 PreRefuge Chapel.L62 30 POCRefuge Chapel1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 4 PERLND 10 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE OPCD *** END OPCODE PARM K *** END PARM END GENER PERLND GEN-INFO PLS ><-------Name------->NBLKS Unit-systems Printer *** User t-series Engl Metr *** in out *** 4 A/B, Pasture, Flat 1 1 1 1 27 0 10 C, Forest, Flat 1 1 1 1 27 0 END GEN-INFO Section PWATER*** ACTIVITY PLS > ************* Active Sections ***************************** ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 4 0 0 1 0 0 0 0 0 0 0 0 0 10 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO PLS > ***************** Print-flags ***************************** PIVL PYR ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 22 4 0 0 4 0 0 0 0 0 0 0 0 0 1 9 10 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO PWAT-PARM1 PLS > PWATER variable monthly parameter value flags *** CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 4 0 0 0 0 0 0 0 0 0 0 0 10 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 PLS > PWATER input info: Part 2 *** FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 4 0 5 1.5 400 0.05 0.3 0.996 10 0 4.5 0.08 400 0.05 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 PLS > PWATER input info: Part 3 *** PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 4 0 0 2 2 0 0 0 10 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 PLS > PWATER input info: Part 4 *** CEPSC UZSN NSUR INTFW IRC LZETP *** 4 0.15 0.5 0.3 0 0.7 0.4 10 0.2 0.5 0.35 6 0.5 0.7 END PWAT-PARM4 PWAT-STATE1 PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** CEPS SURS UZS IFWS LZS AGWS GWVS 4 0 0 0 0 3 1 0 10 0 0 0 0 2.5 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO PLS ><-------Name-------> Unit-systems Printer *** User t-series Engl Metr *** in out *** END GEN-INFO Section IWATER*** ACTIVITY PLS > ************* Active Sections ***************************** ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO ILS > ******** Print-flags ******** PIVL PYR ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT-INFO IWAT-PARM1 PLS > IWATER variable monthly parameter value flags *** CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 PLS > IWATER input info: Part 2 *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 23 PLS > IWATER input info: Part 3 *** PETMAX PETMIN END IWAT-PARM3 IWAT-STATE1 PLS > *** Initial conditions at start of simulation RETS SURS END IWAT-STATE1 END IMPLND SCHEMATIC Source-> <--Area--> <-Target-> MBLK *** Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 4 0.05 COPY 501 12 PERLND 4 0.05 COPY 501 13 PERLND 10 0.13 COPY 501 12 PERLND 10 0.13 COPY 501 13 Routing****** END SCHEMATIC NETWORK Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** User T-series Engl Metr LKFG *** in out *** END GEN-INFO Section RCHRES*** ACTIVITY PLS > ************* Active Sections ***************************** HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO PLS > ***************** Print-flags ******************* PIVL PYR HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit END HYDR-PARM1 HYDR-PARM2 FTABNO LEN DELTH STCOR KS DB50 *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** VOL Initial value of COLIND Initial value of OUTDGT ac-ft for each possible exit for each possible exit END HYDR-INIT END RCHRES RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 24 SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1.444 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1.444 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS-LINK Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 END MASS-LINK END RUN RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 25 Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES File> <Un#> <-----------File Name------------------------------>*** ID-> *** WDM 26 Refuge Chapel.wdm MESSU 25 MitRefuge Chapel.MES 27 MitRefuge Chapel.L61 28 MitRefuge Chapel.L62 30 POCRefuge Chapel1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 4 IMPLND 4 IMPLND 11 IMPLND 14 RCHRES 1 RCHRES 2 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Surface retention 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE OPCD *** END OPCODE PARM K *** END PARM END GENER PERLND GEN-INFO PLS ><-------Name------->NBLKS Unit-systems Printer *** User t-series Engl Metr *** in out *** 4 A/B, Pasture, Flat 1 1 1 1 27 0 END GEN-INFO Section PWATER*** ACTIVITY PLS > ************* Active Sections ***************************** ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 4 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 26 PRINT-INFO PLS > ***************** Print-flags ***************************** PIVL PYR ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 4 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO PWAT-PARM1 PLS > PWATER variable monthly parameter value flags *** CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 