April 1, 2008
Mr. James Bearzi, Chief
New Mexico Environment Department
Hazardous Waste Bureau
2905 Rodeo Park Drive East, Building 1
Santa Fe, New Mexico 87505-6303
Dear Mr. Bearzi,
A New Mexico Environment Department (NMED) Hazardous Waste Bureau letter to the Department of Energy (DOE) and the Los Alamos National Laboratory (LANL) dated February 26, 2008 "Status of Remedy Selection at MDA H" brings attention to the fact that the FLUTe sampling membrane does not provide for collection of reliable and representative samples of soil gas for measurement of volatile organic compounds (VOCs). The NMED letter makes the statement pasted below:
"NMED contacted the manufacturer who acknowledged that there were problems with VOC adsorption in FLUTe systems greater than 50 feet in length. NMED is concerned that the material used for the construction of the membrane may have absorbed some of [sic] VOCs or influenced contaminant detection in other ways."
The Resource Conservation and Recovery Act (RCRA) Facility Investigation at the Sandia National Laboratories (SNL) Mixed Waste Landfill (MWL) measured many VOCs to be present in the soil gas below the MWL. DOE/SNL identifies the VOC tetrachloroethene (PCE) as a primary contaminant of concern for the contamination of the groundwater below the MWL. In the Long-Term Monitoring and Maintenance Plan (LTMMP) for the SNL MWL, DOE/SNL propose to monitor the VOCs with FLUTe membranes installed to a depth of 400 feet below ground surface in three boreholes at locations surrounding the MWL. However, the admission by the manufacturer that "there were problems with VOC adsorption in FLUTe systems greater than 50 feet in length" is proof that the FLUTe membranes will prevent collection of reliable and representative soil gas samples for the proposed unsaturated zone monitoring wells at the SNL MWL.
Therefore, based on this new information, Citizen Action requests NMED to order revision for the LTMMP by SNL. The LTMMP must then be informally presented to the public by DOE/SNL with a public comment period and public hearing. The LTMMP public comment period was closed on January 31, 2008 and the new information regarding concerns for the FLUTe membrane was not available until February 26, 2008. The new information needs to be taken into account by the LTMMP because the FLUTe wells do not provide effective vadose zone monitoring. Revision of the LTMMP must also comply with the requirements set forth in the SNL MWL Corrective Measures Study that require compliance with RCRA Subpart G and Subpart F for closure of the MWL.
On November 5, 2007, the NMED released the Fact Sheet/Statement of Basis for the Selection of the LANL MDA H Remedy (MDA H Remedy Fact Sheet). The remedy selected by the NMED includes
1). complete encapsulation of the nine disposal shafts at MDA H,
2). an engineered evapotranspiration (ET) cover on the land surface above MDA H,
3). active vapor extraction of the soil gas plume at MDA H, and
4). long-term monitoring of soil gas below MDA H to a depth of 254 ft below ground surface (bgs).
The NMED selected this remedy because of a concern that trichloroethene (TCE) contamination in the soil gas below MDA H could result in TCE contamination in the groundwater below MDA H at a level greater than the EPA Drinking Water Standard of 5 ug/L.
The TCE contamination was measured at a concentration of 2,600 ug/cubic meter in soil gas samples that were collected from three boreholes at MDA H with the LANL Packer sampling system on a quarterly schedule from February 2005 to March 2006. From March 2006 to the present time, the soil gas samples were collected with FLUTe membranes that were installed in the same three boreholes at MDA H where gas samples were previously collected with the Packer sampling system.
The VOC contamination measured with the FLUTe membranes during four quarterly sampling events in 2007 are presented in Table 5.0-2 in LANL report LA-UR-07-7803 (November 2007). Table 5.0-2 presents TCE concentrations measured in a total of 48 gas samples collected from sampling ports in the three FLUTe membranes installed in the three boreholes. The measured TCE concentrations range from ND (i.e., "not detected") to a maximum concentration of 9.7 ug/cubic meter. For the 48 soil gas samples, the measured TCE concentrations were greater than 9.0 ug/cubic meter in only four of the samples and greater than 8.0 ug/cubic meter in only ten of the samples.
