Waste Tires in I

A report

on t h e

Environmental Study of the Use sf Shredded Waste Tires

For Roadway Sub-grade Suppon'

February 19, 1990

Minneso ta Pollution Control Agency

Waste Tires in Sub-grade Road Beds

A report on the

Environmental Sludy of the Use of Shredded Waste nres

For Roadway Sub-arade Suppcxt

Published by:

Waste Tire Management Unlt Site Response Section

Groundwater and Solid Waste Dlvlsion Minnesota Pollution Control Agency

520 Lafayette Road St. Paul, MN 55155

(612) 29154303

Study performed by:

Twln Clty Testing Corporatlon 662 Cromwell Avenue

St. Paul. MN 551 14

Project Manager:

Andy Ronchak Waste Tire Management Unlt

Ground Wder and Solld Waste Dlvlsion Minnesota Pollution Control Agency

(612) 296-641 1

Twin City Testing Corporation (Tm) conducted a laboratory study of waste tires rci

evaluate the compounds which are produced by exposure of tires to different leachate environments. Composites of old tires, new tires and asphalt samples were prepared and subjected to laboratory leachate procedures at four different conditions including pH 3.5, pH 5.0, a neutral pH sodium chloride leach solution and pH 8.0 leach solution.

TCT also conducted field sampling at two existing sites where waste tires were used in roadway subgrade construction. Soil and water samples were collected in areas underneath the waste tire subgrade and in background locations to provide a comparison. Soil samples from two tire stockpile sites were also collected.

Samples were chemically analyzed for 14 metals, for total petroleum hydrocarbons using infrared spectrophotometry, and for polynuclear aromatic hydrocarbons using gas chromatography/mass spectroscopy.

Based on the results of the studies conducted, the following conclusions were reached:

Metals are leached from tire materials in the highest concentrations under acid conditions. Laboratory studies indicate barium, cadmium, chromium, lead, selenium and zinc are constituents of concern.

Poiynuclear Aromatic Hydrocarbons (PAHs) and Total Petroleum Hydrocarbons (418.1) are leached from tire materials in the highest concentrations under basic conditions. Constituents of concern included List 1 (carcinogenicj PAHs and List 2 (non-carcinogenic) PAIls.

Asphalt materials may leach higher concentrations of contaminants of concern thari tire materials under some conditions.

Drinking water Recommended Allowable Limits (RALs) may be exceeded under 'iuorst-case" conditions for certain parameters.

Co-disposal limits and E.P. Toxicity limits are generally not exceeded for the parameters of concern.

Field studies did not identlfy significant differences between waste tire areas and control areas for soil samples and for the biological survey. Water samples ar iilc Roodwood site indicated results in excess of the RX-s while background sarnnies did not.

7. Potential environmental impacts from the use of waste tires can be minimized by placement of tire materials only in the unsaturated zone of the roadway subgrade.

Based on the results of the laboratory and field studies conducted.for this project Twin City Testing Corporation recommends tbe following factors be considered for use of shredded waste tires in roadway subgrade construction.

1. That the use bf waste tires be limited to the unsaturated zone in a roadway designed to limit infiltration of water through the waste tire subgrade. Design of the roadway surface and ditches t o promote surface water drainage away from the waste tire subgrade should be included in the design of the roadway.

2. That additional field studies be performed to evaluate new or existing roadways where waste tires are used. Field studies should include sufficient numbers of monitoring w e b in roadways and background areas to provide a statistically significant comparison of tire area and background area samples.

TABLE OF CONTEN3

. . . . . . . . . . . . . . . . . . . . . . . 1.0 INTRODUCTION 1 . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Background 1

. . . . . . . . . . . . . . . . . . . . . 1.2 Scope of Senices 1

. . . . . . . . . . . . . . . . . . . . . 1.3 Literature Search 4

2.0 PROJECT RESULTS . . . . . . . . . . . . . . . . . . . . . 5 . . . . . . . . . . . . . . . . 2.1 Laboratory Leach Tests 5

2.1.1 Samples Received . . . . . . . . . . . . . . . . 5 2.1.2 Experimental Procedures . . . . . . . . . . . 5

. . . . . . . . . . . . . . . . . . 2.1.3 Quality Control 11 . . . . . . . . . . . 2.1.3.2 ICY-AES Analyses 11 . . . . . . . . . . . 2.1.3.3 WAAS Analyses 11

. . . . . . . . . . . . . 2.1.3.4 FAAS Analyses 12 . . . . . . . . 2.1.4 Results of Inorganics Analysis 12

2.1.5 Normalized Inorganics Analyses ...... 13 ..................... 21.6 Discussion 13

. . . . . . . . 2.1.7 Results of Organics Analyses 20 21.7.1 Total Petroleum Hydrocarbons . . 20

. . . . . . . 21.7.2 GCNS PAH Analysis 20

. . . . . . . 21.8 Normalized Organics Analyses 20 . . . . . . . . . . . . . . . . . . . . . 21.9 Discussion 21

. . . . . . . . . . . . . . . . 2 2 Field Sampling Program 23 . . . . . . . . . . . . . . . . . . . . 2.21 Background 23

. . . . . . . . . . . 2.22 Floodwood Roadway Site 23 . . . . . . . . . . . . . . . . . . . 2.2.3 Grasston Site 24

. . . . . . . . . . . . . . . . 22.4 Tire Stockpile Site 26 . . . . . . . . . . . . . . . . . . . . . 2.25 Discussion 26

. . . . . . . . . . . . . . 225.1 Soil Samples 26 . . . . . . . . . . . . 225.2 Water Samples 28

. . . . . . . . . . . . . . . . . . . . . 2.3 Biological Survey 28 . . . . . . . . . . . . 2.3.1 Grasston Roadway Site 28 . . . . . . . . . . . 2.3.2 Roodwood Roadway Site 29

. . . . . . . . . . . . . . . . . . . . . 23.3 Discussion 29

3.0 DISCUSSION PLND CONCLUSIONS . . . . . . . . . . 30 . . . . . . . . . . . . . 3.1 Laboratory Leachate Studies 30

. . . . . . . . . . . . . . . . . . . . . . . . 3.2 Field Studies 31 3.3 Literature Search Comparison . . . . . . . . . . . . 31

. . . . . . . . . . . . . . . . . . . . . 3.4 Biological Survey 31 . . . . . . 3.5 Assessment of Environmental Impacts 32