4 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 PLS > PWATER input info: Part 2 *** FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 4 0 5 1.5 400 0.05 0.3 0.996 END PWAT-PARM2 PWAT-PARM3 PLS > PWATER input info: Part 3 *** PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 4 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 PLS > PWATER input info: Part 4 *** CEPSC UZSN NSUR INTFW IRC LZETP *** 4 0.15 0.5 0.3 0 0.7 0.4 END PWAT-PARM4 PWAT-STATE1 PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** CEPS SURS UZS IFWS LZS AGWS GWVS 4 0 0 0 0 3 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO PLS ><-------Name-------> Unit-systems Printer *** User t-series Engl Metr *** in out *** 4 ROOF TOPS/FLAT 1 1 1 27 0 11 PARKING/FLAT 1 1 1 27 0 14 POND 1 1 1 27 0 END GEN-INFO Section IWATER*** ACTIVITY PLS > ************* Active Sections ***************************** ATMP SNOW IWAT SLD IWG IQAL *** 4 0 0 1 0 0 0 11 0 0 1 0 0 0 14 0 0 1 0 0 0 END ACTIVITY PRINT-INFO ILS > ******** Print-flags ******** PIVL PYR ATMP SNOW IWAT SLD IWG IQAL ********* 4 0 0 4 0 0 0 1 9 11 0 0 4 0 0 0 1 9 14 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 PLS > IWATER variable monthly parameter value flags *** CSNO RTOP VRS VNN RTLI *** 4 0 0 0 0 0 11 0 0 0 0 0 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 27 14 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 PLS > IWATER input info: Part 2 *** LSUR SLSUR NSUR RETSC 4 400 0.01 0.1 0.1 11 400 0.01 0.1 0.1 14 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 PLS > IWATER input info: Part 3 *** PETMAX PETMIN 4 0 0 11 0 0 14 0 0 END IWAT-PARM3 IWAT-STATE1 PLS > *** Initial conditions at start of simulation RETS SURS 4 0 0 11 0 0 14 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC Source-> <--Area--> <-Target-> MBLK *** Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 4 0.03 RCHRES 1 2 PERLND 4 0.03 RCHRES 1 3 IMPLND 4 0.02 RCHRES 1 5 IMPLND 11 0.12 RCHRES 1 5 IMPLND 14 0.01 RCHRES 1 5 Routing****** PERLND 4 0.03 COPY 1 12 IMPLND 4 0.02 COPY 1 15 IMPLND 11 0.12 COPY 1 15 IMPLND 14 0.01 COPY 1 15 PERLND 4 0.03 COPY 1 13 RCHRES 1 1 RCHRES 2 8 RCHRES 2 1 COPY 501 17 RCHRES 1 1 COPY 501 17 END SCHEMATIC NETWORK Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** User T-series Engl Metr LKFG *** in out *** 1 Surface retentio-010 3 1 1 1 28 0 1 2 Bioretention 1 2 1 1 1 28 0 1 END GEN-INFO Section RCHRES*** RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 28 ACTIVITY PLS > ************* Active Sections ***************************** HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 2 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO PLS > ***************** Print-flags ******************* PIVL PYR HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 2 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit 1 0 1 0 0 4 5 6 0 0 0 0 0 0 0 2 2 2 2 2 2 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 FTABNO LEN DELTH STCOR KS DB50 *** 1 1 0.01 0.0 0.0 0.0 0.0 2 2 0.01 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** VOL Initial value of COLIND Initial value of OUTDGT ac-ft for each possible exit for each possible exit 1 0 4.0 5.0 6.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 2 62 5 Depth Area Volume Outflow1 Outflow2 Velocity Travel Time*** ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.008953 0.000000 0.000000 0.000000 0.032967 0.008867 0.000039 0.000000 0.000000 0.065934 0.008737 0.000079 0.000000 0.000000 0.098901 0.008609 0.000120 0.000000 0.000000 0.131868 0.008481 0.000162 0.000000 0.000010 0.164835 0.008354 0.000206 0.000000 0.000025 0.197802 0.008228 0.000251 0.000000 0.000049 0.230769 0.008103 0.000297 0.000000 0.000084 0.263736 0.007979 0.000345 0.000000 0.000132 0.296703 0.007855 0.000394 0.000000 0.000197 0.329670 0.007732 0.000444 0.000000 0.000279 0.362637 0.007610 0.000496 0.000000 0.000381 0.395604 0.007489 0.000549 0.000000 0.000506 0.428571 0.007368 0.000603 0.000000 0.000655 0.461538 0.007249 0.000659 0.000000 0.000832 0.494505 0.007130 0.000716 0.000000 0.001038 0.527473 0.007012 0.000775 0.000000 0.001276 0.560440 0.006895 0.000835 0.000000 0.001549 0.593407 0.006778 0.000897 0.000000 0.001861 0.626374 0.006662 0.000960 0.000000 0.002212 0.659341 0.006548 0.001024 0.000000 0.002607 0.692308 0.006433 0.001090 0.000000 0.003049 0.725275 0.006320 0.001157 0.000000 0.003539 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 29 0.758242 0.006208 0.001226 0.000000 0.004083 0.791209 0.006096 0.001296 0.000000 0.004683 0.824176 0.005985 0.001368 0.000000 0.005342 0.857143 0.005875 0.001442 0.000000 0.006063 0.890110 0.005766 0.001517 0.000000 0.006851 0.923077 0.005657 0.001593 0.000000 0.007708 0.956044 0.005550 0.001671 0.000000 0.008640 0.989011 0.005443 0.001751 0.000000 0.009648 1.021978 0.005337 0.001832 0.000000 0.010737 1.054945 0.005231 0.001915 0.000000 0.011912 1.087912 0.005127 0.001999 