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SWMU Demo Dud Area (DD) Area RCRA Facility Investigation Report

Section 2 - Field Investigation

2.1 - Field Actions

As outlined in Environmental Encyclopedia site-specific work plan (Volume 1-2, SWMU DD Area), and three amendments to the plan (RL33 Rework [May 2000], RL74 [January 1999], and RL83 [August 1999]), the scope of the current RFI was to excavate and sift soil to remove UXO and scrap metal, and advance three soil borings to collect soil samples for VOCs, explosives, and metals analyses. All decontamination, sample preparation, and sample handling followed those protocols established in the Field Sampling and Analysis Plan (Volume 1-5, Field Sampling Plan, Quality Assurance Project Plan, and RL33 Addendum).

In addition to the RFI, interim measures are also being taken at the site, in accordance with the consent order, to address stockpiled sifted soil at the site. Results of sampling associated with the interim measures are also described in this RFI report because they are important for site characterization. However, plans for treatability studies associated with these soils are discussed in the Soil Pile Disposition Assessment Report.

2.1.1   Soil Gas Survey

A soil gas survey has not been conducted at SWMU DD.

2.1.2   UXO Clearance and Magnetometer Survey

UXO identification and removal activities were conducted between February 4 and May 30, 1997. UXO specialists from UXB International in Chantilly, Virginia conducted the UXO identification and removal, with oversight from Parsons. The initial intent of the work was to determine if UXO was a potential concern at the site. During initial surface sweeps in February and March 1997, potentially live ordnance items were identified. In addition, Schonstedt magnetometers indicated buried metal at the site.

Due to the presence of buried metal at the site, sifting was identified as a cost-effective method for removing buried UXO and other metal debris. After decontamination, the sifting equipment was mobilized to the site upon completion of sifting at SWMU B-20/21. The sifting operation commenced on May 20 and continued until May 30, 1997. Magnetometers indicated one trench containing metallic waste. Material in this trench was excavated with a backhoe and loaded into a hopper that encased breaker bars that broke the soil into small particles. The soil then moved up a conveyor belt to a shaker screening plant equipped with a ¾-inch mesh screen. The fine size soil fell through the shaker screen onto a conveyor “stacker,” which stockpiled the sifted soil. Based on visual observation and the presence of older/mature live oak trees, it does not appear that any additional trenches are located at the site.

UXO specialists examined all waste as it was excavated from the trench, as it was loaded into the hopper, and as it was discharged from the sifter. Most UXO was identified during excavation activities. Material left over in the screen after being sifted included metal scrap, limestone cobbles, clumps of hard clay, and UXO. This material was spread out on the ground surface and metal scrap and UXO were removed by a trailer-mounted electromagnet or hand-picked. A final inspection of the remaining material was conducted to ensure that it was UXO-free.

The trench was excavated until no additional waste material was encountered on the bottom or in each of the walls of the trench. The trench was situated adjacent to the paved road to the north, and was approximately 250 feet long by eight feet wide. The trench was very shallow, up to five feet deep.

As material was sifted, discharged soil was stockpiled on site. At the conclusion of sifting operations at the site on May 30, 1997, a total of approximately 600 cubic yards of soil were stockpiled in one pile. All metal scrap found at the site was placed into roll-off containers and later transported to Newell Recycling in San Antonio, Texas. All UXO found at the site was segregated and later detonated at SWMU B-20 on September 25, 1997. The trench was too shallow to leave in place; therefore, the site was regraded with native soil at the conclusion of the UXO removal activities.

2.1.3   Subsurface Soil Samples

To characterize the subsurface soils near the trench, three soils boring were advanced at SWMU DD on March 31, 2000. The borings at locations SB01, SB02 and SB03 (Figure DD-4) were advanced to depths of results 10, 13, and 11 feet bgs, respectively. In addition to the surface soils sample discussed in Section 2.1.5, samples were collected from the boring at depths of 5.0-5.5 feet and at the terminus of each boring. The subsurface samples were collected from bedrock formation using a decontaminated core barrel.

A total of seven rock core samples were collected and submitted for analysis. Additionally, one duplicate rock core sample was collected from the terminus of boring SB03. These samples were submitted to DataChem Laboratory in Salt Lake City, Utah for explosives analysis (SW-8330), and APPL Laboratory in Fresno, California for the following analyses: VOCs (SW-8260B), arsenic (SW-7060A), cadmium (SW-7131A), lead (SW-7421), mercury (SW-7471), and barium, chromium, copper, nickel, and zinc (SW-6010B). At the time of sampling, no discernable evidence of contamination was noted in the core samples. The soil boring locations are depicted on Figure DD-4. Soil boring logs are included in Appendix A.

