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PollutionEngineering November 2012 : Page 38

Advertorial DIRECTIONAL TECHNOLOGIES INC. HOWTO: Rapid Remediation of Large Plumes Using Horizontal Remediation Wells 1-877-788-4HRW • drilling@directionaltech.com L results in an increase in Exhibit 2. Superior Elliptical ZOI for Horizontal the rate of degradation Well vs. Severely limited circular ZOI for of contaminants. A Vertical Well good example of the effectiveness of HRW-ISCO was demonstrat-ed on a dry cleaner site in Maryland. The PCE plume extended later-ally for over 1,000 feet beneath busy streets, utility corridors and Exhibit 1. occupied buildings and required rapid The VOC recovery rates ranged from remediation due to redevelopment of 174 to 320 lbs. per day, with a cumula-the site. Directional Exhibit 1. HSVE-2 VOC concentration and tive VOC recovery of 26,687 lbs. over six Technologies designed Recovery Summary January – July 2012 months. These performance results were and installed 10 HRWs achieved by a single well, indicating that the for injection of perman-Date VOC VOC Cumulative full-scale horizontal well system will, and ganate during the site Concentration Recovery VOCs did, achieve site closure much more rapidly construction program (ppmv) Rate Recovered than any equivalent vertical well system. without interrupting the (lbs./day) (lbs.) Why is HRW performance so impressive? project schedule. The 1/25/2012 1,256 192 1,041 Horizontal well screens deliver fluids (or results were impressive: 2/29/2012 1,300 297 10,665 induce a vacuum) into an impacted soil PCE pre-HRW-ISCO 3/31/2012 1,270 261 18,339 horizon evenly, as a line source, which is concentrations were much more effective than the point sources as high as 13,000 parts 4/22/2012 1,197 252 24,080 provided by a series of vertical wells in the per billion and shortly 5/21/2012 1,197 174 25,154 same formation (see Exhibit 2). after two HRW-ISCO 7/11/2012 1,173 320 25,291 HRWs can be used to rapidly remedi-injections, PCE concen-ated large plumes by providing signifi-trations averaged from 7/16/2012 509 235 26,687 cantly greater contact area with impact-nondetect to 400 ppb. ed media than vertical wells . Coupling HRW also can improve air-sparge article discusses the hows and whys of horizontal directional drilling with long efficiency. For example, HRWs rap-HRW and describes two typical successful engineered well screens results in a idly remediated a large gasoline plume HRW in-situ remediation projects. unique, proven technology that consis-from a subsurface pipeline release in the The advantages of HRW over station-tently delivers superior results for ISCO, Northeast. Directional Technologies ary vertical wells are often dramatic. For air sparging and other remedial treat-installed a network of parallel HRWs, example, HRW delivering ISCO reagents ments, which leads to less time onsite four air sparge and three soil vapor (HRW-ISCO) enhances remediation by and significant cost savings. extraction, approximately 600 feet long : 1) reaching inaccessible locations; 2) Contact Directional Technologies at to remediate the release. The horizontal concentrating the oxidant on hot spots; 1-877-788-4HRW or email them at drill-well performance was extraordinary as and 3) increasing contact area using long ing@directionaltech.com to utilize their the pilot test data for one of the wells horizontal screens compared to vertical 20 years of experience in designing and demonstrates. Daily volatile organic well screens. It is often said that “ISCO installing horizontal remediation systems compound recovery rates (in pounds is a contact sport;” HRW increases the for your next in-situ project. per day) for SVE well HSVE-2 for the contact time for oxidants such as perox-first six months of 2012 are presented in ide, permanganate and persulfate, which arge Plumes present many technical challenges because their aerial extents usually encompass surface features such howas roads, buildings, airports and wetlands, which can be difficult or impossible to access via vertical wells. Horizontal Remediation Wells (HRW) have been found to be extremely effective in delivering chemical treatments such as ISCO reagents, reductants, nanoparticles (ZVI), bioremediation reagents, ozone, oxygen, and air to zones of contamination. This Pollution Engineering NOVEMBER 2012 38

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