0.000000 0.013176 1.120879 0.005023 0.002086 0.000000 0.014533 1.153846 0.004920 0.002173 0.000000 0.015988 1.186813 0.004818 0.002263 0.000000 0.016734 1.219780 0.004717 0.002354 0.000000 0.017869 1.252747 0.004616 0.002446 0.000000 0.019559 1.285714 0.004517 0.002541 0.000000 0.021361 1.318681 0.004418 0.002637 0.000000 0.023279 1.351648 0.004320 0.002735 0.000000 0.025319 1.384615 0.004222 0.002834 0.000000 0.027486 1.417582 0.004126 0.002936 0.000000 0.029783 1.450549 0.004030 0.003039 0.000000 0.032216 1.483516 0.003935 0.003144 0.000000 0.034790 1.516484 0.003841 0.003240 0.000000 0.037510 1.549451 0.003748 0.003339 0.000000 0.040379 1.582418 0.003655 0.003439 0.000000 0.043399 1.615385 0.003564 0.003540 0.000000 0.075512 1.648352 0.003473 0.003644 0.000000 0.076735 1.681319 0.003383 0.003749 0.000000 0.077966 1.714286 0.003293 0.003855 0.000000 0.079204 1.747253 0.003205 0.003964 0.000000 0.080451 1.780220 0.003117 0.004074 0.000000 0.081706 1.813187 0.003030 0.004185 0.000000 0.082969 1.846154 0.002944 0.004299 0.000000 0.084240 1.879121 0.002859 0.004414 0.000000 0.085519 1.912088 0.002774 0.004531 0.000000 0.086806 1.945055 0.002690 0.004649 0.000000 0.088101 1.978022 0.002607 0.004770 0.000000 0.089405 2.000000 0.002525 0.006716 0.000000 0.090278 END FTABLE 2 FTABLE 1 32 6 Depth Area Volume Outflow1 Outflow2 outflow 3 Velocity Travel Time*** ft) (acres) (acre-ft) (cfs) (cfs) (cfs) (ft/sec) Minutes)*** 0.000000 0.002525 0.000000 0.000000 0.000000 0.001712 0.032967 0.009084 0.000297 0.000000 0.054957 0.001712 0.065934 0.009215 0.000599 0.000000 0.058202 0.003434 0.098901 0.009347 0.000905 0.000000 0.060280 0.005166 0.131868 0.009480 0.001215 0.000000 0.062398 0.006909 0.164835 0.009614 0.001530 0.000000 0.064557 0.008663 0.197802 0.009749 0.001849 0.000000 0.066756 0.010426 0.230769 0.009884 0.002173 0.000000 0.068998 0.012201 0.263736 0.010020 0.002501 0.000000 0.071280 0.013986 0.296703 0.010157 0.002833 0.000000 0.073605 0.015781 0.329670 0.010295 0.003171 0.000000 0.075972 0.017587 0.362637 0.010433 0.003512 0.000000 0.078382 0.019403 0.395604 0.010573 0.003859 0.000000 0.080835 0.021230 0.428571 0.010713 0.004209 0.000000 0.083331 0.023067 0.461538 0.010854 0.004565 0.000000 0.085871 0.024915 0.494505 0.010996 0.004925 0.000000 0.088454 0.026773 0.527473 0.011138 0.005290 0.048301 0.089405 0.028641 0.560440 0.011281 0.005659 0.157374 0.089405 0.030520 0.593407 0.011426 0.006034 0.301385 0.089405 0.032410 0.626374 0.011571 0.006413 0.471194 0.089405 0.034310 0.659341 0.011716 0.006797 0.659695 0.089405 0.036220 0.692308 0.011863 0.007185 0.859995 0.089405 0.038141 0.725275 0.012010 0.007579 1.065020 0.089405 0.040072 0.758242 0.012158 0.007977 1.267570 0.089405 0.042014 RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 30 0.791209 0.012307 0.008380 1.460630 0.089405 0.043967 0.824176 0.012457 0.008789 1.637810 0.089405 0.045929 0.857143 0.012608 0.009202 1.793902 0.089405 0.047902 0.890110 0.012759 0.009620 1.925525 0.089405 0.049886 0.923077 0.012911 0.010043 2.031838 0.089405 0.051880 0.956044 0.013064 0.010471 2.115324 0.089405 0.053885 0.989011 0.013218 0.010904 2.182633 0.089405 0.055900 1.000000 0.013269 0.011050 2.275546 0.089405 0.056574 END FTABLE 1 END FTABLES EXT SOURCES Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1.444 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1.444 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP WDM 2 PREC ENGL 1.444 RCHRES 1 EXTNL PREC WDM 1 EVAP ENGL 0.5 RCHRES 1 EXTNL POTEV WDM 1 EVAP ENGL 0.76 RCHRES 2 EXTNL POTEV END EXT SOURCES EXT TARGETS Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** RCHRES 2 HYDR RO 1 1 1 WDM 1000 FLOW ENGL REPL RCHRES 2 HYDR O 1 1 1 WDM 1001 FLOW ENGL REPL RCHRES 2 HYDR O 2 1 1 WDM 1002 FLOW ENGL REPL RCHRES 2 HYDR STAGE 1 1 1 WDM 1003 STAG ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1004 STAG ENGL REPL RCHRES 1 HYDR O 1 1 1 WDM 1005 FLOW ENGL REPL COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS-LINK Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 2 PERLND PWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 2 MASS-LINK 3 PERLND PWATER IFWO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 3 MASS-LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 5 MASS-LINK 8 RCHRES OFLOW OVOL 2 RCHRES INFLOW IVOL END MASS-LINK 8 MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 MASS-LINK 17 RCHRES OFLOW OVOL 1 COPY INPUT MEAN RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 31 END MASS-LINK 17 END MASS-LINK END RUN RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 32 Predeveloped HSPF Message File RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 33 Mitigated HSPF Message File RECEIVED BY DCD 12/6/2021 Refuge Chapel 11/15/2021 9:30:32 AM Page 34 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2021; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com RECEIVED BY DCD 12/6/2021 