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Home My WebLink AboutSITE PLAN - BLD Small parcel storm water managementUTSIDE EDGE OF BUILDING OWNSPOUT FROM ROOF AND GUTTER 71OWNSPOUT OLLECTOR 4" DIAM. PVC 45' ELBOW DOWNSPOUT COLLECTOR 4"x4"x4" PVC WYE & 4"x4" 45' ELBOW RAINS TOWARD CATCH BASIN 90° SECTION VIEW OWNSPOUT FROM ROOF AND GUTTER FINISHED GRADE 4" DIAM. PVC 45' ELBOW 4"x4"x4" PVC WYE & 4"x4" 45' ELBOW ,{)RAINS TOWARD CATCH BASIN SECTION VIEW TYPICAL DETAIL OF ROOF DOWNSPOUT COLLECTOR & CLEANOUT N.T.S. CATCH BASIN SUMP W/ S❑LID LID 4' ❑BSERVATI❑N WELL (❑PTI❑NAL) 6' PERFORATED PIPE 4' GUTTER -RDEJF —=-- '\ DOWNSPOUT "'A 6' SOLID PIPE PLAN VIEW ROOF -DRAINAGE COLLECTION SYSTEM (ROOF--NN,„ GUTTER GE❑TEXTILE COVER N.T.S. DOWNSPOUT OVERFLOW s SPLASH BLOCK CATCH BASIN SUMP W/ S❑LID LID 6' PERFORATED PIPE 1' MIN. 1'[MIN. 5' MIN. I --VARIES 10' ,MIN. PROFILE VIEW ROOF -DRAINAGE COLLECTION SYSTEM N. T. S. ' S❑LID PIPE • COMPACTED BACKFILL • D - e e, o° o o �- NATURAL GROUND 4' INFILTRATION TRENCH A - A TYPICAL END VIEW N.T.S. VARIABLE USE GEOTEXTILE FABRIC TO LINE TOP, SIDES AND BOTH ENDS OF TRENCH. FABRIC MUST BE OVERLAPPED A MINIMUM OF 18 INCHES. SIDE OF INFILTRATION TRENCH TRENCH BOTTOM 6" DIAM. PERFORATED PVC 0 0 0 OBSERVATION WELLS 4" DIAM. PIPE; PERFORATED PVC IN INFILTRATION TRENCH; AND SOLID PVC ABOVE TRENCH; WELLS LOCATED IN THE MIDDLE +/— OF TRENCH. OBSERVATION WELLS SET IN LANDSCAPING SHALL HAVE PVC CAPS SET AT LANDSCAPING GRADE GRAVEL BASE AND/OR TOP SOIL VARIABLE DEPTH PVC SOUD PIPE 6 DIAM. FLOWS FROM CATCH BASIN END OF INFILTRATION TRENCH PVC PERFORATED PIPE 6" DIAM. TRENCH BOTTOM INFILTRATION TRENCH TYPICAL SIDE VIEW OF END N. T.S. - TYPICAL INFILTRATION TRENCH FOR ROOF RUNOFF - 4' WIDE BY 4' HIGH - TRENCH LENGTH EQUALS 46' PER 1000 FEET OF ROOF AREA NATURAL GROUND 5.25' VARIABLE USE GEOTEXTILE FABRIC TO UNE TOP, SIDES AND BOTH ENDS OF TRENCH. FABRIC MUST BE OVERLAPPED A MINIMUM OF 18 INCHES. INFILTRATION TRENCH FILLED WITH WASHED ROCK AND AN 18' DIAM. HID HANCOR POLYETHELENE PIPE 18" I.D. HANCOR HID PERFORATED PIPE INFILTRATION TRENCHES INCLUDING AN 18" DIAM. PIPE TYPICAL END VIEW N.1 S OBSERVATION WELLS 4" DIAM. PIPE; PERFORATED PVC IN INFILTRATION TRENCH; AND SOLID PVC ABOVE TRENCH; WELLS LOCATED IN THE MIDDLE +/— OF TRENCH. OBSERVATION WELLS SET IN LANDSCAPING SHALL HAVE PVC CAPS SET AT LANDSCAPING GRADE • • o ° 0 0 O ° GRAVEL BASE AND/OR TOP SOIL VARIABLE DEPTH • PVC SOUD PIPE 6 DIAM. • T FLOWS FROM CATCH BASIN END OF INFILTRATION TRENCH PVC PERFORATED o HID HANCOR PIPE 18" DIAM. 1L TRENCH BOTTOM INFILTRATION TRENCH TYPICAL SIDE VIEW OF END N.T.S. - TYPICAL INFILTRATION TRENCH FOR ROOF RUNOFF - 4' WIDE BY 4' HIGH - WITH 18" DIAM. CORRUGATED & PERFORATED HANCOR HiQ OR EQUAL - TRENCH LENGTH EQUALS 36 FT. PER 1000 FEET OF ROOF AREA NOTE: ENDS OF PIPE MUST BE PLUGGED OR CAPPED 1 EROSION & STORMWATER CO, LOCATED IN THE NW; /4 OF THEM/VI/4 OF SHORT PLATS 1233 AND 1235 RECORDS OF MA PROPOSED IN LOT STORMWATERCONL D AND/OR LANDSCAPE LTRATI❑N TRENCH 1/ \i, NI, NI, ,J, • NI, NI, NI, 4 y • YARD AND/OR LANDSCAPE INFILTRATI❑N TRENCH � 4, � NI, NI, • NI, NI, NI/ NI, NI, NI, CATCH BASIN y ROOF `I' `INFILTRATI❑N TRENCH y 4, NI' '4' ROOF a MEN LW Ii litairal II .........w Ni, IE11111111mir M .. MIN ■41.■■ ■.■ ■ler.111 N.