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Home My WebLink AboutCOM2011-00006 Stormwater Pollution Plan, Drainage Erosion Report - COM Engineering / Geo-Tech Reports - 10/11/2010 TO BE KEPT IN THE PARCEL FILE Construction Stormwater Pollution Prevention Plan for South Shore Enterprises Vehicle Storage Building 750 East Dalby Road q 31 Lot 3 of Parcel No. 32232 43 0001# Union, Mason County, Washington October 11, 2010 Project#1027 Prepared For: South Shore Enterprises, LLC PO Box 249 �L CLYDE s Union, Washington 98592 � ' of WASfj, rI Prepared By: Envirotech Engineering A 74 NE Hurd Road �°.4 RFC s�R�° Belfair, Washington 98528 -ssiDNALti�G` Phone: 360-275-9374 Fax: 360-275-4789 Envirotech Engineering (Envirotech) has completed this construction stormwater pollution prevention plan in conjunction with the stormwater management plan for the South Shore Enterprises Vehicle Storage Building. The proposed development is located at 750 East Dalby Road(Lot 3 of Parcel 32232 43 00010)in Union,Washington(Project). Project Description Information pertaining to the Project was provided by Rick Buechel with South Shore Enterprises, LLC. The property is currently developed land with an existing 5000 sf building, 7000 sf concrete slab that was utilized for 2 pre-existing buildings, a driveway,parking areas,on- site septic system and an off-site water well. The property has been recently divided from a large lot to a parcel of approximately 5.78 acres in size. Existing land use near the Project includes a mixture of commercial and residential rural development. The proposed redevelopment includes constructing a 2400 sf metal building within the existing concrete slab area, and improving parking and driveway areas. A new parking area will replace a portion of the driveway and i er parking area, and encompass less than 4,820 sf of pollution generating surfaces. For additional drainage facilities, new clearing will constitute approximately 1000 sf of area. Earthwork consisting of cut and fill is estimated to be 85 cubic yards. The existing building is planned to be utilized as office space for four employees. The proposed metal building is glanned to be used for vehicle and equipment parking�raae. See the accompanying stormwater management plans for an illustration of current and proposed site features. Existing Site Conditions The Project is currently developed, vacant land as previously mentioned. Past timber harvesting and vegetation clearing is apparent for this property. Native vegetation on the property and nearby properties includes firs, alders, hemlocks, blackberry, and other trees and shrubs common to this area. The area of development has mild grades with steps in the terrain of up to 3.5 feet. Ascending grades are located to the northwest of the development with slopes ranging from less than 10%to just over 40%. Descending slopes are generally to the east, with maximum grades of approximately 20%. Stormwater runoff originating upslope from the anticipated development appears to be moderate to extreme. Drainage diversions and past drainage maintenance issues have been an on-going process. Envirotech Engineering South Shore Enterprises SWPPP Ph. 360-275-9374 Page 1 of 7 750 E Dalby Road, Union Fax: 360-275-4789 Lot 3 of Parcel 32232 43 00010 October 11, 2010 r Adjacent Areas Beyond the property lines,rural commercial and residential development exists. Site disturbance is not expected to disturb adjacent areas, including streams, lakes, wetlands, residential areas,or roads. Downstream runoff appears to be directed to the stream that runs through the property near the south end of the property,and extends to the Hood Canal. Critical Areas Stream/wetland were delineated on the property. Slopes exceeding 40%were also evident on the property. Other than following government ordinances, the geotechnical report, and the engineered drainage plan,there are no additional requirements for working near critical areas. Soils Information on infiltration rates and soil conditions pertaining to the Project was accomplished by Envirotech. See the Soils Report prepared for the South Shore Enterprises Vehicle Storage Building, dated March 22, 2010. Selected information pertaining to the drainage aspect of the project is provided below. Additional soils information is provided below in order to comply with the 2005 Department of Ecology Stormwater Manual. Specifically, soils for this project were described utilizing the Unified Soil Classification System (USCS) and the U.S. Department of Agriculture (USDA) Textural Classification System. Soils within the upper 3 feet of natural ground were observed to be moist, brown, loose to medium dense silty sand with gravel(SM). According to the USDA Textural Classification System, the upper 36 inches of soil were classified as sandy loam. Per the SCS classification, the site soils where drainage features will exist were classified as Alderwood Gravelly Sandy Loam, Ab. According to the Stormwater Management Manual for Western Washington prepared by the Washington State Department of Ecology Water Quality Program, infiltration rates of the soils encountered at a depth of at least 42 inches below the ground surface is 4.14 inches/ hour. This infiltration rate includes a factor of safety of 2, as recommended by the stormwater manual. Percolation tests were not completed for this Project. Per our site visit, groundwater was encountered at a depth of 3 feet below the existing ground surface near anticipated stormwater outlet locations. Shallower groundwater,as little as 12 inches below the ground surface,was observed directly downslope from anticipated facilities. The fines content of the site soils has a low plasticity, indicating that silt is most likely prevalent over clay. Based on the fines content and slope gradients, soil erodibility is considered moderate Envirotech Engineering South Shore Enterprises SWPPP Ph. 360-275-9374 Page 2 of 7 750 E Dalby Road, Union Fax: 360-275-4789 Lot 3 of Parcel 32232 43 00010 October 11, 2010 for this project. Due to the types of fine soils, the settleability is considered moderate. Based on the soil density and gradation, a moderately high permeability can be expected. Erosion Problem Areas Due to the soil conditions and relatively minor grades, erosion problems are not expected to occur on the property when following basic erosion control protocol. Construction Phasing It is expected that this project will be a single phase construction operation. The following includes the recommended construction sequence and procedure for project development: 1. Delineate clearing and easement limits. 2. Construct all required temporary erosion control features. 3. Clear vegetation required for site development. 4. Perform initial earthwork and rough grading for constructing driveways,and building pads. Top soil may be stock-piled for future use. If necessary, exposed soils in stock piles must be protected with plastic covering or County approved method. 5. Complete final grading of the subgrade, materials placement and structure construction per the plans and specifications. This includes dredging sediments from temporary sediment ponds, if necessary. 6. Maintain all temporary erosion and sediment control facilities, as needed, in order to provide the required protection of downstream water quality. Additional temporary erosion control shall be rendered, if necessary. 7. Provide permanent erosion control in order to stabilize the project. 8. Remove temporary erosion sedimentation control facilities after construction is complete, site is sufficiently stabilized,and accepted by the County. Construction Schedule The construction of the project is anticipated to occur in late 2010 or early 2011. Wet season erosion control constraints may be necessary for this project. There are no wet season construction constraints for the nearby critical areas unless provided in the geotechnical report prepared by others. Engineering Calculations The drainage report consists of calculations for 100yr-24hr storm events. Based on the size of the project, silt fencing is anticipated to accommodate expected runoff from a 2yr-24hr temporary erosion storm event. Envirotech Engineering South Shore Enterprises SWPPP Ph. 360-275-9374 Page 3 of 7 750 E Dalby Road, Union Fax: 360-275-4789 Lot 3 of Parcel 32232 43 00010 October 11, 2010 Specific Construction SWPPP Items The following 12 items have been addressed per the 2005 Department of Ecology Stormwater Manual. 1.0 Mark Clearing Limits Clearing limits shall be delineated on-site. Currently, the areas to be developed are cleared. A small area for the dispersion trench is the only area that requires clearing. Activities are not permitted beyond tE—e cesiggnated clearing limits without prior approval. 2.0 Establish Construction Access Construction access is designated at the entrance from Dalby Road. One construction access is recommended for this project.Wheel wash construction vehicle tires, if necessary,prior to exiting the site, with wash water directed to temporary drainage facilities. 