Significant Project Features:
- CVOC Contaminated Zone Remediation with the use of Zero Valent Iron (ZVI) and Bentonite;
- ISS using Delmag RH-28 drill rig
- Target mixing depth of 45’ BGS
- 10,304 CY of soil mixed
- Target ZVI Addition of 1.25% by weight of soil
- Target bentonite addition of 1% by weight of soil
Background
Geo-Solutions completed an in-situ Chemical Reduction (ISCR) project at a former dry cleaning site. The site is located at 1011 East Columbia Street in Evansville, IN. GSI Environmental (GSI) along with Specialty Earth Sciences (SES) provided oversite for this project.
Description of Work
Geo-Solutions completed the RSM of the chlorinated volatile organic compound (CVOC) contaminated soils on this project using a Delmag RH-28 drill rig fitted with a 9 foot diameter auger to mix zero valent iron (ZVI) and bentonite with the site soils. The RSM was completed from 5 to 45 feet below an average existing ground surface of EL 389 feet so the RSM was completed from EL 384.5 feet to EL 344.5 feet. The target volume of contaminated soil treated was 9,037 CY; however, a total of 10,304 CY were mixed in order to provide complete coverage of the target zone.
In total, the 10,304 CY of soil was mixed with 277,400 lbs of bentonite and 369,000 lbs of ZVI which equates to an overall bentonite addition of 1.05% by dry weight of soil and an overall ZVI addition of 1.40% by dry weight of soil using an assumed dry soil density of ~95 pcf.
Wet samples for Quality Control testing of the freshly mixed soil-bentonite were collected immediately after column completion at a frequency of one sample for every 500 CY of mixing completed. The samples were spaced out within the mix area to ensure a good representation of the entire mix area. These samples were collected using an in-situ sampler. For analytical testing, Geo-Solutions transferred a portion of the sample into a glass jar for SES. SES sent the samples for analytical testing while Geo-Solutions performed magnetic separation testing on the samples to ensure the target ZVI addition was met.
