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TR N EW S 288 SEPTEM BERâO CTO BER 2013 19 Donaldson is Senior Research Scientist, Virginia Center for Transportation Innovation and Research, Charlottesville. Wallingford is Hazardous Materials Program Manager, Virginia Department of Transportation, Richmond. Many storm water pipes and culverts havereached the end of their service life, andtheir repair or replacement is a signifi- cant maintenance concern. Trenchless technologies that repair pipes in place have become a frequent alternative to pipe replacement. Many U.S. trans- portation agencies routinely repair storm water culverts with cured-in-place pipe (CIPP), a trench- less technology favored by the underground pipe industry. In conventional CIPP installations, a flexible liner saturated with a thermosetting styrene-based resin is pulled or inverted through the host culvert and cured by recirculating steam or hot water for up to several hours. The result is a rigid liner within the damaged or deteriorated host pipe. The waste by-products of CIPP include styrene- contaminated cure water or steam condensate. According to several reports in the past decade, styrene contamination from conventional CIPP installation has caused fish kills and has affected downstream wastewater treatment processes. No previous field investigations, however, had exam- ined the potential effects of CIPP on water quality. Alternative CIPP technologies include vinyl ester- based resin systems, which are typically steam-cured, and a styrene-based resin system cured with ultravi- olet (UV) light. In addition, spraying coating mate- rial to line the culvert interior is gaining acceptance for the repair of storm water culverts. The spray-on coatings have rapid setup times and become fully cured within 24 hours. Impacts of Storm Water Pipe Lining on Water Quality Virginia Research Leads to Improved Construction Specifications B R I D G E T D O N A L D S O N A N D E D W A L L I N G F O R D Conventional CIPP liner inserted into host pipe. Environmental Sustainability in Transportation P H O TO : B R ID G ET D O N A LD SO N, V C TIR
TR N EW S 28 8 SE PT EM BE Râ O CT O BE R 20 13 20 Testing the Technologies From 2006 through 2012, the Virginia Center for Transportation Innovation and Research, a division of the Virginia Department of Transportation (DOT), evaluated three CIPP technologies: conventional styrene-based, vinyl ester-based, and styrene-based UV; and two spray-on technologies: cementitous and polyurea. The goal was to determine the potential impacts on water quality. Field evaluations were con- ducted for each technology during and up to 120 days after the installation of the storm water culvert lining. In addition, laboratory leaching tests were conducted for the spray-on liners. Water quality analyses of conventional ther- mosetting, styrene-based CIPP installations revealed styrene concentrations at levels that exceeded the toxicity thresholds for certain aquatic species. Tests of the vinyl ester-based CIPP showed that concen- trations of the chemical diallyl phthalate also exceeded the toxicity thresholds. Styrene concentra- tions after UV-CIPP installations were significantly lower than those from the thermosetting styrene- based resin systems; however, at one site, the con- centration immediately after installation was above the toxicity thresholds. Although minimal effects on water quality were detected in field tests of the spray-on liners, the lab- oratory leaching tests suggested potential impacts from elevated pH and alkalinity from the cementi- tious spray, and elevated chemical oxygen demand, total organic carbon, and total nitrogen from the polyurea spray. These results strongly supported the need to develop additional control specifications to ensure environmental protection. New Specifications Applying the findings from this research, Virginia DOT developed contractor construction specifica- tions for all CIPP and spray-on lining technologies. Key requirements include the following: u Submittal of design calculations and job-spe- cific installation specifications before construction; u Deployment of spill prevention measures at the inlet and outlet ends of the pipe to capture any release of raw resin with CIPP or of overspray with spray-on products; u Continuous time and temperature monitoring of the liner with multiple thermocouples and a data logger for CIPP installations; u Rinsing the finished liner and properly captur- ing and disposing of any cure water and rinse water; and u Testing soil and water before and after the CIPP and polyuria spray-on installations. These measures not only ensure protection of the environment but also increase the performance of the finished products by requiring tighter quality con- trols. The specifications are available on the web at www.virginiadot.org/business/resources/const/07Rev Div_III.pdf (pages 3-146 to 3-150). Polyurea spray-on installation. P H O TO : B R ID G ET D O N A LD SO N, V C TIR Conventional CIPP steaming process. P H O TO : B R ID G ET D O N A LD SO N, V C TIR