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Home My WebLink AboutHydraulic Report for GRD2007-00024 - PLN General - 11/10/2008 • x c t o r ,_f N 6 1 N E E R I N 6 1 N C 309 WASHINGTON STREET NE • OLYMPIA WA 98501• TEL:360 352-2477• FAX: 360 352-0179 www.vectorengineeringinc.com November 10,2008 Mr.Robert D.Fink,AICP Mason County—Department of Community Development Mason County Bldg 1 P.O.Box 279 Shelton,WA 98584 Subject: Byerly Belfair Development Hydraulic Report Permit#: GRD 2007-00024 PAR2007-00052 Parcel Nos. 12332-50-00019 Applicant: RWJJ,INC PO BOX 2582,BELFAIR WA 98528-2582 Planner: Jim Scholz Public Works Contact: Fred Perryman VEI#: 8001-020 Skil ings Connolly Project No.07031 Dear Mr.Fink, The Byerly Belfair Development Hydraulic Report dated August, 3 2007, received on June 19,2008 prepared by Skillings Connolly,Inc., 5016 Lacey Boulevard SE,Lacey,Washington 98503 for Lot D of the Byerly Belfair Development Project(short plat no. 1651), a proposed commercial development project at 23295 NE State Route 3,Belfair WA 98528 was reviewed by Vector Engineering,Inc. It is recommended that the revised hydraulic information report and plans dated October 21, 2008 be accepted. No further review by Vector Engineering is necessary. We have enjoyed working with you on this storm drainage review to support the goals of the Department of Community Development of Mason County,Washington.We look forward to cooperating with you on any future project or review. The invoice,the geo tech work order,the storm drainage technical information report,original plans, the first and second revised storm drainage technical information reports, first and revised plans and our review are enclosed. Please feel free to contact me if you have any questions regarding these comments, or if you feel any features need further discussion or attention. Sincerely, Russell W. La Force, P.E. Design Engineer Enc. Page 1 of 1 X:\8000 Files\8001 Mason County Geotech Reviews\8001-020_Mason_Co(Byerly)SW\Communication\Transmittal Letters\Stormwater Report GRID 2007-00024 Review Acceptance.doc %z- e: c t o r E N G I N E E R I N G 1 N C 309 WASHINGTON STREET NE • OLYMPIA WA 98501• TEL:360 352-2477• FAX: 360 352-0179 www.vectorengineeringinc.com Review of Storm Drainage Technical Information Report November 10,2008 Subject: Byerly Belfair Development Hydraulic Report Permit#: GRD 2007-00024 PAR2007-00052 Parcel Nos. 12332-50-00019 Applicant: RWJJ,INC PO BOX 2582,BELFAIR WA 98528-2582 Planner: Jim Scholz Public Works Contact: Fred Perryman VEI#: 8001-020 Skillings Connolly Project No.07031 The Byerly Belfair Development Hydraulic Report dated August, 3 2007, received on June 19,2008 prepared by Skillings Connolly,Inc.,5016 Lacey Boulevard SE,Lacey,Washington 98503 for Lot D of the Byerly Belfair Development Project(short plat no. 1651),a proposed commercial development project at 23295 NE State Route 3,Belfair WA 98528 was reviewed by Vector Engineering, Inc. The Department of Community Development requested the review for the purpose assisting the Department in determining whether the proposed development will cause negative impacts downstream. The Department of Community Development reviews all development applications to determine stormwater runoff impacts per Mason County Ordinance 06-114 STORMWATER MANAGEMENT ORDINANCE approved December 2, 1997 and Mason County Resource Code 14.48 STORMWATER MANAGEMENT approved in 2006. From the Mason County website regarding this site in the application for PAR2007-00052, there is a note "STORMWATER: Stormwater Site Plan to be designed at a minimum to the 1992 version of the Department of Ecology Stormwater Management Manual for the Puget Sound Basin." The biofiltration strip and site was designed using the 2005 version of the Department of Ecology Stormwater Management Manual for the Puget Sound Basin. The hydraulic report states the proposed development will initially consist of 9,560 cubic yards of fill,one wetland buffer,two level building pads,one parking area,one sidewalk, one biofiltration strip, two foundation drains, two flow spreaders, and one storm drain outfall. Seven sheets of plans; cover, erosion control plan, (site plan, grading, and drainage plan), utility plan, paving and stripping plan, notes and details were provided in the report. The project site has been filled along the east edge and contains two biofiltration strips used to treat runoff from lots A,B,and C.The lot slopes westerly between 8 and 10%to a large wetland. A previous drainage report was completed for all 4 lots in 2000. The stormwater site plan titled Byerly-Belfair Development Lots A,B, C &D dated March 24, 2000 was received on July 15, 2008. The cover of the report has two permit numbers written on it, GRD2000-0005 and GRD2000-0006. A revised hydraulic report dated September 2008 was received on Page I of 3 X:\8000 Files\8001 Mason County Geotech Reviews\8001-020_Mason_Co(Byerly)SW1Communication\Transmittal Letters\Stonnwater Report GRD 2007-00024 Review.doc September 22, 2008. The report was reviewed and a letter with additional comments was sent. On November 4,2008 responses to the letter were received along with a second revised hydraulic report and plans. Findings 1. Development exceeding 5,000 square feet of impermeable surfacing and land disturbing activities of one acre or more must have the large parcel ESC plan (if required) and the permanent stormwater quality control (PSQC) plan (if required) prepared and stamped by a licensed civil engineer. • The proposed development is planned to have 13,000+/- square feet (0.30 acres) of impervious area and with land disturbing activities impacting 36,000+/-square feet(0.83 acres)of the 2.28-acre parcel. 