Figure V-7.4.1a Typical Bioretention D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure V-7.4.1a Typical Bioretention Revised February 2016 Notes: 1. Scarify subgrade 3" min. before bioretention soil installation 2. Compact BSM to 85% per ASTM 1577 Edge of pavement or curb-cut 3" woodchip mulch, aggregate, or sod Sidewalk 3" woodchip mulch, aggregate, or sod 3" coarse compost in ponding area 18" Bioretention Soil Media (BSM) BSM bottom width varies, 1' minimum Provide a 1" drop from the edge of pavement Provide a 1" drop from the edge of sidewalk 6" min. freeboard Overflow standpipe Ponding depth varies Seasonal high water table, bedrock, or other impervious layer NOT TO SCALE Minimum separation varies, see design guidance 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 7 - Page 961 RECEIVED BY DCD 12/6/2021 Attachment 11 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards) Action Needed (Procedures) Inspection Routine Main- tenance Facility Footprint Earthen side slopes and berms B,S Erosion gullies/rills)greater than 2 inches deep around inlets,outlet,and alongside slopes l Eliminate cause of erosion and stabilize damaged area regrade,rock,vegetation,erosion control matting) l For deep channels or cuts over 3 inches in ponding depth),temporary erosion control measures should be put in place until permanent repairs can be made. l Properly designed,constructed and established facilities with appropriate flow velocities should not have erosion prob- lems except perhaps in extreme events.If erosion problems persist,the following should be reassessed:1)flow volumes from contributing areas and bioretention facility sizing;2)flow velocities and gradients within the facility;and 3)flow dissipation and erosion protection strategies at the facility inlet. A Erosion of sides causes slope to become a hazard Take actions to eliminate the hazard and stabilize slopes A,S Settlement greater than 3 inches relative to undis- turbed sections of berm) Restore to design height A,S Downstream face of berm wet,seeps or leaks evid- ent Plug any holes and compact berm may require consultation with engineer,particularly for larger berms) A Any evidence of rodent holes or water piping in berm l Eradicate rodents see Pest control") l Fill holes and compact may require consultation with engineer,particularly for larger berms) Concrete sidewalls A Cracks or failure of concrete sidewalls l Repair/seal cracks l Replace if repair is insufficient Rockery sidewalls A Rockery side walls are insecure Stabilize rockery sidewalls may require consultation with engineer,particularly for walls 4 feet or greater in height) Facility area All maintenance vis- its at least bian- nually) Trash and debris present Clean out trash and debris Facility bottom area A,S Accumulated sediment to extent that infiltration rate is reduced see Ponded water")or surface storage capacity significantly impacted l Remove excess sediment l Replace any vegetation damaged or destroyed by sediment accumulation and removal l Mulch newly planted vegetation l Identify and control the sediment source if feasible) l If accumulated sediment is recurrent,consider adding presettlement or installing berms to create a forebay at the inlet During/after fall leaf drop Accumulated leaves in facility Remove leaves if there is a risk to clogging outlet structure or water flow is impeded Low permeability check dams and weirs A,S Sediment,vegetation,or debris accumulated at or blocking or having the potential to block)check dam, flow control weir or orifice Clear the blockage A,S Erosion and/or undercutting present Repair and take preventative measures to prevent future erosion and/or undercutting A Grade board or top of weir damaged or not level Restore to level position Table V-A.21: Maintenance Standards - Bioretention Facilities 2019 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1019 RECEIVED BY DCD 12/6/2021 Attachment 12 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards) Action Needed (Procedures) Inspection Routine Main- tenance Ponded water B,S Excessive ponding water:Water overflows during storms smaller than the design event or ponded water remains in the basin 48 hours or longer after the end of a storm. Determine cause and resolve in the following order: 1.Confirm leaf or debris buildup in the bottom of the facility is not impeding infiltration.If necessary,remove leaf lit- ter/debris. 2.Ensure that underdrain if present)is not clogged.If necessary,clear underdrain. 3.Check for other water inputs e.g.,groundwater,illicit connections). 