■ M�ee OEN UN... UN• ROOF INFILTRATI❑Nw . TRENCH N NI/ y •1, I YARD AND/OR LANDSCAPE INFILTRATI❑N TRENCH ❑CATING THE YARD AND/OR LANDSCAPE INFILTRATI❑N TRENCH ON THE EASTERLY SIDE OF THE HOME SHOULD BEFALL❑WED ONLY IN THOSE LOTS ABUTTING THE'C❑UNTY R❑AD. TYPICAL LAYOUT AND_.POSS/BL E.,L.,QCATIONS OF INFILTRATION TRENCHES FOR LAWNAND ROOF USE GEOTEXT1LE FABRIC TO LINE TOP, SIDES AND BOTH ENDS OF TRENCH. FABRIC MUST BE OVERLAPPED A MINIMUM OF 18 INCHES SIDE OF INFlL TRA TION TRENCH NATURAL GROUND 4' c o .0 OBSERVATION WELLS 4" DIAM. PIPE; PERFORATED PVC IN INFILTRATION TRENCH; AND SOLID PVC ABOVE TRENCH; WELLS LOCATED IN THE MIDDLE +/— OF TRENCH. OBSERVATION WELLS SET IN LANDSCAPING SHALL HAVE PVC CAPS SET AT LANDSCAPING GRADE END OF INFILTRATION TRENCH TRENCH BOTTOM INFILTRATION TRENCH INFILTRATION TRENCH TYPICAL END VIEW TYPICAL SIDE VIEW OF END N.T.S. N:T:S - TYPICAL INFILTRATION TRENCH FOR LAWN AND/OR LANDSCAPING RUNOFF - 4' WIDE BY 4' HIGH - TRENCH LENGTH EQUALS 36' PER 1000 FEET OF LAWN AND/OR LANDSCAPING NATURAL GROUND 5.25' VARIABLE USE GEOTEXTILE FABRIC TO LINE TOP, SIDES AND BOTH ENDS OF TRENCH. FABRIC MUST BE OVERLAPPED A MINIMUM OF 18 INCHES. INFILTRATION TRENCH FILLED WITH WASHED ROCK AND AN 18' DIAM• HIO HANCOR ° POLYETHELENE PIPE END OF INFILTRATION TRENCH n ° O ° o NIG RANCOR PPE 18" DIAM. TRENCH BOTTOM •'0.o 0-0-0 -a- :b 0 a• o 0 OBSERVATION WELLS 4" DIAM. PIPE: PERFORATED PVC IN INFILTRATION TRENCH; AND SOLID PVC ABOVE TRENCH; WELLS LOCATED IN THE MIDDLE +/— OF TRENCH. OBSERVATION WELLS SET IN LANDSCAPING SHALL HAVE PVC CAPS SET AT LANDSCAPING GRADE 18" LD. HANCOR HID PERFORATED PIPE s o ° 4e INFILTRATION TRENCHES INCLUDING AN 18" DIAM. PIPE INFILTRATION TRENCH TYPICAL END VIEW TYPICAL SIDE VIEW OF END N.T.S. N.T.S. - TYPICAL INFILTRATION TRENCH FOR YARD AND/OR LANDSCAPING RUNOFF - 4' WIDE BY 4' HIGH - WITH 28" DIAM. CORRUGATED & PERFORATED HANCOR HiQ OR EQUAL - TRENCH LENGTH EQUALS 25 FT. PER 1000 FEET OF LAWN AND/OR LANDSCAPING AREA NOTE: ENDS OF PIPE MUST BE PLUGGED OR CAPPED ADJACENT TO SHELTON VALLEY ROAD OL FACILITIES FRAME AND GRATE (SEE STANDARD PLAN FOR DETAILS) 6" RISER SECTION 12" RISER SECTION 410h1 rib MAP 13 3AR EACH WAY CATCH BASIN TYPE 1 (MEASUREMENT AT THE TOP OF 7HE BASE) 12" NOTES FOR TYPE 1 CB: I. IF WIRE MESH IS USED AS AN ALTERNATE TO REBAR, IT SHALL NOT BE PLACED IN KNOCKOUTS. 2. THE BOTTOM OF THE PRECAST BASE SECTION SHALL BE MINIMUM 4" THICK AND MAY BE ROUNDED. 3. KNOCKOUTS MAY BE ON ALL FOUR SIDES, EITHER ROUND OR "D" SHAPE. PIPE TO BE INSTALLED IN FACTORY SUPPUED KNOCKOUTS. HOLE SIZE SHALL BE EQUAL TO PIPE OUTER DIAMETER PLUS CATCH BASIN WALL THICKNESS, 20" MAX. 4. THE MAXIMUM DEPTH FROM THE FINISHED GRADE TO THE PIPE INVERT IS V-0". 5. THE TAPER ON THE SIDES OF THE PRECAST BASE SECTION AND RISER SECTION SHALL NOT EXCEED 4% 6. FRAME AND GRATE MAY BE INSTALLED WITH FLANGE DOWN OR CAST INTO RISER. RECTANGULAR ADJUSTMENT SECTION 113 BAR EACH CORNER 36" i 13 BAR EACH SIDE 13 BAR EACH WAY TYF'F.30 YARD DRAIN NOT TO SCALE PLACEMENT OF METAL FRAME AND GRATE FOR ASPHALT INSTALLATION CATCH BASIN TYPE 1 RISER AS REQUIRED INLET PIPE CB FLOOR TO BE KEPT IN THE PARCEL FILE ya6 5- (9,a —%4 PLACEMENT OF METAL FRAME 4_ND GRATE FOR LANDSCAPING ItISTALLATION PVC CAP TYPICAL SPILL CONTROL SEPARATOR CATCH BASIN TYPE 1 NOTES: -TYPE 30 1. AS AN ACCEPTABLE ALTERNATE TO KBAR, WIRE MESH HAVING A MINIMUM AREA OF 1).12 SQUARE INCHES PER FOOT MAY BE USE!). WIRE MESH SHALL NOT BE PLACED IN KNOCKOUTS. 2. THE KNOCKOUT DIAMETER SHALL NOT BE GREATER THAN 20". KNOCKOUTS SHALL FAVE 4. FRAME AND GRATE MAY BE INSTAL IMTH lE FLANGE DOWN OR CAST INTO ADJUSTMEN SECTION. 