PSA - Groundwater Remedy and Quarterly Sampling Plan - Oliver Industrial Park - Hull and Assoc.

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Hull & Associates Inc. Page 7 PRB-C PRB-C encompasses approximately an area of 16,328 square feet. This area will be treated with a 25 foot vertical contaminated zone from 20-45 feet below ground surface (bgs). An injection radius of 20 feet is proposed to treat the area. Based on the area to be treated and the injection radius, 13 injection points would be required to treat the area with 5 injection intervals at 23-25, 28-30, 33-35, 38-40 and 43-45 feet bgs. Soil concentrations are assumed to be moderate to low in PRB-3 based on groundwater concentrations present, therefore, soil absorption correction is moderate to low (IET has assumed the value to be 5%). SCOPE OF SERVICES 1. SATURATED ZONE INJECTIONS The following sequence will be followed when injecting into the saturated zone in the on -site and off -site treatment areas. 1. Subsurface Pathway Development Initially, nitrogen gas shall be delivered to the subsurface via IET proprietary injection trailer system. Nitrogen gas is used so as not to introduce oxygen into an environment targeted for anaerobic processes. The gas is introduced at approximately 175 psi such that delivery pathways and voids are established. Pathway development shall be verified by observing a substantial pressure drop. 2. Sodium Sulfite, Nutrient and Micro Nutrient Injection A solution of sodium sulfite, nutrient and micro nutrients (riboflavin and vitamin B-12) are immediately injected into the subsurface fractures and voids that were developed during the gas injection step. Sodium sulfite acts as an oxygen scavenger, iron reducer and sulfate source. As an oxygen scavenger, the sodium sulfite prevents the oxidation of the ZVI by the dissolved oxygen while promoting anaerobic conditions that are favorable for the biodegradation of the CVOCs. Nutrients, injected as organic ammonia and ortho-phosphate, are required for the maintenance of the microbial metabolic pathways, ATP/ADP synthesis and organelle development. 3. ZVI and Provect-IR Injection ZVI and Provect-IR are injected immediately following the sodium sulfite/bioslurry solution to reduce concentrations of dissolved -phase CVOCs while providing for rapidly generated hydrogen for the microbial stimulation.