Laserfiche WebLink
Geosyntec <br /> consultants <br /> 6. DATA GAPS INVESTIGATION <br /> The hydrogeologic CSM, EVS® model, and MAROS evaluation were used to evaluate <br /> data gaps at RRI. The following data gaps were identified, which are discussed in more <br /> detail below: <br /> • Recent surveyed top of casing elevations for RRI wells and piezometers; <br /> • Water quality in surface water drainage channels; and <br /> • Lateral and vertical extent of VOCs in groundwater in areas where existing data <br /> does not define the extent. <br /> 6.1 Top of Casing Elevations <br /> Accurate top of casing elevations are needed to calculate groundwater elevations and <br /> evaluate groundwater flow directions and gradients at RRI.As described in Section 2,the <br /> land surface at RRI subsides over time as the sediments compact,causing the top of casing <br /> elevations to change. The groundwater gradients at RRI are low and small variations in <br /> top of casing elevations may alter the apparent groundwater flow direction. The most <br /> recent surveyed top of casing elevation data currently available in the project database <br /> are from 2007. To address this data gap a licensed land surveyor will survey the top of <br /> casing elevations for the wells and piezometers at RRI that are located and observed to <br /> be in good condition during the field inspection described in Section 5.2. Additionally, <br /> stream gauges located and in good condition based on the field inspection will be <br /> surveyed. The 2018 Annual Groundwater Monitoring report will include an evaluation <br /> of the historic surveyed elevations to the 2018 surveyed elevations. <br /> 6.2 Surface Water Ouality in Drainage Channels <br /> Groundwater at RRI discharges into the surface water drainage channels, as described in <br /> the CSM presented in Section 2. The water quality of surface water in the drainage <br /> channels in areas where groundwater concentrations are above MCLs was identified as a <br /> data gap at RRI. Surface water samples from the drainage channels will be collected for <br /> analysis of VOCs and general chemistry parameters at the following locations, as shown <br /> in Figure 26: <br /> • At Site 3, samples will be collected at two locations(SW-03, SW-04). <br /> RRI Groundwater Monitoring Work Plan 26 1 June 2018 <br />