5. THE PRECAST BASE SECTION MAY HA A ROUNDED FLOOR AND THE WALLS MAY eg SLOPED AT A 1,ATE OF 1:24 OR STEEPER. 6. OPENING SHALL BE MEASURED AT T1-111 TOP - OP THE PRECAST BASE UNIT. TYPICAL CROSS SECTION OF TRAPEZOIDAL BASIN; INFILTRATION POND NOT TO SCALE ALTERNATE TO ROCK FILLED TRENCH FOR ROOF AND LAWNS AND LANDSCAPING; END SLOPES AND SIDE SLOPES SHALL BE NO STEEPER THAN 3' HORIZONAL TO 1' VERTICAL. FOR 2000 SQ. FT. OF IMPERVIOUS SURFACES SUCH AS ROOFS, A POND HAVING A FLOOR AREA EQUAL TO 4 FT. WIDE BY 14 FT. LONG AND 3 FT DEEP HAS THE CAPACITY TO CARRY A 100 YEAR - 24 HOUR - STORM EVENT. THE POND SHALL BE LENGTHENED 11 FEET FOR EACH ADDITIONAL 1000 SQ. FT. OF IMPERVIOUS AREA. FOR 5000 SQ. FT. OF LAWNS AND LANDSCAPING, A POND HAVING A FLOOR AREA EQUAL TO 4 FT. VVIDE AND 36 FT. LONG AND 3FT. DEEP HAS A CAPACITY TO CARRY A 100 YEAR - 24 HOUR - STORM EVENT. THE POND SHALL BE LENGTHENED 10 FEET FOR EACH ADDITIONAL 1000 SQ. FT. OF LAWN AND/OR LANDSCAPING. GEOTEXTILE FABRIC SPECIFICATIONS LINING FOR THE INFILTRATION TRENCH PROPERTY TEST METHOD UNITS SPECIFICATION MATERIAL NONWOVEN GEOTEXTILE UNIT WEIGHT OZ./SQ. YD. 8 (MIN.) FILTRATION RATE IN./SEC. 0.08(MIN.) PUNCTURE 'STRENGTH ASTM D-751 (MODIFIED) LBS. 125 (MIN.) MULLEN BURST STRENGTH ASTM D-751 PSI. 400 (MIN.) EQUIV. OPENING SIZE US STANDARD SIEVE NO. 80 (MIN.) OUTLET LIJ LU fjc lu Li cNI co co Z Lui LULU CO CD co LLJ • • • • 0 0 0 co co CQ op NI' PI PERMANENT STORMWATER CONTROL (SWC) FACILITY REVIEW I. PROJECT OVERVIEW LAND DEVELOPMENT Eight parcel development (Lots B-1, B-2, B-3, B-4 of Short Plat 1235 and Lots CI, C2, C3, C4 (of Short PIat1233) ranging in size from 0.95 to 2.01 acres. Total acres equals 11.19.The project site is located on the West Shelton Valley Road„in Mason County, on a portion of the NW1/4 of the NW1/4 of Section 25, T.20 N., R.4 W., W.M. The development includes a single access easement 30 ft. wide serving lots B-3, B-4, C-3 and C-4. This access is measured per the plat map to be approximately 790 feet in length. For runoff purposes the driving width will be 20 feet of I impervious surface and the remainder of the easement will be considered cut and fill slopes. For SWC calculation purposes, assume that each lot will have 2000 sq. ft. of impervious area including roofs, cement patios and cement or asphalt driveways. These impervious areas must be collected and discharged into an infiltration trench for on site disposal. Once the runoff from the impervious areas is directed to an on site infiltration facility and no longer sheet flows off site, that area can be deducted from the total post developed area when calculating post development runoff. Also, each lot is assumed to have a minimum of 5000 sq.ft. of lawn and landscaping. This area must be directed to an infiltration trench or pond for on site disposal. Once the runoff from the lawns and landscaped areas is directed to an on site infiltration facility, and no longer sheet flows off site, the area can be deducted from the total of post developed area when calculating post developed runoff. MINIMUM REQUIREMENTS The project is intended to comply with D.O.E's 1992 Stormwater Management Manual for the Puget Sound Basin, New Development Minimum Requirements #1 through #11. Minimum Requirement #1: EROSION AND SEDIMENT CONTROL An erosion and stormwater control plan