'REE OF RUM WALTER o ~~~~~~~~~~~~~~D.B. Telephone: (907)

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1 WALTERC~File: 180 'REE OF RUM WALTER o ~~~~~~~~~~~~~~D.B. Telephone: (907) DEPT. OF ENVIRONMENTAL CONSERVATION Fax:o v Northern Regional Office 420oYY 1001 Noble Street, Suite 350, Fairbanks, AK NRO File: June 30, United States Air Force 343 CES/CEV Attn: Captain Max Gandy 2258 Central Avenue, Ste 1 Eielson AFB, AK Dear Captain Gandy: Re: Remedial Investigation for Operable Unit Two The following are the State's comments for the Remedial Investigation Report for Operable Unit Two. General Comments Please expand on your interpretations of vertical distribution of contaminants. What information would need to be collected to give more information on this subject? The extent of vertical contamination can greatly impact the amount of ground water needed to be remediated. This remedial investigation does not adequately address co-mingling of plumes caused at 13/26 by additional known sources. 2.0 Field Investigation Summary Document should indicate where 1992 field investigation data is located Well Integrity Is there a report of well inspections? Please provide a copy to ADEC or if it has been provided, when and what report is it in? printed on recycled paper by' C. D

2 Captain Max Gandy -2 - June 30, Analytical Program This section should identify detection limits for contaminants of concern. This document should note that the analysis in 0U2 contains the non-specific Total Residual Petroleum Hydrocarbon values obtained from test method 418.1, instead of Gasoline Range/Diesel Range organic as specified in 18 AAC 78 and the standardized Quality Assurance Program Plan. These test methods were agreed upon by Remedial Project Managers in the 0U2 Management Plan The document should include some discussion about the base being build on fill. That in outlying areas of the base, there is potential for old slough beds and underground channels, and silt areas, which would have an impact on the homogeneity of the ground water. Table 4.7 Title should include that these results are for Potable Drinking Water Wells on base. 4.5 So what level of background are we using at Eielson? More discussion in Baseline Risk Assessment. 5.2 Source Areas ST10/SS14 The following sources are located within the boundaries of ST1O/SS14 and have been identified with past RCRA concerns. Additional action will be required at these sites. Building Up to 200,000 pounds of lead contaminated sandblast grit were stored within fenced area outside this building. Additional surface soil sampling for lead is requested at the storage site. POL Drum Storage Area - Leaking drums containing hazardous waste have been stored near Hardfill Lake. Soil samples at the drum storage site have not occurred at this time. A visual inspection collecting surface soil samples for constituents of concern should be conducted. Subsurface and/or ground water samples may be requested based on the surface soil results.

3 Captain Max Gandy June 30, 1993 ST10 A summary of work completed to verify that leaks are not currently occurring should be included. SS14 What was the reasoning in choosing the cross section as described? Please identify the risk based level for soil contamination for BTEX. Table 5.6 Please convert the BTEX concentrations in Fuels to PPM BTEXs, so that Tables 5.6 and 5.7 are in the same units, then expand the comparison paragraph. If we have a significant seasonal change in product thickness, can this information be used in the remediation effort? 5.3 Source Area STIl1 When the modeling exercise was completed, the mixing depths of 29 m and 91.4 m probably did not approximate real conditions very closely, since evidence suggests that contaminants do not move vertically. Information about vertical movement of contamination is inadequate at this time. Source Areas ST13 and DP 26 Pg 5.48 In 1992, the report to ADEC was in reference to underground storage tanks located on Oscar Row. The tanks were #28 and #32, and the lateral refuel line Pit # Surface Soill Contamination We are seeing elevated levels of DDT, TPH, and semivolatiles in composite surface samples. How do the levels compare with other surface soil results on base? The statements provided sound like a universal disclaimer to existing contamination. Request resample of surface soil area near 13CMVPO4.