2. A licensed civil engineer shall prepare the storm drainage technical information report. • Bryan J. Ewing, a licensed professional engineer, prepared the initial hydraulics report. • Robert G. Connolly, a licensed professional engineer, prepared the first and second revised hydraulics reports. 3. The site lies within the Belfair Urban Growth Area of Mason County. 4. Stormwater water negative impacts consist of increasing the flow rate, increasing the flow volume,or decreasing the water quality downstream of the development. 5. Redevelopment is the creation, addition, or replacement of impervious surfaces and structural development,that is not part of a routine maintenance activity 6. The report was developed using the 2005 Department of Ecology Stormwater Management Manual for the Puget Sound Basin with Chapter I-2 Minimum Requirements for All New Development and Redevelopment of the Manual superceded by Mason County Code Title 14.48.140 New Development and Redevelopment—Minimum Requirements as amended required by the ordinance. 7. MGS Flood was used to calculate to on-line and off-line treatment flows. 8. Due to the location of the proposed site and its close proximity to Hood Canal, no storage or quantity treatment was determined to be required. • The site is about 2,000 feet from Hood Canal. Private property owned by others and a road are in between the site and Hood Canal. 9. The stormwater flow is to be discharged on the ground at 4 separate location, then cross an 80-foot wetland buffer to a wetland then into a waterway,then Union River, and into Hood Canal. • Minimum Requirement #6 Wetlands of the 1992 Stormwater Manual is for situations where stormwater discharges directly or indirectly into a wetland and must be met. (a) Stormwater discharges must be controlled and treated to the extent necessary to meet the State Water Quality Standards. (b)Discharges Page 2 of 3 XA8000 Files\8001 Mason County Geotech Reviews\8001-020_Mason_Co(Byerly)SW\CommunicationVfransmittal Letters\Stormwatcr Report GRD 2007-00024 Review.doc to wetlands shall maintain the hydroperiod and flows of existing site conditions to the extent necessary to protect the characteristics uses of the wetland. 10. Engenious Systems StormSBED using the Santa Barbara Urban Hydrograph method was used to calculate flow rates and volumes. 11. The report includes a downstream analysis. • The report states that runoff from the site flows to 91 acres of wetlands. The addition of 1.12 acres of additional impervious area will create an additional flow so insignificant to be nearly immeasurable when compared to the runoff generated by the surrounding 91 acres. The report states, "Neither the hydroperiod or quality of the existing wetland will be altered." No analysis was provided to validate the conclusion. • The facility has not been designed to maintain the existing peak flow rates up to the 100-year/24-hour storm. The project drains to a large natural wetland to which the existing developed lots drain. Conclusions and Recommendations In the reviewer's opinion, the report was prepared by a qualified licensed professional engineer and does provide sufficient information to determine the proposed commercial./industrial development will not increase downstream flooding. It is recommended that the storm drainage technical information report be accepted. No further review by Vector Engineering is necessary. Adequate erosion and sediment control features need to be implemented during land disturbing activities to protect neighboring properties and State waters from adverse stormwater runoff impacts. The migration or release of silty water or mud from the applicant's property will be considered a violation of County and State water quality protection regulations. The conclusions presented in this report are based on Vector Engineering,Inc.' understanding of the project requirements.Vector Engineering,Inc.warrants that its services were performed with the level of care and skill ordinarily exercised by members of the same profession currently practicing in the same locality under similar conditions. No other warranty or representation,expressed or implied,is included or intended hereunder. Sincerely, o� AY Nit l 4 (Signature) (Date) �y��oF WA�yi c�0� Russell W. La Force,P.E. Seal: �V Design Engineer a ) 4, Vector Engineering,Inc. �'�F 9FGlsTERF'° 309 Washington Street NE _ SS/ONAv- Olympia,WA 98501 (360)352-2477 EXPIRES 05-25-c�q Page 3 of 3 XA8000 Files\8001 Mason County Geotech Reviews\8001-020 Mason_Co(Byerly)SW\Communication\Transmittal Letters\Stonnwater Report GRD 2007-00024 Review.doc