All sampling points were surveyed by Parsons ES using a Trimble Asset-grade GPS Surveying methodology is described in the Amendment to the Field Sampling Plan (Parsons ES, 2001b). All sample location and analytical data will be incorporated into the CSSA GIS after it has been approved by AFCEE and CSSA.

2.1.4   Groundwater Samples

Groundwater sampling was not conducted at SWMU DD. Groundwater was not encountered in the soil borings.

2.1.5   Surface Soil Samples

On March 31, 2000 surface soil samples were collected at the DD Area during the soil boring activities to assess soil conditions near the trench. Surface soil samples were collected from the 0-0.5 foot depth intervals from soils boring locations SB01, SB02, and SB03 (Figure DD-4). The surface soil samples were collected using a decontaminated trowel.

Three surface soil samples, SB01(0.0-0.5 ft), SB02(0.0-0.5 ft), SB03(0.0-0.5 ft), and one field duplicate sample, SB03(0.0-0.5 ft FD1), were submitted for analysis. The samples were submitted to DataChem Laboratory for explosives analysis (SW-8330), and to APPL Laboratory for VOCs (SW-8260B), arsenic (SW-7060A), cadmium (SW-7131A), mercury (SW-7471), lead (SW-7421), and barium, chromium copper, nickel, and zinc (SW-6010B) analyses. No visible evidence of contamination was noted during the collection of the samples.

2.1.6   Soil Stockpile Disposition Samples

Three sifted soil samples were collected from the sifted soil stockpile and submitted to ITS Laboratories in Richardson, Texas, in August 1997. The samples were analyzed for VOCs (SW-8260); SVOCs (SW-8270); explosives (SW-8330); barium, chromium, copper, nickel, and zinc (SW-6010A); arsenic (SW-7062); cadmium (SW-7131); lead (SW-7421); and mercury (SW-7471). Due to questionable activities by the ITS Laboratories, these data are considered unsuitable for documentation of site closure by the EPA. However, since the sifted soils are currently being addressed under RL83 (Volume 1-2, SWMU DD Area), and additional sampling and borings were proposed, it was agreed that the original three sifted sample results would be used as preliminary screening data only.

Three additional soil samples were collected from the soil stockpile on April 20, 2000, and analyzed for arsenic (SW-7060A), cadmium (SW-7131), mercury (SW-7471), lead (SW-7421), and barium, chromium, copper, nickel, and zinc (SW-6010B). In addition, one soil stockpile sample and a duplicate sample were also analyzed for VOCs (SW-8260B), SVOCs (SW-8270C), and explosives (SW-8330). The soils were sampled to assess the treatment/disposal options, and to determine a viable method for disposition. These samples were submitted to APPL Laboratory in Fresno, California for VOCs, SVOCs, and metals analyses, and DataChem Laboratory in Salt Lake City, Utah for explosives analysis. Samples were collected at random depths and locations in the pile, using an EPA-approved random sampling methodology for stockpiles described in 40 CFR 761.

2.2 - Results and Comparisons

2.2.1   Soil Gas Survey

A soil gas survey has not been conducted at SWMU DD.

2.2.2   UXO Clearance and Magnetometer Survey

During the UXO clearance activities, the disposal trench on site was excavated and material in it was sifted. As described in Section 2.1.2, the trench was approximately 250 feet long by eight feet wide. The trench was very shallow, up to five feet deep. UXO was found on the ground surface and in the trench. A total of 240 items were recovered, including 118 mine fuses, 92 Stokes mortars/fuses, twelve 37mm projectiles, six bursters, five .30 cal M1/M2 balls, four practice bomb fuses, and three 3-inch mines. An itemized list is included in Appendix B. Only items that were thought to be live or contain explosives are included in the list. The UXO items recovered were destroyed by detonation on September 25, 1997 at SWMU B-20.

All items that were not live or did not resemble live ordnance were taken offsite for recycling as scrap metal. In the DD area, approximately 600 cubic yards of material were sifted. A total of 10,040 pounds of metal debris were removed and recycled. The sifted material was stockpiled into one stockpile. The trench was too shallow to leave in place; therefore, the site was regraded with native soil at the conclusion of the UXO removal activities. Photographs of the sifting operation are provided in Appendix F.

2.2.3   Subsurface Soil Samples

Analytical results from the subsurface soil samples indicate that the concentrations of all analytes were below the RLs or background concentration for the Glen Rose Formation with the exception of cadmium and methylene chloride. Cadmium was detected above the background concentration (0.1 mg/kg) in the 4.5-5.0 ft deep sample in boring SB03 (0.20 mg/kg). Methylene chloride was detected slightly above the RL (0.005 mg/kg) in the 9.5-10.0 ft deep sample in boring SB01 (0.0054 mg/kg). The presence of methylene chloride in this soil boring sample is believed to be a laboratory artifact and not representative of soil conditions at the site. A summary of analytical results for the subsurface soil samples is included in Table DD-1. Complete analytical results are included in Appendix C of this report.