4.Verify that the facility is sized appropriately for the contributing area.Confirm that the contributing area has not increased.If steps 1-4 do not solve the problem,the bioretention soil is likely clogged by sediment accumulation at the surface or has become overly compacted.Dig a small hole to observe soil profile and identify compaction depth or clogging front to help determine the soil depth to be removed or otherwise rehabilitated e.g.,tilled).Consultation with an engineer is recommended. Bioretention soil mix As needed Bioretention soil mix protection is needed when per- forming maintenance requiring entrance into the facil- ity footprint l Minimize all loading in the facility footprint foot traffic and other loads)to the degree feasible in order to prevent com- paction of bioretention soils. l Never drive equipment or apply heavy loads in facility footprint. l Because the risk of compaction is higher during saturated soil conditions,any type of loading in the cell including foot traffic)should be minimized during wet conditions. l Consider measures to distribute loading if heavy foot traffic is required or equipment must be placed in facility.As an example,boards may be placed across soil to distribute loads and minimize compaction. l If compaction occurs,soil must be loosened or otherwise rehabilitated to original design state. Inlets/Outlets/Pipes Splash block inlet A Water is not being directed properly to the facility and away from the inlet structure Reconfigure/repair blocks to direct water to facility and away from structure Curb cut inlet/outlet M during the wet season and before severe storm is fore- casted Weekly during fall leaf drop Accumulated leaves at curb cuts Clear leaves particularly important for key inlets and low points along long,linear facilities) Pipe inlet/outlet A Pipe is damaged Repair/replace W Pipe is clogged Remove roots or debris A,S Sediment,debris,trash,or mulch reducing capacity of inlet/outlet l Clear the blockage l Identify the source of the blockage and take actions to prevent future blockages Weekly during fall leaf drop Accumulated leaves at inlets/outlets Clear leaves particularly important for key inlets and low points along long,linear facilities) A Maintain access for inspections l Clear vegetation transplant vegetation when possible)within 1 foot of inlets and outlets,maintain access pathways l Consultation with a landscape architect is recommended for removal,transplant,or substitution of plants Table V-A.21: Maintenance Standards - Bioretention Facilities (continued) 2019 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1020 RECEIVED BY DCD 12/6/2021 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards) Action Needed (Procedures) Inspection Routine Main- tenance Erosion control at inlet A Concentrated flows are causing erosion Maintain a cover of rock or cobbles or other erosion protection measure e.g.,matting)to protect the ground where con- centrated water enters the facility e.g.,a pipe,curb cut or swale) Trash rack S Trash or other debris present on trash rack Remove/dispose A Bar screen damaged or missing Repair/replace Overflow A,S Capacity reduced by sediment or debris Remove sediment or debris/dispose Underdrain pipe Clean pipe as needed Clean orifice at least biannually may need more fre- quent cleaning dur- ing wet season) l Plant roots,sediment or debris reducing capa- city of underdrain l Prolonged surface ponding see Ponded water" l Jet clean or rotary cut debris/roots from underdrain(s) l If underdrains are equipped with a flow restrictor e.g.,orifice)to attenuate flows,the orifice must be cleaned regularly. Vegetation Facility bottom area and upland slope veget- ation Fall and Spring Vegetation survival rate falls below 75%within first two years of establishment unless project O&M manual or record drawing stipulates more or less than 75%survival rate). l Determine cause of poor vegetation growth and correct condition l Replant as necessary to obtain 75%survival rate or greater.Refer to original planting plan,or approved jurisdictional species list for appropriate plant replacements See Appendix 3 Bioretention Plant List,in the LID Technical Guid- ance Manual for Puget Sound,Hinman and Wulkan,2012)). l Confirm that plant selection is appropriate for site growing conditions l Consultation with a landscape architect is recommended for removal,transplant,or substitution of plants Vegetation general)As needed Presence of diseased plants and plant material l Remove any diseased plants or plant parts and dispose of in an approved location e.g.,commercial landfill)to avoid risk of spreading the disease to other plants l Disinfect gardening tools after pruning to prevent the spread of disease l See the Pacific Northwest Plant Disease Management Handbook Pscheidt and Ocamb,2016)for information on dis- ease recognition and for additional resources l Replant as necessary according to recommendations provided for facility bottom area and upland slope vegetation". Trees and shrubs All pruning seasons timing varies by species) Pruning as needed l Prune trees and shrubs in a manner appropriate for each species.Pruning should be performed by landscape pro- fessionals familiar with proper pruning techniques l