. . . . . . . . . . . . . . . 3.6 Discussion of Alternatives 32

. . . . . . . . . . . . . . . . . . . . . . . . . 4.0 CONCLUSIONS 33

5.0 RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . 34

6.0 STANDARD OF CARE . . . . . . . . . . . . . . . . . . . 34

TABLES

TABLE 1: SUMMARY OF WASTE T7RE SAMPLES FOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . METALSTESTING 7

TABLE 1A: SUMMARY OF WASTE TIRE COMPOSITES AND ASPHALT FOR METALS TESTING . . . . . . . . . . . . . . . . 8

TABLE 1B: SUMMARY OF LEACH TEST CONDITIONS FORMETAISTESTING . . . . . . . . . . . . . . . . . . . . . . . . . 9

TABLE 2: SUMMARY OF ANALmcAL METHODS AND . . . CONCENTRATION LIMITS FOR METALS TESTING 10

TABLE 3: SUMMARY OF ANALYTICAL RESULTS FOR METALS TESTING OF NEW TIRE COMPOSITES i

.. . . . . . . . . . . . . . . . . . . . . . . . IN UG/L OF LEACHATE 16

TABLE 4: SUMMARY OF ANALYTICAL RESULTS FOR METALS TESTING OF OLD TIRE COMPOSITES IN UG/L OF LEACHATE . . . . . . . . . . . . . . . . . . . . . . . . . 17

TABLE 5: SUMMARY OF ANALYTICAL RESULTS FOR METALS TESTING OF ASPHALT

. . . . . . . . . . . . . . . . . . . . . . . . . IN UG/L OF LEACHATE 18

TABLE 6: SUMMARY OF CHEMICAL ANALYSIS - METALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

TABLE 7: SUMMARY OF CHEMICAL ANALYSIS . . . . . . . POLYNUCLEAR AROMATIC HYDROCARBONS 22

FIGURE 1:

FIGURES

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.1 Background

The use of waste tires as a lightweight subbase material for roadway support over wetlands has generated much interest in recent years.

Construction of a roadway across soft wetland soil deposits usually presents stability problems. The weight of the soil Ell creates large settlements and lateral bulging of the underlying soft soil deposits. One method for dealing with this problem is to substitute a lightweight Ell material for the heavy soil materials.

Traditionally, lightweight fill consists of woodchips or sawdust. These lightweight materials are substituted for the heavier soil materials in the subbase of the road embankment. A typical design is shown on Figure 1. . ..-

,A disadvantage of using woodchips for the lightweight subbase is the fact that wood is bio- degradable. Rotting of the subbase is a real concern and must be addressed in the roadway design. Most designers restrict the use of woodchips to below the groundwater to minimize rotting.

Shredded waste tires are a possible alternative to woodchips. The waste tires have comparable b ~ & densities to the woodchip a. In addition, the waste tires are not subject to rotting. Therefore, the concerns for subgrade bio-degradation would be eliminated if waste tires could be substituted for wood chips.

A few test applications of the use of waste tire products have been made. These preliminary projects indicate that the application has great promise. The remaining question to answer is the potential environmental impacts of using waste tires as road subbase materials.

. .

In order to address this question, Twin City Testing Corporation ( T o was commissioned to conduct a study to assess the potential environmental impacts &om the use of waste tire materials in wetland environments. This report presents the results of our study.

The intent of this study is not a comprehensive look at the environmental impacts of waste tire usage in wetlands. Instead, the study was designed to accomplish the following goals:

1. Subject the tire materials to a variety of vigorous leach environments. Attempt to simulate potential worst-case scenarios.

,Minnesou Polluiion Canirol h e n q February 19. 1990

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Determine the compounds that leach during these extreme conditions. Identify those which have potential adverse environmental impact.

Collect soil and groundwater samples at existing field sites where tire subgrades have been constructed. Measure and compare the concentrations of compounds identified in the leach tests.

Perform a limited biological field survey at the field sites to assess impacts of tire usage on the ecosystem.

The emphasis of thjs study i s the labcratory leach test program. A literature search was made to locate other such studies. Two other leach test studies are referenced in this report. The results of this study are compared with the other studies.

In addition to the waste tire samples, a typical asphalt mix sample was also subjected to the leach test procedures. The intent was to provide a point of reference to a commonly used road construction material.

This report includes the following:

Summary of the literature search.

Description of the methods and presentation of the results of the leach test program.

Results of the biological field surveys.

Description of the soil and groundwater sampling and the results of the analytjd testing.

Comparison of the leach test results with two other similar studies.

Assessment of environmental impacts based on study results.

Recommendations for usage of waste tire products to mininize the environmental impacts.

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Figure 1 : Typical Roadway Section on Soft G r o u n d

W e s o u PoUuuon Convol Agency February 19, 1W

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13 Literature Search

The following databases were searched for s~rnilar leach studies on waste tire producls:

NTIS, Compendex Plm (onbe form of Engineering Index), Enviroline, Pollution Abstracts, TRIS(Transportaion Research Board), and Chem Abstracts.

There were no papers which included either leach tests on tire products or environmental assessments of waste tire subgrade usage.

The following two documents were provided to us. These papers are referenced laterin this report.

1. Memo from Robert Grefe, State of Wisconsin DNR, to Tuncer Edil, Univ. of Wisconsin, entitled " Waste Characterization Recommendations for Waste Tires", dated January 31, 1989

2. Report entitled " Shredded Tires for Landfills as Row-Zone Material", by Jaw. Corp., to Domino S a h g e hc., dated 4/11/88. This report was provided by Mr. Monte Niemi.

Minnesota Pollution Control Agency F e b m r j 19. 1990

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2 0 PROJECT RESULTS

21 Laboratow h c h Tests

I 21.1 Samples Received

Fourteen tires were collected from the Gordy Gotkedson tire dump near Mora, Minnesota in August 1989. Seven "old" tires were collected from the south end of the tire dump. This stockpile is approximately 15-20 yean old. Seven "new" tires were collected from the north stockpile. These tires were approximately 5-10 years old. The descriptions of each tire are summarized in Table 1. The new and old tires were divided into four composites each and were assigned a unique TCT sample identification number and are summarized in Table Ik Weights used for the leach tests are also included in Table lk An unconsolidated asphalt sample was provided for this study from TCTs Construction Materials Department

I 212 Exr>erimental Procedures

Sample preparation consisted of cutting a twg inch cross-section of each of the fourteen tires with a band saw and then cutting each of the cross-sections into four separate pieces, Each of the four pieces were included in a seven tire mmposite (old and new tires) for each of the four leach tests described below. The asphalt sample required no further treatment and was directly weighed for the extraction procedure.

The laboratory leach test program consists of four leach tests designed to simulate a range of pH conditions. The leach tests use USEPA's SW-846 Method 1310 a s a leachate preparation model. Conditions for this leach test study are summarized in Table 1B and are further described a s follows:

Minnesola PoUuIion Cnnuoi Agenff February 19. 1990

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Leach Test #I

Follows SW-846 Method 1310 with modification of the sample weight and extraction fluid. The emaction fluid was adjusted to an approximate pH of 3.5 with acetic acid.

Leach Test #2

Follows SW-846 Method 1310 with modification of sample weight only. The extraction fluid is maintained at an approximate pH of 5.0 with acetic acid.

Leach Test #3

Follows similar agitation and monitoring techniques as the others but uses a 0.9% sodium chloride solution as an extraction fluid to simulate road salt applications. No pH adjustment was attempted. The rationale for this concentration of sodium chloride was based on information provided by the Minnesota Department of Transportation

w o n .

