THE WATER QUALITY EFFECTS OF TIRE DERIVED AGGREGATE AND RUBBER MODIFIED ASPHALT PAVEMENT[轮胎衍生.ppt

THE WATER QUALITY EFFECTS OF TIRE DERIVED AGGREGATE AND RUBBER MODIFIED ASPHALT PAVEMENT,November 29,2006,INTRODUCTION,This report addresses the water quality and environmental toxicity effects of tire derived aggregate(TDA)and rubber modified asphalt(RMA)on the surrounding environments using these resources.Several studies were conducted to address these concerns and are discussed in the following slides,FIELD STUDIES OF TDA USED ABOVE THE GROUNDWATER TABLE,There have been several field studies that have monitored the water quality effects of TDA placed above and below the groundwater table These studies may be separated into two groups based on the methods used to collect the samples for analyses:In the first group,samples were taken directly from water that had passed through the TDA Using this method there is minimal opportunity for substances released by the TDA to be adsorbed by surrounding soil or diluted by mixing with groundwater In the second group,samples were taken from groundwater monitoring wells located adjacent to the TDA fill Using this method substances released by the TDA may be adsorbed by the surrounding soil or diluted by mixing with groundwater,Field Study Descriptions,The following Field Studies were made:University of Wisconsin Field Trial North Yarmouth MaineDOT Field Trial Witter Farm Road Field Trial Ohio Tire Shred Monofills Dingley Road Test Project Virginia DOT Test Embankment Binghamton Test Embankment,University of Wisconsin Field Trial,An experimental test embankment was built as part of an access road at a landfill near Madison,Wisconsin During construction,pan lysimeters were placed beneath areas containing TDA to collect samples.One lysimeter was overlain by 5 ft(1.52 m)of TDA with a 4-in.(100-mm)nominal size topped with a 1-ft(0.3-m)thick soil cover.The other lysimeter was overlain by 5 ft(1.52 m)of TDA with a 2-in.(50-mm)nominal size topped with a 1-ft(0.3-m)thick soil cover.Each lysimeter was made of a 10-mil-thick PVC liner,and was covered with a nonwoven geotextile.Samples were tested 10 times over a 26 month period for eight metals,two anions,and five water quality index parameters.,North Yarmouth MaineDOT Field Trial,This field trial was built on Route 231 in North Yarmouth,Maine,in the summer of 1993.It was studied from January 1994 to June 1999 to determine long-term water quality effects of TDA placed above the water table using about 100,000 tires processed to a maximum size of 3 in.(75 mm).The site consisted of five 100-ft(33-m)long sections,four of which were constructed using a 2-ft(0.61-m)thick layer of TDA topped with 2.5 to 4.5 ft(0.76 to 1.37 m)of granular soil and 0.42 ft(0.127 m)of pavement.The fifth section was established as a control section with conventional soil fill.Two high-density polyethylene-lined seepage collection basins were installed under the sections containing TDA,and another basin was installed under the control area.The basins extended beyond the edge of the overlying pavement to capture runoff from the road that infiltrated into the road shoulder.Organic substances,inorganic substances with primary and secondary drinking water standards,pH,and other water quality index parameters were also tested The samples taken were also used to evaluate the toxicity effects on aquatic life,Witter Farm Road Field Trial,The Witter Farm Road TDA field trial was constructed near the University of Maine in Orono to analyze insulation and drainage properties of a TDA layer placed below a paved road,as well as to collect data on the effects of TDA with a maximum size of 3 in.(76 mm)on water quality.The TDA or mixtures of TDA and aggregate base extended across the width of the road in a 6-in.(150-mm)or 12-in.(300-mm)thick layer.The TDA was topped by 13 in.(330 mm)or 25 in.(635 mm)of aggregate base followed by 5 in.(127 mm)of hot-mix asphalt pavement.In addition,a 6.5-ft(2.0-m)deep edge drain,backfilled with TDA or mixtures of TDA and aggregate base,was located beneath one shoulder.Water discharging from the edge drain was sampled on one date and analyzed for twelve metals,two anions,and organic compounds,Ohio Tire Shred Monofills,In this study,leachate was collected from two Stark County,Ohio monofills that contained tire shreds and soil cover.The monofills had leachate collection systems that tested above groundwater table conditions.The tire shred layer was 18 ft(5.5 m)thick at the site.Some of the samples were taken directly from the leachate collected from the bottom of the landfill.The samples taken were collected on eight dates spanning a two year period.The samples were analyzed for twelve commonly occurring cations and anions,as well as,an additional 19 trace elements.Results for total dissolved solids,pH,conductivity,and alkalinity were also reported.,Dingley Road Test Project,This project was constructed in August,2002 consisting of a 950-ft(290-m)long gravel surfaced test site using 20,000 tire shreds on Dingley Road in Richmond,Maine.The tire shreds used were of varying size,up to a maximum of 2 in.