Document GK4DRE573wMNg6RMk8n8VKrgx

2195 Front Street Logan, OH 43130 OhisEfft Stale of OMo Envlim W eatU PttrteeUoo Agency Southeast D istrict Office TELE; (740) 385-8501 FAX; (740) 385-6490 AR226-2607 Bob Jatt>Governor Christopher Jones, Director May 13,2002 Mr. Andrew S. Hatien, Project Director DuPont Engineering Barley Mill Plaza - Bldg. 27 Lancaster Pike & Rte. 141 Wilmington, DE 19805 Re: Comments on April 2002 Proposed Sampling Investigation Plan for Little Hocking W ater Association W ell Field Washington County Little Hocking, Ohio Dear Mr. Harden: On April 23,200 2, the Ohio Environmental Protection Agency Southeast District Office received the April 2002 Proposed Sampling Investigation Plan for the Little Hocking W ater Association W ell Field. The work plan outlines the technical approach to determine the horizontal and vertical extent of C-8 in ground water in the vicinity of test well TW -4. Ground water C-8 concentrations were measured in TW -4 at approximately 37 ug/l, . . Ohio EPA has completed a review of the workplan. In addition, the Little Hocking W ater Association, Inc; and their consultants, Burgess & Niple, Limited: and Bennett & Williams Environmental Consultants, Inc. have collectively reviewed the work plan. Ohio EPA comments are presented first, followed by Little Hocking's comments as submitted to the Ohio EPA by letter dated May 3 ,2 0 0 2 . Ohio EPA request that DuPont address each of the comments provided below. Ohio EPA Comments 1. Ohio EPA request that DuPont collect and analyze soil samples in the Little ' Hocking W ell Field to evaluate presence or absence of C-8. These soil samples should be collected in the vicinity of TW -4 and at the locations and vertical depths as indicated below in comment 3. Ohio EPA is aware that the methodology to run soil samples for C-8 may not be fully developed by Exygen at this time. Please provide a time frame for the collection and analysis of soil from the Little Hocking W ell Field. 2. Ohio EPA request that duplicates of water samples be collected at an approximately 10% rate for analysis by the US EPA Laboratory in Colorado. . 0 Mit] an Ricyeted Paper ASH028105 EID781385 EID781385 UTTLE HOCKING WATER ASSOCIATION WELL FIELD WASHINGTON COUNTY PAGE 2 Little Hocking W ater AssoefetoJSaipQente 1. The Plan proposes to use a Geoprobe for penetration into the ground. The primary advantage of the Geoprobe is that it does not generate wastewater or cuttings, and as such, there is no disposal required. The primary disadvantages are that the method may not allow penetration to the bottom o f the aquifer and that the sample obtained is quite small and no sample may be recovered from coarser material. 2. The upper sample Is proposed to be taken at the top of the saturated zone, but the aquifer is more permeable in its lower 20 feet of section. It will not be known whether or not the upper part of the aquifer is confined. W e therefore propose that, in the event that some wells do not fully penetrate the aquifer, the contractor be prepared to propose another method that will allow full penetration of die aquifer. Because the complete chemical properties of C -8 are not known to us at this time, we concur that collection of both shallow and deep samples address potential density Issues. According to the 3M Materials Safety Data Sheet, the specific gravity Is 0.4-Q.5. This means that C-8 in pure form should float. However, it is imperative that the bottom of the aquifer be reached for sampling in light of the information contained in Dupont's information contained in "TE3170 PTFE Fluoropotymer Dispersions All In"wherein ammonium perfluorooctanoate (C -8) is listed- as one of the compounds and the generic description o f the compound include a notation that the specific gravity is 1.4 1.5. This means that the compound is more dense than water and will sink in >) the water column. There is no data provided to indicate that the surfactant, C-8, becomes stable when combined with other compounds. Further, there is no data to indicate whether or not the C-8 assumes the greater specific gravity of the new compound and is therefore denser than water and in a form that dissociates, 3. In order to took at potential differential vertical densities and solubilities, we suggest that at least two of the wells be sampled at five-foot intervals throughout the entire section from the ground surface to the bedrock surface (which is ' approximately 55 feet below ground surface). This includes sampling both