2012-02-28_REVISION - M1980244 (60)

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Historic # Recreation _ Buffer Bndy. ~° .,_ / es Pond a receives Runoff from Emergency - ! South Tributary Spillway North tributary is bypassed around �� tructure y Spillway Riser between Ponds / /Pond b Receives Runoff _ from South side 3 EMP -022 i Plan View 1" =100 ft (DSize) Total Buffer Encroachment 1.2 Acres Minimal Area outside Historic Recreation Buffer 70 i Historic Recreation - Buffer Bndy. 92- `I\ From Basin PG Al 2�EMP -021 Plan View 1" =100 ft (DSize) I 17058 Cut I� Historii'c & 6506 fill 7— Not Net Shortage 552 .� Recreation Capacity ond EMP -096 ty 2.8 AF / 2447 Cu I 2993 fill t Buffer Bndy. . Net Excess 543 Capacity 1.6AF 111 ire Lower South Ditch Flow from Basins PG -B1 and PG -C1 V 1 EMP -009 Four Ponds, a, b, c, and d Plan View 1" =100 ft (DSize) ow from Basin PG -E1 Pond EMP -09 c North Ditch is Grade Ditch on 10120 ! Primarily an .. Follows Old Inside of Existing 10120 �. interceptor, abandoned rade Roadway 10080 not a conveyance 10080 - -- 1aa4o 10000 ch�ncl I - I - �` 10000 996 PROFILED, Sht.5 South Ditch L ° t - 9960 992E o - - into EMP -09a 9`6 ° - 9920 9880 North Ditch - 9880 t EMP -09b -- t j 9840 mo ' --� - t ��; -_ - 3.q4!° YP) 9317 Cut ,- -- PROFILE 9840 LE C, Sht S - -� -i 2842 rill a \\ Net Excess 6476 � Capacity 3.9 AF Pond EMP -09 c North Ditch is Grade Ditch on 10120 ! Primarily an .. Follows Old Inside of Existing 10120 �. interceptor, abandoned rade Roadway 10080 not a conveyance 10080 - -- 1aa4o 10000 ch�ncl I - I - �` 10000 996 PROFILED, Sht.5 South Ditch L ° t - 9960 992E o - - into EMP -09a 9`6 ° - 9920 9880 North Ditch - 9880 t EMP -09b -- t j From Basins PG B1 and PG F1 XEdge of Schist Island Mine Area and Backfill Note: All but Pond 009a will be eliminated in 2017 and must be reconstructed in 2018 when backfill begins Natural Channel Tributary Flow RAM e -, A Pond EMP -09 d 4100 Cut 1500 rill Net Excess 2600 Capacity 1.7 AF Profile F, Sht. 5 EMP -21 F Profile E 10120 _ 1.35% - - 10120 � '! 1- 10080 10080 Z? 10040 Oro , o 10040 10000 5.850/0 - 0.17% I 10000 996 rn o o- er rn N N- 9960 co Ln DATUM ELFV � o � 6 �1 � � � M ai n rr � K o0 _N � z 9920 0 0 0 0 0 0 0 ��o Q— 9900.00 Q � � � � 9900. 00 0 0 0 0 0 0 0 0 0 rn o rn rn 0+00C rn z rn rn 30 +00 25 +00 20 +00 15 +00 10 +00 5 +00 0 +00 5 +00 10 +00 r, PROFILES E & F - Upper South and North Ditches to EMP -21, to replace EMP -08a in 2014 Profile View 1" =500 ft (DSize) EMP -08a 90280 -3 "52% (Av �� to serve asDetention -- 9) Pond 10240 10200 Open Ditch Graded on Existing 10160 d �oa,dways Qo ® - ai o CO N N co DATUM FLF it rn Lci r\ ii, tr, 2, N �- .� c� on co �n L , c, M 10100.00 N N N N N N N N N N N N n N, n r .1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 !+ P n n n n P n P n n P ti A P e+ n P n F+ 0 +00 5 +00 10 +00 15 +00 20 +00 25 +00 30 +00 35 +00 40 +00 45 +00 4 PROFILE G- Poverty Gulch /Schist Island - Upper Ditch to EMP08a Profile View 1" =500 ft (DSize) Notes and General Specifications: I. Ditches along access roads should generally be triangular cross - section to facilitate cleaning with a road - grader. The dimensions of ditches are listed on Sheet 5, along with the expected armoring requirements (3" Riprap, 6" Riprap or vegetated channels). The freeboard is calculated to include a minimum of 6- inches at the 100 year calculated discharge plus the velocity head depth. 2. EMP Ponds and their embankments are intended to be watertight because of their proximity to high walls of the mining areas and to the Historic Recreation Buffer Zone. Accordingly, they shall be constructed to conform to the following general specifications: a. Remove soils within the footprint of the pond area down to suitable non - organic soils with no less than 15 -20% fines ( <200 mesh). Proof roll the footprint and compact as needed to achieve a target density of no less than 90% in the basin and no less than 95% Std. Proctor in the embankment. b. Select soils for the embankment that have at least 15% fines. Place and compact the embankment soils in 8 -inch maximum loose layers and compact to at least 95% Std. Proctor density. c. Maximum slope of embankment shall be 2:1. Maximum slope inside sediment basin shall be 1.75:1. Maximum slope of reseeded areas shall be 3:1. 