has been completed for this eight lot development. See civil drawings for details. Minimum Requirement #2: PRESERVATION OF NATURAL DRAINAGE SYSTEMS * Natural drainage patterns shall be maintained, and discharges from the site shall occur at the natural location, to the maximum extent practicable. This proposal will not alter the natural drainage patterns off site. Drainage shall be collected on site in a rock lined ditch, running toward county mad and discharging to existing man made ditches and pasture land. Minimum Requirement #3: SOURCE CONTROL OF POLLUTION * Source control BMPs shall be applied to all projects to the maximum extent practicable. Source control BMPs shall be selected, designed, and maintained according to an approved manual. The owner/contractor, when necessary, shall cover migration -sensitive soils with straw mulch or black plastic to prevent off -site migration of soil. Minimum Requirement #4: RUNOFF TREATMENT BMPS * First priority for treatment shall be to infiltrate as much runoff as possible, if site conditions are appropriate and ground water quality will not be impaired. The access road shall slope downward toward the cut of the banks The ditch shall be lined with quarry rock to slow stomiwater and provide treatement. Check dams will be installed. Rock lined ditches and check dams provide a degree of treatment. Minimum Requirement #5: STREAMBANK EROSION CONTROL * This requirement applies only to situations where stormwater runoff is discharged to a stream. Does not apply. The natural runoff from this property enters pastureland via man made ditches. Minimum Requirement #6: WETLANDS * This requirement applies only to situations where stormwater discharges directly or indirectly through a conveyance system into a wetland. N/A Minimum Requirement #7: WATER QUALITY SENSITIVE AREAS * Where local governments determine that the Minimum Requirements do not provide adequate protection of water quality sensitive areas, either on -site or within the basin, more stringent controls shall be required. To date Mason County has not imposed additional requirements Minimum Requirement #8: OFF -SITE ANALYSIS AND MITIGATION * All development projects shall conduct an analysis of off -site water quality impacts resulting from the project and shall mitigate these impacts. The analysis shall extend a minimum of one-fourth of a mile downstream from the project. The calculated Post Development Discharges are less than the Pm Developed Discharges. Further analysis is not necessary. EROSION & S TORMWA TER CONTROL -PLAN FOR EIGhT L OTS A DJA CEI�IT TO SHEL TON VALLEY ROAD LOCATED /N THE NW >/.4; OF THENW>/4 OF{SECT/ON 25,: T. 20 N., R 4 W., W.M. SHORT PLATS 1233`ANO=>235 RECORDS OF, MASON COUNTY, WASH/NGTON STORMWATER CALCULATIONS AND CONSTRUCTION NOTES Minimum Requirement #9: BASIN PLANNING * An adopted and implemented basin plan may be used to develop requirements for water quality sensitive areas that are tailored to a specific basin. N/A Minimum Requirement #10: OPERATION AND MAINTENANCE * An operation and maintenance schedule shall be required for all proposed stormwater facilities and BMPs, and the party (or parties) responsible for maintenance and operation shall be identified. The private facility maintenance checklist should be tailored to the facility. After the leaves have dropped each fall, the rocklined drainage ditch and check dams shall be checked