All of the TCE concentrations measured in the soil gas samples collected with the three FLUTe membranes were three orders of magnitude lower than the TCE concentration of 2,600 ug/cubic meter that was cited in the NMED MDA H Remedy Fact Sheet as the level of TCE contamination uniformly present below MDA H. The TCE concentration cited in the Fact Sheet was for measurements in the three boreholes with the LANL Packer sampling system.
Because of the very low concentrations measured with the FLUTe membranes for TCE and the other VOCs, NMED has ordered the following actions by DOE/LANL in a letter dated February 26, 2008:
"NMED therefore directed the Permittees in a December 21, 2007 letter to evaluate the effects of the FLUTe system on VOC sample measurements. The Permittees must collect data from existing boreholes at MDA H with and without the membranes for at least two quarters for comparison purposes." (p. 2)
There is no merit in the direction of NMED for the intercomparison of data from a small number of new soil gas samples collected from the existing boreholes at MDA H with the FLUTe membranes and with the LANL Packer sampling system. The large amount of historical data collected from the existing boreholes with both the LANL Packer System and with the FLUTe membranes is superior to the new data to be collected "for at least two quarters for comparison purposes." Collecting the new data will require repeated installation and removal of the two sampling systems in the three boreholes. The periods of time the boreholes are open will allow cross-flow and cross-contamination of the in situ soil gas and dilution of the contamination in the soil gas by atmospheric air that will flow into and out of the open boreholes in response to the daily change of barometric pressure.
Furthermore, the manufacturer has acknowledged that the FLUTe membranes are inappropriate for sampling soil gas for VOCs at depths greater than 50 feet. This admission by the manufacturer is a reason to not use the FLUTe membranes for monitoring soil gas at MDA H or at the SNL MWL. At MDA H, the release of VOCs is from disposal shafts constructed to a depth of 60 ft below ground surface (bgs) and the three boreholes for sampling VOCs are drilled to depths of 256 ft bgs, 249 ft bgs, and 97 ft bgs, respectively. An excerpt from the NMED MDA H Fact Sheet is pasted below that describes the results from soil gas monitoring below MDA H for the time period before taking measurements with the FLUTe membranes:
"The Permittees have been conducting quarterly monitoring and submitting Periodic Monitoring Reports to NMED since (LANL 2005c, 2006a, 2006b, 2006c). Analytical results confirm the presence of VOCs and tritium in all vapor samples. The results do not indicate an increasing or decreasing trend over time and do not show increasing or decreasing trends with depth. However, the monitoring locations do not include the Cerro Toledo Interval or the underlying Otowi Member of the Bandelier Tuff." (p. 5)
The fact that the results do not indicate an increasing or decreasing trend over time for the quarterly samples collected over a period of one year and the sudden decrease in TCE concentrations from 2,600 ug/cubic meter to less than 10 ug/cubic meter when sampling began with the FLUTe membranes is evidence that the FLUTe membranes do have properties for adsorption of TCE from the soil gas.
In addition, the fact that the results do not show increasing or decreasing trends with depth is proof that DOE/LANL have not used an appropriate sampling methodology
for soil gas samples collected with either the LANL Packer sampling system or with the FLUTe membranes. NMED also has a concern that the three boreholes are not drilled deep enough to monitor soil gas contamination in the Cerro Toledo Interval or the underlying Otowi Member of the Bandelier Tuff.
There are many deficiencies with all of the soil gas data collected at MDA H. The data do not support any decision on the remedy for MDA H. There is an immediate need to drill the three existing boreholes and two new boreholes to an appropriate depth for monitoring soil gas in the Cerro Toledo Interval and the underlying Otowi Member of the Bandelier Tuff. The two new boreholes should be drilled at appropriate locations within 25 feet of the nine disposal shafts. The required depth for the five boreholes is approximately 400 ft bgs.
It is essential to permanently install a multiple-port sampling system in all of the boreholes and for this system to be constructed with materials that will produce reliable and representative gas samples for measurement of in situ concentrations of VOCs and tritium. Soil gas samples should be collected from the multiple-port sampling systems installed in the five boreholes for a minimum period of eight quarters.