All pruning of mature trees should be performed by or under the direct guidance of an ISA certified arborist A Large trees and shrubs interfere with operation of the facility or access for maintenance l Prune trees and shrubs using most current ANSI A300 standards and ISA BMPs. l Remove trees and shrubs,if necessary. Fall and Spring Standing dead vegetation is present l Remove standing dead vegetation l Replace dead vegetation within 30 days of reported dead and dying plants as practical depending on weather/planting season) l If vegetation replacement is not feasible within 30 days,and absence of vegetation may result in erosion problems, temporary erosion control measures should be put in place immediately. l Determine cause of dead vegetation and address issue,if possible Table V-A.21: Maintenance Standards - Bioretention Facilities (continued) 2019 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1021 RECEIVED BY DCD 12/6/2021 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards) Action Needed (Procedures) Inspection Routine Main- tenance l If specific plants have a high mortality rate,assess the cause and replace with appropriate species.Consultation with a landscape architect is recommended. Fall and Spring Planting beneath mature trees l When working around and below mature trees,follow the most current ANSI A300 standards and ISA BMPs to the extent practicable e.g.,take care to minimize any damage to tree roots and avoid compaction of soil). l Planting of small shrubs or groundcovers beneath mature trees may be desirable in some cases;such plantings should use mainly plants that come as bulbs,bare root or in 4-inch pots;plants should be in no larger than 1-gallon con- tainers. Fall and Spring Presence of or need for stakes and guys tree growth, maturation,and support needs) l Verify location of facility liners and underdrain if any)prior to stake installation in order to prevent liner puncture or pipe damage l Monitor tree support systems:Repair and adjust as needed to provide support and prevent damage to tree. l Remove tree supports stakes,guys,etc.)after one growing season or maximum of 1 year. l Backfill stake holes after removal. Trees and shrubs adja- cent to vehicle travel areas or areas where visibility needs to be maintained) A Vegetation causes some visibility line of sight)or driver safety issues l Maintain appropriate height for sight clearance l When continued,regular pruning more than one time/growing season)is required to maintain visual sight lines for safety or clearance along a walk or drive,consider relocating the plant to a more appropriate location. l Remove or transplant if continual safety hazard l Consultation with a landscape architect is recommended for removal,transplant,or substitution of plants Flowering plants A Dead or spent flowers present Remove spent flowers deadhead) Perennials Fall Spent plants Cut back dying or dead and fallen foliage and stems Emergent vegetation Spring Vegetation compromises conveyance Hand rake sedges and rushes with a small rake or fingers to remove dead foliage before new growth emerges in spring or earlier only if the foliage is blocking water flow sedges and rushes do not respond well to pruning) Ornamental grasses perennial) Winter and Spring Dead material from previous year's growing cycle or dead collapsed foliage l Leave dry foliage for winter interest l Hand rake with a small rake or fingers to remove dead foliage back to within several inches from the soil before new growth emerges in spring or earlier if the foliage collapses and is blocking water flow Ornamental grasses evergreen) Fall and Spring Dead growth present in spring l Hand rake with a small rake or fingers to remove dead growth before new growth emerges in spring l Clean,rake,and comb grasses when they become too tall l Cut back to ground or thin every 2-3 years as needed Noxious weeds M March October, preceding seed dis- persal) Listed noxious vegetation is present refer to current county noxious weed list) l By law,class A B noxious weeds must be removed,bagged and disposed as garbage immediately l Reasonable attempts must be made to remove and dispose of class C noxious weeds l It is strongly encouraged that herbicides and pesticides not be used in order to protect water quality;use of herbicides and pesticides may be prohibited in some jurisdictions l Apply mulch after weed removal see Mulch") Weeds M March October,Weeds are present l Remove weeds with their roots manually with pincer-type weeding tools,flame weeders,or hot water weeders as Table V-A.21: Maintenance Standards - Bioretention Facilities (continued) 2019 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1022 RECEIVED BY DCD 12/6/2021 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards) Action Needed (Procedures) Inspection Routine Main- tenance preceding seed dis- persal) appropriate l Follow IPM protocols for