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REV: 10-05-2022 VR <br />rate for each individual injection point to range between 3 and 5 gpm per <br />interval. The ZVI slurry injection shall require an estimated initiation pressure <br />between 70 and 110 psi with a target maintenance pressure of 65 to 80 psi. <br />Consultant shall adjust injection volumes and pressures based on actual <br />injection rates encountered in the field. <br />1.2.2. Drilling and Delivery Specifications <br />The ZVI injection points within the PRB Emplacement Area shall be installed <br />by Consultant via a direct push drill rig. Prepared ZVI slurry shall be placed <br />in a top down injection process at 2-foot intervals. The depth of injection for <br />consecutive rows (odd vs even) shall be off-set in depth by 1-foot to produce <br />a staggered vertical profile to allow overlap of emplacement areas. <br />Consultant shall use a drill rig to advance 1.5-inch direct-push rods equipped <br />with an injection tip through the pre-cleared borehole location to the pre- <br />determined total depth. Injections shall span vertically from 6 to 18 ft bgs, or <br />7 to 19 ft bgs, to develop the aforementioned staggered vertical injection <br />scenario. Adjacent rows of injection points shall be offset (odd vs even) for a <br />zig-zag pattern and shall run perpendicular to the inferred direction of <br />groundwater flow. The Drive rods shall be advanced through pre-cleared <br />boreholes to the initial shallow depth. The PRB probe points shall be located <br />in the designated PRB Emplacement Area and properly set back from the El <br />Camino Real sidewalk and trees to avoid damage to existing structures or <br />features. <br />Consultant shall specify and adhere to any required or proposed set-back <br />distances from public sidewalks, trees or other private property structures or <br />features required to perform the work. This includes, but is not limited to, a <br />minimum 2 feet setback from the sidewalk to avoid irrigation systems in the <br />landscape island for this area. Consultant shall use flow meters and pressure <br />gauges to control injection volume and pressures and measure groundwater <br />from monitoring wells during injections. Based on injection point feedback, <br />targeted injection depths, reported ZVI volume and pressures, the Consultant <br />shall calculate and field-verify the targeted radius of influence and distribution <br />of reagent. <br />Once injection of ZVI is completed at each DPT probe location, the temporary <br />push point shall be properly sealed at surface with a cement grout, concrete <br />(blackened if necessary) or asphalt patch, to match existing conditions and <br />cover types. <br />Consultant shall use flow meters and pressure gauges to control injection <br />volume and pressures and make every effort to minimize daylighting of <br />reagents. Consultant shall document injection point feedback, injection <br />depths, ZVI volumes, and pressures at each injection point. Mixing of slurry <br />to meet injection load/mass requirements per interval shall be the <br />responsibility of the Consultant. If ground heave or flow back (daylighting) is <br />encountered during injection, the Consultant shall stop injection immediately <br />and evaluate options with the site representative for repair, cleanup, and <br />adjustment to the injection pressure and flow rate, and/or an alternate push <br />probe location. <br />1.3. “D” Wells Area: Enhanced Reductive Bioremediation (ERB) <br />ATTY/AGR.2022.348/Regenesis Bioremediation Products (Page 15 of 34)