3.0 Control Flow Rates At all times, flow rates shall be controlled for this project. Natural drainage patterns shall be protected as much as possible during construction,and concentrated flow should not be permitted except as designed. 4.0 Install Sediment Controls Sediment controls deemed adequate for this project is silt fencing and inlet barriers. If necessary, additional temporary sediment controls shall be located downslope from disturbed areas. If sediment control is not working as intended,additional controls such as sediment traps,hay bales, plastic covering or other standard control will be necessary. 5.0 Stabilize Soils Soil stabilization is necessary for this project. Temporary seeding and permanent soil stabilization requirements are provided in the design drawings. 6.0 Protect Slopes Special slope protection is not required for this project due to lack of slope issues where development is expected to occur. Envirotech Engineering South Shore Enterprises SWPPP Ph. 360-275-9374 Page 4 of 7 750 E Dalby Road, Union Fax: 360-275-4789 Lot 3 of Parcel 32232 43 00010 October 11, 2010 7.0 Protect Drain Inlets All existing catch basins on this property shall be protected from construction runoff via protective barriers, inserts, or other appropriate means. 8.0 Stabilize Channels and Outlets There are no channels required for this project. Rock protection is required at the runoff exit point from existing drain pipes. 9.0 Control Pollutants Pollution generated from construction must be controlled at all times. Control of pollutants other than sediments includes the following: • All pollutants other than sediments shall be handled and disposed of in a manner that does not cause contamination of stormwater. • Cover, containment and protection from vandalism shall be provided for all chemicals, liquid products, petroleum products, and non-inert wastes present on the project site. • Maintenance and repair of heavy equipment and vehicles involving oil changes, hydraulic system drain down, solvent and de-greasing cleaning operations, fuel tank drain down and removal, and other activities which may result in discharge or spillage of pollutants to the ground or into stormwater runoff must be conducted using spill prevention measures, such as drip pans. Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Emergency repairs may be performed on-site using temporary plastic placed beneath and, if raining, over the vehicle. • Wheel wash or fire bath wastewater shall be discharged to a separate on-site treatment system or to the sanitary sewer, if available. • Application of agricultural chemicals including fertilizers and pesticides shall be conducted in a manner, and at application rates that will not result in loss of chemical to stormwater runoff. Manufacturers' recommendations for application rates and procedures shall be followed. See Appendix A for BMP protocol that the contractor must adhere to for concrete and other materials. 10.0 Control Dewatering Although dewatering will not be likely for this project, special provisions are required to be followed when dewatering. The outlet for dewatering shall be located in a position as to prevent sediments and pollution from leaving the site. This may be accomplished by pumping water into a sedimentation pond,or other standard control. Envirotech Engineering South Shore Enterprises SWPPP Ph. 360-275-9374 Page 5 of 7 750 E Dalby Road, Union Fax: 360-275-4789 Lot 3 of Parcel 32232 43 00010 October 11, 2010 11.0 Maintain BMP's All BMP's must be inspected and maintained accordingly. This includes the following: Stabilized Construction Entrance The stabilized construction entrance shall be inspected at reasonable increments. Increased usage of the construction entrance warrants more frequent inspections. Additional rock shall be added periodically to maintain proper function of the pad. Silt Fence All silt fencing shall be inspected immediately after each rainfall and at least daily during prolonged rainfall. Any required repairs shall be made immediately. Permanent Vegetation / Permanent vegetation shall initially be inspected regularly to insure establishment and healthy growth. Once established, vegetation may need to be periodically fertilized for continuous growth. Vegetation shall be re-established in areas,if necessary. While active construction is in process,all temporary erosion and sediment control facilities shall be inspected and immediately maintained if necessary per the requirements provided above. In the event that construction activities are discontinued for at least 4 consecutive days, the owner shall be responsible for the inspection, and immediate maintenance if necessary, of all temporary erosion and sediment control facilities immediately after storm events, and at least once every 7 days. In addition to the aforementioned inspection and maintenance schedule, the owner shall install additional erosion and sediment control facilities if proposed erosion and sediment control measures prove to be inadequate. Maintenance Responsibility Inspection, maintenance, and financial liability of all temporary/ permanent erosion and sedimentation control facilities shall ultimately be the responsibility of the owner utilizing the facilities. An Operation & Maintenance Declaration of Covenant will be required to cover all } privately owned and maintained stormwater facilities. Currently, the following proponent is in charge of this responsibility: South Shore Enterprises, LLC 360-898-2481 PO Box 249 Union,Washington 98584 Envirotech Engineering South Shore Enterprises SWPPP Ph. 360-275-9374 Page 6 of 7 750 E Dalby Road, Union Fax: 360-2754789 Lot 3 of Parcel 32232 43 00010 October 11, 2010 Furthermore, the owner shall establish a Certified Erosion and Sediment Control Lead (CESCL) for construction observation and oversight of the project to ensure compliance with the ESC components of the approved Drainage and Erosion/ Sediment Control Plans. This designation currently belongs to: Rick Buechel South Shore Enterprises,LLC 360-898-2481 PO Box 249 Union,Washington 98584 12.0 Manage the Project The designated manager for this project include: Rick Buechel South Shore Enterprises, LLC 360-898-2481 PO Box 249 Union,Washington 98584 Envirotech Engineering South Shore Enterprises SWPPP Ph. 360-275-9374 Page 7 of 7 750 E Dalby Road, Union Fax: 360-275-4789 Lot 3 of Parcel 32232 43 00010 October 11, 2010 APPENDIX A BEST MANAGEMENT PRACTICES (BMPs) BMP C1 S1: Concrete Handling Purpose Concrete work can generate process water and slurry that contain fine particles and high pH, both of which can violate water quality standards in the receiving water. This BMP is intended to minimize and eliminate concrete process water and slurry from entering waters of the state. Conditions of Use Any time concrete is used,these management practices shall be utilized. Concrete construction projects include, but are not limited to,the following: • Curbs • Sidewalks Roads Bridges Foundations Floors • Runways Design and . Concrete truck chutes,pumps, and intemals shall be washed out only Installation into formed areas awaiting installation of concrete or asphalt. Specificadons • Unused concrete remaining in the truck and pump shall be returned to the originating batch plant for recycling. Hand tools including, but not limited to,screeds, shovels,rakes,floats, and trowels shall be washed off only into formed areas awaiting installation of concrete or asphalt. • Equipment that cannot be easily moved, such as concrete pavers, shall only be washed in areas that do not directly drain to natural or constructed stormwater conveyances. • Washdown from areas such as concrete aggregate driveways shall not drain directly to natural or constructed stormwater conveyances. • When no formed areas are available,washwater and leftover product shall be contained in a lined container. Contained concrete shall be disposed of in a manner that does not violate groundwater or surface water quality standards. Maintenance Containers shall be checked for holes in the liner daily during concrete Standards pours and repaired the same day. February 2005 Volume 11-Construction Stormwater Pollution Prevention 4-43 t Mason County Construction Stormwater Pollution Prevention Plan Checklist Project Name: � i �/ �n�ef �� .0 [� —�� '`,�a� ire, C r�> � � ,� �t; , County Project No (:20/`7 Q0ZZ Review Date: - 51-11 Construction SWPPP Reviewer: <G Minimum Requirements of the DOE 2005 Stormwater Manual The Stormwater checklist identifies the minimum requirements of the DOE 2005 Stormwater Manual. The Checklist is intended to identify the locations within the plan that addresses the minimum requirements. Mason County will not perform a technical evaluation of the submittal. Rather, the checklist provides a guide to allow Mason County to review the submittal and determine if the applicant has addressed the minimum features that make up a Stormwater plan. It is incumbent upon the applicant and his/her engineer to fulfill all the applicable requirements of the 2005 Stormwater Plan as it relates to the proposed project. Review by Mason County is intended to determine if the plan has addressed the minimum requirements. Applicant's engineer shalt be responsible for the technical accuracy of the submitted Stormwater plan. During construction of the project, the stormwater plan engineer of record or his/her authorized representative shall inspect the site to ensure the stormwater plan is being implemented as designed. Upon completion of the project, the engineer or his authorized representative shall be required to certify that the stormwater plan has been implemented as designed. Failure to meet the minimum requirements could result in delay or rejection of the -0 O application until the deficiencies are corrected. D co X m Section I - Construction SWPPP Narrative C) >Z MM 1. Construction Stormwater Pollution Prevention Elements r-- a. Describe how each of the Construction Stormwater Pollution Prevention Element has Z been addressed though the Construction SWPPP. t— --� b. Identify the type and location of BMPs used to satisfy the required element. m = _c. Written justification identifying the reason an element is not applicable to the M proposal. 