saturated and unsaturated sections (e.g. collecting both soil and groundwater samples). A surface sample of soil should also be collected at these locations. The Geoprobe borings that we propose for this sampling include: a. the first Geoprobe boring south of TW -3 and b, the first Geoprobe boring east of TW -4. ASH028106 EID781386 EID781386 LITTLE HOCKING WATER ASSOCIATION WELL FIELD WASHINGTON COUNTY PAGE 3 4. In order to gather additional information between the two wells with the highest detections to date (TW -4 and PW -5), we recommend that two additional borings should be advanced between TW -4 and PW -5. These borings should be advanced at approximately equal intervals between these two existing wells, 5. In addition to the water sampling and analyses proposed in the Geoprobe holes, existing test wells (TW-1 through TW -6 and TW -9 through T W -11) and production wells PW-1 through PW -3 and PW -5) should be sampled and analyzed at the same time as the Geoprobe investigation. In addition, water levels should be collected from all existing production and test wells prior to beginning the Geoprobe investigation, W ater levels should be recorded for the Geoprobe borings as the borings progress. In addition, the level of the Ohio River should be recorded at the time of the tests. 6. The Work R an does not contain a map that shows the location of all the test wells. The W ork Plan map should be revised to include all wells on the property, (The Work Plan map is attached for reference, A plat map showing the location of all the test wells and production wells is also attached). ?. According to the Work Plan, the probe assembly used will be decontaminated between sample locations according to the procedures described in the Quality Assurance Project Plan (Dupont, 2002)" However, the Work Plan is not specific as to whether or not other procedures in this document will be followed. For example, the W ork Plan states T he temporary well points or Screen Point 15 Groundwater Sampler will be purged a minimum o f three volumes before groundwater Is sampled." However, there are no stated requirements for collection of indicator parameters such as pH, temperature, specific conductance, and turbidity in the event of Geoprobe sampling. The QAPP addresses these types of procedures on page 14, but it is not d ear If any of these procedures will be used. Also page 11 implies that pH and specific conductance meters will be calibrated, but does not mention other meters. This needs clarification. ASH028107 EXD781387 E ID 7 8 1 3 8 7 LITTLE HOCKING WATER ASSOCIATION WELL FIELD WASHINGTON COUNTY PAGE 4 . 8. If the QAPP is to be used for determining water stability before sampling, pH, temperature, specific conductance and turbidity should be collected at a minimum. PH is of specific importance because the well with the highest reported value for C-8 (TW -4) had a field pH of 11.5 (as reported on the Chain of Custody) during the January 22,200 2 sampling event. This value was significantly higher than TW-1 at 8.2 and the remaining wells in the 7.0 to 7.6 range. Turbidity may also be Important in that Geoprobe samples typically have a higher turbidity due to the temporary nature of the well screen Installation and the lack of well development. Because not a lot of information is available about C-8, sorption to the finer particles, sequestering of the finer particles and subsequent removal of the surfactant through filtering prior to laboratory analysis may prove to be a factor in concentrations. A report by A. N. W elter for 3M dated March 2 3 ,1 9 7 9 shows that FC-143 (aka C -8) sorbs only slightly (5% ) to a sandy loam soil and then is readily desorbed. However, no studies on clay-rich soils or soils with appreciable organic content were included. It has been reported to the authors that Dupont currently uses granular activated carbon to lower concentrations of C-8 prior to discharge. Turbidity may prove to be a factor In interpreting the results, and therefore should be monitored and recorded. 