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I '84 IT � - 5750 _ FG:S� 574CL \ /SF -SE - _ j - 57501 - - - - ' ' S7 r i L o i 5.5/ 1 ----- --_ - / o i - - - - - - - - - �XTCH"�57G1_.5! __� _ _ _ _ __-_- _--- _=_ -_-____ - TO -------_ - 10A°/0 \ _ 0576` _ --- _---__- '//_ /�' -��--- - - �4ATCI EX. ----- - _-- f-/ - INSTALLI8"NOMINAL \ .� f--- _--�IAT£HEXS"L33 --- __�_ - RIPRAPIO'WIDEFROM - `,j -- -_-- --- _- -- _- _ _--_------- ---- -_-- _ _--_ _---------- --- - MAT�kI{�E:5758 ]' - - - _ - - OUTLET FOR 60' -I-7_0_--_ DRAINAGE BASIN HYDROLOGY FOR APPLICATION OF RATIONAL METHOD RAINFALL INTENSITIES FOR VARIOUS RETURN PERIODS Time C 2yr 5yr 10yr 25yr 100yr MIN. in/hr in/hr in/hr in/hr 5 3.231 3.959 4.409 4.994 5.824 10 2.38 3.00 3.39 3.90 4.65 15 1.14 1.79 2.33 3.14 3.93 BASIN Pre -Development 1 Post -Development Surface AREA AREA AREA rational Basin SF AC % coefficient Surface Basin AREA SF impv-pave 0 0.00 0 0.90 impv-roof 0 0.00 0 0.90 pery 363087 8.34 100 0.25 impv-pave impv-roof pery 202768 0 160319 Total 363087 8.34 100 1 Total 363087 Weighted Rational Coefficient SURFACE AREA C PRODUCT CLASS 6 0.00 0.90 0.00 METAL ROOF 0.00 0.90 0.00 NATIV E 8.34 0.35 2.92 TOTAL 8.34 2.92 CW = 0.35 AREA AREA rational AC % coefficient 4.65 56 0.90 0.00 0 0.90 3.68 44 0.25 8.34 100 Weighted Rational Coefficient SURFACE AREA C PRODUCT CLASS 6 4.65 0.90 4.19 METAL ROOF 0.00 0.90 0.00 NATIVE 3.68 0.35 1.29 TOTAL 8.34 5.48 CW - 0.66 25-YEAR STORM PRE -DEVELOPMENT C I (in/hr) A (ac) I Q (cfs) POST-DEVELOPMEN- C I (in/hr) A (ac) Q (cfs) Q=C'I`A 0.35 3.90 8.34 1 11.37 Q=C'I`A 0.66 3.90 8.34 21.36 Ic = 1U min Ic = 1U min Vol = (.5)Q(Tc+1.67Tc) = 151.85 cfs-min Vol = (.5)Q(Tc+1.67Tc) = 285.12 cfs-min Vol (co = Vol*(60)= 9,111.23 Vol (co = Vo/(60)= 17,107.00 Pre/Post runoff volume difference=1 7,995.76 CF iUbW9=0 i.*Col.]IT,I PRE -DEVELOPMENT C I (in/hr) A (ac) Q (cfs) POST-DEVELOPMEN- C I (in/hr) A (ac) Q (cfs) Q=C'I*A 0.35 4.645 8.34 13.55 Q=C`I'A 0.66 4.65 8.34 25.44 Tc = 10 min Ic = 10 min Vol = (.5)Q(Tc+1.67Tc) = 180.91 cfs-min Vol = (.5)Q(Tc+1.67Tc) = 339.67 cfs-min Vol (60 = Vol*(60)= 10,854.49 Vol (60 = V01*(60)= 20,380.10 Pre/Post runoff volume difference=l 9,525.60 CF PROPOSED LEGEND EXCAVATION CALCULATIONS CUT: 32,615 CY PROPOSED CONTOUR FILL: 84,615 CY 7900 PROPOSED CONTOUR INTERVAL IMPORT: 52,000 CY EXISTING CONTOUR 6600 EXISTING CONTOUR INTERVAL DRAINAGE CALCULATIONS (25 YR) SF - SILT FENCE PRE -DEVELOPMENT: 9,112 CF 2.0% PROPOSED SLOPE POST -DEVELOPMENT: 17,107 CF FG:6800.00' ­4 PROPOSED SPOT ELEVATION STORAGE REQUIRED: 7,996 CF EXISTING LEGEND DRAINAGE CALCULATIONS (100 YR) PRE -DEVELOPMENT: 10,555 CF - - EXISTING PROPERTY LINE POST -DEVELOPMENT: 20,381 CF - - - - - - EXISTING CONTOUR STORAGE REQUIRED: 9,526 CF 7900 EXISTING CONTOUR INTERVAL EX-UE EX-UE EXISTING ELECTRIC STORAGE PROVIDED: 14,013 CF °O1O°O°O°°°°°°O°O°O°O°° EXISTING CULVERT EROSION CONTROL NOTES: GRAPHIC SCALE 50 0 25 50 100 200 1. CONTRACTOR MUST UTILIZE "BEST MANAGEMENT PRACTICES" (BMP), TO CONTROL EROSION AND SEDIMENTATION DURING CONSTRUCTION. 