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HomeMy WebLinkAboutSP-23-027 - Supplemental - 0550 Dorset Street (6)Version: 4/28/2017 Project Name: Response Attachment location 1 SW2 2 SW2 Attachment Location C2.0 C2.0 Response Attachment location 5 C2.0 6 C2.0 7 C2.0 8 C2.0 9 n/a Option 1: Leave undisturbed native vegetation and soil, and protect from compaction during construction. Option 2: Amend existing site topsoil or subsoil in place. Option 3: Remove and stockpile existing topsoil during grading. Option 4: Import topsoil mix, or other materials for mixing, including compost, of sufficient organic content and depth. Is compost or other materials used to amend soils specified to have a C:N ratio below 25:1? Is it specified that compost shall meet the definition of "compost" or meet the contaminant standards in the Vermont Solid Waste Management Rules? If Exceptional Quality (EQ) biosolids are used as a soil amendment, do they comprise no more than 35% of the total volume of soil, and is it specifed that they be well mixed before or during application? Does the site layout retain the duff layer and native topsoil in an undisturbed state to the maximum extent practicable? Is the organic matter content of the topsoil layer specified to be at least 4%? 4 Feasibility (3.1) Have all areas that will not be disturbed and areas exempt from the Standard, including the reason for the exemtion, been identified on a plan sheet? Have all areas of disturbance within the site that are subject to the Post- Construction Soil Depth and Quality Standard been identified on a plan sheet? This includes all disturbed areas on slopes ≤ 33% which are not covered by an impervious surface, part of a structural stormwater treatment practice, or engineered as structural fill once development is complete. Which of the following methods are utilized to meet soil quality requirements for this site? Post-Construction Soil Depth and Quality Standard 3 Is the minimum topsoil depth specified as: 4 inches The depth of the 0 and A horizons on the NRCS Official Soil Series Description of the native mapped soils (provide documentation) Treatment (3.2) South Burlington High School Basketball Court Yes No Yes No Yes No Yes No Yes No Yes No Yes No Page 1 of 2 Response Attachment location C2.0 10 11 12 13 14 15 Attachment location: Indicate the specific location (i.e. appendix, page, plan sheet) where the requisite support documentation has been provided within the application. Includes construction details and notes on the various methods the contractor may use to meet he Standard? Instructions to establish dense an vigorous vegeative cover over turf areas? Vegetation and Landscaping (3.3) Does the application include a site-specific plan for soil management that: Includes a statement that soil depth and quality shall be established towards the end of construction, and once established, be protected from compaction? Identifies all areas on the site subject to the standard? Includes instructions for contractor verification of the Standard, including a sampling scheme that includes nine 8-inch deep test holes per acre of area subject to the Standard? Instructions that test holes shall be excavated using only a shoven driven soley by the inspector's weight and shall be at least 50 feet apart from each other? Yes No Yes No Yes No Yes No Yes No Yes No Page 2 of 2 Version:10/22/2018 Project Name: Discharge Point: Disconnection Area # Disconnected Area For Permit Coverage Not for Permit Coverage Total to Practice 1 Total Area (acres)0.200 0.000 0.200 2 0.120 0.000 0.120 WQV for credit WQV not for credit Total WQV 3 WQV to practice 0.0098 0.0000 0.0098 95 4 FALSE 0 FALSE Response Attachment location 5 C1.0 6 C2.0 7 C2.0 8 C2.0 9 C1.0 10 C1.0 11 12* 1 0 Response Attachment location 13 C1.0 14 C1.0 Impervious (acres) Modified CN for WQ (1.0") storm Runoff conveyed to disconnection area by Is the runoff conveyed as sheet flow across the disconnection area for the applicable design storms and prevented from channelizing? Is the disconnection surface directed away from buildings so as to protect foundations and basements? South Burlington High School Basketball Court Disconnection to Filter Strips or Vegetated Buffers (4.2.3) S/N1 1 Conveyance (4.2.3.2) * Questions preceded by an asterix (*) may change based on previously entered values Feasibility (4.2.3.1) Do the site plans show a permeable vegetated area with the required flow path length, as specified in the Treatment section below? Do the underlying soils of the disconnection area meet the Post-Construction Soil Depth and Quality Standard? Do the plans specify that vegetated buffers shall remain in a natural state and must be protected to ensure that no future development, disturbance, or clearing occur within the area? Do the plans specify that filter strips shall be identified