9. The QAPP recognizes that three consecutive readings of the measured field parameters are used as the criteria to indicate stabilization of the sampled water and initiate sampling. However, the QAPP states that the readings of the parameters must be within 10 percent on the three consecutive readings, in fact, the 10 percent rule should only apply to specific conductance and turbidity. One tenth of a unit should be the criteria for pH and C. This is due to the large nature of the increments in these measurements. For example, 10 percent of a pH of 7 means that the pH can vary between as low as 6,3 or as high as 7,7 and be considered stable. Considering that each pH unit is an order of magnitude greater than the next whole number, this shows that 10 percent is not the correct interpretation for stability. However, a one tenth of a pH unit when used as the criteria for stability means that a pH of 7 can be as low as 6.9 or as high as 7.1 and meet the stabilization criteria. 10. The QAPP indicates on page 9 that the sample will be analyzed using a LC/MS/MS and that "Selectivity for C-8 is demonstrated by the presence in the chromatogram o f a peak o f a daughter ion at 369 amu from a parent o f 413 a m u " W e recommend that, as part of the reporting process, a library search be performed and the results be reported for other chemicals present as indicated by peaks on the same chromatogram. ASHQ2B1Q8 EID781388 E ID 7 8 1 3 8 8 LITTLE HOCKING WATER ASSOCIATION WELL FIELD WASHINGTON COUNTY PAGES 11. The Work Plan states, T h e sampling process will use a narrow diameter bailer, tubing/check valve system, and peristaltic pumps," The reviewed Materials Data Safety Sheet states that the compound is 33 to 40 percent volatiles by volume. According to the Technical Guidance Manual for Hydrogeologic Investigations and Ground W ater Monitoring (Ohio EPA, February 1995), peristaltic pumps promote "degassing and loss o f VOCs; therefore, these devices are not recommended for collecting samples to be analyzed for volatile o r semi-volatile compounds and dissolved gasses. The National Council o f Industry for A ir and Stream Improvement (NCASI, 1984) found a 10 to 30 percent loss in VOC concentrations from peristaltic/vacuum flask systems compared to results for bailers, bladder pumps, or submersible pumps," The sample extraction methodology should be revised to exclude peristaltic pumps or sampling method that uses suction lift (and thereby creates a vacuum). Other methods of sample extraction should be specified that minimize volatilization. In the Screen Point 15 Groundwater Sampler this may effectively limit the sampling device to a mini bailer. 12. The Work Plan does not specify the material to be utilized as screen in either the Geoprobe or the Screen Point 15 Groundwater Sampler. Screens for these devices are manufactured in aluminum, stainless steel and PVG. The QAPP indicates on page 12 that aluminum foil should be avoided. Does this mean that the Work Plan will only accept stainless steel or plastic? if so, this'should be stated. 13. The Work Plan states on page 2 "Once groundwater is sampled, the wellbore will be backfilled with bentonite." However, neither the type of bentonite (pellets, slurry, etc.) nor the method o f bentonite emplacement is specified. These penetrations into the subsurface are being made in the welifield and if not sealed will provide a direct route for contamination from the surface. Given tile concern about the route of migration for the 0 8 at Dupont to the welifield (l.e. airborne and subsequent infiltration, groundwater migration, or combination of both), ensuring sealing of the boreholes is imperative. The Work Plan should specify . that a bentonite/cement slurry or neat cement grout mixture will be emplaced from the bottom of the boring until retoms are seen at the surface. Both the Geoprobe and Screen Point 15 Groundwater Sampler can m eet these objectives and grout can be emplaced through a tremie tube. 14. The Work Plan should acknowledge that the Geoprobe is good for preliminary screening efforts, but that permanent sampling points and further investigation may be necessary at the welifield. These investigations would include looking into the reasons for the high C-8 level In Production W eil #5. ASH028109 EID781389 EID781389 LITTLE HOCKING WATER ASSOCIATION WELL FIELD WASHINGTON COUNTY PAGE 6 15 W e will require copies of all field notes and/or data collection sheets E n g in eer ' will need this infonnation in order to interpret the sample results and to facilitate their investigations of this contaminant. if you have any questions, concerning the above comments, please contact me. Sincerely, Steven E. Williams Hydrogeologist SEW /jm d Enclosures cct Mike Preston, Ohio EPA, DDAGW, SEDO Sarah W allace, Ohio EPA, DDAGW, SEDO Mr. Robert L. Griffin, P.E. Little Hocking W ater Association Ms. Linda Aller, Bennett & Williams Mr. Ron Schultz, Burgess & Nlple file ` ASH028110 EID781390 EID781390