and repaired as required. At the same time in the fall, the House gutters, downspouts and sumps shall be checked and cleaned and repaired when necessary. Minimum Requirement #11: FINANCIAL RESPONSIBILITY * Performance bonding or other appropriate financial instruments shall be required for all projects to ensure compliance with these standards. We expect Mason County will not make any requirements regarding performance bonding. II. PLOT PLAN See these Civil Drawings III. GENERAL SITE CONDITIONS SUMMARY The purpose of this proposal is to provide an erosion and stormwater control plan(s) for eight lots to accommodate the proposed improvement. SCS Soils Description The Soil Conservation Service - Soil Survey of Mason County Series 1951, No. 9, Issued September 1960, shows this property having soils type (Cc) Cloquallum Silt Soils, 5-15 percent slopes; Hydrologic Soils Group C. IV. SPECIAL REPORTS AND STUDIES Geotechnical Testing Lab, Olympia, Washington completed evaluation of the surface and subsurface conditions on each of the eight lots to satisfy the requirements of the Mason County Critical Areas Ordinance. V. BASIN AND COMMUNITY PLANNING N/A VI. STORM EVENT DESIGN ASSUMPTIONS STORMWATER CONTROL REVIEW Based on DOE's Stormwater Management Manual: * STORM EVENT Total Area ** Rain Precipitation (in.) Six-month, 24-hour Storm Event Two-year, 24-hour Storm Event Ten-year, 24-hour Storm Event Hundred -year, 24-hour Storm Event Rainfall Choice Hydrograph Santa Barbara Urban Hydrograph Method * DRAINAGE BASIN Cloquallum Silt Soils (Cc) Hydrologic Soil Group Pre - developed minus roof area minus lawn area etc Post - developed Imp. Access Rd Post - developed Undisturbed Post - developed Gravel Drives Post - developed Access cuts/fills Post - developed composite CN# 11.19 acres 2.62" 4.10" 6.00" 8.10" IA SBUH** C 11.19 acres at CN# 81 w/ Tc = 22.52 minutes 0.37 acres 0.73 acres 0.37 acres at CN# 98 w/ Tc = 16.0 minutes 9.36 acres at CN# 81 0.18 acres at CN# 89 0.18 acres at CN# 90 9.72 acres at CN# 81.31w/ Tc = 16.0 minutes. DESIGN RESULTS Storm Event 6-Month Two-year Pre Flow -cfs 1.73 4.35 Pre Volume -cf 41,818 89,298 Post Flow -cfs 1.87 4.43 Post Volume -cf 39,204 82,328 Ten-year Hundred -year 8.15 12.56 157,252 236,531 8.10 12.31 142,877 214,444 Please notice that in every study year the cubic foot post development discharge is less than the Pre developed discharge. It is considered insignificant that the Post Flow for the 6-Month and the Two-year are 0.13 cfs and 0.08 cfs higher than the Pre Flows. REFER TO CIVIL DRAWINGS FOR INFILTRATION TRENCH AND OPEN POND DESIGNS CHANGED CONDITIONS: The conclusions and recommendations in these Civil Drawings are based on interpretation of the site conditions. In the event that the scope of the project, surface/subsurface, or contractual conditions differ from those relied on in these civil drawings, the Civil Engineer should be advised immediately. A review of the changed conditions will be conducted and alternative or remedial recommendations given at that time. GENERAL NOTES: 1. ALL APPROVALS AND PERMITS REQUIRED BY THE COUNTY SHALL BE ❑BTAINED BY THE CONTRACTOR PRI❑R TO THE START OF C❑NSTRUCTI❑N, 2. IT SHALL BE THE SOLE RESPONSIBILITY OF THE CONTRACTOR TO OBTAINTSTREET USE AND OTHER RELATED OR REQUIRED PERMITS PRIOR TO ANY CONSTRUCTION ACTIVITY IN MASON COUNTY RIGHT OF WAY. 3, THE CONTRACTOR SHALL BE FULLY RESPONSIBLE FOR