Leach- Test #4

Utilizes an extraction fluid mixture of ammonium hydroxide and ammonium acetate to maintain a pH of 8.0. No pH adjustment was required.

Minnwta Pollution Conuol Agency February 19. 1990

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TABLE 1: SUMMARY OF WASTE TDRE SAMPLES FOR METALS TESTING

Sample Identiiication Description and Size

Site Designation

Bridgestone RD-108 Steel belted radial, white waU, 165SR13 New Wards Gas Miser iT Steel belted radial, white wall, P155/80R13 New Goodyear Eagle GT Steel belted radial, black wall, P225/70HR15 New Michelin XZX Steel belted radial, black wall, P175175R13 New Starfire Vantage Fiberglass radial, white wall, P225/75R15 New Goodyear Eagle ST Fiberglass radial, black wall, P185/70R13 New Goodyear Super Single 6 ply nylon, black wall, 12-16.5NHS New

Firestone 721 Steel belted radial, white wall, P195/75R14 Old Remington ST - - Steel belted radial, white wall, BR78-13 Old Remington XT-120 Steel belted radial, black wall, BR70-13 Old Remington CushionAire Poly 4, black wall, H78-15 Old Goodyear Custom Power Cushion 6 ply plyglass, black wall,L7&15 Old Sieberling Nylon 100 4 ply, white wall, 7.19-15 Old UnLroyal Industrial Lug 10 ply, black wall, 6.50-10 NH Old

Minnesoia Polluuon Conrrol Agency Febmry 19. 1990

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TABLE lA SUMMARY OF WASIT3 TIRE COMPOSITES AND ASPHALT FORm'4LS-G

-

TCT Sample Sample No. Description

New Tires Composite for Leach Test #1 Old Tires Composite for Leach Test #1 Asphalt - Leach Test #1 New Tires Composite for Leach Test #2 Old Tires Composite for Leach Test #2 Asphalt - Leach Test #2 New Tires Composite for Leach Test #3 Old Tires Composite for Leach Test #3 Asphalt - Leach Test #3 New Tires Composite for Leach Test #4 Old Tires Composite for Leach Test #4 Asphalt - Leach Test #4

Minnesora PoUuuon Conuoi Agency Febnwry 19, 1990

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-TABLE 1B: SUMMARY OF LEACH 'IEST CONDITIONS FOR METALS TFSI'ING

TCJT Sample Acid DI Water Initial F%la( Sample Weight Volume Extractant Volume Leach No. (Grams) Used (ml) Reagent Used (ml) pH

144656 602.8 124.3 1 1281 558 3.25 144659 643.8 104 1 1368 5.28 3.24 144662 107.0 709 1 2140 6.19 3.39 145000 624.5 4.45 1 1327 559 523 145005 583.4 3.7 1 1240 5.35 5.06 145008 146.2 251.7 1 2924 6.21 5.16 145010 614.1 na 2 2456 5.62 6.35 145013 606.5 na 2 2426 5.25 5.45 145015 123.8 na 2 2476 5.69 8.86. 145020 624.1 na 3 2496 8.10 8.00 145021 639.1 na 3 2556 8.07 8.00 145024 118.9 na 3 2378 8.10 8.12

na = none added. 1 = Acetic Acid 2 = 0.9% w/v Sodium Chloride Solution 3 = Ammonium Hydroxide/Ammonium Acetate Solution

Mianemia PoUuIion Conuol Agency Febmry 19, 1990

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TABLE 2 SUMMARY OF ANALYTICAL hG3XODS AND CONCENTRATION UMlTS FOR XlETALS TESIWG

-

Analyte Analytical Method

Method Detection Limits (u&) Leach Test

#1 #2 #3 , $4

Minnesow Pollution Coouol &en? Februaq 19. 1990

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213 Ouality Control

Each of the tire composite and asphalt leachates had an overspike determination 'performed. The overspike concentrations used were either 500 ugfl or 1250 ugfl of analyte. Additional quality control measures included analyses of at least one reagent blank, analyses of calibration check standards at periodic time intervals to monitor stability and Lu aXcr idh the need iur d U t Z i i ~ i 7 Zfid i i j e t h G d G? S Z i i & i < Z d d i t i G f i ~ .

Method detection limits were established by measuring each analyte in deionized water blanks. The standard deviation was calculated and multiplied by a factor of three. It should be noted that data measured at the detection level but below a factor of 10

*times the standard deviation has a degree of uncertainty. 4

213.2 ICP-AES Anahses

Thirteen metals were determined by 1 0 using a Thermo Jarrell Ash P300 Sequential Dual Monochromator ICP. The ICP determinations for all metals were based on analyses of sample leachates in matrices as described in Table lB.

Metats testing by ICP was based on a two-point calibration (5.0 ppm of each analyte and a blank solution) performed prior to initiating analyses of leachates. Four 1 second integrations for each analyte was measured with the exception of &c which was rn at four 0.2 second integrations. Aqueous standards were matrix matched to preclude sample transport irregularities.

Mercury was determined by (NAAS using a Thermo Jarrell Ash Video 12E atomic absorption spectrometer. The leachates were digested in acid media in heating mantles with sequential additions of oxidizing reagents of increasing strengths. The digests were then prepared for analyses.

Instrument calibration was based on measurements of aqueous standard solutions and a standard blank solution. Calibration standards were analyzed prior to the sample analyses Nn.

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Silver was determined by FAAS using a Thermo Jarrell Ash Video 12E atomic absorption spectrometer. Concentration measurements by FAAS were based on instrument calibrations prior to initiating analyses of leachates by using two aqueous standard solutions and a standard blank. Instrument caliirations by the method of multiple standard additions were necessary for the determination of silver in the test leachates.

21.4 Results of 1nor.mnia Anafvsis

The analytical methods used to determine the 14 metals in this testing program are referenced in Table 2. The method detection limits derived kom this study are also tabulated in Table 2. The method detection limits for the 14 metals were based on analyses of blank leachate solutions.

The analytical results for new tire composites, old tire composites and asphalt for each of the leach tests are summarized in Tables 3, 4 and 5. Analyte concentrations measured below the method detection limits (MDL) for the respective metals have been reported as less than the MDL for the specified metal. The MDLs vary according to instrument conditions and sample matrix at the time of analyses.

The ICP analyses of the leachates were repeated in some cases to facilitate interpretation of the analytical. data. This would allow verification of the measured analyte concentrations which were close to or exceeded the MDL for some metals and verification of overspike recoveries that were close to acceptable recovery criterion.

For all leach tests silver and mercury were not present in new tires, old tires and asphalt leachates. Arsenic and lead were also not detected with the only excep'tion of new tires sample leachate in leach test #2 and new tire sample Ieacbate in leach test $1, respectively. Selenium was only present in the most rigorous acid leach for all of the samples but not observed in the other samples or leach tests.