(51 mm)The TDA layer used was 6 or 12 in.(150 or 300 mm)thick and the granular soil cover was 12,18,or 24 in.(300,457,or 600 mm)thick.Six PVC wells,including one positioned at a control site,were installed to collect groundwater samples.Water samples were taken on three occasions from December 1993 to January 1995,Virginia DOT Test Embankment,On Route 646,in Williamsburg,Virginia a mixture of TDA and soil was used to construct the approach fills for a new overpass The approach fills were 20 ft(6 m)with a mixture of 50/50 TDA/soilThe soil used for mixing was silty sand.The section was topped by 5 ft(1.5 m)of soil.Two groundwater monitoring wells were installed One was located 500 ft(150 m)upgradient from the TDA/soil mixture section(MW-1)The other(MW-2)was located immediately downgradient from the toe of the TDA/soil mixture section.The wells were monitored eight times between February,1994 and January,1997 for selected metals,hardness,pH,total organic carbon,total organic halides,and specific conductivity,Binghamton Test Embankment,TDA was used in construction of the subgrade for an interstate exit ramp near Binghamton,New York.The TDA layer was up to 10 ft(3 m)thick and was covered by 4.9 to 6.6 ft(1.5 to 2.0 m)of embankment fill The TDA also had a nominal maximum size of 12 in.(300 mm).Three groundwater monitoring wells and two TDA fill sampling ports were installed.One of the monitoring wells was placed up-gradient from the TDA.The other two wells were positioned down-gradient.One of the sampling ports was placed directly below the TDA fill area,and the other port was placed adjacent to the TDA fill area.Samples were monitored for selected metals and water quality index tests.,Data Summary:Statistical Methods,To allow for easy comparison of the data from the projects,the mean and standard deviation of each measured parameter was computed for each sample location that had three or more sampling events For data sets where all the results were above the detection limit,the mean and standard deviation were computed using standard statistical methods However,statistical analysis of data sets that have one or more results below the test method detection limit presents special challenges,Water Quality Index Tests,A range of water quality index tests were performed in the field studies including:pH,total dissolved solids(TDS),total solids(TS),biological oxygen demand(BOD),and chemical oxygen demand(COD),Inorganic Chemicals with a Primary Drinking Water Standard,Thirteen inorganic chemicals with primary drinking water standards were directly monitored on filtered samples in one or more of the field studiesIn addition,since wells for drinking water are designed to minimize infiltration of solids,it was appropriate to compare drinking water standards to the results from filtered samples when available No studies considered the following chemicals with primary drinking water standards:asbestos,cyanide,and nitrite;however,there is no reason to believe that these inorganic chemicals are present in tires.,Drinking Water Standard,The preponderance of evidence shows that TDA would not cause primary drinking water standards to be exceeded Moreover,the evidence shows that TDA is unlikely to increase levels of metals with primary drinking water standards above naturally occurring background levels.,Inorganic Substances with a Secondary Drinking Water Standard,Secondary standards are“non-enforceable guidelines regulating contaminants that may cause cosmetic effects(such as skin or tooth discoloration)or aesthetic effects(such as taste,odor,or color)in drinking water”Nine inorganic chemicals with secondary drinking water standards were directly monitored on filtered samples in one or more of the field studies The mean concentrations of aluminum,copper,fluoride,silver,and zinc were below their corresponding secondary standard except for aluminum at the C&E monofill,Organic Compounds,There are two field studies that monitored for organics in samples taken directly from water that had passed through the TDA The projects are:North Yarmouth MaineDOT field trial and Witter Farm Road field trail Samples were tested for volatile organic compounds(VOCs)in accordance with EPA Method 8260(Determination of Volatile Organics by Purge-and-Trap Capillary Column GC/MS)Samples were also tested for semi-volatile organic compounds(SVOCs)in accordance with EPA Method 8270(Determination of Semi-volatile Organics by Capillary Column GC/MS),Organic CompoundsContinued,Results from the North Yarmouth project showed the following:3 compounds concentrations were below the Regulatory allowable limits(RAL)that had been established for the compounds.There were five instances of compounds being found above the test method reporting limit,with the highest concentration being 0.024 mg/L of aceton The results for the single sample from the Witter Farm Road showed all