GENERAL51208 - Laserfiche WebLink

Home Browse Search

Memo to Berhaa Keffelew CRESSON Leak Collection Audit page 3 required to quantify, record and report the volume of fluids pumped from the leak collection sump. Further, the operator is required to sample and analyze the water chemistry of the leak collection effluent. During my February 3, 1995 inspection, I inspected the leak collection pipelines, controls pressure transducer readouts and flow meter. Two submersible pumps are installed through 6 inch plastic pipe from the southern rim of the heap leach pad. Cresson has encountered difficulty placing these pumps into operation. John Hardaway reported that they had been removed seven times for modifications. He believed they would be fully operational by the following day. John reported that as of February 3rd the pumps have been activated four times with a total of 7700 gallons of effluent being returned to the heap fluid circuit. During their inspection on February 17, 1995, Messrs. Keffelew and Long were informed by John Hardaway that additional fluid had been pumped from the leak collection sump, at an increasing frequency. However, John also informed them that CC&VG had determined that the flow meter was reading erroneously high because of air entrained in the effluent flow. CC&VG had grossly recalibrated the flow rate based on simple volumetric measurements during pumping episodes. However CC&VG had not reduced the recalibrated flow volumes. During my February 3rd inspection, John Hardaway indicated that samples of the effluent are collected by CC&VG each time the pumps are activated. Field determinations for Cyanide are made by CC&VG using a simplistic HACH test kit. Samples are then submitted to Accu-Labs Cyanide analysis, which routinely requires a month or more for reporting. As of February 3rd only one analytical set of results, for a sample collected two days after fluid from ponds 5 and 5A was first applied to the ore. Mr. Hardaway postulated that this initial fluid is largely remnant from precipitation which fell during construction and was entrained while the leak collection filter layer was open to the environment. During the February 17th inspection, John reported to Berhan and Mike that the Cyanide concentration in the leak collection effluent has been increasing. Leak Collection Audit As I mentioned in concluding my introduction, I believe it would be appropriate for CC&VG to complete an audit of the fluid collected by the leak collection system. The permit does not specify the performance of this audit. In light of the fact that remedy of any liner or leak collection system problems will become increasingly difficult as more ore and processing fluid are placed on the pad, it is important to verify proper operation as early as possible.