2. CONTRACTOR IS RESPONSIBLE FOR INSTALLATION AND MAINTENANCE OF ALL TEMPORARY EROSION CONTROL MEASURES. 3. DUST CAUSED BY DEMOLITION, EXCAVATION, TOPSOIL REMOVAL OPERATIONS, OR ROAD BASE PLACEMENT SHALL BE CONTROLLED BY THE CONTRACTOR AT HIS EXPENSE. THE ENGINEER OR CITY MAY REQUIRE THE CONTRACTOR AT ANY TIME TO DISCONTINUE CONSTRUCTION ACTIVITIES UNTIL DUST CONDITIONS ARE REDUCED TO THE COUNTY'S SATISFACTION. 4. BMP'S SHALL BE INSTALLED BEFORE ANY EARTH DISTURBING AND/OR DEMOLITION ACTIVITIES COMMENCE. 5. STORMWATER DISCHARGES FROM CONSTRUCTION ACTIVITIES SHALL NOT CAUSE, HAVE THE REASONABLE POTENTIAL TO CAUSE, OR MEASURABLY CONTRIBUTE TO AN EXCEEDANCE OF ANY WATER QUALITY STANDARD. 6. SEDIMENT CAUSED BY ACCELERATED SOIL EROSION SHALL BE REMOVED FROM RUNOFF WATER BEFORE IT LEAVES THE CONSTRUCTION SITE. 7. BULK STORAGE STRUCTURES FOR PETROLEUM PRODUCTS AND ANY OTHER CHEMICALS SHALL HAVE SECONDARY CONTAINMENT OR EQUIVALENT PROTECTION TO CONTAIN ALL SPILLS AND PREVENT ANY SPILLED MATERIAL FROM ENTERING STATE WATERS. 8. THE EROSION CONTROL PLAN SHALL BE CONTINUOUSLY UPDATED TO REFLECT NEW OR REVISED BEST MANAGEMENT PRACTICES (BMP'S) DUE TO CHANGES IN DESIGN, CONSTRUCTION, OPERATION, OR MAINTENANCE OF THE CONSTRUCTION SITE. UPDATES MUST BE MADE WITHIN 72 HOURS FOLLOWING THE CHANGE IN BMP'S. 9. THE CONTRACTOR SHALL INSPECT THE CONSTRUCTION SITE (INCLUDING ALL BMP'S, STORAGE CONTAINERS, AND CONSTRUCTION EQUIPMENT) A MINIMUM OF EVERY 14 CALENDAR DAYS AND WITHIN 24 HOURS AFTER A PRECIPITATION EVENT OR SNOW MELT THAT MAY CAUSE SURFACE EROSION. 10. THE CONTRACTOR SHALL KEEP A RECORD OF ALL INSPECTIONS ON SITE AND AVAILABLE FOR REVIEW BY COUNTY STAFF. INSPECTION REPORTS MUST IDENTIFY ANY INCIDENTS OF NON-COMPLIANCE WITH THE TERMS AND CONDITIONS OF THE PERMIT. 11. STRAW BALES SHALL NOT BE USED FOR PRIMARY EROSION OR SEDIMENT CONTROL (I.E. STRAW BALES MAY BE USED FOR REINFORCEMENT BEHIND ANOTHER BMP SUCH AS SILT FENCE). 12. BMP'S INTENDED FOR SHEET FLOW SEDIMENT RUNOFF SHALL BE PLACED PARALLEL TO THE SLOPE. 13. ALL BMP'S SHALL BE CLEANED WHEN SEDIMENT LEVELS ACCUMULATE TO HALF THE DESIGN OF THE BMP UNLESS OTHERWISE SPECIFIED. 14. A VEHICLE TRACKING PAD (VTP) AND/OR STABILIZED STAGING AREAS SHALL BE PLACED AT ALL EXITS FROM THE SITE TO PREVENT TRACK -OUT ONTO CITY STREETS. IF TRACK -OUT DOES OCCUR, THE CONTRACTOR SHALL IMMEDIATELY SWEEP THE STREET OF DEBRIS. 