12 Required Elements- Construction Stormwater Pollution Prevention Plan 1. Mark Clearing Limits, See page/paragraph f/,Z- _2. Establish Construction Access, See page/paragraph _3. Control Flow Rates, See page/paragraph _4. Install Sediment Controls, See page/paragraph ¢/S 5. Stabilize Soils, See page/paragraph 4A Stormwater Checklist DOE 2005 Manual.doc 1 Updated May 20, 2009 Mason County Construction Stormwater Pollution Prevention Plan Checklist _6. Protect Slopes, See page/paragraph ¢17 7. Protect Drain Inlets, See page/paragraph At 8. Stabilize Channels and Outlets, See page/paragraph S/Z 9. Control Pollutants, See page/paragraph S'/3 10. Control De- Watering, See page/paragraph sY( _ 11. Maintain BMPs, See page/paragraph C/ 1 — 12. Manage the Project, See page/paragraph 7143 2. Project Description a. Total project area. Acres._7$ Sq. Ft. _b. Total proposed impervious area. Acres Sq. Ft. 7,`2.2� loctj c. Total proposed are to be disturbed, included off-site borrow and fill areas. Ac. _ Sq. Ft. i 0o0 _ d. Total volumes of proposed cut and fill. Cubic Yards 3. Existing Site Conditions a. Description of the existing topography. See page/paragraph _ b. Description of the existing vegetation. See page/paragraph 1 /3 c. Description of the existing drainage. See page/paragraph i/S 4. Adjacent Areas _ I. Description of adjacent areas that may be affected by the site disturbance — a. Streams, See page/paragraph Z/-Z b. Lakes, See page/paragraph Z/L c. Wetlands, See page/paragraph 2/� — _ d. Residential Areas, See page/paragraph 2/Z e. Roads, See page/paragraph__ 2%2 — f. Other, See page/paragraph — H. Description of the downstream drainage path leading from the site to the receiving body of water. (Minimum distance of 400 yards), See page/paragraph Z/3 5. Critical Areas _�Description of critical areas that are on or adjacent to the site. See l�agearagraph /`r` i b. Description of special requirements for working in or near critical areas. — '' See page/paragraph I- 6. Soils Description of on-site soils. a. Soil name(s) , See page/paragraph _ b. Soil mapping unit, See page/paragraph 2/7 Stormwater Checklist DOE 2005 Manual.doc 2 Updated May 20, 2009 Mason County Construction Stormwater Pollution Prevention Plan Checklist _c. Erodibility, See page/paragraph Z//o _d. Settleability, See page/paragraph 3�/ e. Permeability, See page/paragraph s// f. Depth, See page/paragraph Z 6 —g. Texture, See page/paragraph 7//�2 2 h. Soil Structure, See page/paragraph Z/6 7. Erosion Problem Areas Description of potential erosion problems on site. See page/paragraph 31Z 8. Construction Phasing _a. Construction sequence, See page/paragraph 3/+ _ b. Construction phasing (if proposed) , See page/paragraph 3/3 9. Construction Schedule 1. Provide a proposed construction schedule, See page/paragraph 3Z5 _ 11. Wet Season Construction Activities _ a. Proposed wet season construction activities, See page/paragraph 3 15 b. Proposed wet season construction restraints for environmentally sensitive/critical areas. See page/paragraph 10. Engineering Calculations _ 1. Provide Design Calculations. a. Sediment Ponds/Traps, See page/paragraph b. Diversions, See page/paragraph // _c. Waterways, See page/paragraph Nfl _ d. Runoff/Stormwater Detention Calculations, See page/paragraph 1 1. Operations and Maintenance. / a. An operation and maintenance schedule shall be provided for all proposed stormwater facilities and BMPs, and the party (or parties) responsible for maintenance and operation shall be identified. An operation and maintenance (OEtM) Declaration of Covenant will be required to cover all privately owned and maintained stormwater facilities. O&M Declaration of Covenant forms are available at the Mason County Permit Assistance Center, 426 W. Cedar Street, Shelton, WA 98584. The proponent shall record a copy of the completed Declaration with the Mason County Auditors' office. A copv of the recorded document must be submitted to the Permit Assistance Center together with this completed Checklist. See page/paragraph E/7 Stormwater Checklist DOE 2005 Manual.doc 3 Updated May 20, 2009 Mason County Construction Stormwater Pollution Prevention Plan Checklist Section II - Erosion and Sediment Control Plans 1. General a. Vicinity Map, See page/paragraph .s/ud_ 1 _ b. Clearing and Grading Approval Block, See page/paragraph S"'j,_f 1 ; Z fi 3 c. Erosion and Sediment Control Notes, See page/paragraph Sdt Z 2. Site Plan ____a. Legal description of subject property _ b. North Arrow c. Indicate boundaries of existing vegetations, e.g, tree lines, pasture areas, etc. _d. Identify and label areas of potential erosion problems, See page/paragraph /I/A e. Identify any on-site or adjacent surface waters, critical areas and associated buffers _ f. Identify FEMA base flood boundaries and Shoreline Management boundaries (if applicable), See page/paragraph /l1/A g. Show existing and proposed contours h. Indicate drainage basins and direction of flow for individual drainage areas _i. Label final grade contours and identify developed condition drainage basins _j. Delineate areas that are to be cleared and graded _ k. Show all cut and fill slopes indicating top and bottom of slope catch tines 3. Conveyance Systems _a. Designate locations for swates, interceptor trenches, or ditches _ b. Show all temporary and permanent drainage pipes, ditches, or cut-off trenches Required for erosion and sediment control _c. Provide minimum slope and cover for all temporary pipes or call out pipe inverts _d. Show grades, dimensions, and direction of flow in all ditches, swates, culverts, and pipes —e. Provide details for bypassing off-site runoff around disturbed areas f. Indicate locations and outlets of any dewatering systems 4. Location of Detention BMPs _a. Identify location of detention BMPs. 5. Erosion and Sediment Control Facilities _a. Show the locations of sediment trap(s), pond(s), and pipe structures. b. Dimension pond berm widths and inside and outside pond slopes. _c. Indicate the trap/pond storage required and the depth, length, and width dimensions. d. Provide typical section views through pond and outlet structure. _e. Provide typical details of gravel cone and standpipe, and/or other filtering devices. _f. Detail stabilization techniques for outlet/inlet. g. Detail control/ restrictor device location and details. Stormwater Checklist DOE 2005 Manual.doc 4 Updated May 20, 2009 Mason County Construction Stormwater Pollution Prevention Plan Checklist _ h. Specify mulch and/or recommended cover of berms and slopes. i. Provide rock specifications and detail for rock check dams. —j. Specify spacing for rock check dams as required. k. Provide front and side sections of typical rock check dams. — 1. Indicate the locations and provide details and specifications for silt fabric. m. Locate the construction entrance and provide a detail. 6. Detailed Drawings a. Any structural practices used that are not referenced in the Ecology Manual should be explained and illustrated with detailed drawings. 7. Other Pollutant BMPs _ a. Indicate on the site plan the location of BMPs to be used for the control of pollutants other than sediment, e.g. concrete wash water. 