Ag, Al, As, GI, Cr, Hg, Pb, Se, Sn and Zn were not detected at their respective MDLs in leach test #4 for aU. sample leachates. Only 5 metals Ba, Ck, Fe, Mg, and S were detected. Ag, As, Cd, Cr, Hg, Pb and Se were not detected in leach test #3 for all sainples. Only 7 metals Ba, Ca, Fe, Mg, S, Sn and Zn were detected for all samples in leach test #3.

Minnesota Polluuon Conuol Agency Febrwty 19, 1W

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Ag, As, Cd, Cr, Hg, Pb and Se were not detected in leach test #2 for old tire and asphalt sample leachates. Al, Ba, Ca, Fe, Mg, S, Sn and Zn were present in these leachates. New tire sample leachates essentially exhibit the same characteristics with the exception that As, Cd and Cr were detected at or very near the MDL

The results of the metals analyses were "normalized" by a calculation procedure in order to express all results in terms of weight of the constituent of concern per unit weight of tire. Because the volume of extraction fluid varied for each sample and the weight of each tire sample was different, the "normalizing" calculation allows direct comparison of the results of each laboratory sample. The "normalized" result was obtained by multiplying the concentration for each parameter (in ug/l) by the volume of extraction fluid (in liters) and dividing the product by the weight (in kilograms) of the tire sample. The results for "normalized" metals analyses are reported in milligrams per Hogram of tire (m-$kg) or parts per million.

The "normalized" results are summarized in Table 6.

The results of chemical analysis for metals generally indicates that metals are found at higher concentrations in the laboratory extraction fluid when the pH of the extraction fluid is low. The highest metals concentrations were found at pH 35 conditions for parameters such as calcium, iron and magnesium. In general, asphalt samples exhibited higher concentrations of metals than waste tire samples under all leach conditions.

Leachate samples represent a ''worst -casen condition when compared to actual site conditions where waste tires might be used. PH conditions at actual sites are more neutral as indicated by the pH readings from field samples.

Recommended Allowable Limits

Although not directly comparable, the leachate sample results were compared to Recommended AUowable Limits (RAL) set by the k h e s o t a Department of Health for drinking water. The RALs for the various parameters are listed in Table 6 and Table 7. The only metals samples to exceed the RALs were arsenic in new tire samples at pH 5.0, cadmium for new and old tire samples at pH 3.5, cadmium in new tire samples at pH 5.0, chromium at pH 3.5 for new tires, old tires and asphalt samples, lead at pH 3.5 for new tires, selenium at pH 3.5 for new tires , old tires and asphalt, dnc at pH 3.5 and pH 5.0 for new and old tire samples and zinc for old tires samples with a NaCl leachate solution. (Iron also exceeded the secondary MCL although the MCL is based on secondary drinking water standards which are of aesthetic concern rather than health concern).

Chronic Toxicitv Criteria

The laboratory leachate sample results were also compared to the Aquatic LiCe Criteria denoted as Chronic in Table 6 and Table 7. These criteria apply to acceptable limits for the listed parameters in surface waters based on chronic toxicity. Chronic toxicity criteria were exceeded in laboratory leachate samples for barium in samples of new tires at pH 3.5 and pH 8.0 and for asphalt samples at pH 3.5, 5.0 and 8.0. Cadmium was detected in excess of chronic toxicity criteria in new tire samples at pH 3.5 and 5.0 and in old tire samples at pH 3.5. Chromium exceeded the criteria at pH 3.5 in new and old tire samples and for the asphalt sample. Iron exceeded the chronic taxicity criteria for all samples except for new tires at pH 8.0. Zinc exceeded chronic toxicity criteria for new and old tire samples at pH 3.5 and 5.0 and for old tire samples in a NaCl leach. All other metals did not exceed chronic toxicity criteria for laboratory leachate analyses. It should be noted that the laboratory leachate tests represent ''worst-case " conditions and that surface waters generally provide a large dilution factor.

Co-disposal Criteria

The results of laboratoxy analyses of tire and asphalt samples were also compared to co- disposal criteria. Co-disposal criteria have been used until recently to determine the acceptability of wastes for disposal in IandfiUs by analysis of samples using a water leachate procedure. The cudisposal process has been replaced by Industrial Solid Waste Management Plans. For purposes of this repo& we have compared the results of the laboratory leachate studies performed under more aggressive leaching procedures with the co-disposal limits. The results exceed the co-disposal limits for the following samples:

Barium at pH 3.5 in asphalt samples, cadmium in new and old tire samples at pH 3.5, chromium at pH 3.5 in old tire samples, lead in new tire samples at pH 3.5 and Selenium at pH 3.5 for new tires, old tires and asphalt samples.

EP Toxicitv Criteria and TCLP Criteria

The results of laboratory leachate samples were compared with EP Toxicity criteria and TCLP cxiteria. EP Toxicity tests are performed using a pH controlled leachate procedure under acid conditions (pH 4) to determine if wastes are to be classified as hazardous wastes due to leachable metals. TCLP tests are performed using a similar leachate procedure but with a neutral pH water leach rather than an acid leach. The acceptable concentrations are listed in Table 6 and Table 7 and are similar for each procedure. None of the laboratory leachate samples exceeded the EP tokcity criteria or the TCLP criteria.

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TABLE 3: SUMMARY OF ANALYTICAL RESULTS FOR METALS TEliTING OF NEiW TIRE WMP05ITES IN UG/L OF LEACHATE

TCT No. 144656 14500 145010 145020 Leach Leach Leach Leach

Analyte Test Test Test Test # 1 #2 #3 #4

Minnesota i"oUuuon Control Agency February 19. I990

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TABLE 4: SUMMARY OF ANALYTICAL RESULTS FOR METALS ?'ESTING OF OLD TIRE COMPOSITES D-4 UG/L OF LEACHATE

TCT No. 144659 145005 145013 145021 Leach Leach Leach Leach

Analyte Test Test Test Test # 1 #2 #3 #4

Minnesola PoUuuon Control &en? February 19, 1990

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TABLE 5: SUMMARY OF ANALYTICAL RESULTS FOR METALS TESTING OF ASPHALT IN UG/L OF LEACHATE

TCT No. 144662 145008 145015 145024 Leach Leach Leach Leach

Analyte Test Test Test Test #1 #2 #3 #4

Ncu 51

O l d < l

Asphat t

ucu 07

O l d 1 2

A;phslt

He" 3 O l d 3

A s p a l t

Hew CL

O l d CL

A s p a I t

lSPO9P ? C . v - t i r c

159114 F L - " - [ i r e

15P121 ~ ~ - u - b a c t

159117 F i - 2 - t i r e

159108 FL-s-back

159071 P C . 5 - t i r e

161251 T i r e g r a b 1

16125'- T i r e g rab2

159099 F i e l d pn 6.1

15911L F i e l d pn 6.9

. 159121 f i e l d pH 6.6

UAL 0.050 1.500 0.005 0.120

Chron ic 0.050 0.147 0.030 1.000 0.001 0.010

o - d i s p o s a l . 0.500 0.100 10.000 0.100 0.500

P T o x i c i t y 5.000 5.000 100.000 1.000 5.000

CLP 5.000 5.000 100.000 1.000 5.000

Ll .