2.2.4   Groundwater Samples

Groundwater sampling was not conducted at the DD Area.

2.2.5   Surface Soil Samples

Results of the surface soil sampling indicate that metals and VOCs were present in the samples above background concentrations or RLs. A summary of the soil sample results is presented in Table DD-1. A comprehensive list of laboratory analytical data is included in Appendix C.

The metal constituents detected above background concentrations include copper, lead, mercury, and zinc. Copper was detected above the background concentration (23.2 mg/kg) in samples SB02 (38.17 mg/kg), SB03 (61.15 mg/kg), and SB03 FD1 (63.28 mg/kg). Lead was detected above the background concentration (84.5 mg/kg) in samples SB01 (162.36 mg/kg), SB02 (749.06 mg/kg), SB03 (445.63 mg/kg), and SB03 FD1 (427.04 mg/kg). Mercury was detected above the background concentration (0.77 mg/kg) in samples SB03 (2.80 mg/kg) and SB03 FD1 (2.54 mg/kg). Finally, zinc was detected above the background concentration (73.2 mg/kg) in samples SB03 (111.09 mg/kg) and SB03 FD1 (122.29 mg/kg).

The VOCs detected above the RLs were toluene and methylene chloride. Toluene was detected above the RL (0.005 mg/kg) in samples SB01 (0.0205 mg/kg), SB02 (0.0100 mg/kg), SB03 (0.0213 mg/kg), and the field duplicate sample SB03 FD1 (0.0055 mg/kg). Methylene chloride was detected above the RL (0.005 mg/kg) in sample SB01 (0.0063 mg/kg). Methylene chloride is a common laboratory contaminant and was detected in the laboratory blank sample. Therefore, the presence of methylene chloride in the soil samples is believed to be a laboratory artifact and not representative of soil conditions at the site.

2.2.6   Soil Stockpile Disposition Samples

The three sifted soil pile samples (SIFT01, SIFT02, and SIFT03) collected in August 1997 exhibited concentrations of cadmium, copper, lead, mercury and zinc that exceeded background levels. However, these samples were analyzed by ITS Laboratories, who participated in questionable laboratory activities. Therefore, this data was determined to be unsuitable for use in documenting site conditions. These results did indicate that additional characterization sampling was warranted at the site.

Results of the four sifted soil samples collected in April 2000 (SIFT04, SIFT05, SIFT06, and a duplicate of SIFT06) revealed the presence of copper, lead, mercury, and zinc at concentrations above the background concentrations for CSSA soils. Summarized results are provided in Table DD-2 and a complete list of results included in Appendix C. Frequency of detection and maximum concentrations are summarized in Table DD-3. Copper was detected above the background concentration (23.2 mg/kg) in samples SIFT04 (300.05 mg./kg), SIFT05 (75.85 mg/kg), SIFT06 (112.31 mg/kg), and SIFT06 FD1 (9849.4 mg/kg). Lead was detected above the background concentration (84.5 mg/kg) in samples SIFT04 (1212.67 mg/kg), SIFT05 (514.72 mg/kg), SIFT06 (416.43 mg/kg), and SIFT06 FD1 (484.0 mg/kg). Mercury was detected above the background concentration (0.77 mg/kg) in samples SIFT04 (7.58 mg/kg), SIFT05 (1.26 mg/kg), SIFT06 (3.41 mg/kg), and SIFT06 FD1 (5.78 mg/kg). Zinc was detected above the background concentration (73.2 mg/kg) in samples SIFT04 (175.62 mg/kg), SIFT05 (162.33 mg/kg), SIFT06 (132.29 mg/kg), and SIFT06 FD1 (185.13 mg/kg).

Results of the SVOC analysis indicates the presence of several constituents above their respective RLs in sample SIFT04. These analytes include benzo(a)anthracene (1.7 mg/kg), benzo(a)pyrene (1.5 mg/kg), benzo(b)fluoranthene (2.0 mg/kg), benzo(g,h,i)perylene (0.92 mg/kg), chrysene (1.6 mg/kg), fluoranthene (3.6 mg/kg), indeno(1,2,3-cd)pyrene (0.89 mg/kg), naphthalene (1.0 mg/kg), phenanthrene (3.4 mg/kg), and pyrene (2.9 mg/kg). The RL for each of these compounds is 0.7 mg/kg.

Additionally, several VOCs and SVOCs were detected in the samples at concentrations above the laboratory method detection limit but below the RLs, including methylene chloride, toluene, TCE, bis(2‑ethylhexyl)phthalate, 4-chloroaniline, dibenz(a,h)anthracene, dibenzofuran, fluorene, and 2-methylnaphthalene. Results of the explosive analysis indicates that these compounds were not present above detection limits in the samples.

Table DD-3 - Summary of Metals Levels above Background in Sifted Soil

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