2022-09-26_PERMIT FILE - M2022042 (6)

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Windsor East Mine, Exhibit G – Water Information September 2022 Page 9 | 11 2.2.1 Water Quality Parameters Martin Marietta will collect water samples from each of the wells and discharge outflow sites and submit the samples to an analytical laboratory to determine water quality for a set of parameters. The DRMS recommends a set of parameters for analysis for aggregate mine permitting. These include a list of dissolved metals, radiological parameters, and miscellaneous parameters which include pH and total dissolved solids (TDS). The nature of activities associated with sand and gravel mining involves excavation of large volumes of aggregate materials using industrial machinery. These activities inherently do not result in the generation or release of coliform bacteria, asbestos, chlorophenol, foaming agents, odor or phenol compounds. They also don’t result in a change in corrosivity of water, or color change. As a result, these parameters which are otherwise a part of the DRMS requirements for water quality analysis are excluded from the list of water quality parameters. Likewise, sand and gravel mining does not lead to the generation or release of gross alpha or beta and photon emitters as part of the operation. Martin Marietta acknowledges the preference on the part of DRMS to have gross alpha radiological analysis performed and will include it in the list, but excludes beta and photon emitters from analysis. Table 5 presents the complete list of water quality parameters proposed for analysis. 2.2.2 Windsor East Monitoring Wells The monitoring plan will consist of regular data collection from the five monitoring wells installed around the perimeter of Windsor East (Figure G-3). Monitoring data will be used to identify potential changes in alluvial groundwater flow or elevation associated with mining and reclamation activities. Baseline data collected from the monitoring program will provide a range of relative water levels associated with pre-mining groundwater conditions. Experience at other sand and gravel mine sites in similar geologic settings shows that groundwater levels tend to fluctuate between two to four feet each year; levels are highest in the summer and lowest in the winter and early spring. Martin Marietta will conduct monthly water level monitoring for the five monitoring wells around Windsor East during dewatering and until groundwater levels have recovered once dewatering ends. Groundwater samples will be collected to document baseline water quality prior to mining, then determine whether any changes have occurred as a result of mining activities. One quarterly water quality sample for laboratory analysis will be collected during each of the five quarters of monitoring to document the baseline water quality around the mine. Based on the historical water level fluctuations observed in the wells associated with the Parsons Mine, the seasonal high and low water levels for groundwater have been evaluated. Water levels are seasonally at their highest elevations in August or September following the irrigation season, and typically at their lowest elevations in February to March when irrigation has been suspended for the longest period of time. During high groundwater levels, the sample is expected to be representative of the groundwater which flows from the agricultural fields toward the river, and during the periods of low groundwater the sample is expected to be representative of alluvial channel water flowing from the west. After five quarters, water quality sample collection will continue to be conducted twice per year while mining, with sample collection timed to be consistent with high and low groundwater levels. The results of water quality sample analysis will be provided to DRMS following the baseline water quality evaluation, and during annual reporting thereafter. Appendix G-3 includes procedures for collecting water samples. These procedures include a process of pumping to purge standing well water, then using the pump to remove water for sample collection, then placing the water in sample bottles obtained from the analytical laboratory. At the end of purging, the pH of the water will be recorded using a handheld pH meter. Samples for dissolved constituents, primarily inorganics and metals, will first be filtered through a 0.45-micron filter to remove suspended solids. Samples will then be stored on ice in a cooler for transport and submitted for analysis of the constituents listed in Table 5 under chain-of-custody protocols. If sufficient data is collected during the life of the mining operation, and a demonstration can be made that project impacts to the groundwater system have been minimized, Martin Marietta may request the approval of a Technical Revision to revise the water level monitoring frequency or water quality sample collection frequency at a later date.