THE LOCATI❑N AND 'PROTECTION OF ALL EXISTING UTILITIES.' THE CONTRACTOR SHALL VERIFY THE LOCATIONS PRIOR TO CONSTRUCTION BY CALLING THE UNDERGROUND LOCATE LINE AT 1-800-424-5555 A MINIMUM OF 48 HOURS PRI❑R TO ANY EXCAVATION, 4, THE CONTRACTOR IS RESPONSIBLE FOR INSTALLING ANY: BURIED UTILITIES �AND ELECTRICAL. LINES TO (' PLICABLE CODES, 5. ALL W❑RKMANSHIP AND MATERIALS SHALL BE IN ACCORDANCE WITH MASON COUNTY STANDARDS AND THE 2000 EDITION OF THE STATE OF WASHINGT❑N STANDARD :j SPECIFICATIONS FORR❑AD, BRIDGE AND MUNICIPAL C❑NSTRUCTI❑N (WSD❑T/APWA). 6. IT IS RECOMMENDED THAT ALL SURVEYING ':AND CONSTRUCTIONSTAKING 'BE PERFORMED BY AN ENGINEERING OR SURVEYING FIRM CAPABLE OF PERFORMING SUCH WORK, ''THEE ENGINEER OR SURVEYOR DIRECTING SUCH WORK SHALL BE. LICENSED BY THE STATE' OF WASHINGTON, P' 7. WHEN PROJECT IS COMPLETE CONTRACTOR SHALL LEAVE THE SITE INrA ,NEAT AND PRESENTABLE C❑NDITION, CLEAR OF DIRT AND/OR DEBRIS. 8. THE CONTRACTOR SHALL BE RESPONSIBLE FOR PROVIDING ADEQUATE SAFEGUARDS, SAFETY DEVICES, PROTECTIVE EQUIPMENT, FLAGGERS, AND ANY OTHER,' NEEDED ITEMS TO PROTECT THE LIFE, HEALTH, AND SAFETY OF'THE PUBLIC AND TO PROTECT PROPERTY IN CONNECTION WITH THE PERFORMANCE OF WORK COVERED BY THE CONTRACTOR. ANY WORK WITHIN THE. TRAVELED RIGHT•=OF-1WAY THAT MAY INTERRUPT NORMAL TRAFFIC FLOW SHALL REQUIRE AT LEAST ONE FLAGGER FOR EACH;: LANE OF TRAFFIC AFFECTED. ALL SECTIONS OF THE WSDOT STANDARD SPECIFICATIONS 1007,23-TRAFFIC CONTROL SHALL APPLY. 9, THE CONTRACTOR SHALL NOTIFY THE PROJECT ENGINEER IN THE EVENT;OR DISCOVERY OF POOR DRAINING SOILS, STANDING GROUNDWATER, OR SEVERE DISCREPANCIES FROM;; SOIL INFORMATION AS ORIGINALLY,: REVIEWED. �' EARTHWORK SITE PREPARATION Ia, 1. ALL AREAS TO BE EXCAVATED SHOULD BE CLEARED OF DELETERIOUS,MATTER TTER INCLUDING DEBRIS, AND ,,. VEGETATION, 2. WHERE PLACEMENT OF FILL MATERIAL IS REQUIRED, THE EXPOSED SUBGRADE AREAS SHOULD BE CLEARED OF DELETERIOUS MATERIAL TO A FIRM AND UNYIELDING SURFACEPRIOR TO PLACEMENT OF ANY ! ILL. ANY SOFT, LOOSE OR ❑THERWISE UNSUITABLE AREAS DELINEATED'DURING CONSTRUCTION, SH❑ULD,-BE- COMPACTC' ED, IF PRACTICAL,.. OR OVER -EXCAVATED. AND REPLACE" WITH 7"' ``TURA FILL. ' ..... CONSTRUCTION NOTES : 1. WITHIN_ THE LOT DEVELOPMENT, ALL STORM SEWER PIPES SHALL BE PVC AS PER ASTM D-3034. d. CATCH BASIN SHALL BE TYPE 30 AND TYPE 1, ALL IN ACCORDANCE WITH THE ABOVE -MENTIONED SPECIFICATIONS. (SEE GENERAL NOTE 5), THE CONTRACTOR MUST USE DUE ARE WHEN SETTING THE CATCH BASINS AND THE STORM DRAINAGE PIPES, i:,..°' 3. WITHIN THE ACCESS EASEMENT, THE CULVERT CAN BE HANCOR HIQ POLYETHELENE PIPE. DIAM. TO COMPLY :WITH MASON COUNTY STANDARDS, OR A MINIMUM OF 12' ID DIAM >`:= STANDARD STORMWATER NOTES. y a 1. IN ANY AREA THAT HAS BEEN STRIPPED OF VEGETATION OR EXPERIENCED LAND DISTURBING ACTIVITIES AND WHERE NO FURTHER WORK IS ANTICIPATED FOR A PERIODI XCEEDING THE LISTED CRITERIA BELOW, ALL DISTURBED AREAS MUST BE IMMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING, OR OTHER APPROVED EROSION CONTROL TREATMENT APPLICABLE'J'T❑ THE TIME OF YEAR IN QUESTION. ''GRASS SEEDING ALONE WILL BE ACCEPTABLE ONLY :DURING 'THE' MONTHS OF APRIL THROUGH SEPTEMBER, INCLUSIVE. SEEDING MAY PROCEED, WHENEVER IT IS IN THEINTEREST OF THE DEVELOPER/CONTRACTOR, BUT MUST BE AUGMENTED WITH MULCHING, NETTING, OR OTHER TREATMENT, 2. ALL .EXISTING EROSION CONTROL AND STORMWATER FACILITIES SHALCBE' REGULARLY INSPECTED AND MAINTAINED