weed management see Additional Maintenance Resources"section for more information on IPM protocols) Excessive vegetation Once in early to mid-May and once in early-to mid- September Low-lying vegetation growing beyond facility edge onto sidewalks,paths,or street edge poses ped- estrian safety hazard or may clog adjacent permeable pavement surfaces due to associated leaf litter, mulch,and soil l Edge or trim groundcovers and shrubs at facility edge l Avoid mechanical blade-type edger and do not use edger or trimmer within 2 feet of tree trunks l While some clippings can be left in the facility to replenish organic material in the soil,excessive leaf litter can cause surface soil clogging As needed Excessive vegetation density inhibits stormwater flow beyond design ponding or becomes a hazard for pedestrian and vehicular circulation and safety l Determine whether pruning or other routine maintenance is adequate to maintain proper plant density and aesthetics l Determine if planting type should be replaced to avoid ongoing maintenance issues an aggressive grower under per- fect growing conditions should be transplanted to a location where it will not impact flow) l Remove plants that are weak,broken or not true to form;replace in-kind l Thin grass or plants impacting facility function without leaving visual holes or bare soil areas l Consultation with a landscape architect is recommended for removal,transplant,or substitution of plants As needed Vegetation blocking curb cuts,causing excessive sediment buildup and flow bypass Remove vegetation and sediment buildup Mulch Mulch Following weeding Bare spots without mulch cover)are present or mulch depth less than 2 inches l Supplement mulch with hand tools to a depth of 2 to 3 inches l Replenish mulch per O&M manual.Often coarse compost is used in the bottom of the facility and arborist wood chips are used on side slopes and rim above typical water levels) l Keep all mulch away from woody stems Watering Irrigation system if any) Based on man- ufacturer's instruc- tions Irrigation system present Follow manufacturer's instructions for O&M A Sprinklers or drip irrigation not directed/located to properly water plants Redirect sprinklers or move drip irrigation to desired areas Summer watering first year) Once every 1-2 weeks or as needed during prolonged dry periods Trees,shrubs and groundcovers in first year of estab- lishment period l 10 to 15 gallons per tree l 3 to 5 gallons per shrub l 2 gallons water per square foot for groundcover areas l Water deeply,but infrequently,so that the top 6 to 12 inches of the root zone is moist l Use soaker hoses or spot water with a shower type wand when irrigation system is not present o Pulse water to enhance soil absorption,when feasible Table V-A.21: Maintenance Standards - Bioretention Facilities (continued) 2019 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1023 RECEIVED BY DCD 12/6/2021 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards) Action Needed (Procedures) Inspection Routine Main- tenance o Pre-moisten soil to break surface tension of dry or hydrophobic soils/mulch,followed by several more passes. With this method each pass increases soil absorption and allows more water to infiltrate prior to runoff l Add a tree bag or slow-release watering device e.g.,bucket with a perforated bottom)for watering newly installed trees when irrigation system is not present Summer watering second and third years) Once every 2-4 weeks or as needed during prolonged dry periods Trees,shrubs and groundcovers in second or third year of establishment period l 10 to 15 gallons per tree l 3 to 5 gallons per shrub l 2 gallons water per square foot for groundcover areas l Water deeply,but infrequently,so that the top 6 to 12 inches of the root zone is moist l Use soaker hoses or spot water with a shower type wand when irrigation system is not present o Pulse water to enhance soil absorption,when feasible o Pre-moisten soil to break surface tension of dry or hydrophobic soils/mulch,followed by several more passes. With this method each pass increases soil absorption and allows more water to infiltrate prior to runoff Summer watering after establishment) As needed Established vegetation after 3 years) l Plants are typically selected to be drought tolerant and not require regular watering after establishment;however, trees may take up to 5 years of watering to become fully established l Identify trigger mechanisms for drought-stress e.g.,leaf wilt,leaf senescence,etc.)of different species and water immediately after initial signs of stress appear l Water during drought conditions or more often if necessary to maintain plant cover Pest Control Mosquitoes B,S Standing water remains for more than 3 days after the end of a storm l Identify the cause of the standing water and take appropriate actions to address the problem see Ponded water") l To facilitate