compounds were below the test method reporting limit,Aquatic Toxicity,Samples from the North Yarmouth Project were used to perform two USEPA freshwater short-term toxicity tests One test was three-brood survival and reproduction test with the crustacean Ceriodaphnia dubia In this test,females are exposed to samples for the period of time it takes for control treatment females to produce three broods,typically about 7 days.Then survival and reproduction of these two groups are compared The other test was seven-day survival and growth of larval fathead minnows(Pimephales promelas)At the completion of the test,survival and growth for minnows exposed to field samples are compared to control samples,Aquatic ToxicityContinued,On both sample dates there was 100%survival and growth of fathead minnows in samples from the control section and TDA Sections C+D.For Ceriodaphnia dubia there was 100%survival and reproduction in the samples from TDA Sections C+D on both sample dates.These results show TDA placed above the groundwater table on this project had no effect on aquatic toxicity for these two species.,Water Quality Index Tests,A range of water quality index tests were performed on projects with samples from adjacent wells including:pH,total dissolved solids(TDS),total solids(TS),biological oxygen demand(BOD),and chemical oxygen demand(COD).The pH from the Richmond,Maine project was within the secondary drinking water standard(USEPA,2006).However,two wells from the Binghamton project and both wells from the Virginia project were more acidic than the standard The TDS was below the secondary drinking water stand-ard for the Richmond project,Inorganic Chemicals with a Primary Drinking Water Standard,Five inorganic chemicals with primary drinking water standards(barium,cadmium,chromium,copper,and lead)were monitored on filtered samples in one or more of the field studies The results in both the control and TDA wells were below the corresponding RAL,except for barium concentrations in the control well at the Binghamton Project,Inorganic Substances with a Secondary Drinking Water Standard,Seven inorganic chemicals with secondary drinking water standards were monitored in one or more of the field studies with adjacent monitoring wells The mean concentrations of aluminum,chloride,sulfate,and zinc were below their corresponding secondary standard on the projects where these parameters were measured Secondary standards for iron was exceeded on the Binghamton and Virginia projects for both the control wells and the wells adjacent to the TDA sections.On the Binghamton project iron levels were higher in the wells adjacent to the TDA section compared to the control well.However,the iron concentration was about the same in the TDA and control wells in the Virginia project.,Inorganic Substances with a Secondary Drinking Water Standard,The secondary drinking water standard for manganese was exceeded for all control and TDA wells.For the Richmond project,the manganese level in three TDA wells was about the same as the control well,while for the remaining three wells the concentration in the TDA wells was lower than the control well.For the Binghamton project,the manganese concentrations in the TDA wells were elevated.For the Virginia project,the control and TDA wells had about the same manganese concentrations.,Organic Compounds,The Virginia DOT project monitored total organic carbon(TOC)and total organic halides(TOX).For the control well,TOC was below the detection limit of 1 mg/L for 16 out of 32 tests.For the well adjacent to the TDA section,28 out of 32 tests were below the detection limit.For the control well,TOX was below the detection limit of 0.02 mg/L for 24 out of 32 tests.For the well adjacent to the TDA section,28 out of 32 tests were below the detection limit.Thus,there was no indication that the TDA increased the TOC and TOX in the groundwater.,Summary of Water Quality Effects of TDA Placed Above the Groundwater Table,The preponderance of evidence shows that TDA does not cause metals with primary drinking water standards to be exceeded.Moreover,the data shows that TDA is unlikely to increase levels of metals with primary drinking water standards above naturally occurring background levels.For other chemicals with secondary drinking water standards,there is no evidence that TDA affects naturally occurring background levels.,Summary of Water Quality Effects of TDA Placed Above the Groundwater Table,Volatile and semi-volatile organics were generally below test method reporting limits.Moreover,for those substances with drinking water standards,the levels were below the standards.A few substances are occasionally found above the test method detection limit,however,the highest concentrations were found in the control section indicating that organics from other sources associated with active roadways are more prevalent,Summary of Water Quality Effects of TDA Placed Above the Groundwater Table,Aquatic toxicity tests results showed that water collected direct