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Page 4 January 24,2025 Brusca File No. 260-004 Additional Groundwater Monitoring Well Workplan used for the well. The lower 20 feet of the casing (about ten feet below the water level and ten feet above)will be screened. The screened portion of the well will be factory slotted(0.020-inch slots). The annular space surrounding the screened portion of the well and extending two feet above will be backfilled with washed graded silica sand. A one-to two-foot-thick bentonite plug will be installed and hydrated within the annular space directly above the sand filter, and the remaining annular space above will be backfilled with neat cement grout. A two-inch diameter locking well plug will be installed at the upper end of the well casing, and the top of the monitoring well will be protected with a traffic-rated, flush-mounted vault. The top of the well casing will be surveyed for location and elevation by a licensed land surveyor. Well Development Well development will be performed no sooner than 72 hours following well construction; this will allow adequate time for the grout in the well to set completely. A bailer or surge block will be used to gently tap the bottom of the well to suspend and remove settled particles. Development will be accomplished by pumping; pumping of the well will begin from a depth of about five feet from the bottom of the well and continue until approximately ten well volumes have been removed, and pH, temperature, and conductivity have stabilized. The pump will be raised periodically during development to remove fines from most of the water column. Initial Groundwater Sampling Initial groundwater sampling will be performed at least 24 hours after well development so that aquifer conditions can equilibrate prior to sampling. Prior to sampling, the static water level within the well will be measured with a water level meter to the nearest 0.01 foot. Additionally, the well will be gauged with an interface probe to determine whether free product (NAPL) is present, and if so,to measure the NAPL thickness. Groundwater purging and sampling of the groundwater monitoring well will be performed via low flow (minimal drawdown) micro-purging techniques using a bladder pump and controller. Advantages of this purging/sampling methodology include significant reduction in the sampling- induced turbidity and minimizing the amount of generated purge water. The flow and pump controller will be monitored and adjusted to establish optimum flow, and the groundwater depth within the well will be continuously monitored to minimize drawdown. The temperature, pH, conductivity, dissolved oxygen, oxygen reduction potential, and turbidity of the well water will be measured using a flow-through cell and parameters meter during purging of the well. Following stabilization of the water quality parameters, a groundwater sample will be collected via the tubing used for purging;the groundwater sample will be pumped directly into laboratory- provided sample containers (VOAs), labeled, placed on ice, and logged onto a chain-of-custody form prior to transport to the analytical laboratory. Equipment Decontamination and Investigation Derived Wastes Decontamination will include thoroughly cleansing and rinsing drilling, purging, measuring, and sampling equipment. Additionally, soil cuttings and wastewater generated during well installation, development and sampling will be containerized in 55-gallon drums and stored on the subject property pending disposal.