50. 3 .

18.

37.

1.

3 .

1'. 0.

(. 0.

<.

1

1

i

5.0

5.0

For r a m l c s 1LL.656-145021 t h e r e s u l t s ucre cxprczscd as m l k g ( m i l l i g r a m per k i l o g r a m 1 of o f : i r e szu;ale ( "no- l i

For z s m l c s 159099-16125L :he r c s u l t s erprcsrcd as m / t g o f s o i l or m g l l ( r n i l l i g r l m per L i t e r ) of uarcr as re:

H g l k p and mg/ l arc e q v i v a l m : t o parrs per m i l l i o n .

The e q v i v s l c n r c n n c m c r a t i o n z in t h e cs:ii;ated p a r c v a t e r v o l m arc 0.8 t i m e r the Lcacharc values rrpor;ed (see page

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21.7 Results of Oreanics Anahses

21.7.1 Total' Petroleum Hvdmxbons

The freon - extractable oil content of the leachate samples was determined using a modification of EPA Method 418.1 This analytical method follows the protocols used in EPA Method 418.1 with modiEications for use with an D M IW42 Fourier Transform infrared spectrometer. Through the use of a computer aided analytical method, the detection limit is lowered to approximately 0.3 m u for water and leachate samples and to near 0.5 m a g for soil samples by the use of peak area algorithms.

The Report of Chemical Analysis is attached in the Appendix. The results are summarized in Table 7, attached.

21.72 GUMS PAH An-

The Ieachate samples were analyzed by gas chromatography/mass spectroscopy (GC/MS) for determination of thirty-two polynuclear aromatic hydrocarbons (PAHs) at part per trillion (ng/l) levels.

The results of the PAH analyses are presented in the Report of Chemical Analysis attached in the Appendix The results are summarized in Table 7, attached.

I 21.8 Normalized hahrses

The results of the Total Petroleum Hydrocarbons (418.1) analysis and the Polynuclear Aromatic Hydrocarbons (PA*) analysis were normalized as described in part 21.3 above. The results of the"normalized" 418.1 analyses are expressed in miUigrams per kilogram of tire (mgikg) or parts per d o n . The results of the "normalized" PAH analyses are expressed in nanograms per Bogram of tire ( n a g ) of parts per trillion.

21.9 Discussion

Minnesow PoUuuon Conuoi a e n v February 19, 1990

Page 21

The results of chemical analpis of extraction fluids for Total Petroleum Hydrocarbons (418.1) and Polynuclear Aromatic Hydrocarbons (F'AHs) indicates that the highest concentrations were observed in condition #4 @H of 8.0). Asphalt samples exhibited generally similar or higher concentrations under all conditions when compared with tire samples. The RALs for List 1 carcinogenic PAHs and List 2 non-carcinogenic PAHs were generally exceeded under all conditions. Chronic toxicity criteria were also exceeded under most conditions for List 1 carcinogenic PAHs and List 2 non-carcinogenic PAHs. Co- disposal criteria, EP toxicity criteria and TCLP criteria do not apply to PAH compounds.

Newer tires appear to contain slightly higher concentrations of leachable PAH compounds than older tires.

...--......--...-.-. 1U656 N ~ M #1

ILL659 Old t i1

144662 Asphal r

145000 tien #2

145005 Old 1 2

1.55008 Asphalt

145010 . New $2

1L5013 .Old $3 145015 Aswal t

145020 We!. %

1L5021 Old %

145024 Asphalt

159099 PC-V-tire

159114 FL-V-tire

159121 FL-V-back

159117 FL-S-tire

159108 FL-S-back

159071 PC-S-tire

161251 iire grab1

1612% iire grab2

159099 Field pH

15911L Cield pH

159121 iield pH

Swmary of Chemic~l Analysis

Poiynucirar i r m r i c Hycrocarkns

ard iorai Perr0te.m Hybroc~r:ons

Waste iirc Projec:

4231-90-177

Total Pe:ioicin

Hvdroc~rban:

?AH (carcinosenic) ?AH (ncn-carcinogenic)

................................... LID NO 430

230 497 130

NO NO I 5 3

200 425 498

es 187 z4a

NO NO 310

339 1354 ~ 7 9

100 LOO 171

36 728 436

790 3159 1271

25? 9% 605

6 118 317

Detection Limit 0.5 q/l 4-20 ppt 4-20 pp:

RAL

Chronic

AIL PAH concenrrations expressed as ng/i (nanograffi per liter) o r

n w k g (nanograms per kilogram) vhicn is equivalent ro parrs per rrillion For samles 14L656-IL502L, ;he concenrrarions are exFressed in ng/kg (nanograms per tiiogram) o f tire material

ihe qrtivalenr concenrrarions i" tne esrimaced porcuater v o l m a r c 0.8 rimes :he values rcporred (se. page j:

Condirian $1 = pH 3.5 leach

Corairian $2 = pn 5.0 leach

Condirian $3 = 0 . C NaCl leacn

C O M i t i m l = pH 8.0 leacn

iL = Flowvood Road Sir?

PC = Pine Camry Road sire

S = soil sam(e

W = water saiijle - . i i r e grao = soil s a m l e u m e r stockoiie

Type ...........

He" ll

Old $1

*$;%,it

He" $2

OLd l2

Arphal r Hew 3

Old $3

iiph~l t

He" L

Old ZL

As~nalt

159099 PC-W-tire

159ilL ii-u-tire

159121 fL-!J.back

159117 iL-S.rire

159103 fl-s.back

1590il PC-S-tirs

16i251 lire grab1

161251 lire grab2

RAL 0.050 1.500 0.005 0.120 0.300 0.001 0.020 0.015 5.000

Chronic 0.050 0.1l.7 0.030 1.000 0.001 0.010 0.300 0.001 5.000

Co-disposal 0.500 0.100 10.000 0.100 0.500 3.000 0.020 0.500 0.500 0.100 50.000

EP iaricity 5.000 5.000 100.000 1.000 5.000 0.200 5.000 1 .DO0

TCLP 5.000 5.000 100.000 1.000 5.000 0.200 5.000 1.000

for sawler l1L656-lL5024 :he r e s u i t s were crpresses' as mglkg (milligrams psr kilogram) o i of tire sarsle ["norm;lli:cS"i

& o r sapier, 159099-16125' ihr rcsulcs w e r e expreascd as mg/kg o i soil or ng/l !milligrams per liter) o: u a r c r as recciuvc

ngtk.9 a d mg/l a c t cquivalenr to parts per miliicn.

lhc cquivalenr concentrationr in :he esrimared poreuarer VO~LT a r e 0.8 times the leachare valvcs reporrcd !see pegc 311.