15. ALL PORTA-POTTY STRUCTURES MUST BE FIRMLY SECURED WITH #4 REBAR ANCHORS OR EQUAL. MUST BE PLACED AWAY FROM FLOW LINES OF STREET, SWALES, RAIN GARDENS & AWAY FROM INLETS. 16. STOCKPILES OF SOIL OR OTHER ERODABLE MATERIALS MUST BE MANAGED SO THAT STORMWATER DOES NOT COME IN CONTACT WITH THE PILE AND POTENTIALLY WASH POLLUTANTS OFFSITE. AT A MINIMUM STOCKPILES SHALL BE ROUTINELY WETTED AND/OR BLANKETED AS WELL AS INCLUDE AN EROSION SOCK PERIMETER BARRIER TO PREVENT WIND EROSION AND SEDIMENT TRANSPORT OFFSITE. STOCKPILES THAT ARE INACTIVE FOR MORE THAN 7 DAYS WILL REQUIRE SOIL BINDER OR HAVE MUCLH/MULCH TACKIFIER APPLIED. 17. EROSION CONTROL BLANKETS SHALL BE INSTALLED ON ALL SLOPES EXCEEDING 3:1. BERM GRADING NOTES: 1. EXISTING CONTOURS ILLUSTRATED HEREIN ARE AT 2 FT INTERVAL, BASED ON AERIAL TOPOGRAPHY. 2. PROPOSED CONTOURS ARE AT 2 FT INTERVALS. 3. BERM GRADING PROVIDES GENERAL DIRECTION FOR THE CONTRACTOR. SLOPES AS LABELED SHALL BE MAINTAINED. CONTRACTOR SHALL INSTALL BERM AND COMPACT ACCORDING TO GEOTECHNICAL ENGINEER'S DIRECTION. REVEGETATION SHALL OCCUR IMMEDIATELY AFTER BERM GRADING IS COMPLETE. 4. BERM VOLUME = 15,000 C.Y.±. NO CUT/FILL EXPANSION FACTOR HAS BEEN APPLIED. 5. THE UTILITIES AS SHOWN, MAY NOT REPRESENT ACTUAL FIELD CONDITIONS. IT IS THE RESPONSIBILITY OF THE CONTRACTOR TO CONTACT ALL UTILITY COMPANIES FOR FIELD LOCATIONS OF UTILITIES PRIOR TO CONSTRUCTION. ( IN FEET ) 1 inch = 50 ft. 3" (MINUS) ROCK, OR RECYCLED 12' MIN. CONCRETE \ J 6" OF ROCK \ +/+ + F LA AGGREGATE ++ + + F LA + `+`+`+' BASE COURSE +++++++ MIRAFI EXISTING FABRIC GRADE VEHICLE TRACKING CONTROL N.T.S. REVEGETATION NOTES: 1S, (MgklU M/ SILT FENCE INSTALLATION -NTS- NOTE: EROSION CONTROL MEASURES SHALL BE MAINTAINED UNTIL LANDSCAPING IS COMPLETED, OR AS DIRECTED BY LOCAL JURISDICTION POST ANCHORED TO FABRIC MATERIAL (ANCHORED IN TRENCH) 4N4" TRENCH COMPACTED BACKFILL FLOW 1/2H (12"MIN) _ tr SECTION SF -NTS- SILT FENCE DETAIL (NOT TO SCALE) A A ;EDIMENTATION LOG - 12" MIN. DIAMETER 3E A STAKE EVERY 24" AT ALTERNATE DEGREE ORIENTATION THROUGHOUT 1E SEDIMENTATION LOG. USE TWO STAKES 1 1/2' x 1 1/2 " x SUFFICIENT LENGTH TO EMBED AT LEAST 12" INTO SOIL AT EACH END OF LOG STAKE AT 90 DEG TO EACH OTHER y / FEATURES REQUIRING Y PROTECTION SECTION A - A SCL SEDIMENT CONTROL LOG (NOT TO SCALE) SEDIMENT CONTROL LOG INSTALLATION NOTES 1. SEE PLAN VIEW FOR: LOCATION OF SEDIMENT CONTROL LOG. 2. SEDIMENT CONTROL LOGS SHALL BE INSTALLED PRIOR TO ANY LAND DISTURBING ACTIVITIES. 3. SEDIMENT CONTROL LOGS SHALL CONSIST OF STRAW, COMPOST, EXCELSIOR OR COCONUT FIBER. 