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Home My WebLink AboutBLD2006-00632 Drainage & Control Plan n ,h 66 - 6 [3 Drainage Report Gibbs Proposed Home 44 Argyle Lane Port Ludlow, WA February 18, 2007 Prepared By E3RA, Inc 9802 29th Ave W, #B102 Everett, WA 98204 425-356-3372 • • • TA3LE OF CONTENTS Certification Introduction Minimum Requirements 1. Preparation of Stormwater Site Plans 2. Construction Stormwater Pollution Prevention (SWPP) 3. Source Control of Pollution 4. Preservation of Natural Drainage Systems and OutfaIfs 5. On-site Stormwater Management Appendices • • CERTIFICATION I hereby state that this Drainage Report for the Spencer Proposed Home has been prepared by me or under my supervision and meets the standard of care and expertise which is usual and customary in this community for professional engineers. •--- o PROF ,11417/ btu I V ii f ill , 11, 236: ,i ��, cid Is :4-I • No.2330 p ; r' �`pIONAL# , ip� ,,•O ,...a r- ,.• �2� • SEDIM .. I EXPIRES 12/5/6) 3 • • INTRODUCTION This report is intended to meet the stormwater requirements of the City of Port Ludlow for the construction of a single family house on an existing lot. The subject property is located at 44 Argyle Lane in Port Ludlow in Jefferson County, • Washington. The Parcel Number is 995600013. Existing Conditions The existing site consists of a recently logged parcel. The lot slopes at approximately 6 percent from east to west. The site soils are consistent with Indianola soils comprised of sand. Proposed Conditions A home will be constructed on the lot with a paved driveway. • The grading of the site will not be significantly changed. The new impervious area of the site will be 4,983 square-feet, of this 1,216 square-feet will be the paved driveway. Based on the minor increases in impervious area, Minimum Requirements#1 through#5 apply to this project: Minimum Requirement#1: Preparation of Stormwater Site Plans A stormwater site plan has been developed for this site. The plan is contained in the appendix of this report. _ The major elements of the plan include: • Grading the driveway to drain to drain to a driveway drain. • Installing infiltration trenches for the roof and driveway runoff. Minimum Requirement #2: Construction Stormwater Pollution Prevention Plan (SW.PPP) Construction stormwater pollution prevention consists of the following 12 elements: Element 1: Marking Clearing Limits The clearing limits for this project are essentially the property lines. The property lines will be marked with silt fencing. 4 • • Element 2: Establish Construction Access Construction vehicle access will be limited to one route, the proposed driveway. • The construction access shall be stabilized with a pad of quarry spalls. A wheel wash is not anticipated for this project. If sediment is tracked off-site, the public roads shall be cleaned thoroughly at the end of each day, or more frequently, should conditions require it. The cleaning will be accomplished with a street-sweeper. Element 3: Control Flow rates The flow rates from this property will not be significantly increased due to the construction of this project. The site soils already have a low runoff potential and there will be modest increase to the impervious area. Potential increases to the runoff from this site are best described as de minimus. Element 4: Install Sediment Controls The following Best Management Practices (BMPs) are specified for this project: • Stabilized Construction Entrance • Silt Fence • Temporary and Permanent Seeding Element 5: Stabilize Soils All exposed soils will be stabilized according to the following schedule: • October 1 through April 30: No soils shall remain exposed and unworked for more than 2 days. May 1 through September 30: No soils shall remain exposed and worked for . more.than 7 days. • Element 6: Protect Slopes There will be no significant slopes on this project. Element 7: Protect Drain Inlets There are no know drain inlets nearby. 5 • • Element 8: Stabilize Channels and Outlets There are no channels or outlets on or near this project. Element 9: Control Pollutants On-site fueling of equipment will not be permitted on this project. Maintenance and repair of equipment or vehicles will not be permitted on this project. Element 10: Control De-Watering De-watering is not anticipated on this project. Element 11: Maintain BMPs All BMPs will be inspected, maintained, and repaired to assure their continued performance. The inspection schedule, maintenance, and repairs shall be conducted in accordance with industry standards and/or manufacturer's recommendations. All sediment control BMPs shall be inspected weekly or after a runoff producing event during the dry season and daily during the wet season. All temporary erosion and sediment control BMPs will be removed within 30 days after final stabilization. Element 12: Manage The Project The clearing and grading will occur only as necessary to permit the construction activities, IE construction phasing. A Certified Professional in Erosion and Sediment Control, Robert Elslip, P.E., C.P.E.S.C., (cell: 206-226-5777), will be on call at all times Minimum Requirement#3: Source Control of Pollution Source control of pollution is meant to prevent pollution before it occurs. Source controls for this project will include: • Construction Phasing to reduce exposed soils • Temporary or permanent seeding to reduce exposed soils • Prohibiting the fueling and/or maintenance of vehicles on-site. 6 • • Minimum Requirement#4: Preservation of Natural Drainage Systems and Outfalls No natural drainage systems or outfalls exist on or near this project. This project will not alter the existing drainage patterns. Minimum Requirement#5: On-site Stormwater Management The drainage from the roof downspouts shall be infiltrated. Roof area 3,757sf Driveway 1,226 sf 30 LF of infiltration trench per 1,000 sf of roof area. 4,983/1000*30=149.5 LF of infiltration trench needed. A small portion, approximately 200 sf, of the driveway will be allowed to sheet flow to the roadside ditch due to site constraints. A yard drain has also been provided as an overflow for the infiltration trenches under the driveway. • • APPENDIX A • Grading and Drainage Plan • TESC Pan • Details • Notes 8 • • APPENDIX C TEST PIT LOGS • • SPENCER TEST PIT LOGS xx Argyle lane (all test pits owner excavated) Depth(feet) Material Description Sample No. TP-1 Location: 15'east of Argyle Lane Approximate ground surface elevation:Unknown 0.0—1.0 Topsoil 1.0—2.0 Medium dense,moist,tan silty gravelly SAND(SP) 2.0—8.0 Medium dense,moist,gray silty gravelly SAND(SP) No caving apparent No water present Logged By: CRL on 1/22/07 Depth(feet) Material Description Sample No. TP-2 Location: 80' east of Argyle Lane Approximate ground surface elevation:Unknown 0.0—1.0 Topsoil 1.0—2.0 Medium dense,moist,tan silty gravelly SAND(SP) 2.0—7.0 Medium dense,moist,gray silty gravelly SAND(SP) No caving apparent No water present Logged By: CRL on 1/22/07 Depth(feet) Material Description Sample No. TP-3 Location: 130' east of Argyle Lane Approximate ground surface elevation:Unknown 0.0—1.0 Topsoil 1.0—2.0 Medium dense,moist,tan silty gravelly SAND(SP) 2.0—5.0 Medium dense,moist,gray silty gravelly SAND(SP) No caving apparent Water pooled at 4.25' Roots through out Logged By: CRL on 1/22/07 10 • APPENDIX D REFERENCES • Stormwater Management Manual for Western Washington 2005 • Site Plan transmitted to E3RA on by Tim Gibbs