I Corjiiion Yl = pH 3.5 leach

Cordiiian $2 = pH 5.0 leach Condirion Y3 = O.9X NaCl leach condition % i ;N 8.0 Leach

FL = ilooduod Rood Sire PC = Pine Counry Rood Site S = soil zmjlc '.' = k'aier sm;ie

lire grab = soil sar;3ir m o c r sisckpiie

Tc;:rndi'f 2: Chcmicai i n ~ i i ~ > :

Po i j . n ~ c ! c ~ r A;cmj:ii ! $ j c ; c : ~ r ? . ~ n . :

ard i o r ~ i ?c:ra!ccv H~<rsca;can::

Waste i i r e P ro jec :

L;;i-"O.i;;

lLL656 New Y1

i L L 6 j P O l d $1

ILL662 A s w a l t

115000 Hew #2

145005 OLd $2

115008 Asphai t

1L5010 Hew -1 115013 O L d 3

lL5015 A S ~ h a l t

1L5020 Hew $ 1

115021 O l d YL

115C2L Asoha l r

157099 P C - V - t i r e

1 5 9 i l L F L - V - t i r e

153121 FL-U-back

1 5 3 i i 7 FL -S - : i r e

159 i08 F L - 5 - b x k

15307; P C - S - t i r e

161251 T i r e grab1

161251 i i r e grab2

D e t e c t i o n L i m i t 0.5 mg/ l

RAL

Chron i c

PAH ( c ~ r ~ i n o ~ e n i c )

! l o r m i i z e d

s m 0 ; 517

L i s t 1 L i s c 1

.................... NO NO

230 L97

HD NO

200 L25

88 1 3 i

NO NO

339 .:- 123L

100 LOO

36 728

i 9 0 T i 5 9

23 9 95 L

b 118

~ 5 5 0 p?b

<550 pp3

<550 p p ~

d l 0 ppb

<L30 ppb

L - 2 0 ppr

28

2 1

n o r m i i:C:

s m o i S1;% 3:

i i s t 2 L i s : 2

w / Z s n;/k .........................

A i l PhH c o n c e n t r a t i o n s expressed as ng/L ( n m o g r a m p e r L i t e r ) o r

ng/kg (nanograms pi- k i l o g r a m ) v h i c h i s e q u i r a l e n c t o p a r i s per t r i i l i o n

;or ssmoies 1~1656-11502f,, t h e c o n c c n r r z t i o n s a r e expressed in ng/kg (nanocrams pe r k i l o g r a m ) o i t i r e m a r e r i s [ . -. i n e % e i v a i e n i c o n c e n t r a t i o n s in t h e e s t i m a t e d pa rewa te r v o i w are 0.8 t i m e s t h e v a l u e s r sps ryed (se. page j l )

C o n d i t i o n :l = pH 3.5 Leach

C o n j i r i a n $2 = pH 5.0 Leach

C o n d i t i o n C3 = 0.92 NaCL leach

: o r d i t i o n SL = pH 8.0 Leach

i L = FloDduocd Road S i t e

PC = P ine County Road s i t e

5 = s a i l s a e e l e

U = e a t e r 5 a m l e - . I i r e g rab = s o i i sample urr ler s t o c k t i l z

Mimesom PoUution Conuol Agenq February 19, 1990

Paze 23

2 2 Field Sampling P r o m

.The field sampling program was conducted at two sites where waste tires had been used to construct a roadway over wetland areas. The areas were chosen by representatives of TCT, the MPCA and the DNR. The purpose of the field sampling program is to collect and analyze soil and groundwater samples from &ting tire sites for the parameters of concern identified by the laboratory leachate studies. The samples were chosen to represent soil and groundwater conditions under the roadbed where tires were used in the subgrade and in a background area to serve as a con.tr01. Soil samples were also collected from existing tire stockpile sites as a comparison with the field and laboratory results.

222 Floodwood Roadwav Site

This site is on the Hedbom Forest Road located approxhately 8 miles west of Floodwood Minnesota. The road was constructed by the Minnesota DNR over a wetland in 1986. During construction of the road, several test sections were constructed which utilized various waste tire subgrades.

The area selected for sampling was designated TS #4 by the DNR. At this area a turnout was constructed using shredded tires in the subgrade, The turnout surface was very soft. Therefore, an auger boring was put down 3 feet fr6m the turnout on the main road. The soil prose encountered is as follows:

Depth Soil Type

O - 3 f t . Fill, silty sand , geotextile fabric at 3 feet.

3 - 12 ft. Peat, fine fibrous

12 - 19 ft. Silty clay

The soil boring was 5 feet from the tire area. A soil sample was collected at 4 font depth ' - below the road surface. A four inch night auger was advanced to a depth of 5 feet. The -sample was taken from the auger flights at the 4 foot depth. 1

Ln order to collect the groundwater sample, a second auger boring was advanced with the

bhesora Pollution Conuol Agenq Februr ; 19, 1%

Page 24

4 inch flight auger to a depth of 19 feet. T h i s second boring was within 2 feet of the first borehole. Groundwater filled the hole to approximately 8 feet below road surface. The groundwater sample was collected from the open borehole using a bailer. The borehole was bacldilled with native material. This boring was also 3 feet from the tire area.

Background samples were collected approljmately 114 mile east on the north side of the road. At this location, a hand auger was used to collect a soil sample at a depth of 5 feet. The soil conditions consisted of fibrous peat throughout the boring depth.

After the soil sample was collected, a temporary PVC well screen was installed in the hole. The purpose of the well screen was to minimize sediment in the water sample. A bailer was used to collect the water sample. After sampling, the well screen was removed and the hole backEilled with native material.

The samples were transported back to the laboratory in a portable cooler.

The results are presented in the Appendix and are summarized in Table 6 and Table 7.

Samples are identified by the prefix 'FL".

223 Grasston Site

This site is located on Royalton Township Road approximately 112 mile east of Grasston Minnesota in Pine County. This road begins at Pine County 7 and extends south. The road is a dirt single lane road that was constructed in the late 1970's.

During the construction, several soft areas were traversed by placing whole tires as a subgade material. Evidence of the tires is visible at the surface in places.

Minnesou Pollution Conuol Agency Febnury 19, 1990

Paye li.

One such area is located about 600 feet south of Pine County 7. At this location a 4 inch flight auger boring was done in the roadway. The boring drilled to a total depth of 15 feet. A soil sample was collected at a depth of 5 feet ( directly below the tire area). The soil profile encountered is listed below:

Depth Soil Type

0 - 4 f t . Fill, Silty Sand with some clay, whole tires in fill

4 - 15 ft. Peat, h e Brous

It was necessary to collect 6 liters of groundwater for the laboratory analyses. In order to be able to obtain sufficient water volumes, it was necessary to extend the hole to a depth of 15 feet

A temporary PVC well screen was placed in the borehole to minimize sediment in the water samples. The groundwater samples were collected with a bailer.

A background soil sample was collected approximately 20 feet west of the roadway. At this location, a hand auger sample was collected at a depth of 4 feet The soil profile consisted of peat throughout the boring depth.