It is very likely that the results collected from properly monitoring the five boreholes will show even higher concentration of TCE than 2,600 ug/cubic meter for ports at depths from 60 ft to 200 ft. Ports in the lower 200 ft of the boreholes are expected to show a decreasing trend for VOCs and tritium. Reliable soil gas data is important for long-term monitoring for early detection of the release of contamination from MDA H.
However, the soil gas data does not replace the need for the installation of a minimum of two groundwater monitoring wells into the regional aquifer at locations within 50 feet of MDA H and one background water quality well at an appropriate location west of MDA H. The network of groundwater monitoring wells are a requirement of the Resource Conservation and Recovery Act (RCRA). The RCRA requirements are described below. The results from the properly instrumented soil gas boreholes and from the monitoring wells located close to MDA H may show that the VOC and tritium contamination released from MDA H is not a source for contamination of groundwater. The results may show that complete encapsulation of the nine disposal shafts is not a required remedy. Active vapor extraction of the VOCs also may not be needed as a remedy.
We would like to address issues of appropriate standards for protection of the public health, safety and the environment by comparing the differences between NMED’s enforcement of corrective measures at LANL and SNL. Our conclusion is that LANL MDA H, a legacy era nuclear weapons dump with much less contamination than the
SNL MWL, is receiving substantially more enforcement and remediation requirements.
The SNL MWL is a 2.6 acre dump where greater than 700,000 cubic feet of hazardous and radioactive wastes are buried in seven trenches and more than 40 pits. The LANL MDA H is a 0.6 acre site where 14,000 cubic feet of hazardous and radioactive wastes are buried in nine shafts. The volume of wastes at MDA H is only 2% of the volume at the MWL. The top of the regional zone of saturation is approximately 1000 ft below ground surface (bgs) at MDA H compared to approximately 470 ft bgs at the MWL.
The SNL MWL trenches and pits are unlined and there are no leak detection systems to monitor releases. In addition, NMED has not enforced the requirement of RCRA 40 CFR §264.98 (a)(2) for active monitoring of the release of contamination to the unsaturated zone below the buried wastes. Furthermore, the DOE/SNL long-term monitoring and maintenance plan (LTMMP) for the SNL MWL does not include active monitoring for soil gas contamination below the buried wastes in the MWL. Instead, DOE/SNL propose to monitor the VOCs with FLUTe membranes installed to a depth of 400 feet below ground surface in three boreholes at locations outside the perimeter of the dirt cover that will be installed over the MWL.
The three FLUTe wells will not place the MWL in compliance with §264.98 (a)(2) because the proposed wells are located outside the dump (LTMMP, p. B-9, Fig B-3.1-1) and also the FLUTe membranes will not produce reliable and representative soil gas samples because of the adsorption properties. Compliance with §264.98 (a)(2) requires monitoring wells must by law be placed within the dump to detect “[t]he mobility, stability and persistence of waste constituents or their reaction products in the unsaturated zone beneath the waste management area.”
The Vadose Zone Soil-Vapor monitoring proposed under the LTMMP (p.3-12 to 3-17) can not provide “the early warning system for protecting the groundwater” that is required by law as the LTMMP claims. Given the lack of liners at the MWL, early detection of contamination in the unsaturated zone beneath the MWL pits and trenches is a necessity at the MWL. The early detection of contamination requires a large network of multiple port vadose zone monitoring wells that are installed within and immediately at the boundary of the MWL. The number of wells is not known but is a minimum of ten. The number and location of the monitoring wells must be determined by careful sampling of the soil gas below the MWL with a large number of temporary probe holes. On February 14, 2008, NMED approved a DOE/SNL sampling plan to use probe holes for collecting and analyzing soil gas samples below the MWL. The sampling plan does not take measurements at enough locations or to the necessary depth. The deficiencies in the plan are described below.
The soil gas data collected for the RFI Phase 2 are proof that the three FLUTe wells proposed in the LTMMP are too distant from the MWL for the early detection of releases below the buried wastes. Two figures in the RFI Phase 2 report show that the PCE concentrations measured at the proposed distance away from the MWL for the FLUTe wells are 10 times lower than the PCE concentrations measured within the MWL unclassified area. (RFI Phase 2 p. 4-76 PCE in Soil Gas at 10 ft and p. 4-83 PCE in Soil Gas at 30 ft).