and protected to ensure that no future development, disturbance, or clearing may occur within the area, except as stipulated in the vegetation maintenance plan? Is the maximum slope of the filter strip no steeper than 15% or the maximum slope for the vegetated buffer now steeper than 8%? Are disconnection areas configured such that there is no overlap between adjacent disconnection areas? For sites with septic systems, is the disconnection flow path cross-gradient or down-gradient of the leachfield? Yes No NoYes Yes No NoYes NoYes Yes No Yes No Yes No Yes No Yes No Sheetflow Level Spreader Page 1 of 3 0 15 (cfs)0 16 18 40 19 0 20 Response Attachment location 21* 2 1 Response Attachment location 22 acres 0.120 SW2 24 C1.0 25 ft 35 26 ft 35 27*inches 28 TV (cu-ft)435.6 29 TV (ac-ft)0.010 Response Attachment location 30* What is the treatment volume provided by the STP? What is the treatment volume provided by the STP? ↑ Enter this value on the Standards Compliance Worksheet Treatment (4.2.3.4) Has infiltration rate documentation been provided for the use of shorter disconnection flow path lengths? fc ≥0.5 in/hr for TV=WQV fc <0.5 in/hr for TV=WQV What is the slope of the disconnection area? What is the required length of the disconnention area? What disconnection length is provided? Has pre-treatment been provided for the level spreader either in a forebay sized for 10% of the WQv or otherwise in accordance with Section 4.1? Treatment Volume Calculation Disconnected Impervious for permit coverage (from question 2) 23 Soil HSG fc ≥1 in/hr for TV=HCV Engineered Level Spreader Requirements (if applicable) What type of vegetation covers the disconnection area? Pretreatment (4.2.3.3) 17* What is the required level spreader length per cfs in feet? What is the required level spreader length in feet? Has the level spreader been designed in accordance with all design requirements in section 4.2.3.2? What is the peak discharge of the largest storm event routed to the level spreader? NoYes A A/B <8% 8-15% C/D NoYes NoYes Grass Forested Mixed Page 2 of 3 Response Attachment location 31 C2.0 1 2 1 80 110 2 35 50 3 65 85 Landscaping (4.3.3.5) Is a dense vegetative cover (minimum 90% coverage) specified for the disconnection area on the plan sheet/detail sheet? Attachment location: Indicate the specific location (i.e. appendix, page, plan sheet) where the requisite support documentation has been provided within the application. NoYes Page 3 of 3 For additional information please go to the 2017 Vermont Stormwater Management Manual, Sections 2.2.6 and 2.5. Project Name: South Burlington High School Basketball Court Discharge Point: s/N1 Overbank Flood Protection Standard Waiver Worksheet Fill out this worksheet for each discharge point in which use of this waiver is sought. Overbank Flood Protection Standard (QP10) Waiver (check only one): 1. The pre-routed, post-development discharge for the 10-year, 24-hour storm is less than 2 cubic feet per second. Enter the total pre-routed post-development stormwater discharge rate (cfs): 0.55 Guidance: “Pre-routed post development discharge” means the runoff after development, including post-development conveyance, but without STPs. When examining whether or not the site qualifies for this waiver, off-site runoff does not need to be considered, however the overall common plan of development shall be considered. Please attach the runoff calculations/hydrologic modeling for the pre-routed, post-development during the 10-year, 24-hour storm event. 2. A site that has a direct discharge to waters with a drainage area equal to or greater than or equal to 10 square miles. Name of Waters at Discharge Point: Drainage Area of Waters at Discharge Point (square miles): 3. A downstream analysis was completed, pursuant to Section Error! Reference source not found. of the 2017 VSMM, that indicated extreme flood control is not necessary for the site. Has adequate conveyance from the site to the discharge point been verified? Yes No Has supporting information (e.g. narrative description, calculations, modeling) for the completed downstream analysis been included with the application? Yes No For a project that has more than one discharge point and that discharges to different receiving waters, waiver eligibility shall be determined on a “per receiving water” basis. Receiving waters are considered separate if the drainage area at their downstream point of confluence is greater than 10 square miles. For example, if discharge point S/N 001 discharges directly to the Winooski River (drainage area of greater than 10 square miles), but discharge point S/N 002 discharges directly to a small tributary of the Winooski River, then S/N 001 could be waived from the Overbank Flood Protection Standard using Waiver 2, but S/N 002 could not. However S/N 002 may still be eligible for Waivers 1 or 3.