.-

Groundwater samples were attempted by augenhg to 9 feet and waiting for the hole to fill with water. Although the water table appeared to be about 4 feet deep (based on soil sample observations), insignificant quantities of water recharged the borehole. A second 9 foot deep hole was advanced, but again only minor amounts of water were encountered. After about 30 minutes of waiting, it was decided to forego the water sampling.

%The samples were transported back to the laboratory in a portable cooler.

The results are presented in the Appendix and are summarized in Table 6 and Table 7.

Samples are identifjed by the prefix "PC'.

Minnesow PoUution Control . February 1)

F

2 2 4 Ti Stcxkpile Site

This site is at the Anoka County Compost and Disposal Tree site. Two soil samples collected at the site. The first sample was collected of the surface soils located di below a very old stockpile. Several tires at the toe of the stockpile were removt expose the underlying soils. Based on the type of tires in the stoclqile, it is estimatec the pile is about 25 to 30 years old.

A second, newer pile was also sampled. Here again, the tires were removed at th: of the pile exposing the underlying soils. The so& were sampled from the surface. tires in this pile are estimated at 15 to 20 years old

Both soil samples were silty sands.

The results of the tire stock pile samples are designated as tire grab 1 and tire grab summary Table 6 and Table 7. The laboratory Report of Chemical Analysis is atta in the Appendix.

The intent of the field studies was to provide a limited comparison of the concentra of target parameters in soils and water underlying existing waste tire roadway subgr compared with background locations nearby. It was not within the scope of s e ~ u this project to perform a comprehensive field study of e*ting waste tire sites. Re of the field studies were compared with RALs and chronic toxicity criteria for v samples. M s p o s a l criteria, EP toxicity criteria and T W criteria are not applicab soil samples collected in the field which were not extracted with a leach procedure. B on the results of the Limited assessment performed, the following observations were m

Soil sample results for metals analyses were compared from the tire area and background area at the Floodwood site. The results are summarized in Tab1 Aluminum, iron, magnesium, and zinc exhibited higher concentrations in backpc samples than in tire area samples. Arsenic, barium, calcium and selenium exhibited hi concentrations in tire areas than in backpound samples. For the other metals anal! the tire area and background areas were similar. At the Pine County site, a soil sample was collected from the tire area. The resulrs o

Minnesota Pollution Con~rol A g e n q Februaiy 19, 1990

Page 27

Pine County tire area sample were similar to the Roodwood site tire area results with the exception of lead which was non-detectable at the Floodwood site and 43 m-g'kg at the Pine County site.

,Metals in soil samples from the two tire stockpile sites were similar in concentrations to the Roodwood and Pine County soil samples. An exception was lead which was not- detected at the Floodwood site but was present at the Pine County site and the tire stockpile sites.

Because metals in soils are naturally occurring and wide variability among samples can exist, comparison of the results of the field soil samples does not indicate any siguficant differences between field sites, between tire area and background samples or at tire i stockpile sites.

PAH analyses indicated non-detectable concentrations in the three soil samples reported. AD soil samples were reported to have a detection limit of 550 parts per billion @pb). The detection limit was elevated from the normal 10 ppb range due to matrix interferences.

Total petroleum hydrocarbons for the tire stock pile sites were similar in each of the two samples collected with results of 47.6 m a g and 55.5 m a g at the two stockpile sites. These results appear to be higher than concentrations observed at the field sites and may be indicative of potential concerns at tire stockpile sites. Additional field studies of tire stockpile sites may be needed to further characterize the &ects of tire stockpiles on underlying soils.

Minnemia Pollution Conuol Agency February 19, 1932

Page 28

2252 Water Samples

The results of water samples collected at the Floodwood site tire area exceeded the Recommended Allowable Limits (RALs) for barium, cadmium, chromium and lead while background samples did not exceed the RALs. The results of water samples at the Pine (h.xnty site exceeded the R4Ls for List 1 carcinogenic and List 2 non-carcinogenic PAHs. Based on the results of this liuiited assessmen& it appears that the me of waste tires may have an impact on groundwater. Additional field studies utilizing monitoring wells and repeated sampling may be needed to provide information concerning the potential impact of tire sites on groundwater.

A general vegetation survey of the Roodwood Roadway Site and the Grasston Roadway Site were conducted by TCT representatives on October 23, 1989.

23.1 Grasston Roadwav Site

The Grasston Roadway site is located on a minimum maintenance road west of Grasston Minnesota. The sampled area was located at the west edge of a dry wetland with tamarack trees bordering the west side of the road. A sixty foot h e transect was randomly placed from the east side of the road into the wetland area. Twenty-nine points were randomly placed along the line transea. At each point, a pick was lowered and the first vegetation type (grass, forb, or shrub) First encountered or hit was recorded. Of vegetation encountered along the transect, 52 % were grasses, 21 % were forbs, and 27 % was litter. No shrubs were encountered along the sample transect. Vegetation encountered included Fhalans arundinacea. Twha latifolia, and species of &. A satisfactory control area for comparison could not be located at the sample site due to the variation of the vegetation around the sample site. However, funher along the minimum maintenance road, a waste tire roadway site which ran through the Enter of a wetland was observed. No major differences in vegetation composition could be visioly observed between waste tire and non-waste tire areas at this nearby site.

23.2 Flmdwood Roadway Site

The second waste tire site was located on a gravel road south of Roodwood, Minnesota. : The waste tire and non-waste tire (control) sample areas were located between the road '.and a creek north of the road. At the waste tire sample area, three twenty foot line

transects were randomly placed with twebe to fifteen randomly placed points along each line transect. A total of forty points were recorded for the three line transects with points encountering 60 % grasses, 15 % forbs, 2 % shrubs, and 8 % litter. Vegetation observed included Phalaris arundinacea and species of m. A non-waste tire control area was located approximately 200 feet east of the waste tire area. This area had a steeper embankment from the road to the creek. Three twenty foot line transects were randomly placed at this sample site with seven to nine random points along each transect. A total of twenty four points were placed on the three transects with recorded vegetation composed of 67% grasses, 8% forbs, 4% shrubs and 21 % litter. Vegetation observed included species of Pea and Bromus. Differences in overall vegetation composition between the two sample areas (waste tire and control areas) were not observed at this site.

233 Discussion

The use of a biological s w e y is a qualitative indicator of environmental impacts from the usage of waste tires at existing sites. The environmental impacts of pollutants or contaminants may be detected by stressed vegetation or veget;ttion which is more tolerant of pollutants may be more prevalent in an area afFected by pollutants. The results of the biological survey indicated no observable difference in vegetation composition at either of the two study areas when comparing waste tire areas and control areas. Based on these results, it is our opinion that additional biological sweys are not likely to indicate &y observable difFerences at waste tire sites when compared to background sites.

Minnexlta Pollution Control Agency February 19. 1990

Page M

3.0 DI.SCLJSSION AND CONCLUSIONS

3.1 Laboratom Leachate Studies

The review of the laboratory leachate studies indicates that metals concentrations exceed the RALs for more constituents at pH 3.5 conditions than at neutral or basic conditions. Constituents of concern include barium, cadmium, chromium, lea4 selenium and zinc. Elevated levels of iron are also detected from all leachate samples with higher concentrations at pH 3.5 and declining concentrations as pH increases. The presence of iron in water may be more of an aesthdc concern than a health concern.