3. An emergency spillway shall be constructed at each pond with a finished invert elevation approximately 2.0 feet lower than the crest and abase width of 6.0 feet The spillway shall be armored with 6 "angular nprap place on 6- inches of sandy - gravel bedding and a layer of Minfi drain fabric. 9840 mo ' --� - t ��; -_ - 3.q4!° YP) ,- -- PROFILE 9840 LE C, Sht S - -� -i DATUM FLFV 980Qfl d � 00 o s_ o o � o r\ o `n m N N L0 N. 9800 - 9750. 00 9761 0 ° 0 o o 0 0 �v rn rn w °��r °' rn rn rn rn d 00 00 co r�co- -� 0) 0) 01 aoi 15 +00 10 +00 5 +00 0 +00 5 +00 10 +00 15 +00 20 +00 25 +00 30 +00 .35 +00 6 PROFILES C & D - Lower North Ditch Cross Country to EMP -09 and Lower South Ditch along Access Road to EMP -009 Profile View 1 " =500 ft (DSize) - - From Basins PG B1 and PG F1 XEdge of Schist Island Mine Area and Backfill Note: All but Pond 009a will be eliminated in 2017 and must be reconstructed in 2018 when backfill begins Natural Channel Tributary Flow RAM e -, A Pond EMP -09 d 4100 Cut 1500 rill Net Excess 2600 Capacity 1.7 AF Profile F, Sht. 5 EMP -21 F Profile E 10120 _ 1.35% - - 10120 � '! 1- 10080 10080 Z? 10040 Oro , o 10040 10000 5.850/0 - 0.17% I 10000 996 rn o o- er rn N N- 9960 co Ln DATUM ELFV � o � 6 �1 � � � M ai n rr � K o0 _N � z 9920 0 0 0 0 0 0 0 ��o Q— 9900.00 Q � � � � 9900. 00 0 0 0 0 0 0 0 0 0 rn o rn rn 0+00C rn z rn rn 30 +00 25 +00 20 +00 15 +00 10 +00 5 +00 0 +00 5 +00 10 +00 r, PROFILES E & F - Upper South and North Ditches to EMP -21, to replace EMP -08a in 2014 Profile View 1" =500 ft (DSize) EMP -08a 90280 -3 "52% (Av �� to serve asDetention -- 9) Pond 10240 10200 Open Ditch Graded on Existing 10160 d �oa,dways Qo ® - ai o CO N N co DATUM FLF it rn Lci r\ ii, tr, 2, N �- .� c� on co �n L , c, M 10100.00 N N N N N N N N N N N N n N, n r .1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 !+ P n n n n P n P n n P ti A P e+ n P n F+ 0 +00 5 +00 10 +00 15 +00 20 +00 25 +00 30 +00 35 +00 40 +00 45 +00 4 PROFILE G- Poverty Gulch /Schist Island - Upper Ditch to EMP08a Profile View 1" =500 ft (DSize) Notes and General Specifications: I. Ditches along access roads should generally be triangular cross - section to facilitate cleaning with a road - grader. The dimensions of ditches are listed on Sheet 5, along with the expected armoring requirements (3" Riprap, 6" Riprap or vegetated channels). The freeboard is calculated to include a minimum of 6- inches at the 100 year calculated discharge plus the velocity head depth. 2. EMP Ponds and their embankments are intended to be watertight because of their proximity to high walls of the mining areas and to the Historic Recreation Buffer Zone. Accordingly, they shall be constructed to conform to the following general specifications: a. Remove soils within the footprint of the pond area down to suitable non - organic soils with no less than 15 -20% fines ( <200 mesh). Proof roll the footprint and compact as needed to achieve a target density of no less than 90% in the basin and no less than 95% Std. Proctor in the embankment. b. Select soils for the embankment that have at least 15% fines. Place and compact the embankment soils in 8 -inch maximum loose layers and compact to at least 95% Std. Proctor density. c. Maximum slope of embankment shall be 2:1. Maximum slope inside sediment basin shall be 1.75:1. Maximum slope of reseeded areas shall be 3:1. 3. An emergency spillway shall be constructed at each pond with a finished invert elevation approximately 2.0 feet lower than the crest and abase width of 6.0 feet The spillway shall be armored with 6 "angular nprap place on 6- inches of sandy - gravel bedding and a layer of Minfi drain fabric.