The LANL MDA H and the SNL MWL are both RCRA "regulated units" where groundwater monitoring must be in compliance with RCRA 40 CFR §§264.90 through 264.101 (RCRA Subpart F). In a recent LANL report - Technical Area 54 Well Evaluation and Network Recommendations, Revision 1 (LA-UR-07-6436, October 2007), NMED and DOE/LANL acknowledge that the groundwater monitoring at MDAs G, H, and L must be in compliance with RCRA Subpart F, but NMED has not enforced this requirement for the SNL MWL. The requirements in the LANL report for groundwater monitoring at MDAs G, H, and L are pasted below:
“The following requirements from 40 CFR 264.90-.99, Subpart F apply to permitted units or regulated units that received waste after July 26, 1982. The regulations apply throughout the active life of the units and the closure and post-closure period if the units are not “clean-closed” under RCRA. The groundwater-monitoring network and facility process must be able to detect, evaluate, and respond to releases of hazardous waste or hazardous waste constituents into the uppermost aquifer. Detection monitoring is required to establish that a release has occurred. It is assumed that because of the significant depth to groundwater beneath TA-54, vadose-zone monitoring will be a key component of the overall monitoring program in support of both CMEs and the RCRA Part B permit.
“An integrated groundwater-monitoring system must consist of a sufficient number of near-field wells and downgradient monitoring wells installed at appropriate locations and depths to obtain representative groundwater samples from the uppermost aquifer. These samples must represent both the quality of background water not affected by the regulated unit and the quality of groundwater passing beneath the regulated unit to allow for detection of contamination in the uppermost aquifer.” (p. 6)
The above requirements for RCRA regulated waste disposal sites at LANL TA-54 are especially pertinent to the LTMMP for the SNL MWL, the SNL Draft RCRA Permit, and the SNL Solid Waste Management Units (SWMUs) slated for No Further Action.
The SNL MWL is also a RCRA regulated unit because of the period of time that it received wastes. It is notable that the New Mexico Court of Appeals did not take jurisdiction over this issue and the issue is raised both for the record for the LTMMP and the SNL Draft RCRA Permit. As will be discussed below, the MWL does not have adequate soil gas monitoring or groundwater monitoring as is required by NMED at LANL for MDAs G, H, and L within TA 54.
The SNL MWL Corrective Measures Study p.19) states that
“Hazardous waste landfill closure requirements are codified under 126.96.36.1990 New Mexico Administrative Code (MAC), 40 CFR Part 264, “Standards for Owners and Operators of Hazardous Waste Treatment, Storage, and Disposal Facilities,” Subpart G (Facility Closure Standards) and Subpart N (Landfills). The NMED, the lead regulatory agency, has adopted the federal regulations as written and incorporated them into the New Mexico Hazardous Waste Management Regulations 20.4.1 NMAC. These standards are performance-based regulations that specify performance criteria without specifying design, construction materials, or operating parameters. The EPA has provided numerous guidance documents to aid in interpreting the level of performance required to design, construct, and operate a compliant closure system. The closure performance standard is defined in 188.8.131.520 NMAC, 40 CFR 264.111 as follows:
“The owner or operator must close the facility in a manner that:
(a) Minimizes the need for further maintenance; and
(b) Controls, minimizes or eliminates, to the extent necessary to protect
human health and the environment, post-closure escape of hazardous
waste, hazardous constituents, leachate, contaminated runoff, or hazardous
waste decomposition products to the ground or surface waters or to the
(c) Complies with the closure requirements of this subpart . . .”
The SNL MWL is not in compliance with Subpart G (40 CFR 264.117 (a)(1)(i) ) because monitoring and reporting that must comply with Subpart F are not provided for in the LTMMP as is required for the closure of a landfill. Additionally, the necessity of providing clean closure or obtaining a post-closure permit for the MWL or documents in lieu thereof have not been addressed as required by 40 CFR 270 et seq.