4. NOT FOR USE IN CONCENTRATED FLOW AREAS. 5. THE SEDIMENT CONTROL LOGS SHALL BE TRENCHED INTO THE GROUND A MINIMUM OF 2-INCHES. SEDIMENT CONTROL LOG MAINTENANCE NOTES 1. THE SWMP MANAGER SHALL INSPECT SEDIMENT CONTROL LOGS DAILY, DURING AND AFTER ANY STORM EVENT & MAKE REPAIRS OR CLEANOUT UPSTREAM SEDIMENT AS NECESSARY. 2. SEDIMENT ACCUMULATED UPSTREAM OF SEDIMENT CONTROL LOGS SHALL BE REMOVED WHEN THE UPSTREAM DEPTH IS WITHIN z THE HEIGHT OF THE CREST OF LOG. 3. SEDIMENT CONTROL LOGS SHALL BE REMOVED AT THE END OF CONSTRUCTION, ONCE PROPER VEGETATION HAS BEEN ESTABLISHED. IF ANY DISTURBED AREA EXISTS AFTER REMOVAL IT SHALL BE COVERED WITH TOPSOIL AND REVEGETATED/STABILIZED IN A MANNER APPROVED BY THE LOCAL JURISDICTION. 1. ALL REVEGETATION WORK PERFORMED SHALL FOLLOW REQUIREMENTS NOTED BELOW. REVEGETATION OF ALL DISTURBED AREAS AND CUT/FILL SLOPES SHALL OCCUR IMMEDIATELY AFTER GRADING INSTALLATION IS COMPLETED. 2. DISTURBED AREAS INCLUDING CUT/FILL SLOPES, STAGING AREAS, SHALL BE REVEGETATED WITH A NON -IRRIGATED SEED MIX. CONTRACTOR SHALL PROVIDE THE SEED MIX SUBMITTAL FOR REVIEW AND APPROVAL BY THE ENGINEER OF RECORD AND GARFIELD COUNTY PRIOR TO CONSTRUCTION. REVEGETATION REQUIREMENTS - SEEDING * ALL SEED MUST BE CERTIFIED WEED FREE. NO SEED CAN CONTAIN ANY SPECIES ON THE COUNTY OR STATE NOXIOUS WEED LISTS: * A VIABLE SEEDBED MUST BE PREPARED BY EITHER DISKING OR HAND RAKING. * PURITY TAGS MUST BE SUBMITTED TO COUNTY STAFF PRIOR TO INSTALLATION. * A SEED DRILL SHOULD BE USED ON SLOPES THAT ARE LESS THAN 2:1, AND THE DRILL TUBE SPACING SHOULD BE 6-7 INCHES SEED INTO THE SOIL. * SEEDING RATE: IF A SEED DRILL IS USED, 6-10 PLS/ACRE. OTHERWISE, 8-12 PLS/ACRE. * ON SLOPES THAT ARE GREATER THAN 2:1 WHERE DRILLING THE SEED IS NOT PRACTICAL, HAND RAKING IS REQUIRED TO INCORPORATE THE SEED ONTO THE SOIL. * A PLANTAGO-BASED TACKIFIER OR SIMILAR, APPROVED PRODUCT MUST BE APPLIED ON ALL MULCH AT THE RATE OF 150 LBS. PER ACRE TO PREVENT WIND FROM BLOWING STRAW OFF THE REVEGETATED AREAS. * THE SITE MUST BE MULCHED WITH WEED -FREE MULCH AFTER PLANTING. MULCH SHOULD BE APPLIED AT THE RATE OF 2 TONS PER ACRE. "EXISTING CDPHE STORM WATER PERMIT SHALL BE AMENDED WITH UPDATED GRADING PLAN. 1 OPRIS ENGINEERING, LLC. CIVIL CONSULTANTS 502 MAIN STREET CARBONDALE, CO 81623 (970)704-0311 FAX:(970)-704-0313 DESIGNED BY AD 1 2/14/22 DRAWN BY AD 2/14/22 CHECKED BY YN 3/01/22 DATE. 03-01-22 JOB NO. 19137.01 Lu G LU 2 0 Q 5� G Lu z 0 I..r� V 8377 -01-202' >L Cyln A, DATE I REVISION TITLE GRADING & EROSION CONTROL PLAN Know what's below. DRAWING NO. Call before you dig. CALL 2-BUSINESS DAYS IN ADVANCE 1 0 F 1 BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES