Article pubs.acs.org/est
Stormwater Chemical Contamination Caused by Cured-in-Place Pipe (CIPP) Infrastructure Rehabilitation Activities Matthew L. Tabor,† Derrick Newman,† and Andrew J. Whelton*,‡ †
Department of Civil Engineering, University of South Alabama, Mobile, Alabama 36688, United States Department of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
‡
S Supporting Information *
ABSTRACT: Cured-in-place pipe (CIPP) is becoming a popular U.S. stormwater culvert rehabilitation method. Several State transportation agencies have reported that CIPP activities can release styrene into stormwater, but no other contaminants have been monitored. CIPP’s stormwater contamination potential and that of its condensate waste was characterized. Condensate completely dissolved Daphnia magna within 24 h. Condensate pH was 6.2 and its chemical oxygen demand (COD) level was 36 000 ppm. D. magna mortality (100%) occurred in 48 h, even when condensate was diluted by a factor of 10 000 and styrene was present at a magnitude less than its LC50. Condensate and stormwater contained numerous carcinogenic solvents used in resin synthesis, endocrine disrupting contaminants such as plasticizers, and initiator degradation products. For 35 days, COD levels at the culvert outlets and downstream ranged from 100 to 375 ppm and styrene was 0.01 to 7.4 ppm. Although contaminant levels generally reduced with time, styrene levels were greatest 50 ft downstream, not at the culvert outlet. Cured CIPP extraction tests confirmed that numerous contaminants other than styrene were released into the environment and their persistence and toxicity should be investigated. More effective contaminant containment and cleaner installation processes must be developed to protect the environment.
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INTRODUCTION More than 12 million linear feet of stormwater culvert is installed in the U.S. annually and more than 1 million existing stormwater culverts require rehabilitation.1,2 Many State Department of Transportation (DOT) agencies responsible for stormwater culvert integrity near roadways frequently select cured-in-place pipe (CIPP) for asset rehabilitation.3−5 In situ culvert repair with CIPP is less expensive than open-trench operations and also avoids traffic disruption and work zone safety issues.6−8 In recent years, CIPP use for stormwater culvert and sanitary sewer applications has resulted in 20 documented incidents including fish kills, odor complaints, and wastewater treatment facility activated sludge inhibitions.9 During the past 5 years, a few California DOT (CALTRANS) regions, New York State DOT (NYSDOT) regions, and Virginia DOT (VDOT) instituted moratoriums on CIPP use. Moratoriums were issued because of documented and suspected environmental contamination incidents.4,10−12 Limited DOT and wastewater utility funded studies reported styrene levels during and following CIPP installations in air (20 to 500 ppm), downstream waters (0.058 to 130 ppm), and process generated hot water (41 to 130 ppm).9,10,18 One week after CIPP stormwater culvert installations, styrene levels ranged from less than 0.005 to 22 ppm9 in downstream waters. As of April 2014, a CIPP moratorium remained in place for one CALTRANS region, whereas NYSDOT and VDOT had adopted more stringent CIPP culvert construction standards and again permitted CIPP use. Continued concerns expressed by State © 2014 American Chemical Society
DOTs about CIPP technology’s environmental contamination potential, however, underscores a need to quantify the chemical contamination potential of CIPP infrastructure rehabilitation activities. No testing has been carried-out to identify if contaminants other than styrene are released from CIPP operations. CIPP operations involve the installation of a polymerimpregnated felt inside a stormwater culvert followed by in situ curing with either hot water, steam, or ultraviolet (UV) light (Figure 1). Curing facilitates resin and hardener cross-linking and a polypropylene liner limits the resin/hardener mixture from contacting hot water or steam during curing. CIPP is generally created using an unsaturated polyester resin,13−15 while vinylester and epoxy resins are less frequently applied.13,16 Styrene is the most popular formulation dilutent because of its copolymerization efficiency, affordability, and availability and is present up to 50% by weight.14,15 Other CIPP ingredients include sodium metasilicate, ethylene glycol, and diphenylmethane diisocyanate.17 Some catalysts used by CIPP manufacturers to initiate cross-linking include Perkadox at 1% by weight and Trigonox 0.05% by weight.18 Figure 2 shows CIPP ingredient chemical structures and their manufacturer reported degradation products. The volume of process waste generated is directly proportional to the pipe size and process Received: Revised: Accepted: Published: 10938
April 17, 2014 July 31, 2014 August 15, 2014 August 15, 2014 dx.doi.org/10.1021/es5018637 | Environ. Sci. Technol. 2014, 48, 10938−10947
Environmental Science & Technology
Article
Figure 1. CIPP installation at Site 2: (a) corrugated metal, concrete encased stormwater culvert before rehabilitation; (b) inverted polymerimpregnated felt installation; (c) steam curing process of the material; (d) rehabilitated CIPP culvert placed back into service.
itself. For hot water curing (65 to 90 °C; minimum 2 h) 10 000s of gallons are generated and condensate curing with steam (125 °C; 7 h for large diameter pipe) 20 to 40 gallons of condensate are generated. The UV curing process does not generate a liquid waste. After CIPP curing, material ends are cut and stormwater flow is reinstated. CIPP particulates and resin globules have been documented in the cutting area and within downstream waters.10 Although State DOT staffs have largely presumed that styrene is responsible for aquatic toxicity, there have been no studies to test this hypothesis or to determine if other more persistent compounds are released. Styrene is a volatile organic contaminant (VOC) (vapor pressure of 4.5 mmHg) and soluble in water (310 ppm at 25 °C).19,20 Typical styrene levels in air and surface water are less than 0.000 006 ppmv and 0.001 ppm, respectively.21,22 Styrene exposure can impair or be lethal to aquatic organisms and its toxicity for select freshwater organisms has been summarized by others23 (Table S1, Supporting Information). Styrene breaks down in the atmosphere due to hydroxyl radical and ozone reactions21,26,27 and is also degraded through microbial action.27,28 Its half-life ranges from 0.75 h to 51 days in rivers and streams and has shown to persist in soil and groundwater for up to 5 days.21,27 There have been reports of spilled CIPP styrene based resin [composition unspecified] persisting in the surface water at ambient temperature for up to 5 months when left untreated.29−31 Testing for other contaminants at this and other styrene based resin sites was not conducted.
