REV104135 - Laserfiche WebLink

Home Browse Search

Now that BMRI is allowed to discharge processed water into the Rito Seco (fronp the nano- filtration system) the primary goal of TR-26 seems to be moving forward. As of December, 1, 1999, the water level in the West pit has been lowered to a msl of 8592 feet in just a few months. Continued pumping of the backfill aquifer will result in a water level of 8580 feet msl in just a couple more months (estimated at 56 days at a rate of 400 gpm). Water sample test results from the backfill monitoring wells indicate that the water quality in the West pit appears to be improving; at least for manganese, sulphate and TDS, which is good news. The arithmetic average of manganese, sulphate and TDS in January, 1999 for 5 backfill wells (BF-2, BF-3, BF- 4, BF-5 and BF-6) was 6.27 mg/I, 818 mg/I and 1346 mg/I respectively. In October, 1999, the average was 3.93 mg/1, 680 mg/1 and 1000 mg/I respectively for the 5 wells. Realizing this is early on in the clean up process, and conditions can change as seasons change, i[ does appear that the approved processing systems are slowly correcting the problem as TR-26 was designed to do, and that the partial approvals were justified. Second, the Division still agrees that the site must be fully covered by financial assurances and the Division is diligently working towazd that end. Attached is a draft copy of the required tasks and cost estimates for the remaining reclamation obligations at the San Luis Project (this does not include the estimated West pit water management costs; they will be submit[@d separately). For now, the DMG is not evaluating [he cost of a slurry wall because, as previously noted, this type of structure has not been proposed to, or approved by, the DMG. The DMG is aware of Rule 4.2.1 and will take into account all expected costs of teclamation and will ensure that the amount of financial warranty shall be sufficient to fulfill the applicable requirements of the reclamation plan which will include measures to protect water resources. Third, as previously mentioned, BMRI has not submitted a proposal to install a slurry wall in, or near, the West pit. There have been discussions between BMRI and the DMG regarding the installation of a slurry walUhydraulic barrier, but no official proposal. It is just another alternative being considered by BMRI. Fourth, transportation of West pit water to the tailings impoundment was approved to allow BMRI to initiate a continuous pumping operation at the West pit in order to meet one of the requirements of TR-26; which is to lower the water level in the backfill material. BMRI did not have enough room at the West pit facility to store all the water that was being purytped since the processed water (from the nano-filtration unit) could not be dischazged to the Rito Seco. The water that was transported to the tailings impoundment was used to irrigate the recently vegetated areas in the impoundment which, of course, enhanced the evaporation process. Question- "How long will the pit water be sent to the tailings facility?" Response - Probably as long as the nano-filtration facility is being used to process the West pit backfill water. It may be necessary to pump the pit water to the tailings impoundttnent during those infrequent times that the nano-Filtration equipment is totally shut down for thtaintenence or for repairs so the[ the water level in the pit can be maintained at the 8580 feet msl elevation.