Laserfiche WebLink
Permit Area <br />9.35 Acres <br />I.1 <br />9860 <br />9855 <br />9850 <br />9845 <br />9840 <br />9835 <br />9830 <br />P�� <br />"' e�5 <br />6 <br />A <br />Stormwater Storage Depth <br />r 74 <br />ACTIVITY <br />MEMBER <br />Free Board <br />:. <br />Note:(>I.Sft 12 ft wide Vol 9.300 cu ff 70k out <br />TOTAL DISTURBED AREA <br />„2211IR <br />„/„//////,//////////,,,/„//,//// <br />SCS RUNOFF CURVE VALUES (CM <br />UNDISTURBED AREAS 42 DISTURBED AREAS 52 CONCRETE-ROOF98 <br />SECTION A -ACROSS WORKING AREA AND STORMWATER STORAGE AREA <br />(SECTION IS TYPICAL AND LOCATION WILL VARY) <br />RECEIVED <br />JUN 0 2 2015 <br />DIVISION OF RECLAMATION <br />MINING AND SAFETY <br />NO FLOW DESIGN NECESSARY OF ACCESS ROAD <br />ENGINEER'S CERTIFICATION <br />This report was prepared by the Engineer who's signature appears below or <br />the engineer's directs Pe i i0 <br />E:q). <br />SIGNATUR�/ <br />No. 22601 q <br />DATE: <br />Shaft <br />9975 — ■ <br />SITE DESCRIPTION <br />MINERAL MOUNTAIN PROJECT <br />ACTIVITY <br />UNDERGROUND MINE <br />TOTAL MINE PERMIT AREA <br />9.35 ACRES <br />TOTAL DISTURBED AREA <br />HISTORICAL DISTURBANCE -4.4 ACRES <br />NEW DISTURBANCE- LESS THAN 0.3 ACRES <br />SCS RUNOFF CURVE VALUES (CM <br />UNDISTURBED AREAS 42 DISTURBED AREAS 52 CONCRETE-ROOF98 <br />DISCRIPTION OF DISTURBED AREAS <br />ROAD SURFACES CONSIST OF POORLY GRADED MDCTUREOF ROCK UPTO SIN <br />DA. HISTORIC MINING DISTURBED SURFACES INCLUDE LEVELED AREAS AND <br />WASTE ROCK PILES <br />DESCRIPTION OF NONDISTURBED VEGETATION AREAS <br />TIMBER COVERED WITH GRASSES AND SHRUBS MIXED IN LESS SHADED AREAS <br />POTENTIAL POLLUTION SOURCES TO STORMWATER <br />NO POLUTION SOURCES - NO HAZARDOUS GEOLOGIC SUBSTANCES, NOOPBJ <br />CONTAINERS OR CHEMICALS STORED OUTSIDE <br />LOCATION OF NON-STORMWATER DISCHARGE <br />NO SOURCES KNOWN <br />NAME AND LOCATION OF PEDEV ING WATERS <br />DISCHARGE TO UNNAMED NORTH -TRENDING DRY GULCH - GULCH CONNECTS TO <br />SPRING CREEK, AN INTERMITTENT STREAM A DISTANCE OF 2,200 FEET <br />NORTHWEST OF THE PERMIT A REA. <br />RESULTS OF CALCULATIONS <br />MAXIMUM SURFACE FLOWS - 24 -HR 100 -YR EVENT <br />NO DIVERSION POINTS NECESSSARY. ALTHOUGH NOT REQUIRED PER <br />REGULATIONS, WORK SURFACE BERM HAD GAPABILTFY OF RETAINING 300 <br />PERCENT OF ENTIRE 10 -YEAR 24 STORM EVENT RUNOFF FROM DISTURBED <br />GROUND ANDOVER 200 PERCENT OF 100 -YEAR 14 HOUR EVENT. DISCHARGES <br />VA RAPID INFILTRATION INTO WORK AREA SURFACE <br />NEW PRECIPITATION WATER GENERATED BY OPERATION <br />2.47 INCHES PRECIPITATION PRODUCES MAXIMUM VOLUME OF 140 CUBIC FEET <br />(NEW DISTURBANCE) (CN= 98) <br />WITH NO FLOW BEYOND SURFACE SHEET FLOW WTTHN CONTAINED AREA FOR <br />(BUILDINGS AND CONCRETE SURFACES ASSOC WITH <br />24-HOUR 10-Y EAR EV ENT <br />CURRENT OPERATION - 700 SQ FT TOTAL) <br />VOLUME GENERATED ON OLD DUMP SURFACE - OLD <br />2.47 INCHES PRECIPITATION PRODUCES 2,700 CU FT FOR THE 10 -YEAR EVENT <br />DISTURBANCE (CURRENT WORK AREA) (CN = 52) <br />TOTAL AREA - 22,000 SO FT <br />TOTAL CALCULATE) STORMWATER GENERATED WITHIN <br />2,850 CU FT (SUM OF BUILDING RUNOFF PLUS HISTORIC GROUND SURFACE) <br />CURRENT WORK AREA (10- YEAR STORM) <br />RLN -OFF STORAGEAREA CAPACITY <br />9,300 CU FT ATA DEPTH OF 18 IN (7,000 SO FT TYPICAL) <br />ANTICIPATED DEPTH OF FILL TO 6 INCH FOR 10 -YEAR EVENT <br />FACTOR OF SAFETY OF 3 INCLUDES VOLUME FOR NEW RUNOFF ASSOCIATED <br />WITH PERK417BD OPERATION PLUS RUNOFF FOR HISTORIC DISTURBANCE <br />DESIGN DETAILS <br />1. STORMWATER CONTAINMENT AREA TO CONSIST OF GENTLY SLOPING DEPRESSION MAINTAINED WITHIN THE WORKING AREA <br />DESIGNED TO CONTAIN THE CALCULATED VOLUME GENERATED BY RUNOFF FROM THE 10 -YEAR STORM EVENT. BOTTOM AND SIDES ARE <br />SUCH TO ALLOW COLLECTED STORMWATER TO BE RELEASED VA NFILTRATION. BERM SPECIFICATIONS INCLUDEA HEIGHT OF 2.0 FEET <br />AND A WIDTH OF NO LESS THAN 2.0 FEET AT A DISTANCE OF 1.5 FEET BELOW THE CREST. THE BERM IS TO BE LOADER- PLACED AND <br />COMPACTED AND SHALL BE COMPOSED OF POORLY SORTED NATIVE MATERIALS SIZED FROM CLAY TO MINUS 4 INCHES. THE STORAGE <br />AREA SHALL BE SUCH THAT A FREE BOARD OF 1.0 FEET WILL BE MAINTAINED. CONTAINMENT IS RECOMMENDED BUT NOT REQUIRED BY <br />REGULATION AT THIS TIME HOWEVER, IF ACID GENERATING ROCK SHOULD BE STORED ON SURFACE, STORMWATER RETENTION SHALL <br />BE MANDATORY. <br />2. NORUN-ON DIVERSIONS ARE NECESSARY, AS TOTAL DISTURBED AREA IS SOSMALL. UPGRADIENT SEDIMENTATION AREAS AND <br />DIVERSIONS IN THE FORM OF ROADS AND TRA LS ARE ALREADY INPLACE CONSTRUCTION OF ADDITIONAL STRUCTURES WOULD ADD <br />LFTTLE INCREASE N PROTECTION AND ONLY INCREASE AREA OF DISTURBANCE THE MAIN ACCESS ROAD SERVESASADNFRSONFOR <br />TOPOGRAPHICALLY UPGRADIENT SHEETFLOW WATERS GENERATED TO THE SOUTH AND DIVERTS THEM TO EASE NO OTHER RETENTION <br />PONDS, LINED OR UNLINED CHANNELS, OR OTHER RUN-ON AND RUN-OFF CONTROLS, OR OUTLET CHANNELS ARE NECESSARY FOR THIS <br />STE, AS ANY COLLECTED SURFACE WATERS ASSOCIATED WIT -1 THE NEW DISTURBANCES ARE DISSIPATED VIA INFILTRATION. <br />3. PERMANENT OR TEMPORARY SOIL STABILIZATION MEASUI SHALL BE APPLIED TO NEWLY DISTURBED AREAS NO LONGER TOBE <br />USED WITHIN 30- DAYS AFTER USE HAS CEASED. IT IS RECOMMENDED THAT PERMANENT SEED MIX IS TO BE APPLIED NO EARLIER IN THE <br />YEAR THAN NOVEVBER AND NO LATER THAN MAY TO MAXIMIZE GERNINATION OF SEE). THE APPROVED MDC SHALL BE APPLIED AT RATES <br />RECOMMENDED BY THE ENGINEER AND SEED VENDORS. <br />4 A SEDIMENT DISSIPATION AREA IS TO BE LOCATED DOWNGRADIENT OF THE WORKING SURFACE AND SERVE ASA BACKUP FOR FOR <br />SEDIMENTOONTROL THE DESIGN CONSISTS OF A NEAR -LEVEL ROAD SURFACE TO COLLECT SEDIMENTS. ALL CONTROLS, ARE TO BE <br />MAINTAINED FOR THE LIFE OF THE PROJECT. <br />5. AREAS WHERE FINE GRAINED SOILS ARE SUBJECT TO EROSION SHALL BE PROTECTED USING SILT FENCE, PLANTEDGRASSES, <br />CRIMPED MULCH, OR OTHER SUITABLE MEANS. <br />RECEIVED <br />JUN 0 2 2015 <br />DIVISION OF RECLAMATION <br />MINING AND SAFETY <br />