8. Monitoring Locations a. Indicate on the site plan the water quality sampling locations to be used for monitoring water quality on the construction site, if applicable. I certify that the stormwater plan submitted for this project fulfills the applicable provisions of the 2005 DOE Stormwater Manual. L h//�// Engineer Date �S7oNAL Applicant Date Place signed stamp here Stormwater Checklist DOE 2005 Manuat.doc 5 Updated May 20, 2009 Mason County ReyieML, .9hecklist For a Storm er Plan Instructions: This checklist is intended to assist Staff in the review of a Stormwater Plan. The Stormwater Plan is reviewed for completeness with respect to the 2005 Department of Ecology Stormwater Manual. If an item is found to be not applicable, the Plan should explain the basis for the conclusion. The Plan is also reviewed for clarity and consistency. If the drawings, discussion, or recommendations are not understandable, they should be clarified. If they do not appear internally consistent or consistent with the application or observations on site, this needs to be corrected or explained. If resolution is not achieved with the author, staff should refer the case to the Planning Manager or Director. Applicant's Name: Permit#_�'A4)c21 ZZ' fIODD Parcel# Date(s) of the Document(s) reviewed: SECTION I-Construction SWPPP Narrative (1) Construction Stormwater Pollution Prevention Elements: (a) Describe how each of the Construction Stormwater Pollution Prevention Element has been addressed through the Construction SWPPP. OK? 1 Comment: (b) Identify the type and location of BMP's used to satisfy the required element. OK? • Comment: �J (c) Written ju5ification identifying the reason an element is not applicable to the proposal. -� 0 OK? Comment: � m (d) 12 Required Elements-Construction Stormwater Pollution Prevention Plan (1) Mark Clearing Limits. OK? V Comment: 0 m (2) Establish Construction Access. m �p OK? V Comment: (3) Control FloN Rates. OK? Comment: T Z (4) Install Sedd ment Controls. r = OK? r/ Comment: m m (5) Stabilize Soils. OK? ✓ Comment: (6) Protect Slopes. OK? ✓ Comment: (7) Protect Drain Inlets. OK? v Comment: (8) Stabilize Channels and Outlets. OK? Comment: (9) Control P Ilutants. OK? Comment: (10)Control De-Watering. OK? ✓ Comment: (11)Maintain BMP's. OK? ✓ Comment: (12)Manage he Project. OK? Comment: Page 1 Form Effective May 2009 (2) Project Description. (a)Total project area (acres/square feet). C/ OK? t/ Comment: �^ a S (b) Total Proposed impervious area (acres/square feet).Sq OK? ✓ Comment: e r c/(c)Total pro area to be disturbed, incl ded off-site born w and fill areas (acres/square feet). OK? ✓ Comment: /,fee, f I (d)Total volumes of proposed cut and fill (cubic yards). OK? ✓ Comment: S G mil. (3) Existing Site Conditions. (a) Descripti�"f the existing topography. OK? Comment: (b) Description gf the existing vegetation. OK? ✓ Comment: (c) Descriptio f the existing drainage. OK?/Comment: (4)Adjacent Areas. (1) Description of adjacent areas which may be affected by the site disturbance (a) Streams / kI0 (0 OK? '✓ Comment: WM q n (o wot l w (b) Lakes / -T OK? ✓ Comment: (c)Wetlands OK? ✓ Comment: (d) Reside5tial Areas OK? V Comment: f le) Road .. r -- OK? Comment: �f) Other / OK? Comment: (II Description of the downstream drainage path leading from the site to the receiving body of water (minimum distance of 400 yards). (f- OK? Comment: �.: (6)Critical Areas: n ( ') Descriptio f critical areas that ar on r adj cent to the ite. /' OK? Comment: rrn 2 15 0 a r-1 '1 ( ) Descriptigrj of special requireme is for working in or near cr ticN areas. �L OK? rr// Comment: r&r 7- Q epp c r_L (6) Soils: Description of on-site soils. (a) Soil nary�e A( �CDIVCI OK? ✓ Comment: �lf od (b) Soil mapping unit OK? ✓ Comment: (c) Erodibili OK? Comment: IXo�N air Y o , (d) Settleability OK? ✓ Comment: rWtr,� (e) Permeaqility OK? V Comment: + l-- (f) Depth OK? ✓ Comment: (g) Texture 1 OK? Comment: h 6 Page 2 Form Effective May 2009 (h) Soil Struyture OK? ✓ Comment: (7) Erosion Problem Areas. (a) Descriptio of potential erosion problems on site OK? Comment: ^# rj-�I e, o (8) Construction Phasing. (a) Construction sequence. OK? " Comment: (b) Construction phasing (if proposed). OK? ✓ Comment: won (9) Construction Schedule. I. Provide a proposed construction schedule OK? ✓ Comment: .2 o/O - II. Wet Season Construction Activities (a) Proposed vet season construction activities. OK? •� Comment: h o no^5 Ar^--is p-1/1, 111 v (b) Proposed Yet season construction restraints for environmentally se sitive/cr ical areas. OK? ✓ Comment: (10)Engineering Calculations. Provide design calculations. J (a) Sediment Ponds/Traps. OK? Comment: / r C ( ac (b) Diversions, i" f OK? Comment: l J (a) Waterways. O OK? Comment: (b) Runoff/Stormwater Detention Calculations. OK? Comment: (11)Operations and Maintenance (a). An operation and maintenance schedule shall be provided for all proposed Stormwater facilities and BMPs, and the party(or parties) responsible for maintenance and operation shall be identified. An operation and maintenance (O & M) Declaration of Covenant will be required to cover all privately owned and maintained stormwater facilities. O & M Declaration of Covenant forms are available at the Mason County Permit Assistance Center, 426 W. Cedar Street, Shelton, WA 98584. The proponent shall record a copy of the completed Declaration with the Mason County Auditors'office. A copy of the recorded document must be submitted to the Permit Assis nce Center together with this completed Checklist., n G OK? V Comment: �10[ FPF SECTION II- Erosion and Sediment Control Plans (1) General. (a) Vicinity 10P. OK? Comment: (c) Erosion d Sediment C te OK? Comment: (2) Site Plan. (a) Legal description of subject property. OK? Comment: (b) North A ow. OK? Comment: Page 3 Form Effective May 2009 (c) Indicate boundaries of existin vegetation, e. . tree lin s, pastur areas, etc. OK?�Comment: n al >l+o wn .�' f rAJ 1, - (d) Identify an label areas of potential erosion problems. OK? Comment: A cr M- (e) Identify a�Y on-site or adjacent surface waters, cn cal areas and a soda ed buffers. OK? ri Comment: 5�3'�arn S�t0-ycJn H f no f hiKl'' — (f) Identify FEJVIA base flood boundaries and Shoreline Management boundaries (if applicable). OK? ✓✓ Comment: *--�e-.-- (g) Show existing and proposed contours. OK? Comment: (h) Indicate drainage basins and direction of flow for individual drainage areas. OK? Comment: (i) Label fina rade contours and identify developed condition drainage basins. OK? ./ Comment: /4_ (j) Delineate�reas that are to be cleared and graded. OK? ✓ Comment: '-V 4 (k) Show all cut and fill slopes in ting top and bottom of slope catch lines. OK?_1'Comment: (3) Conveyance Systems. (a) Designate locations for swales, interceptor trenches, or ditches. OK? `-- Comment: (b) Show all temporary and permanent drainage pipes, ditches, or cut-off trenches. OK? -- Comment: (c) Provide minimum slope and cover for all temporary pipes or call out pipe inverts. OK? Comment: (d) Show grades, dimensions, and direction of flow in all ditches, swales, culverts, and pipes. OK? c/ Comment: (e) Provide details for bypassing Qff-site runoff around disturbed areas. OK? Comment: i /f (f) Indicate locations and outlets of any dewatering systems. OK? Comment: (4) Location of Detention BMP's. (a) Identify location of detention BMP's. OK? ✓ Comment: (5) Erosion and Sediment Control Facilities. (a) Show the locations of sediment trap(s), pond(s), and pipe structures. OK? Comment: (b) Dimension pond berm widths and inside and outside pond slopes. OK? Comment: (c) Indicate the trap/pond storage required and the depth, length, and width dimensions. OK? Comment: (d) Provide typical section views through pond and outlet structure. OK? Comment: (e) Provide typical details of gravel cone and standpipe, and/or other filtering devices. OK?\J Comment: (f) Detail stabilization techniques for outlet/inlet. OK? ,/ Comment: (g) Detail control/restrictor device location and details. OK? I• Comment: (h) Specify mulch and/or recommended cover of berms and slopes. OK? Comment: (i) Provide rock specifications and detail for rock check dams. OK? Comment: Q) Specify spacing for rock check dams as required. OK? Comment: Page 4 Form Effective May 2009 (k) Provide front and side sections of typical rock check dams. OK? I Comment: (1) Indicate� locations and provide details and specifications for silt fabric. OK? Comment: (m) Locate thpconstruction entrance and provide detail. OK? Comment: (6) Detailed Drawings. (a) Any structural practices used that are not referenced in the Ecology Manual should be explained and illustrated with detailed drawings. OK? ✓'T Comment: (7) Other Pollutant BMP's. (a) Indicated on the site plan the location of BMP's to be used for the control of pollutants other than sediment, e.g. concrete wash water. OK? cy Comment: (8) Monitoring Locations. (a) Indicate on the site plan the water quality sampling locations to be used for monitoring water quality on the construction site, if� #icable. OK? Comment: /�/;�/ / Are the Documents signed and stamped? V Type and#of License: A�'�Y��' (� 7r ' / /' o`a e If not approved, what is the next action/recommendation for further action? Reviewed by on Time spent in review: SECOND REVIEW/ UPDATE: Reviewed by on Time spent in second review: THIRD REVIEW/ UPDATE: Reviewed by on Time spent in third review: Disclaimer: Mason County does not certify the quality of the work done in this Stormwater Plan. Page 5 Form Effective May 2009 TO BE KEPT IN THE PARCEL FILE Drainage & Erosion Report South Shore Enterprises Commercial Building 750 East Dalby Roadq Lot 3 of Parcel 32232 43 00010 Union, Mason County, Washington October 11, 2010 Project#1027 Prepared For: South Shore Enterprises, LLC PO Box 249 Union, Washington 98592 CLYL) sT Prepared By: of wn44 sy��c 9��2 Envirotech Engineering 74 NE Hurd Road Belfair, Washington 98528 P�.��RFc,sR�°G`�¢v�� Phone: 360-275-9374 SIONAL'e:�' Fax: 360-275-4789 TABLE OF CONTENTS 1.0 PROJECT DESCRIPTION................................................................................................................1 2.0 EXISTING CONDITIONS.................................................................................................................2 2.1 Topography and Geomorphology.................................................. ................................................2 2.2 Surface Drainage.............................................................................................................................2 3.0 INFILTRATION RATES/SOILS REPORTS................................... ...............................................3 3.1 Subsurface Conditions....................................................................................................................3 3.1.1 Infiltration Rates.......................................................................................................................3 3.1.2 Groundwater.............................................................................................................................3 3.2 Additional Soils Information...........................................................................................................3 4.0 HYDROLOGIC/HYDRAULIC INFORMATION...................................................................... .....4 4.1 Hydrologic Summary......................................................................................................................4 4.2 Best Management Practices............................................................................................................4 4.3 Drainage Tributary to the Project..................................................................................................4 4.4 Drainage System Beyond the Project..............................................................................................4 4.5 Wells and Septic Systems........ ......................................................... .............................................5 4.6 Flood Analysis.................................................................................................................................5 5.0 FACILTY SIZING AND DOWNSTREAM ANALYSIS...................................................................6 5.1 Roof Downspout Dispersion Trench............................. .................................................................6 6.0 CONSTRUCTION SEQUENCE AND PROCEDURE......................................................................7 7.0 TEMPORARY EROSION CONTROL........................................................ .....................................8 7.1 Silt Fencing......................................................................................................................................8 7.2 Stabilized Construction Entrance........................................ ..........................................................9 7.3 Filter Fabric Fence Inlet Barriers...................................................................................................9 8.0 PERMANENT EROSION CONTROL AND SITE RESTORATION................ ...........................10 8.1 Gravel Surface Driveway..............................................................................................................10 8.2 Permanent Seeding........................................................................................................................10 9.0 INSPECTION SEQUENCE..............................................................................................................12 9.1 Inspection and Maintenance Schedule..........................................................................................12 9.2 Inspection and Maintenance Responsibility.................................................................................12 10.0 CONTROL OF POLLUTANTS OTHER THAN SEDIMENTS...................................................14 11.0 PROJECT ENGINEER'S CERTIFICATION...............................................................................15 Appendices Appendix A-Site Map Appendix B-Hydrologic Information 1.0 PROJECT DESCRIPTION Envirotech Engineering(Envirotech)has completed this drainage, erosion and pollution prevention report for a proposed commercial development. The planned development is located at 750 E Dalby Road(Lot 3 of Parcel 32232 43 00010) in Union, Mason County,Washington(Project). See the Vicinity Map below for a general indication of the Project location. Information pertaining to the Project was provided by Rick Buechel with South Shore Enterprises, LLC. The property is currently developed land with an existing 5000 sf building, 7000 sf concrete slab that was utilized for 2 pre-existing buildings, a driveway, parking areas, on-site septic system and an off-site water well. The property has been recently divided from a large lot to a parcel of approximately 5.78 acres in size. Existing land use near the Project includes a mixture of commercial and residential rural development. The proposed redevelopment includes constructing a 2400 sf metal building within the existing concrete slab area, and improve the parkiiT and driveway areas. A new parking area will replace a portion of the driveway and smaller parking area, and encompass less than 4,820 sf of pollution generating surfaces. For additional drainage facilities, new clearing will constitute approximately 1000 sf of area. The existing building is planned to a uti iz as office space for four employees. The proposed metal building is planned to be used for vehicle and equipment parking/ stye. See the accompanying stormwater management plans or an u�i f's anon of current and proposed site features. N�c F — Ro E 2NU ST E 41"ST ESTHST- DOVOS 32 --E MASON AV I E DALBY R') 34 y q E MYLAND DR P tNR31�M 3 ErAMiANRA - - POVMRA qCM RD br 0 5040R 10\ 'f Map from Mason County Website Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 1 of 15 750 E Dalby Road,Union Fax: 360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 2.0 EXISTING CONDITIONS The Project is currently developed, vacant land as previously mentioned. Beyond the property lines, rural commercial and residential development exists. Past timber harvesting and vegetation clearing is apparent for this property. Native vegetation on the property and nearby properties includes firs,alders,hemlocks, blackberry, and other trees and shrubs common to this area. 2.1 Topography and Geomorphology The area of development has mild grades with steps in the terrain of up to 3.5 feet. Ascending grades are located to the northwest of the development with slopes ranging from less than 10%to just over 40%. Descending slopes are generally to the east, with maximum grades of approximately 20%. 2.2 Surface Drainage Stormwater runoff originating upslope from the anticipated development appears to be moderate to extreme. Drainage diversions and past drainage maintenance issues have been an on-going process. Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 2 of 15 750 E Dalby Road,Union Fax:360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 3.0 INFILTRATION RATES/SOILS REPORTS Information on infiltration rates and soil conditions pertaining to the Project was accomplished by Envirotech. See the Soils Report prepared for the South Shore Enterprises Vehicle Storage Building, dated March 22, 2010. Selected information pertaining to the drainage aspect of the project is provided below. Additional soils information is provided below in order to comply with the 2005 Department of Ecology Stormwater Manual. 3.1 Subsurface Conditions Specifically, soils for this project were described utilizing the Unified Soil Classification System (USCS)and the U.S. Department of Agriculture(USDA)Textural Classification System. Soils within the upper 3 feet of natural ground were observed to be moist, brown, loose to medium dense silty sand with gravel(SM). Expanded and specific subsurface descriptions, other than what is provided in this section, are presented in the soil logs located in Appendix B of this report. According to the USDA Textural Classification System, the upper 36 inches of soil were classified as sandy loam. Per the SCS classification, the site soils where drainage features will exist were classified as Alderwood Gravelly Sandy Loam,Ab. 3.1.1 Infiltration Rates According to the Stormwater Management Manual for Western Washington prepared by the Washington State Department of Ecology Water Quality Program, infiltration rates of the soils encountered at a depth of at least 42 inches below the ground surface is 4.14 inches/hour. This infiltration rate includes a factor of safety of 2, as recommended by the stormwater manual. Percolation tests were not completed for this Project. 3.1.2 Groundwater Per our site visit, groundwater was encountered at a depth of 3 feet below the existing ground surface near anticipated stormwater outlet locations. Shallower groundwater, as little as 12 inches below the ground surface, was observed directly downslope from anticipated facilities. 