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Home My WebLink AboutSWP3102057.135 swp-27 -ja r7 6 EROSION CONTROL PLAN SCALE 0 20 40 80 FEET I,I,l I I 1"=40' EXCEPT AS NOTED STA 6+35.87 LIMITS OF ACCESS ROAD RECONSTRUCTION EROSION CONTROL PLAN THE CONTRACTOR IS RESPONSIBLE FOR PROVIDING, INSTALLING, MAINTAINING AND REMOVING ALL EROSION CONTROL MEASURES NECESSARY THROUGHOUT THE PROJECT SITE TO CONTROL EROSION IN WORK AREAS AND KEEP SEDIMENT, DEBRIS, AND ANY OTHER CONTAMINATES FROM ENTERING MAPLEWOOD CREEK. EROSION CONTROL DEVICES THAT SHOULD BE USED INCLUDE HAY BALES, SILT FENCING, SANDBAGS, OR ANY OTHER METHOD APPROVED BY THE CITY. ANY EXPOSED SLOPES, CLEARED AREAS, DEMOLITION AREAS, TEMPORARY ACCESS ROADS, STOCKPILE AREAS, CONTRACTOR STAGING AREAS, OR ANY OTHER AREAS WHERE SURFACE RUNOFF COULD CAUSE EROSION SHALL BE PROTECTED BY THE HAY BALES, SILT FENCING, OR OTHER PROTECTIVE MEASURES. SPECIAL ATTENTION TO EROSION CONTROL SHALL BE GIVEN TO INSTREAM WORK ITEMS INCLUDED IN THIS CONTRACT THAT WILL BE PERFORMED ADJACENT TO OR IN MAPLEWOOD CREEK ITSELF. AS SHOWN ON THIS DRAWING, THERE PLE ARE FOUR GENERAL AREAS (DENOTED A THROUGH D) THAT HAVE BEEN IDENTIFIED AS INSTREAM WORK ITEMS. THESE WORK ITEMS ARE EXPECTED TO BE PERFORMED IN THIS ORDER (A TO D). EROSION CONTROL MEASURES REQUIRED FOR EACH AREA ARE DESCRIBED AS FOLLOWS: AREA A; ACCESS ROAD IMPROVEMENTS AND INSTALLATION OF A 24-INCH DIAMETER CMP CULVERT TO PROVIDE ACCESS ALONG THE ROAD TO THE UPSTREAM CONCRETE WEIR WILL BE PERFORMED IN THIS AREA, PRIOR TO ANY EXCAVATION, GRADING, OR GRAVEL SURFACING OF THE ROAD, SILT FENCING SHALL BE INSTALLED BETWEEN THE ROAD AND MAPLEWOOD CREEK. PRIOR TO EXCAVATION ACROSS THE ROAD AND ON THE STREAM BANK FOR CULVERT INSTALLATION, HAY BALES AND/OR SANDBAGS SHALL BE INSTALLED BETWEEN THE WORK AREA AND MAPLEWOOD CREEK. FOLLOWING INSTALLATION OF THE CULVERT, ANY ACCUMULATED SEDIMENT SHALL BE REMOVED ALONG WITH THE HAY BALES SO THAT THE SEDIMENT DOES NOT ENTER THE CREEK. SILT FENCING SHALL REMAIN IN PLACE UNTIL WORK HAS BEEN COMPLETED IN AREA B. AREA Bt EXCAVATION OF ACCUMULATED SEDIMENTS BEHIND THE EXISTING UPPER CONCRETE DAM, DEMOLITION AND DISPOSAL OF THE DAM AND STREAM BANK STABILIZATION MEASURES WILL BE PERFORMED IN THIS AREA. PRIOR TO ANY WORK BEING PERFORMED IN THE STREAM, THE CONTRACTOR SHALL INSTALL A SMALL SANDBAG COFFERDAM ACROSS MAPLEWOOD CREEK UPSTREAM OF THE AREA THAT WILL BE EXCAVATED. FROM THIS COFFERDAM, A TEMPORARY DIVERSION PIPE SHALL BE INSTALLED PASSING THROUGH THE WORK AREA AND DISCHARGING BACK INTO THE CREEK DOWNSTREAM OF THE SLOPE STABILIZATION AREA. THE CONTRACTOR IS RESPONSIBLE FOR DETERMINING THE SIZE OF THE TEMPORARY PIPE BASED ON EXISTING FLOWS DURING CONSTRUCTION AND TIME EXPECTED DURATION OF THE WORK. IN ADDITION TO THE DIVERSION PIPE, HAY BALES SHALL BE INSTALLED ACROSS THE CREEK TO CONTROL ANY SEDIMENT EROSION THAT MIGHT OCCUR IF PIPE CAPACITY IS EXCEEDED. WHILE THE DIVERSION PIPE IS IN PLACE, ALL INSTREAM WORK IN THIS AREA SHALL BE PERFORMED USING THE HAY BALES