The URL can be used to link to this page

Home My WebLink AboutBLD2020-00574-05- STORMWATER Worksheet A1 Medium & Large Project Report Submit a site plan demonstrating the project. Refer to REFERENCE A1A for examples of Best Management Practices (BMP’s) that you can use. Remember that all site plans submitted for the project must be consistent and accurate. page 1 of 6 Minimum Requirement # 1 : Preparation of Stormwater Site Plan Describe both existing and proposed site conditions for the following items as applicable in the space below each bullet point. Attach additional pages if needed. •structures • •roads • •utility locations • •wellhead locations • •septic drainfield locations and type • •stormwater run-on from neighboring properties • •expected excavation depths and volumes • •expected work to be done in Right-of-Way (ROW) Complete the following: Minimum Requirement # 2 : Construction Stormwater Pollution Prevention Plan (SWPPP) A SWPPP is designed to be a stand-alone document that addresses construction stormwater management concerns. This document is required to be kept by the contractor performing the work at the jobsite for reference and update during the life of the project. Construction BMP’s must be indicated on the stormwater site plan. REFERENCE B1A includes diagrams of common BMP’s that may be used on the site plan. My completed SWPPP (WORKSHEET B1 or equivalent) is included in this application packet! Minimum Requirement # 3 : Source Control of Pollution (not construction related) The intent of source control is to prevent stormwater from coming in contact with pollutants. Source control BMPs can be operational or structural in nature. A roof over a material storage area is an example of a structural source control BMP. Washing your vehicle on the lawn rather than in the street is an operational BMP. This requirement is generally not applicable to Single Family Residences (SFRs); however, ways to minimize pollution from moving downstream should be considered during the design phase of every project. Specifications on standard source control BMPs that are applicable to various commercial and industrial-type facilities can be found in Volume IV of the 2014 Stormwater Management Manual for Western Washington (SWMMWW) (continued on page 2). X Propesed single family residence located at parcel 968900026 N/A Utilities stub outs are already installed and withing the 20' front setback N/A N/A None Excavation to be approximately 2 feet deep with an approximate volume of 220 cubic yards None X Worksheet A1 Medium & Large Project Report page 2 of 6 Check one of the following boxes that best represents your project with regards to MR #3. Minimum Requirement # 3 : Source Control of Pollution (continued from page 1) My project is a Single Family Residence (SFR) and after considering operational and structural measures to prevent stormwater from coming in contact with pollutants, I have: determined this MR to not be applicable. made appropriate adjustments to my project. My project is not a SFR and after reviewing Vol. IV of the SWMMWW, I have determined that this MR is not applicable because of the following reason: My project is not a SFR and after reviewing Vol. IV of the SWMMWW, I have determined that the following source control BMPs are applicable to my project and shall be incorporated into the project design and operation. X X Worksheet A1 Medium & Large Project Report Minimum Requirement # 4 : Preservation of Natural Drainage Systems Creating new drainage patterns results in more site disturbance and more potential for erosion and sedimentation during and after construction. to the maximum extent possible, proponents must 1) maintain the natural on-site drainage pattern and concentrated discharge location at the downstream property boundary, and 2) prevent erosion at and downstream of the discharge location. NOTE: All outfalls require energy dissipation. See Table 4.5.1 in Vol. V of the SWMMWW for minimum design standards for rock protection at outfalls. Choose the option below that best describes your project: page 3 of 6 The project site does not currently have any intermittent, seasonal, or continuous concentrated water moving across any part of the property and the proposed improvements to the site will not create new concentrated flow paths or not discharging to existing drainage systems. The project site has existing concentrated flow drainage systems and outfalls. (NOTE: These items must be graphically shown on the Site Plan or equivalent, to include: type, slope, dimensions, channel lining, direction of flow, buffer, etc.) Select below how it will be addressed. This project will not alter the existing drainage system in any way. If the existing outfall(s) show signs of erosion and scour, energy dissipation measures will be installed or improved upon. Construction activity of any kind will not occur within at least 10 ft. of the edge of the channelized flow. BMP C102: BUFFER ZONES will be implemented during the life of the project to include visible flagging or other demarcation technique. The existing concentrated drainage system traversing the property will be impacted as part of this project, as described in the space below and shown on the site plans. Engineering calculations are required that show the altered drainage design can accommodate the existing flows and the added runoff contributed by the project. X Worksheet A1 Medium & Large Project Report page 4 of 6 My project is a large project. Refer to Worksheet L. If full dispersion isn’t feasible, use LIST #1 (List #2 and List #1 are the same except raingardens are not permitted in List #2). Minimum Requirement # 5 : On-site Stormwater Management On-site stormwater management techniques shall be implemented where possible to accommodate the permanently added stormwater runoff being generated by development. Some on-site stormwater management techniques provide better stormwater detention and treatment than others; however, they are not always appropriate for use due to varying individual site characteristics. Therefore, techniques are presented to applicants on the next pages in a hierarchical order and shall be considered for use in the order listed. The first technique on the list that is determined to be possible shall be implemented. See WORKSHEET C to determine which techniques are feasible. Runoff from developments occurring in drainage basins that drain directly or indirectly to a creek require a higher level of stormwater management, thus, the techniques are presented in three lists below: All properties will be in one of these three categories: My project is located in a drainage subbasin that drains to directly or indirectly to freshwater. PROCEED to Page 5 to use LIST #1. My Project will discharge to a subasin draining to salt water, Dosewallips River, or Hoh River. PROCEED to Page 6 to use LIST #3. X Worksheet A1 Medium & Large Project Report My project does not have disturbed soils not covered by impervious surfaces. 1.Post-Construction Soil Quality and Depth Disturbed soils shall be amended (BMP T5.13: ). My project does not have Roof areas. 1.Full Dispersion (BMP T5.30) OR Downspout Full Infiltration (BMP T5.10A) 2.Rain Garden (LARGE PROJECTS CANNOT USE) (BMP T5.14A) 3.Downspout Dispersion System (BMP T5.10B) 4.Perforated Stub-Out Connection (BMP T5.10) 5.Each BMP above is infeasible, see WORKSHEET C. STOP. COMPLETE AND SUBMIT WORKSHEET B1. NO OTHER INFORMATION REQUIRED AT THIS TIME. My project does not have Other Hard Surface areas 1.Full dispersion (BMP T5.30) 2.Permeable Pavement (BMP T5.15) OR Rain Garden (LARGE PROJECTS CANNOT USE) (BMP T5.14A) Minimum Requirement # 5 : On-site Stormwater Management (continued) LIST # 1 : Applicable to projects that directly or indirectly drain to freshwater. INSTRUCTIONS: Check the first option that will work for Each Category Below: For each category below, proceed through the LIST from top down. Use WORKSHEET C to determine if the BMP can be used. If number 1 on the list is not possible, document why on WORKSHEET C and move down to number 2, and so on. Category A: Lawn and Landscape Areas Category B: Roofs Category C: Other Hard Surfaces, e.g. gravel and paved driveways, solid decks and patios without infiltration below 3.Sheet Flow Dispersion (BMP T5.12) OR Concentrated Flow Dispersion (BMP T5.11) 4.Each item above is infeasible, see WORKSHEET C. STOP. COMPLETE AND SUBMIT WORKSHEET B1. NO OTHER INFORMATION REQUIRED AT THIS TIME. X X X