maintenance,manually remove standing water and direct to the storm drainage system if runoff is from non pollution-generating surfaces)or sanitary sewer system if runoff is from pollution-generating surfaces)after get- ting approval from sanitary sewer authority. l Use of pesticides or Bacillus thuringiensis israelensis Bti)may be considered only as a temporary measure while addressing the standing water cause.If overflow to a surface water will occur within 2 weeks after pesticide use, apply for coverage under the Aquatic Mosquito Control NPDES General Permit. Nuisance animals As needed Nuisance animals causing erosion,damaging plants, or depositing large volumes of feces l Reduce site conditions that attract nuisance species where possible e.g.,plant shrubs and tall grasses to reduce open areas for geese,etc.) l Place predator decoys l Follow IPM protocols for specific nuisance animal issues see Additional Maintenance Resources"section for more information on IPM protocols) l Remove pet waste regularly l For public and right-of-way sites consider adding garbage cans with dog bags for picking up pet waste. Insect pests Every site visit associated with Signs of pests,such as wilting leaves,chewed leaves and bark,spotting or other indicators l Reduce hiding places for pests by removing diseased and dead plants l For infestations,follow IPM protocols see Additional Maintenance Resources" section for more information on IPM Table V-A.21: Maintenance Standards - Bioretention Facilities (continued) 2019 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1024 RECEIVED BY DCD 12/6/2021 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards) Action Needed (Procedures) Inspection Routine Main- tenance vegetation man- agement protocols) Note that the inspection and routine maintenance frequencies listed above are recommended by Ecology.They do not supersede or replace the municipal stormwater permit requirements for inspection frequency required of municipal stormwater per- mittees for stormwater treatment and flow control BMPs/facilities". a Frequency:A Annually;B Biannually twice per year);M Monthly;W At least one visit should occur during the wet season for debris/clog related maintenance,this inspection/maintenance visit should occur in the early fall,after deciduous trees have lost their leaves);S Perform inspections after major storm events 24-hour storm event with a 10-year or greater recurrence interval). IPM Integrated Pest Management ISA International Society of Arboriculture Table V-A.21: Maintenance Standards - Bioretention Facilities (continued) Component Recommended Frequency a Condition when Maintenance is Needed Standards) Action Needed (Procedures) Inspection Routine Maintenance Surface/Wearing Course Permeable Pave- ments,all A,S Runoff from adjacent pervious areas deposits soil,mulch or sediment on paving l Clean deposited soil or other materials from permeable pavement or other adjacent surfacing l Check if surface elevation of planted area is too high,or slopes towards pavement,and can be regraded prior to regrading,protect permeable pavement by covering with temporary plastic and secure covering in place) l Mulch and/or plant all exposed soils that may erode to pavement surface Porous asphalt or per- vious concrete A or B None routine maintenance) Clean surface debris from pavement surface using one or a combination of the following methods: l Remove sediment,debris,trash,vegetation,and other debris deposited onto pavement rakes and leaf blowers can be used for removing leaves) l Vacuum/sweep permeable paving installation using: o Walk-behind vacuum sidewalks) o High efficiency regenerative air or vacuum sweeper roadways,parking lots) o ShopVac or brush brooms small areas) l Hand held pressure washer or power washer with rotating brushes Follow equipment manufacturer guidelines for when equipment is most effective for cleaning permeable pavement.Dry weather is more effective for some equipment. Ab Surface is clogged:Ponding on surface or water flows off the permeable pavement surface dur- ing a rain event does not infiltrate) l Review the overall performance of the facility note that small clogged areas may not reduce overall per- formance of facility) l Test the surface infiltration rate using ASTM C1701 as a corrective maintenance indicator.Perform one test per installation,up to 2,500 square feet.Perform an additional test for each additional 2,500 square feet up to 15,000 square feet total.Above 15,000 square feet,add one test for every 10,000 square feet. l If the results indicate an infiltration rate of 10 inches per hour or less,then perform corrective maintenance to restore permeability.To clean clogged pavement surfaces,use one or combination of the following methods: Table V-A.22: Maintenance Standards - Permeable Pavement 2019 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1025 RECEIVED BY DCD 12/6/2021