DOWNSTREAM OF SMALLER WORK AREAS. THE DIVERSION PIPE WILL LIKELY HAVE TO BE MOVED AS WORK PROGRESSES TO AVOID INTERFERENCE. WHEN WORK IS COMPLETED IN THIS AREA, THE DIVERSION PIPE AND COFFERDAM SHALL BE REMOVED WITH ANY SEDIMENT THAT MIGHT ENTER THE CREEK BEING CONTROLLED BY THE EXISTING SEDIMENTATION BASIN DOWNSTREAM. AREA C: INSTALLATION OF THE BYPASS PIPING AND INTAKE WILL BE PERFORMED IN THIS AREA FOLLOWING COMPLETION OF WORK IN AREA B, SINCE EXCAVATION FOR THE BYPASS PIPING WILL CUTOFF CONTRACTOR ACCESS TO AREAS A AND B. DURING EXCAVATION ADJACENT TO MAPLEWOOD CREEK, HAY BALES AND/OR SANDBAGS SHALL BE INSTALLED BETWEEN THE WORK AREA AND THE CREEK. EXCAVATION AND CONSTRUCTION OF THE BYPASS INTAKE AND INSTALLING THE BYPASS PIPING CAN THEN BE PERFORMED. FOLLOWING CONSTRUCTION OF THE INTAKE, ANY ACCUMULATED SEDIMENT MUST BE REMOVED ALONG WITH THE HAY BALES AND/OR SANDBAGS CAN BE REMOVED SUCH THAT NO MATERIAL ENTERS THE CREEK. AFTER INSTALLATION OF THE BYPASS PIPING, 'TEMPORARY DIVERSION PIPING WILL BE REQUIRED TO EXTEND THE BYPASS PIPE BACK TO MAPLEWOOD CREEK. THE COMBINATION OF THE BYPASS/TEMPORARY PIPING WILL BE USED FOR DIVERSION DURING WORK IN AREA D. AREA D WORK ITEMS TO BE PERFORMED IN THIS AREA INCLUDE EXCAVATION OF THE ACCUMULATED SEDIMENT IN THE EXISTING SEDIMENTATION BASIN, REMOVAL OF THE ECOLOGY BLOCK WEIR ACROSS THE CREEK CHANNEL, CONSTRUCTION OF THE NEW SPILLWAY AND FISHWAY STRUCTURES, REMOVAL OF EXISTING BURIED PIPES EAST OF THE SEDIMENTATION BASIN, PLACEMENT OF THE NEW EMBANKMENT, AND INSTALLATION OF THE NEW BASIN LINER WITH GROUND COVER. PRIOR TO WORK IN ANY OF THESE AREAS, THE BYPASS PIPING AND TEMPORARY PIPING MUST BE IN PLACE CAPABLE OF DIVERTING THE MAPLEWOOD CREEK FLOWS AROUND THE WORK AREA. ALSO, AN UPSTREAM SANDBAG COFFERDAM MUST BE INSTALLED ACROSS THE CREEK IMMEDIATELY DOWNSTREAM OF THE BYPASS INTAKE STRUCTURE. A DOWNSTREAM COFFERDAM DOWNSTREAM OF THE NEW SEDIMENTATION BASIN EMBANKMENT MAY BE REQUIRED, DEPENDING ON THE CREEK FLOWS, TO KEEP THE WORK AREA ISOLATED FROM STREAM FLOWS. WHEN THE WORK IN THIS AREA IS COMPLETED, THE COFFERDAMS AND THE TEMPORARY DIVERSION PIPING SHALL BE REMOVED. ANY SEDIMENT OR DEBRIS THAT MAY HAVE BEEN ACCUMULATED BEHIND EACH COFFERDAM SHALL BE REMOVED ALONG WITH THE COFFERDAM SUCH THAT THE SEDIMENT AND DEBRIS ARE NOT RELEASED INTO MAPLEWOOD CREEK. 01-aos?'oa NORTHWEST, INC. Engineers and Scientists Bellevue, Washington 2353-130TH AVE NE, SUITE 200 BELLEVUE, WASHINGTON 98005 FAX: (206) 883-7555 TEL, (206) 882-2455 25792 �sSIONAL ��G1 EXPIRES 12--21-97 A AS -BUILT NOTES ADDED NO. REVISION Dw 14 BY I APPR RECOMMENDED FOR APP OVAL. S �� 7�-�6 Y BY BY CITY OF RENTON DEPARTMENT OF PUBLIC WORKS MAPLEWOOD CREEK SEDIMENTATION BASIN RECONSTRUCTION AND IMPROVEMENT PROJECT EROSION CONTROL PLAN DESIGNED: R,S.P. HNW DATE: 7-15--96 FILE NAME: SHEET10 DRAWN: C.L.C. HNW 5-r�-9a CHECKED; SCALE: AS NOTED RELD BOOK: PAGE: DATE APPROVED: SHEET; 10 OF: 10 DIRECTOR OF PUBLIC WORKS v s1d SCANNED MAY - 9 1999 r m 0 d x bCn Cn W W� a 0 z Cn z c� H_ O z