BY THE CONTRACTOR DURING THE CONSTRUCTION PHASE Or THEtDEVELOPMENT PROJECT. EROSION CONTROL NOTES: L WHEN NECESSARY, TEMPORARY AND PERMANENT EROSION CONTROL MEASURES SHOULD BE IMPLEMENTED AND MAINTAINED DURING CONSTRUCTION AND/OR 'AS' SOON AS PRACTICAL':THEREAFTER TO LIMIT THE ADDITIONAL' INFLUX OF WATER TO EXPOSED AREAS, •r` h' 2. EROSION CONTROL MEASURES COULD INCLUDE; BUT NOT BE LIMITED T❑t.SILT FENCES, BERMS AND SWALES, 'WITH GROUND'C❑VER/PROTECTION IN EXPOSED AREAS. ANY RE-;CO(fJTOURING OF THE SITE 'f.: . 2t. ,. WILL CREATE A NEED FOR EROSION CONTROL MEASURES.., `'f_'�^;:r 3. THE EXISTING ACCESS EASEMENT WILL BE USED AS `'THE CONSTRUCTION'IENTRANCE, 4, SHOULD TEMPORARY EROSION AND SEDIMENTATON CONTROL MEASURES ,NOV''PROVE ADEQUATE TO CONTROL EROSION AND SEDIMENTATION, THE CONTRACTOR SHALL INSTALL'AD4DITIONAL FACILITIES AS NECESSARY TO PROTECT ADJACENT PROPERTIES, SENSITIVE AREAS,;AND/ORSTORM DRAINAGE SYSTEMS. 5, THE CONTRACTOR SHALL PROVIDE MATERIALS ❑N-SITE READILY AVAILABLE TO IMMEDIATELY STABILIZEDENUDED AREAS DURING PERIODS OF INCLEMENT WEATHER WHICHIRESULT IN EROSION AND SEDIMENT TRANSPORT OFF -SITE. AS A MINIMUM THE CONTRACTOR SHALL .HAVE ON HAND 5' STRAW HAY BALES AND ONE (20 FT. BY 100 FT.) ROLLS OF 6 MIL PLASTIC COVERING, 6. ALL WORK ASSOCIATED WITH STABILIZING THE DISTURBED AREAS SHALL.BE IN ACCORDANCE WITH THE MASON COUNTY STORMWATER MANAGEMENT MANUAL, ' 7. ALL NECESSARY FACILITIES SHALL BE MAINTAINED ON SITE TO 'PREVEN :: DEBRIS, DUST,' AND MUD FROM ACCUMULATING ON THE PUBLIC RIGHT OF WAY, .F: THE F❑LLOWING SHALL BE ADHERED TO ON ALL C❑NSTRUCTI❑N SITES WITH EROSIVE SOILS AND/OR A GRADIENT OF GREATER THAN 2 PERCENT FOR LIMITING EXPOSED S❑ILS TO ER❑SIVE PR❑CESSES, MAY 1 TO SEPTEMBER 30 (DRY SEASON) THE CLEARING OF LAND, INCLUDING THE REMOVAL OF EXISTING VEGETATI❑N OR OTHER GROUND COVER, MUST BE LIMITED TO ONLY AS MUCH LAND AS CAN RECEIVE APPROPRIATE PROTECTIVE COVER OR BE ❑THERWISE STABILIZED, AFTER HAVING BEEN CLEARED OR ❑THERWISE DISTURBED, BY NO LATER THAN SEPTEMBER 30 OF A GIVEN YEAR, UNLESS IMMEDIATE STABILIZATI❑N IS SPECIFIED IN THE EROSI❑N AND SEDIMENTATION CONTROL PLAN, ALL AREAS CLEARED OR ❑THERWISE DISTURBED MUST BE APPROPRIATELY STABILIZED THROUGH THE USE OF MULCHING, NETTING, PLASTIC SHEETING, EROSION BLANKETS, FREE DRAINING MATERIAL, ETC., BY SEPTEMBER 30 OR SOONER PER THE APPROVED PLAN OF ACTION, UNLESS ❑THERWISE APPROVED BY THE COUNTY, SEEDING, FERTILIZING, AND MULCHING OF CLEARED OR ❑THERWISE DISTURBED AREAS SHALL BE PERFORMED DURING THE FOLLOWING PERI❑DS' MARCH I TO MAY 15 AND AUGUST 15 TO OCTOBER 1, SEEDING AFTER OCTOBER 1 WILL BE DONE WHEN PHYSICAL COMPLETION OF THE PROJECT IS IMMINENT AND THE ENVIRONMENTAL C❑NDITI❑NS ARE C❑NDUCIVE TO SATISFACTORY GROWTH, IN 'THE EVENT THAT PERMANENT STABILIZATION IS NOT POSSIBLE, AN ALTERNATIVE METHOD OF GROUND COVER (SUCH AS MULCHING, NETTING, PLASTIC SHEETING, EROSION BLANKETS, ETC,) MUST BE INSTALLED BY' NO LATER THAN SEPTEMBER 30, IN THE EVENT THAT CONSTRUCTION ACTIVITIES OR OTHER SITE DEVELOPMENT ACTIVITIES ARE DISCONTINUED FOR 4 CONSECUTIVE DAYS OR MORE, THE PROPONENT SHALL BE RESPONSIBLE FOR THE INSPECTION OF ALL EROSION AND SEDIMENTATION CONTROL FACILITIES IMMEDIATELY AFTER STORM EVENTS, AND AT LEAST ONCE EVERY WEEK. THE PROPERTY OWNER SHALL BE RESPONSIBLE FOR THE MAINTENANCE AND REPAIR OF ALL EROSION AND SEDIMENTATION CONTROL FACILITIES, . OCTOBER 1 TO APRIL 30 (WET SEASON) ON SITES WHERE