The goal of this study was to identify the chemical and aquatic toxicity characteristics of CIPP condensate generated during steam curing and the cured CIPP material after installation. Specific objectives included: (1) characterize the aquatic toxicity and chemical composition of CIPP condensate, (2) identify contaminants released from CIPP materials during a 35 day period, and (3) provide recommendations for reducing the stormwater quality impacts of this technology.
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MATERIALS AND METHODS Field Sites and Sample Collection. Two CIPP stormwater culvert installation sites in central Alabama were studied. CIPP at Site 1 had been cured 1 week prior to the research team’s arrival (4 ft diameter, 158 ft length, 0.75 in. thick), while Site 2 (4 ft diameter, 235 ft length, 0.75 in. thick) was being prepared for CIPP installation when the research team arrived. CIPP at Site 1 was installed July 2, 2013 and Site 2 on July 9, 2013. At both sites, CIPP was being installed in corroded asphalt corrugated metal pipes. Steam curing for the CIPP occurred at 125 °C for approximately 6 to 7 h in this study. Contractors installed plastic mats upstream and downstream of the culvert to prevent environmental contamination. Three water samples were collected in amber glass bottles with polytetrafluoroethylene (PTFE) lined caps headspace free at the culvert inlet, outlet, and 50 ft downstream. Field and trip blanks were also applied. Visual observations indicated that the volume of water pooled upstream and downstream of each culvert differed from the water volume flowing through the 10939
dx.doi.org/10.1021/es5018637 | Environ. Sci. Technol. 2014, 48, 10938−10947
Environmental Science & Technology
Article
Figure 2. Manufacturer reported degradation products for commonly used (a) Perkadox and (b) Trigonox CIPP formulation initiators. (†) Contaminants detected in stormwater during the present study; (‡) contaminants detected in condensate during the present study.
accumet basic AB15 plus pH meter. Calcium and magnesium ion concentrations were determined by titration using ethylenediaminetetraacetic acid in accordance with SM 2340C. HACH digestion reagent vials were used to facilitate the closed reflux, dichromate colorimetric method for quantifying chemical oxygen demand (COD) in accordance with SM 5220D. COD colorimetric determinations and aromatic organic constituents were analyzed by ultraviolet (UV) absorbance at 254 nm using a HACH DR 5000 UV−vis spectrophotometer. Prior to UV254 absorbance characterization, all field water samples were filtered with 0.25 μm Whatman glass fiber (GF/ C) filters. Total organic carbon (TOC) concentration was characterized using a Shimadzu TOC-L TOC analyzer. TOC standard solution (Aqua Solutions, Deer Park, TX) was diluted in deionized water to produce 0, 2, 4, and 5 ppm standards. Headspace Solid Phase Microextraction Gas Chromatography−Mass Spectrometry (SPME GC−MS). All analytical standards were obtained from Sigma-Aldrich (St. Louis, MO) and deionized water blanks were applied for quality
culvert. Grab samples were collected on the water surface from pooled water entering the culvert inlet and downstream. The minimal water flowing out each culvert outlet was completely redirected into the bottle until filled. Onsite water temperature, pH, dissolved oxygen (DO), and turbidity levels were measured. A sample of CIPP condensate waste was also collected. Three large pieces of excess CIPP at Site 2 (3 ft × 4 ft × 0.75 in. thick) were removed from the field and underwent the toxicity characterization leaching procedure (TCLP)32 at room temperature. CIPP sample (100 g where 5.08 cm length × 5.08 cm width × 1.9 cm height per CIPP piece) was placed in each extraction vessel along with 2 L of laboratory prepared synthetic stormwater.33 CIPP surface area in each vessel was 451.61 cm2/L. TCLP was conducted by applying three 18 h contact periods. Water Quality Analysis. Alkalinity concentration was determined in accordance with standard method (SM) 2320B.34 Sulfuric acid (0.025 N) was used for end point titration. Water pH was measured using a Fisher Scientific 10940
dx.doi.org/10.1021/es5018637 | Environ. Sci. Technol. 2014, 48, 10938−10947
Environmental Science & Technology
Article
Table 1. Volatile Organic Contaminants (VOC) Found in Diluted CIPP Condensatea detected when condensate diluted compound name b
acetone methylene chloridec methyl ethyl ketone chloroformd benzened styrened isopropylbenzene N-propylbenzene 1,3,5-trimethylbenzene 1,2,4-trimethylbenzene
compound characteristics
RT, min
1:10
1:100
MW, g/mol
VP, mmHg at 25 °C
log Kow
Cw, ppm
daphnid toxicity 48 h LC50, ppm
2.1 2.4 3.0 3.3 3.6 6.5 6.9 7.3 7.5 7.9
√ √ √ √ √ √ √ √ √ √
√ √
58.08 84.93 72.11 119.38 78.11 104.15 120.19 120.19 120.19 120.19
232 435 90.6 197 94.8 6.4 4.5 3.42 2.48 2.1
0.24 1.25 0.29 1.97 2.13 2.95 3.66 3.69 3.42 3.63
miscible 13000 223000 7950 1790 310 61.3 52.2 48.2 57
210045 22046
