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CIVIL RESOURCES, LLC ENGINEERS & PLANNERS TECHNICAL REVISION Operations &Water Delivery System Rev.0 DraftF1 Final® TO: Mr. Eric Scott Division of Reclamation, Mines, and Safety 1313 Sherman Street, Room 215 Denver, Colorado 80203 FROM: Civil Resources, LLC DATE: February 2811, 2022 RE: Heit Sand and Gravel Mine, Permit No. M-2003-016 Technical Revision#4—Pump Station Design Memo This memorandum summarizes the proposed Technical Revision(TR)of the Active Construction Permit No. M-2003-016 for the Heit Sand and Gravel mine originally granted September 26, 2004.The proposed TR includes an updated Reclamation Plan which entails the construction of a pump station for future returns to the South Platte River(SPR)via a pipe network.The mine is in Section 13,Township 2 North, Range 67 West of the 61h Principal Meridian in Fort Lupton, Colorado. Specifically, the site is located north of Weld County Road (WCR)20 and West of WCR 25. RECLAMATION PLAN The Reclamation plan concept includes the following: 1. Pump station building including filling the south east comer of the pit at a 4:1 reclamation slope, 2. Gravity delivered pipe to bottom of pump station, 3. 18-inch and 24-inch discharge pipes crossing slurry wall at two locations, 4. 42-inch reinforced concrete pipe (RCP)and 24-inch Ductile Iron Pipe(DIP)crossing the slurry wall discharging to a The proposed pump station will be located at the southeast comer of the Heit Sand and Gravel Mine as shown in Attachment A.This structure consists of a 36-feet deep reinforced concrete well that will house two(2)submersible pumps that will be used to pump water to the 18-inch header at the top of the well.This will merge the pumped water and allow it to be discharged through an 18-inch diameter DIP for return to the SPR.The structure will be 12'-4"wide x 20'-10"long and be constructed on a constant elevation grade of 4855-feet.The maximum water surface elevation of the storage facility is 4849- feet.The structure will have a 24-inch DIP inflow pipe that will deliver water from the SPR. It will also have a 36-inch diameter concrete encased RCP gravity flow line(Inv. El:4820')that will allow the discharge of water in and out of the Heit Pit.This pipe will be filled with the extended 3:1 reclamation slope where it will enter the pit through a flared end section lined 2-feet deep with type M rip rap.The pump station will be enclosed by a 26'x 20' structural CMU block building that will have two(2) 12-foot roll up garage doors for access to the wells and pump station controls/telemetry.The roof of the building will be sloped at a 1:6 appropriate gutters and downspouts for drainage.The specifications will be in Attachment A. In the southeast corner of the Heit Sand and Gravel Mine,the reclamation slope becomes a 4:1 slope instead of a 3:1 slope in order to utilize excess overburden or claystone as fill method. In the southwest corner of the Heit Sand and Gravel Mine,a proposed 42-inch RCP and a 24-inch DIP will cross the slurry wall delivering water from the Little Dry Creek(LDC)to the Heit Storage Facility.The area of crossing will be shallow and be excavated and repaired by the contractor as shown on Sheet 2 Attachment A. Similarly,the shallow inflow and outflow pipes (24-inch DIP and 18-inch DIP)for the pump station will be crossing the existing slurry wall and require excavation and repair from the contractor. B308 COLORAD❑ BLVD, STE 200 0 FIRESTONE, COLORAD❑ 80SO4 0 PHONE: 303.833. 1 41 6