UNINTERRUPTED CONSTRUCTION ACTIVITY IS IN PROGRESS, THE CLEARING OF LAND, INCLUDING THE REMOVAL OF EXISTING VEGETATION OR OTHER GROUND COVER, SHALL BE LIMITED TO ONLY AS MUCH LAND AREA AS CAN BE COVERED OR STABILIZED WITHIN 24 HOURS IN THE EVENT A MAJOR STORM IS PREDICTED AND/OR EROSION/ SEDIMENT TRANSPORT OFF -SITE IS OBSERVED, ADDITIONALLY, ALL CLEARED OR DISTURBED AREAS WILL RECEIVE APPROPRIATE PROTECTIVE COVER OR BE ❑THERWISE STABILIZED (SUCH AS MULCHING, NETTING, PLASTIC SHEETING, EROSION BLANKETS, FREE DRAINING MATERIAL, ETC.) WITHIN 5 DAYS AFTER HAVING BEEN CLEARED OR ❑THERWISE DISTURBED IF • NOT BEING ACTIVELY WORKED, FILTER FABRIC FENCING, SEDIMENT TRAPS, SEDIMENT PONDS, ETC., WILL NOT BE VIEWED AS ADEQUATE COVER IN AND OF THEMSELVES. IN THE EVENT THAT ANY LAND ARE,-, NOT BEING ACTIVELY WORKED REMAINS UNPROTECTED OR HAS LOT BEEN APPROPRIATELY STABILIZED 5 DAYS AFTER HAVING BEEN CLEARED, ALL CONSTRUCTION ACTIVITY ON THE SITE, EXCEPT FOR APPROVED EROSION AND SEDIMENTATION CONTROL ACTIVITY, SHALL IMMEDIATELY CEASE UNTIL SUCH A TIME AS SAID LAND AREA HAS BEEN APPROPRIATELY PROTECTED OR STABILIZED. THE CONTRACTOR SHALL AT ALL TIMES HAVE AVAILABLE FOR THE PROJECT SUFFICIENT QUANTITIES OF PROTECTIVE COVERING MATERIALS TO IMMEDIATELY STABILIZE ALL DISTURBED AREAS IN CASE THE PROJECT ENGINEER OR COUNTY DIRECTS HIM/HER TO COVER DUE TO OBSERVED MIGRATION OF S❑ILS OR INCLEMENT WEATHER, (REFER TO EROSION CONTROL NOTES #4 AND #5 ABOVE). SEEDING — FOR ALL RAW SLOPES ( NOT INCLUDED IN LANDSCAPING) IT MAY BE NECESSARY TO PROTECT RAW SLOPES FROM EROSION BY APPLYING SEED. 1. SEED MIXTURE SHALL BE AS SHOWN BELOW, AND SHALL BE APPLIED AT THE RATE OF 120 POUNDS PER ACRE. 2, SEED BEDS PLANTED BETWEEN MAY 1 AND OCTOBER 31 WILL REQUIRE IRRIGATION AND OTHER MAINTENANCE AS NECESSARY TO FOSTER AND PROTECT THE ROOT STRUCTURE. 3. FOR SEED BEDS PLANTED BETWEEN OCTOBER 31 AND APRIL 30, ARMORING OF THE SEED BED WILL BE NECESSARY, (e,g., GE❑TEXTILES, JUTE MAT, CLEAR PLASTIC COVERING). 4.' BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR DIKES, SWALES, LEVEL SPREADERS AND SEDIMENT BASINS, 5. THE SEEDBED SHALL BE FIRM WITH FAIRLY FINE SURFACE, FOLLOWING SURFACE ROUGHENING, PERFORM ALL OPERATIONS ACROSS OR AT RIGHT ANGLES TO THE SLOPE, 6.' FERTILIZERS ARE TO BE USED ACCORDING TO SUPPLIERS' RECOMMENDATIONS. AMOUNTS USED SHOULD BE MINIMIZED, ESPECIALLY ADJACENT TO WATER BODIES AND WETLAND$; USE THE F❑LL❑WING RECOMMENDED SEED MIXTURE FOR EROSION CONTROL, OR A COUNTY -APPROVED ALTERNATE SEED MIXTURE. Name Redtop (Agrostis alba) Annual rye (Lollum multiflorum) Chewing fescue (Festuca rubra commutata) (Jamestown, Banner, Shodow, or Koket) White dutch clover (Trlfolium repens) Proportions Percent Percent by Weight Purity Germinatiq 10 percent 40 percent 40 percent 10 percent 92 98 97 90 90 80 96 90 MULCHING— FOR ALL RAW SLOPES (NOT INCLUDED IN LANDSCAPING) IT MAY BE NECESSARY TO PROTECT RAW SLOPES FROM EROSION BY APPLYING MULCH, 1, MULCH MATERIALS USED SHALL BE WOOD FIBER CELLULOSE, AND SHALL BE APPLIED AT THE RATE OF 1000 POUNDS PER ACRE. 2, MULCH SHALL BE APPLIED IN ALL AREAS WITH EXPOSED SLOPES GREATER THAN 211, 3, MULCHING SHALL BE USED IMMEDIATELY AFTER SEEDING OR IN AREAS WHICH.: CANNOT BE SEEDED BECAUSE OF THE SEASON, 4., ALL AREAS NEEDING MULCH SHALL BE COVERED BY NOVEMBER 1. cr co co rn ti -J U Q 61 z •�m0� zowo �1 0 u) 0 I � 0 o� 0 CO CO CN 0) CON M • QQ cQ O ffi N `c12(L(f)M U