APPCOR12056

• Permit No: C1983058
• IBM Index Class Name: Application Correspondence
• Doc Date: 6/10/1983
• Doc Name: TWIN PINES FINDINGS
• From: MLRD
• To: CAROL RUSSELL AND ED BISCHOFF
• Media Type: D
• Archive: No

III IIIIIIIIIIIII III
DEPARTMENT OF NATURAL RESOURCES 999
D Monte Pascoe E,er, wivn Deep or
MINED LAND RECLAMATION DIVISION
DAVID C. SHELTON, Director
R ¢ha~tl D Lamm
Governor
June lU, 1983
T0: Carol Russell and Ed/Bischoff
FRUM: Bob Liddle /~ ~:^~C•'~
RE: Twin Pines Findings
Ponds, Impoundments, Diversions
Asa result of surface and underground disturbance at the Twin Pines No. 2
i4ine, water discharged from the mine would be high in total suspended solids.
To mitigate this condition, the operator has designed a sediment control
system which will remove suspended solids prior to the water being discharged
to the receiving stream. The final water discharged will be able to meet both
Federal I~PDES discharge requirements, as well as Colorado Department of Health
Receiving Stream Standards. The Division was responsible for reviewing the
sediment control system from both a design and performance standpoint to
ensure that the above standards will be met.
A discussion of the drainage and sediment control system, as well as detailed
engineering designs, can be found in Volume 1, Section 2.U5 and in Volume 2,
Mine Site Plan Map.
The operation utilizes one upland diversion ditch that diverts undisturbed
drainage away from the active, disturbed areas. This practice reduces the
volume of water that comes in contact with disturbed areas and, therefore,
reduces the amount of water needing treatment prior to discharge.
Runoff from disturbed areas is routed to sedimentation ponds through the use
of collection ditches. These sedimentation ponds reduce the levels of
settleable and suspended solids to levels that meet State and Federal
discharge standards. After treatment, the water is discharged back to the
national stream course downstream of the disturbed areas.
One small area (one acre in size) of disturbance does not pass through the
sediment pond system. The area is the upper bench, which is used for the
water tank. There are no activities planned for this bench that would
generate large amounts of sediment. the operator, therefore, proposes to
route the water through a small shallow sediment basin prior to discharge to
the receiving stream. The Division has granted the operator a small area
exemption for this area. The proposed sediment control plan will be adequate
to treat the runoff from this small area. A large-scale pond is not practical
or warranted for the limited extent of disturbance on this bench.
a23 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. [phone]