4 Captain Max Gandy June 30, 1993 After validation of soil samples collected from the deep monitoring well, if sample results are verified, perhaps we should rethink the depth of contamination in the soils at this site. What is the estimate of distance expected to find contamination from this source at the 100 foot depth? Could contamination from this source be migrating as far as the drinking water well 8? Though we have used a model to approximate future concentrations at this site, the model contains too many uncertainties, and there are insufficient data points to reflect actual conditions at this site to determine areal extent vs. volume of benzene at this site. There is too short of a time span of data to predict degradations of the plume at this time Floating Fuel Contamination How much benzene is there in the floating product as compared to fresh product? 5.5 Source Area 18 It appears that the majority of testing at Site 18 missed the petroleum contamination. I anticipate testing of the two underground 25,000 gallon diesel tanks this summer. It appears that there has been contamination from an underground source in the past, if not currently. It is also unclear at how closely the contamination at ST18 is associated with Sfte 48 in OUl. Given the close proximity to Site 48, the extremely high levels of TPH contamination and the close proximity of the Base Drinking water well, contamination at this site should be addressed along with Shte 48 in Operable Unit Source Area ST19 Given the length of time since the reported spill at this site, the distance from potable water wells, the information projected from the MEPAS model which, shows a progressive decrease in the benzene levels in the water contamination levels. It is anticipated that ground water monitoring at the Site STi19 will verify conditions speculated by the MEPAS model. If predictions are accurate, benzene levels will continue to decrease; and toluene levels will not rise above risk based levels, This source additionally is isolated from other sources and provides a good test of ground water modeling on base.

5 Captain Max Gandy June 30, 1993 The ground water monitoring program should additionally collect samples in the fall to obtain most concentrated samples to approximate worst case contamination. It is my understanding that a leak detection system is to be installed along this line. ARARs 7.2 Surface Water Alaska Water Quality Standards apply to both surface waters and to ground water. The State of Alaska has consistently applied water quality criteria when a hydraulic connection exists between the ground water and the surface water. Water Quality Standards apply regardless of the presence of fish, human consumption or recreation. Within operable Unit 2, Standards apply to Hardfill Lake and at the intersection of site 1 1 with Garrison Slough. 7.3 Petroleum Contaminated Solils 18 AAC requires cleanup of petroleum contamination to the satisfaction of the Regional Supervisor. 18 MAC 78 Underground Storage Tank Regulations currently specifies the level of cleanup required for tank remediations that occur under the Leaking Underground Storage Tank Program. A Guidance for non-ust petroleum contamination mirrors 18 AAC 78. Numeric soil cleanup levels include a matrix with cleanup levels for Gasoline Range Organic, Diesel Range Organic, and total BTEX compounds. While none of the petroleum contamination in 0U2 has come from leaking underground storage tanks, this regulation provides guidance for corrective action 18 MAC AAC specifies that alternate cleanup levels can be proposed by the responsible party by conducting a contaminant leaching assessment. The leaching assessment must identify cleanup levels which will not lead to ground water contamination above applicable water quality criteria, or 18 MAC 70, and must not pose a risk to humans, wildlife or the environment. 18 MAC addresses surface water and ground water cleanup and contains provisions for proposing alternative cleanup levels Sole Source Aquifer There are no existing wellhead protection regulations for the State of Alaska except the section in 18 AAC , "No person may cause pollution or contamination to enter a public water system, or create or maintain a condition that has significant potential to cause the pollution or contamination of a public water system."

6 Captain Max Gandy June 30, 1993 Conclusions Based on the information presented in this Remedial Investigation and the Baseline Risk Assessment, the following decisions are concurred with by the State of Alaska: Action at Sites 1 1 and 19 will be limited to monitoring of soil and ground water to verify existing and projected levels of contamination. Request for action will result if unexpected results during monitoring, or if new information on the risks associated with petroleum contamination warrant a change. It is requested that consideration of Site 18 be included with the Record of Decision on OUl Site 48, based on the close proximity of Sites 18 and 48. Sites 10/14 and 13/26 are expected to begin actions as determined in the feasibility study and subsequent record of decision. Thank you for the opportunity to comment on this remedial investigation. Sincerely, V\J jip T~ Rielle Markey Remedial Project Manager RM/mrh hquwuns.2io.e..2o) cc: William D. McGee, ADEC/NRO/Fairbanks Mary Siroky, ADEC/SPAR/Juneau Shep Dale, ADEC/SCRO/Anchorage Mary Jane Nearman/USEPA/Seattle