Laserfiche WebLink
r <br /> ' BRANNAN ' <br /> Founded 1906 <br /> To: Eric Scott, Environmental Protection Specialist <br /> Division of Reclamation, Mining and Safety <br /> 1313 Sherman St., Room 215 <br /> Denver, CO 80203 <br /> From: Steve Kelton (skelton@brannanl.com) <br /> Subject: Technical Revision, Morton Lakes(M-2008-082), concerning slurry wall installation <br /> Date: February 3, 2023 <br /> This Technical Revision is submitted to supplement the M-2008-082 permit record with recently <br /> developed information pertaining to slurry wall installation at the referenced Morton Lakes site. No <br /> changes are proposed to the Mining Plan or Reclamation Plan currently approved by Reclamation Permit <br /> No. M-2008-082. <br /> First, Operator Ready Mixed Concrete Company, LLC (a wholly-owned subsidiary of Brannan) is <br /> proceeding with slurry walls for Morton Lakes Stage 7A and 7B.The cost for 7A is$1,440,435.12, and the <br /> cost for 7B is$1,487,037.46, for a total cost of$2,927,472.58 (see attached contract costs as bid by Hall- <br /> Irwin Corporation). These slurry walls will contain, individually, Reservoirs 4A and 4B as depicted on the <br /> approved Reclamation Plan. The beneficial post-mining use and functional aspects of these slurry walls <br /> are as contemplated by the current M-2008-082 Reclamation Permit. <br /> Second, the State Engineer's Office expressed concern in communication with the DRMS that slurry <br /> walls at Morton Lakes Stage 7A and 7B might have negative impacts to the groundwater recharge <br /> facilities.To address those concerns,the Operator hired BBA Water Consultants, Inc.,to model expected <br /> impacts. Per your request,we have attached Hydrogeologic Investigation of the Morton Lakes Site Stage <br /> 7A and 7B Gravel Pit Lining(`BBA Investigation"), dated December 21, 2022. <br /> The BBA Investigation notes that the lining of the Stage 7A and 7B gravel pits during mining will have an <br /> effect on the ground water elevations around the pits causing mounding (higher water levels) in some <br /> areas around the pits and shadowing (lower water levels) in other areas around pits. This mounding and <br /> shadowing are not problematic. After extensive modeling, the BBA Investigation (see p. 5) concludes: <br /> The lining of the pits does not significantly change ground water flow <br /> paths nor restrict ground water flow from interacting with the South <br /> Platte River. The proposed gravel pit lining, therefore, does not impact <br /> local ground water flows including return flows associated with any <br /> nearby existing recharge projects and no additional infrastructure <br /> (including subsurface drains) is required to address any potential <br /> changes to ground water flow paths around the pits. <br /> Existing monitoring practices and water-related permit requirements cover both quantitative and <br /> qualitative concerns under Construction Materials Rules (i.e., Rules 3.1.6 and 3.1.7). The Operator will <br /> continue to diligently monitor and regulate activity at the Morton Lakes site pursuant to these Rules and <br /> Page 1 of 2 <br />