3.2 Additional Soils Information The fines content of the site soils has a low plasticity, indicating that silt is most likely prevalent over clay. Based on the fines content and slope gradients, soil erodibility is considered moderate for this project. Due to the types of fine soils,the settleability is considered moderate. Based on the soil density and gradation,a moderately high permeability can be expected. Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 3 of 15 750 E Dalby Road,Union Fax: 360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 4.0 HYDROLOGIC/HYDRAULIC INFORMATION 4.1 Hydrologic Summary Currently, there are over 14,000 sf of impervious surfaces on the property. The existing driveway will be re-protected with crushed gravel or asphalt. New parking will cover an existing portion of the driveway and parking, and consist of about 4,820 sf of pollution impervious surface. The proposed building will encompass approximately 2400 sf over the existing impervious concrete pad. TheSanta Barbara Urban Hydrograph (SBUH) method was utilized for estimating peak design flows. The SBUH method is based on a runoff curve number approach, and uses Soil Conservation Service (SCS) equations for computing soil absorption and precipitation excess. This analysis is based on a Type IA rainfall distribution and a 24 hour storm duration. The following design parameters were used for stormwater drainage design: • Design storm for water quality, 6mo-24hr(2.7 inches); • Design storm for erosion control, 2yr-24hr(4.2 inches); • Design storm for stability, I00yr-24hr(8.3 inches); • Hydraulic soil group `B' • Curve Number of 98 for impervious areas;and, • Curve Number of 30 for pre-existing conditions. 4.2 Best Management Practices Best Management Practices (BMPs) for this project includes vegetated filter cytri s, oil/ water separators, dispersion trenches, outlet protection pads, and gravel surfaced driveways/ parking arms. The proposed developmen areas o the property are relatively flat. Stormwater originating from the new roof will be tight-lined to the dispersion trench. A drainage system is in place for the surface, parking and driveway runo mprovements should be made to ensure that tee connections are in the catch basins, and an outlet rock pad is utilized. Runoff from the new parking area does not meet the threshold for treatment. Although treatment facilities are not required, the outlet distributes the runoff through undisturbed vegetation for treatment. Permanent vegetation_is required in all denuded areas. Natural drainage patterns are to be maintained to the maximum exte practicable. 4.3 Drainage Tributary to the Project The watershed located directly upslope from the project is not large, but produces significant runoff. Stormwater entering the property appears to be managed with trenches, ditches and catch basins. The current stormwater system should be monitored carefully during the wet season, and maintained or redesigned as necessary. 4.4 Drainage System Beyond the Project Most of the natural drainage from the site appears to be directed to a stream running through the property, and directed to the east. Ultimately, the stormwater is anticipated to be received by the Hood Canal. Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 4 of 15 750 E Dalby Road,Union Fax: 360-2754789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 c� :. .. _. �� ,' = - - • � r �� '� - � - ,:; �.. � '?. �. °f -. i � _ .., r . _ _ _ c _. -- ,. .. ,. ,. J •. ♦ t ► _ � - - - _. r., _.. e .,. Off-site analysis and / or mitigation is not deemed necessary for this Project. This is based on the scale of the proposed Project with relation to existing impervious surfaces, and the expected low impact to downstream properties. 4.5 Wells and Septic Systems Records, research and site observations revealed one existing well, and one septic drainfield, nearest the planned drainage enhancements. Indications of existing or proposed wells or septic systems will not be located within the setback distances for stormwater retention/ detention facilities identified in the 2005 Stormwater Management Manual for Western Washington. 4.6 Flood Analysis This project is not situated within a flood zone per Mason County website supplied FEMA flood map. Since the property contains a stream that could influence the redevelopment, a minimum flood analysis was performed via owner survey and a site reconnaissance. Based on owner information, the stream has not caused adverse damages to this property in the past. The site visit, completed approximately 2.5 years after a severe storm exceeding the 100 year - 24 hour event, concurred with this report as signs of stream flooding were not observed. Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 5 of 15 750 E Dalby Road,Union Fax: 360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 �:: -- �; S- ., .. .�. 4 .. _ _�. � .. `y' 5.0 FACILTY SIZING AND DOWNSTREAM ANALYSIS Treatment facilities are not required for this project. Proposed facilities include a dispersion trench. 5.1 Roof Downspout Dispersion Trench Storm water runoff from the proposed roof cannot be infiltrated due to the presence of high ' groundwater. Based on the governing storm water manual, the runoff from each 700 sf of roof area shall be directed to a standard 2 feet wide dispersion trench at 10 feet in length. The resulting trench length from the proposed 2400 sf building is 35 linear feet. Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 6 of 15 750 E Dalby Road,Union Fax: 360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 6.0 CONSTRUCTION SEQUENCE AND PROCEDURE The following includes the recommended construction sequence and procedure for project development: 1. Delineate clearing and easement limits. 2. Construct all required temporary erosion control features. 3. Clear vegetation required for site development. 4. Perform initial earthwork and rough grading for constructing driveways,parking areas,and building pads. Top soil may be stock-piled for future use. If necessary,exposed soils in stock piles must be protected with plastic covering or County approved method. 5. Complete final grading of the subgrade,materials placement and structure construction per the plans and specifications. This includes dredging sediments from temporary sediment ponds,if necessary. 6. Maintain all temporary erosion and sediment control facilities, as needed, in order to provide the required protection of downstream water quality. Additional temporary erosion control shall be rendered, if necessary. 7. Provide permanent erosion control in order to stabilize the project. 8. Remove temporary erosion sedimentation control facilities after construction is complete, site is sufficiently stabilized,and accepted by the County. Emvirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 7 of 15 750 E Dalby Road,Union Fax: 360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 7.0 TEMPORARY EROSION CONTROL The primary methods used for trapping sedimentation before it reaches off-site storm drainage systems or adjoining properties includes stabilized construction entrance, silt fencing, inlet protection barriers, mulching and other possible controls such as piled vegetation, hay bales or temporary ponds. Stabilization of temporary conveyances, if constructed, are required. The nature of this Project should not require significant de-watering or underground utility construction. If significant de-watering or underground utility construction is necessary,then these occasions will require downstream erosion and sediment control features. This may include silt fencing, interceptor swales,or other appropriate erosion control. 7.1 Silt Fencing Silt fencing shall be located and installed according to the details provided on the engineering plans and specifications with the following materials and guidelines: 1.FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL AND CUT TO THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS. WHEN JOINTS ARE NECESSARY,FILTER CLOTH SHALL BE SPLICED TOGETHER ONLY AT A SUPPORT POST,WITH A MINIMUM 6-INCH OVERLAP,AND SECURELY FASTENED AT BOTH ENDS TO THE POST. 2.POSTS SHALL BE SPACED A MAXIMUM OF 6 FEET APART AND DRIVEN SECURELY INTO THE GROUND OA NIMUM OF 30 INCHES). 3. A TRENCH SHALL BE EXCAVATED APPROXIMATELY 8 INCHES WIDE AND 12 INCHES DEEP ALONG THE LINE OF POSTS AND UPSLOPE FROM THE BARRIER.THIS TRENCH SHALL BE BACKFILLED WITH WASHED GRAVEL. 4. WHEN STANDARD STRENGTH FILTER FABRIC IS USED,A WIRE MESH SUPPORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE OF THE POSTS USING HEAVY DUTY WIRE STAPLES AT LEAST 1 INCH LONG,TIE WIRES OR HOG RINGS.THE WIRE SHALL EXTEND INTO THE TRENCH A M[MMUM OF 4 INCHES AND SHALL NOT EXTEND MORE THAN 24 INCHES ABOVE THE ORIGINAL GROUND SURFACE. 5.THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED TO THE FENCE, AND 20 INCHES OF THE FABRIC SHALL BE EXTENDED INTO THE TRENCH.THE FABRIC SHALL NOT EXTEND MORE THAN 24 INCHES ABOVE THE ORIGINAL GROUND SURFACE. FILTER FABRIC SHALL NOT BE STAPLED TO EXISTING TREES. 