WORK PLANS - Laserfiche WebLink

Home Browse Search

Nutrien Ag Solutions, Inc. - 2 - 18 December 2023 construction issues, such as fouling, MW-9 will be installed and monitored after development. If the pH remains above 9 and 1,2,3-TCP concentrations are similar to those recently observed in MW-6RR, the Work Plan indicates a lactic or citric acid solution will be injected into groundwater to create an environment that supports denitrifying and dechlorinating bacteria. Once monitoring results indicate a stable pH at a safe level for these bacteria, a carbon source will be injected upgradient of MW-9 to support EISB. To address elevated nitrate concentrations in MW-3R, the Work Plan proposes injecting RNAS Remediation Product's Newman Zone, a carbon source intended to stimulate anaerobic microbial respiration of nitrate. Should the groundwater become sufficiently anaerobic as a result of adding Newman Zone to the treatment area, reduction of 1,2,3- TCP through biotic and abiotic pathways is a possible secondary effect. Injections are proposed up-gradient of MW-3R, and possibly in the northern corner of the Site, pending results from installing and monitoring MW-9. Exact specifications will be finalized in the forthcoming Notice of Intent for coverage under Order R5-2015-0012, General Order for In-Situ Groundwater Remediation and Discharge of Treated Groundwater to Land (General Order). Monitoring of MW-9 is anticipated to have happened prior to issuance of a Notice of Applicability which would permit EISB injections upgradient of MW-9 and/or MW-3. Upgradient of MW-3, and potentially MW-9, seven temporary injection wells will be advanced to 70 feet bgs using a truck-mounted direct-push drilling rig. At five-foot intervals and in each boring, three injections will occur between 55 feet bgs 70 feet bgs. A mixture of 200 pounds of Newman Zone and 420 gallons of water — per the manufacturers specification — will be applied to each boring, distributed approximately evenly between the three application depths. This material will be injected at a rate and pressure not to exceed 20 gallons per minute and 50 pounds per square inch, respectively. Upon completion, the temporary wells will be tremie grouted with neat cement and drill cutings stored in 55-gallon drums for characterization and disposal. Site monitoring wells will be sampled prior to conducting the pilot test, which will serve as a baseline. Following implementation of the pilot test, samples will be collected from the Site monitoring wells monthly for six months, followed by quarterly for one year, and incorporated into the semi-annual monitoring routine thereafter. Monitoring wells MW- 5R and MW-8R are intended to serve as compliance wells and MW-4 will serve as a background well, in respect to the General Order requirements. Central Valley Water Board concur with the proposed Work Plan, including the monitoring well replacement and EISB specifications. Please proceed with the destruction of monitoring well MW-6RR and installation of monitoring well MW-9 and notify Central Valley Water Board staff of the field schedule at least 48 hours in advance. Injection well construction and application of Newman Zone at the Site may