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Mr. John Sliman -2- July 23, 2014 <br /> Therefore,the initial groundwater monitoring for the first few years should be much more <br /> meticulous than the routine monitoring that is described by the program. Several other wells <br /> are located within the estimated dewatering zone of influence that could be monitored to <br /> develop background data. Specifically,well Permit Numbers 11369,46203, 54581,277098, <br /> and 279125 are in the vicinity of Southwest Farms. In addition, existing wells are located <br /> northeast of the pit that could be monitored. Depending on the usage of the existing wells, <br /> Fremont Paving should also consider installing new monitoring wells that are distant from <br /> existing wells so the collected data is not influenced by drawdown in the casings of <br /> production wells. Vicinity observations during the first few years should also be very <br /> thorough to improve reliability of evaluation of groundwater data trends. <br /> Our other specific comments on the program are presented below: <br /> • The proposed monitoring well locations are insufficient for evaluating groundwater <br /> trends on Southwest Farms property. MW#1 and MW#2 (shown on Figure 1 of the <br /> program)are located near the Excelsior Ditch Lateral. Also,a compacted clay cutoff <br /> wall and overburden fines backfill are located between these wells and Evans Pit#2. <br /> These wells could underestimate the groundwater impacts caused by pit dewatering <br /> because of recharge from ditch leakage(when water is being conveyed in the ditch) <br /> and hydraulic barriers formed by the overburden fines backfill and cutoff wall. <br /> • The monitoring frequency is insufficient. The program states that monitoring will be <br /> performed monthly for the first 2 years and quarterly thereafter. We recommend that <br /> monitoring be performed at least biweekly for the first year to identify normal <br /> groundwater trends. After the first year,we recommend that monitoring be <br /> performed at least monthly. <br /> • The program makes no mention about how and when the monitoring data will be <br /> reported to the DBMS. In our opinion. the data should be provided to the DBMS <br /> within 1 week of collection. Also,a report that summarizes the collected data and the <br /> interpretation of the data should be submitted to the DRMS annually. <br /> • The program does not include a contingency plan that would be implemented if <br /> groundwater levels are observed to decline. In our opinion,at a minimum,the <br /> monitoring frequency should be increased if declining groundwater levels are <br /> observed. Ideally, Fremont Paving should also perform computer groundwater <br /> modeling to evaluate whether the pit dewatering is contributing to the declining <br /> groundwater levels. <br /> • The program states the property owner will assume monitoring responsibilities after <br /> October 31, 2014. We assume this means the pit owner, and not Southwest Farms. <br /> In our opinion,the program does not protect Southwest Farms from groundwater impacts <br /> caused by dewatering of Evans Pit#2. The program states that many years' of monitoring <br /> will be required prior to evaluation of the data. This would allow dewatering of Evans Pit#2 <br /> to impact adjacent groundwater levels for many years before action is taken. Also, if <br /> declining groundwater levels are observed, it is likely that Fremont Paving will argue that the <br /> decline represents a historical trend that is related to irrigation, climate change, or factors <br /> 14 1 09-14-07-22-Monitoring-Plan-Commems <br />