6.WHEN EXTRA-STRENGTH FILTER FABRIC(MONOFILAMENT),AND CLOSER POST SPACING IS USED,THE WIRE MESH SUPPORT FENCE MAY BE ELIMINATED. IN SUCH A CASE,THE FILTER FABRIC IS STAPLED OR WIRED DIRECTLY TO THE POSTS WITH ALL OTHER PROVISIONS OF ABOVE NOTES APPLYING. 7.FILTER FABRIC FENCES SHALL NOT BE REMOVED BEFORE THE UPSLOPE AREA HAS BEEN PERMANENTLY STABILIZED. 8. FILTER FABRIC FENCES SHALL BE INSPECTED IMMEDIATELY AFTER EACH RAINFALL AND AT LEAST DAILY DURING PROLONGED RAINFALL. ANY REQUIRED REPAIRS SHALL BE MADE IMMEDIATELY. Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 8 of 15 750 E Dalby Road,Union Fax: 360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 _. -- .: �- v _ -� �. ... � _ _, � w .: _, .. w _ • :� ., , . .. .... , �. _ .. .. �. T ..: '.r• _ � �- -. .. � \ `. '. .. ._ i.. .i. .. Y: ... .�. .. _ . .. r - r• ,,. � .. .. �,. �.. � --� 1 � -� �. may. '_ :� � ... - � _ - - � ,_ _, t .. •. .. .. ., ., .. .. .. .; .__ .. .: ., ... .. _ .. � .. - � t _. .. - .. _ .. 9. SILT FENCES WILL BE INSTALLED PARALLEL TO ANY SLOPE CONTOURS. 10. CONTRIBUTING LENGTH TO FENCE WILL NOT BE GREATER THAN 100 FEET. 11.DO NOT INSTALL BELOW AN OUTLET PIPE OR WEIR. 12.INSTALL DOWNSLOPE OF EXPOSED AREAS. 13.DO NOT DRIVE OVER OR FILL OVER SILT FENCES. 7.2 Stabilized Construction Entrance Details and location regarding the stabilized construction entrance shall be constructed according to sheet 2 of the engineering plans and specifications.The stabilized construction entrance shall be constructed according to the following general guidelines: 1. Material shall range from 4 inches to 8 inches quarry spalls. 2. Construction entrance extents shall extend to a minimum depth of 12 inches,a minimum width of 20 feet,and a minimum length of 100 feet. 3. Construction entrance surface shall be sloped at least 2%in the direction shown on the engineering plans for the roadway. 4. If the pad does not adequately remove mud from the vehicle wheels,the wheels shall be hosed off before the vehicle leaves the site. 7.3 Filter Fabric Fence Inlet Barriers 1.THIS DEVICE IS APPLICABLE WHERE THE INLET DRAINS A RELATIVELY SMALL(LESS THAN 1 ACRE)FLAT AREA(LESS THAN 5%SLOPE) 2.PLACE 2"X 2"WOODEN STAKES AROUND THE PERIMETER OF THE INLET A MAXIMUM OF 3-FEET APART AND DRIVE THEM AT LEAST 18-INCHES INTO THE GROUND. THE STAKES MUST BE AT LEAST 3-LONG. 3. EXCAVATE A TRENCH APPDXIMATELY 8-INCHES WIDE AND 12-INCHES DEEP AROUND THE OUTSIDE PERIMETER OF THE STAKES. 4. STAPLE THE FABRIC FILTER TO THE WOODEN STAKES SO THAT 32-INCHES OF THE FABRIC EXTENDS AND CAN BE FORMED INTO THE TRENCH. USE HEAVY-DUTY WIRE STAPLES AT LEAST%z-INCH LONG. 5. BACKFILL THE TRENCH WITH 3/. -INCH MINUS WASHED GRAVEL ALL THE WAY AROUND. 6. DO NOT PLACE FABRIC UNDER THE GATE, AS THE COLLECTED SEDIMENT MAY FALL INTO THE DRAIN WHEN THE FABRIC IS RETIEVED. MAINTENANCE: INSPECTIONS SHOULD BE MADE ON A REGULAR BASIS, ESPECIALLY AFTER LARGE STORM EVENTS. IF THE FABRIC BECOMES CLOGGED, IT SHOULD BE REPLACED. SEDIMENT SHOULD BE REMOVED WHEN IT REACHES APPROXIMATELY 1/3 THE HEIGHT OF THE FENCE. IF A SUMP IS USED, SEDIMENT SHOULD BE REMOVED WHEN IT FILLS APPROXIMATELY 1/3 THE DEPTH OF THE HOLE. Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 9 of 15 750 E Dalby Road,Union Fax:360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 y r 8.0 PERMANENT EROSION CONTROL AND SITE RESTORATION Site restoration and permanent erosion control includes gravel surfaced roadway, vegetation, mulching, and other standard protocol, if necessary. Additional permanent erosion will include er 3 w inlet/outlet protection. Specific details regarding permanent erosion are illustrated on the drawing dr"-f sheets. All cut and fill slopes shall be stabilized according to sheet 2 of the design plans. This includes temporary stabilization when necessary,and permanent erosion control. 8.1 Gravel Surface Driveway The gravel surfaced driveway will be comprised of 4-inch compacted depth of aggregate overlying prepared subgrade or compacted fill. This gravel surface will encompass the majority of the disturbed project area. If asphalt is planned in the future, additional subgrade preparation will be required per sheet 3 of the plans. 8.2 Permanent Seeding The regenerative plan for this project includes permanent erosion control seeding in the disturbed areas of the Project. Seeding specifications are provided in the construction plans,and summarized below: 1. BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR DIKES, SWALES, LEVEL SPREADERS AND SEDIMENT BASINS. 2. THE SEED BED SHALL BE FIRM WITH FAIRLY FINE SURFACE, FOLLOWING SURFACE ROUGHENING. PERFORM ALL OPERATIONS ACCROSS OR PERPENDICULAR TO THE SLOPE. 3. SEEDING MIXTURE SHALL BE AS SHOWN BELOW, AND SHALL BE APPLIED AT THE RATE OF 120 POUNDS PER ACRE. 4. SEED BEDS PLANTED BETWEEN MAY 15 AND AUGUST 15 WILL REQUIRE IRRIGATION AND OTHER MAINTENANCE AS NECESSARY TO FOSTER AND PROTECT THE ROOT STRUCTURE. 5. SEED BEDS PLANTED BETWEEN NOVEMBER 1 AND APRIL 30,ARMORING OF THE SEED BED WILL BE NECESSARY, (e.g.,GEOTEXTILES,JUTE MAT, CLEAR PLASTIC COVERING). 6. FERTILIZERS ARE TO BE USED ACCORDING TO SUPPLIERS'RECOMMENDATIONS. AMOUNTS SHOULD BE MINIMIZED, ESPECIALLY ADJACENT TO WATER BODIES AND WETLANDS. USE THE FOLLOWING RECOMMENDED SEED MIXTURE FOR EROSION CONTROL, OR A COUNTY APPROVED ALTERNATE SEED MIXTURE. Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 10 of 15 750 E Dalby Road,Union Fax: 360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 • .. � -fir ` _ . ` PROPORTIONS PURITY GERMINATION NAME BY WEIGHT(%) (%) (%) KENTUCKY BLUEGRASS (POA PRATENSIS) 15 85 80 PERENNIAL RYE(LOLIUM PERENNE) 30 95 90 CHEWING FESCUE 15 95 90 (FESTUCA RUBRA COMMUTATA) (JAMESTOWN, BANNER, SHADOW, KOKET) TALL FESCUE (FESTUCA ARUNDINCEA) 40 95 90 Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 11 of 15 750 E Dalby Road,Union Fax:360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 9.0 INSPECTION SEQUENCE Erosion and sediment control measures that may be necessary for this project includes: Temporary stabilized construction entrance; Temporary silt fence; Inlet barriers; and, Permanent vegetation. The following subsections provide details regarding inspection and maintenance schedule, inspection and maintenance responsibility,and an engineer's inspection report. Section 7.3 of this report has information for inlet barriers. Stabilized Construction Entrance The stabilized construction entrance shall be inspected at reasonable increments. Increased usage of the construction entrance warrants more frequent inspections. Additional rock shall be added periodically to maintain proper function of the pad. Silt Fence All silt fencing shall be inspected immediately after each rainfall and at least daily during prolonged rainfall. Any required repairs shall be made immediately. Permanent Vegetation Permanent vegetation shall initially be inspected regularly to insure establishment and healthy growth. Once established, vegetation may need to be periodically fertilized for continuous growth. Vegetation shall be re-established in areas,if necessary. 9.1 Inspection and Maintenance Schedule While active construction is in process, all temporary erosion and sediment control facilities shall be inspected and immediately maintained if necessary per the requirements provided above. In the event that construction activities are discontinued for at least 4 consecutive days,the owner shall be responsible for the inspection, and immediate maintenance if necessary, of all temporary erosion and sediment control facilities immediately after storm events,and at least once every 7 days. In addition to the aforementioned inspection and maintenance schedule, the owner shall install additional erosion and sediment control facilities if proposed erosion and sediment control measures prove to be inadequate. 9.2 Inspection and Maintenance Responsibility Inspection, maintenance, and financial liability of all temporary/ permanent erosion and sedimentation control facilities shall ultimately be the responsibility of the following owner's: South Shore Enterprises, LLC 360-898-2481 Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 12 of 15 750 E Dalby Road,Union Fax:360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 PO Box 249 Union,Washington 98592 An operation and maintenance covenant will be required to cover all stormwater facilities. - - Performance bonding, or other appropriate instrument, shall be required for this project to ensure compliance with the standards presented in this report. Furthermore, the owner may need to retain an Erosion and Spill Control (ESC) Lead for construction observation and oversight of the project to ensure compliance with the ESC components of the approved Drainage and Erosion/Sediment Control Plans. Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 13 of 15 750 E Dalby Road,Union Fax:360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 10.0 CONTROL OF POLLUTANTS OTHER THAN SEDIMENTS Potential source of pollutants may occur from spills, leaks, excessive usage, ordinary usage, or vandalism of several pollutants including the following: Fuel Oil Solvent Degreaser Dust Pesticide Herbacide Fertilizer Other Chemicals The aforementioned pollutants are not expected to be currently on-site. The potential sources may be released into the stormwater due to development of the facilities,and/or future use of the facilities. Control of pollutants other than sediments includes the following: All pollutants other than sediments shall be handled and disposed of in a manner that does not cause contamination of stormwater. Cover, containment and protection from vandalism shall be provided for all chemicals, liquid products, petroleum products,and non-inert wastes present on the project site. Maintenance and repair of heavy equipment and vehicles involving oil changes, hydraulic system drain down, solvent and de-greasing cleaning operations, fuel tank drain down and removal,and other activities which may result in discharge or spillage of pollutants to the ground or into stormwater runoff must be conducted using spill prevention measures, such as drip pans. Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Emergency repairs may be performed on-site using temporary plastic placed beneath and,if raining, over the vehicle. Wheel wash or tire bath wastewater shall be discharged to a separate on-site treatment system or to the sanitary sewer, if available. Application of agricultural chemicals including fertilizers and pesticides shall be conducted in a manner,and at application rates that will not result in loss of chemical to stormwater runoff. Manufacturers' recommendations for application rates and procedures shall be followed. Envirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 14 of 15 750 E Dalby Road,Union Fax:360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 11.0 PROJECT ENGINEER'S CERTIFICATION I hereby state that this drainage and erosion/sediment control plan for the South Shore Enterprises Vehicle Storage Building 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. Please contact Michael Staten at 360-275-9374 if you have any questions, comments,or require additional information. Sincerely, Envirotech Engineering Michael Staten, P.E. Project Director Emirotech Engineering South Shore Drainage,Erosion,Report Ph. 360-275-9374 Page 15 of 15 750 E Dalby Road,Union Fax: 360-275-4789 Mason County Parcel 32232 43 00010,Lot 3 October 11,2010 APPENDIX A SITE MAP N SCALE, 1 INCH 100 FEET �0 251,933 SF 5.78 QUARRY SPALL OUTLET PROTECTION NITS OF IE' DIA. XISTING CPEP PIPE CONCRETE PAD PROPOSED 4' DIA SOLID PVC FOR COLL TING OF WATER ATPI STING T 30 CB PROPOSED -� V4 % rP) T BUILDING L/VATOR F.P.O 6' SEPARATOR ABOVE S GRADE -• q 14% ghhh !FT OTP2 PROPOSE Y WI DISPERSI THE U '` - EXISTING FOR �1 BUILDING SEE DET S. �CO14 EXISTING DRIVEWAY. CLEARING TS RESURFACE WITH GRAVEL AS NECESSARY NEW GRAVEL SURFACED PARKING.GRADE EXISTING TO DRAIN EXISTING PAVED TURNAROUND PARKING EXISTING CHAIN LINK FENCE(APPROXIMATE) V% EXISTING BRIDGE EXISTING K'WI SNA( PAVED INGRESS/DE EGRESS PROJECT/ OWNER/ LOCATION, SOUTH SHORE ENTERPRISES DRAINAGE REPORT SOUTH SHORE ENTERPRISES PARCEL 32232 43 00010, LOT 3 DALBY ROAD MASON COUNTY, WASHINGTON ENGINEER, ENVIROTECH ENGINEERING 74 NE HURD ROAD BELFAIR, WASHINGTON 98528 360-275-9374 SITE PLAN APPENDIX B HYDROLOGIC INFORMATION IQ .11 VOL- ��--fir ��.1 •��\,.i� � .!. �; � Ll ��t• 1 G` '•+ //ter lh -All «1•;,5� Tr��f•;I ,t• v t. ti ti• ,� ,�'/�►�i��.��/ w"�lr - = Srkv i �P,�F!'��•i-•�:._l�w_':��yyr • •�i •":.: I+�u IFS cl 70, MMIM }�- �J/,. 1 -ram•�.; � .i�\�.L; /ISu,�', , ol Olt wm 'AR 'rill jiiI �'^' I AM ., �. *�}, �1„ Icy,. :1 �i�i`•` �I i lam "I PRECIPITATION I OF All INCH 2.3.2 Runoff Parameters All storm event hydrograph methods require input of parameters that describe physical drainage basin characteristics. These parameters provide the basis from which the runoff hydrograph is developed. This section describes only the key parameter of curve number that is used to estimate the runoff from the water quality design storm. . Curve Number The NRCS(formerly SCS)has, for many years, conducted studies of the runoff characteristics for various land types. After gathering and analyzing extensive data,NRCS has developed relationships between land use, soil type, vegetation cover, interception, infiltration, surface storage, and runoff. The relationships have been characterized by a single runoff coefficient called a"curve number." The National Engineering Handbook - Section 4: Hydrology(NEH-4, SCS, August 1972)contains a detailed description of the development and use of the curve number method. NRCS has developed"curve number"(CN)values based on soil type and land use. They can be found in"Urban Hydrology for Small Watersheds", Technical Release 55 (TR-55),June 1986, published by the NRCS. The combination of these two factors is called the"soil-cover complex." The soil-cover complexes have been assigned to one of four hydrologic soil groups,according to their runoff characteristics. NRCS has classified over 4,000 soil types into these four soil groups. Table 2.2 shows the hydrologic soil group of most soils in the state of Washington and provides a brief description of the four groups. For details on other soil types refer to the NRCS publication mentioned above(TR-55, 1986). Table 2.1 Hydrologic Soil Series for Selected Soils in Washin ton State Soil Type Hydrologic Soil Group Sal Type Hydrologic Soil Group Agnew C Hoko C Ahl B Hoodsport C Aits C Hoogdal C Alderwood Hoypus A Arents,Alderwood q Huel A Arents,Everett B Indianola A Ashoe B Jonas B Baldhill B Jumpe B Barneston C Kalaloch C Baumgard B Kapowsin CID Beausite B Katula C Belfast C Kilchis C Bellingham D Kitsap C Bellingham variant C Klaus C Boistfort B Klone B Bow D Lates C Briscot D Lebam B Buckley C Lummi D Bunker B Lynnwood A Cagey C Lystair B Carlsborg A Mal C Casey D I Manley B February 2005 Volume 111-Hydrologic Analysis and Flow Control BMPs 2-11 Table 2.2 Runoff Curve Numbers for Selected Agricultural,Suburban, and Urban Areas Sources:TR 55, 1986,and Stormwater Management Manual, 1992.See Section 2.1.1 forexplanation) CNs for hydrologic soil group Cover type and hydrologic condition. A B C D Curve Numbers for Pre-Development Conditions Pasture,grassland,or range-continuous forage for grazing: Fair condition(ground cover 50%to 75%and not heavily grazed). 49 69 79 84 Good condition round cover>75%and lightly or only occasional) razed 39 61 74 80 Woods: Fair(Woods are grazed but not burned,and some forest litter covers the soil). 36 60 73 79 Good Woods are protected from grazing,and litter and brush adequately cover the soil). 30 55 70 77 Curve Numbers for Post-Deveb mint Conditions Open space(lawns,parks,golf courses,cemeteries,landscaping,etc.) Fair condition(grass cover on 500/a-75%of the area). 77 85 90 92 Good condition cover on>75%of the area 68 80 86 90 Impervious areas: Open water bodies:lakes,wetlands,ponds etc. 100 100 100 100 Paved parking lots,roofs',tinveways,etc. (excluding right-of-way ) 98 98 8 98 Permeable Pavement(See Appendix C to decide which condition below to use) Landscaped area 77 85 90 92 500/9 landscaped area/50%impervious 87 91 94 96 100%impervious area 98 98 98 98 Paved 98 98 98 Gravel(including right-of-way) 76 85 89 91 Dirt(including right-of-way) 72 82 87 89 Pasture,grassland,or range-continuous forage for grazing: Poor condition(ground cover<50%or heavily grazed with no mulch). 68 79 86 89 Fair condition(ground cover 50%to 75%and not heavily gazed). 49 69 79 84 Good condition and cover>75%and lightly or only occasionally ) 39 61 74 80 Woods: Poor(Forest litter,small trees,and brush are destroyed by heavy grazing or regular burning). 45 66 77 83 Fair(Woods are grazed but not burned,and some forest litter covers the soil). 36 60 73 79 Good Woods are protected from grazing,and litter and brush adequately cover the soil). 30 55 70 77 Sutgle family residential': Should only be used for Average Percent Dwelling Unit/Gross Acre subdivisions>50 acres impervious area 1.0 DU/GA 15 Separate curve number 1.5 DU/GA 20 shall be selected for 2.0 DU/GA 25 pervious&impervious 2.5 DU/GA 30 portions of the site or 3.0 DU/GA 34 basin 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 7.5 DU/GA 58 PUD's,condos,apartments,commercial %impervious Separate curve numbers shall businesses,industrial areas dt: must be be selected for pervious and dt subdivisions<50 acres computed impervious portions of the site For a more detailed and complete description of land use curve numbers refer to chapter two(2)of the Soil Conservation Service's Technical Release No.55, 210-VI-TR-55,Second Ed,June 1986). Composite CN's may be computed for other combinations of open space cover type. 'Where roof runoff and driveway runoff are infiltrated or dispersed according to the requirements in Chapter 3,the average percent impervious area may be adjusted in accordance with the procedure described under"Flow Credit for Roof Downspout Infiltration"(Section 3.1.1),and"Flow Credit for Roof Downspout Dispersion"(Section 3.1.2). 3Assumes roof and driveway runoff is directed into stmct/storm systan. 4All the remaining pervious area(lawn)are considered to be in good condition for these curve numbers. February 2005 Volume 111—Hydrologic Analysis and Flow Control BMPs 2-15