Asphalt samples in the laboratory leachate studies also indicated constituents of concern in excess of RALs. These include barium in all pH conditions and c h r o m i q iron and selenium in pH 3.5 conditions.

Polynuclear aromatic hydrocarbons (PAHs) and total petroleum hydrocarbons (418.1) concentrations generally were detected at higher levels in pH 8.0 conditions and decreased as the pH decreased. List 1 carcinogenic PAHs and List 2 non-carcinogenic PAHs in excess of the RALr were detected in nearly all of the laboratory leach test samples. Asphalt samples exhibited generally lower levels of List 1 carcinogenic PAHs and generally higher levels of List 2 non-carcinogenic PAHs when compared with tire samples.

Based on these results, it is our opinion that monitoring of waste tire sites should include chemical anmis for the following parameters:

Barium Cadmium Chromium Lead Selenium Zinc List 1 PAHs (carcinogenic) List 2 PAHs (non-carcinogenic)

Detection limits for future monitoring should be lower than the RALs associated with each compoundj.

Minnesota PoUuuon Cnnuol Agency February 19, 1990

Page 31

3.2 Field Studies

The results of field studies indicated that barium, cadmium, chromium and lead exceeded the RALs for the tire area water sample at the Floodwood site while the background water sample did not exceed the RALs.

Soil sample concentrations generdy were similar to background or naturally occurring concentrations.

Based on these results, it is our opinion that the limited assessment performed for this project indicated potential concerns with the use of waste tires at field sites which requires additional data for adequate evaluation. Additional field studies should include installation of groundwater monitoring wells with samples collected for the parameters listed above in Section 3.1.

3 3 Literatme Search Comparison

The reports of two other leachate studies of waste tire matenab were reviewed and compared with the results of the leachate studies for this project. The results for metals an&es were similar to those obtained in this study at neutral pH conditions. The other studies did not include the pH ranges utilized in this study.

The analyses of tire samples for PAH compounds were non-detectable in the other studies reviewed. The deteddon limits by conventional analytical techniques range from 10-50 parts per billion and therefore are too high to detect the PAH compounds detected at the parts per trillion levels in the laboratory leachate tests conducted for this study. In addition, the other studies utilLzed less aggressive Ieachate environments (more neutral pH) than the current study. It is our opinion that additional literature search activities at this .time, wiU not be likely to provide additional information.

The results of the biological survey conducted indicated no obsewable differences between waste tire areas and background areas. It is our opinion that additional biological surveys are not likely to provide quantitative or qualitative indications of any impact from waste tire usage. For that reason, we do not recommend any additional biological surveys.

3 5 Assessment of Emironmental Imwcts

Based on the leach test results, a computation was performed of the estimated concentrations within the porewater volume at the waste tire subgrade. It was assumed that shredded tires have a dry unit weight of approximately 30 pounds per cubic foot and that average porosity of shredded tires is 0.6. The volume of the voids in 1 cubic foot of tires would therefore be equal to 0.6 cubic fee t Dividing by the unit weight of 30 pounds per cubic foot gjves a result of 0.02 cubic feet per pound of tire material. This is equivalent to 1.25 cubic centimeters per gram of tire (i.e. 1.25 liters of liquid per Hogram of tire).

The following example illustrates the "worst case" concentration of zinc expected in the porewater space (1.25 liters) for 1 kilogram of tire material.

Zinc at p H 3.5 condition for new tires = 50.81 mglkg. 1 kilogram of tire material containing 1.3 liters of fluid.

50.81 m a g * 1 kg / 1.25 1 = 40.65 mg/l

The RAL for zinc is set at 5 mg/l and therefore, the result of the computation would exceed the RAL

3.6 Discussion of Alternatives

'Worst-case" conditions for metals appear to occur at low pH (acid) conditions. 'Worst- case" conditions for organics appear to occur at high pH (basic) conditions. Utilization of waste tires in locations where exposure to pH extremes is not expected is one method of reducing the potential environmental impacts from waste tire materials.

A second method of reducing the potential environmental impacts from waste tire materials would be to restrict the use of tire materials to portions of the roadway which are above the water table in order to minimize the leachate generation potential. Wood chips or soil materials could be utilized for the submerged portion of the roadway subgrade. Wood chips are Jess likely to biologirally decompose when under water and are therefore suitable for the submerged portion of the roadway subgrade. Tire chips are unlikely to leach constituents of concern i f used in the unsaturated portion of the roadway. Appropriate surface water drainage to prevent surface water from h5ltrating into the waste tire subgrade should minimize any potential leachate generation.

Mimesou PoUuuon Conuoi Agency F e b m r y 19, 19SO

Page 33

4.0 CONCLUSIONS

I

Based on the results of the studies conducted, the following conclusions were reached:

Met& are leached from tire materials in the highest concentrations under acid conditions. Laboratory studies indicate barium, cadmium, chromium, lea4 selenium and zinc are constituents of concern.

Polynuclear Aromatic Hydrocarbons (PAHS) and Total Petroleum Hydrocarbons (418.1) are leached from tire materials in the highest concentrations under basic conditions. Constituents of concern included List 1 (carcinogenic) and List 2 (non- carcinogenic) PAHs.

Asphalt materials may leach higher concentrations of contaminants of concern than tire materials under some conditions.

-ded under Drinking water Recommended Allowable Limits (RALs) may be exce, "worst-case" conditions for certain parameters. Parameters include barium, cadmium, chromium, lea4 selenium, zinc, List 1 (carcinogenic) and List 2 (non-carcinogenic) PAHS.

Gxikposal limits and El'. Toxicity limits are generally not exceeded for the parameters of concern.

Field studies and the biological survey did not identify significant differences between waste tire areas and control areas for soil samples. Water samples at the Floodwood site indicated results in excess of the RAIs while background samples did not

Potential environmental impacts from the use of waste tires can be m h h k e d by placement of tire materials onky in the unsaturated zone of the roadway subgrade.

Minnesota Pollution Control Agency February 19. 1990

Page 33

Based on the results of the laboratory and field studies conducted for this project, we recommend the following factors be considered for use of shredded waste tires in roadway subgrade construction.

1. That the use of waste tires be limited to the unsaturated zone in a roadway designed to limit infiltration of water through the waste tire subgrade. Design of the roadway surface and ditches to promote surface water drainage away from the waste tirk subgrade should be included in the design of the roadway.

2. That additional field studies be performed to evaluate new or existing roadways where waste tires are used. Field studies should include sufficient numbers of monitoring wells in roadways and background areas to provide a statistically significant comparison of tire area and background area samples.

6.0 STANDARD OF CARE

The recommendations contained in this report represent our professional opinions. These opinions were anived at in accordance with currently accepted hydrogeologic and engineering practices at this time and location. Other than this, no warranty is implied or intended-