The NMED Response to Public Comments SNL MWL SV SAP (2/15/2008, p. 13) states that “There does not appear to be a significant increase in soil gas concentrations between the depths of 10 and 30 feet.” The Phase 2 RCRA Facility Investigation (RFI) on the contrary shows a great increase in the Total Volatile Organic Compounds (VOCs) in Soil Gas at 30 ft compared to the values measured at 10 ft and in some instances by a factor of four times greater. (Figs. 4.5-28, 4.5-29). The RFI report shows PCE in Soil Gas at 10 ft to be nearly doubled at the 30 ft depth. (Figs. 4.5-21, 4.5-27).
The PCE concentrations in soil gas below the MWL are identified as a source for contamination of groundwater in the MWL Fate and Transport Model (F&TM) (Ho, et al, 2006). However, the modeling of the PCE was from the maximum value of PCE in the soil gas measurements at the MWL measured to a maximum depth of only 30 ft bgs. The value used in the model is increasing from the level measured at 10 ft (5,200 ppb) to 30 ft (5,900 ppb). The data used by the F&TM was ten years old, too sparse and shows a trend to higher values from where the data was collected and there may be higher values at greater depth than 30 ft and at other locations beneath the dump. There is no indication that the highest value at the MWL is presented for the F&TM.
Because of the deficiencies in the F&TM, we have used Henry's Law to calculate the groundwater contamination below the SNL MWL from the PCE contamination of 5,900 ppb that was used in the F&TM model. For the MWL, Henry's law calculates that the PCE concentration of 5,900 ppb in soil gas will contaminate the groundwater with PCE at a concentration of 52 ug/L, a level 10 times greater than the EPA Drinking Water Standard of 5 ug/L. Our calculation with Henry's Law was the same process used by NMED to select complete encapsulation as the required remedy for MDA H to protect groundwater from the release of TCE as soil gas from the disposal shafts.
LANL was required by NMED to conduct quarterly sampling for the past two years to measure the soil gas concentrations for a complete suite of VOCs at multiple depths to a total depth of 250 ft bgs and with a borehole for monitoring to a depth of 250 ft bgs at a distance of approximately 25 ft from the disposal shafts. By contrast at the SNL MWL, however, on February 14, 2008, NMED approved of a sampling plan that will collect new soil gas samples for VOCs at only six probe hole locations within the MWL. Three locations will collect samples at depths of 10 ft and 30 ft, and three locations will collect samples at 10 ft, 30 ft, and 50 ft. The sampling required by NMED at the MWL is a token effort.
The depth of the aquifer below LANL MDA H is approximately 1000 ft bgs. The depth of the aquifer for the SNL MWL is one half that at approximately 470 ft bgs and the MWL contains more than fifty (50) times the volume of waste that is buried at MDA H. Given the concentrations of TCE at MDA H, NMED stated concern that “More specifically, the Permittees have not sampled soil gas at depths greater than 250 feet below the ground surface.” On the other hand, at the MWL, NMED is only requiring one-time sampling for soil gas at a depth of 50 feet at only three locations. Deeper sampling should be required at many more locations.
Soil gas samples should be collected at a minimum of twenty locations within the SNL MWL and to depths of 200 ft bgs on a sampling interval of 10 ft, 30 ft, 50 ft, 100 ft, 150 ft, and 200 ft. The soil gas samples should be analyzed for a complete suite of VOCs and also for tritium. NMED requires LANL to analyze the soil gas samples collected from the three boreholes at MDA H for tritium on a quarterly schedule. At the MWL, no monitoring for tritium is being required although large quantities of tritium were disposed of in the MWL. LANL, on the other hand, is required to collect soil gas samples from the boreholes at MDA H and sample for tritium along with VOCs. Tritium concentrations are required to be measured in the soil gas. NMED is not requiring tritium gas sampling at the MWL.
The remedy required by NMED for the SNL MWL is only a soil cover draped over the surface of the dump with a design identical to the ET cover proposed for LANL MDA H. NMED praises the soil cover for the MWL for protection of groundwater but is non accepting of the nearly identical cover proposed for MDA H because it doesn’t protect groundwater. The NMED criticism is pasted below:
“In order to ensure the continued performance of an ET cover, the Permittees proposed to conduct regular maintenance and monitoring throughout the 100-year institutional control period once the vegetative cover has been established. However, this alternative, similar to other containment alternatives listed by the Permittees, does not address the plume of VOCs and tritium that are currently present in the soil pore gas in the vicinity of MDA H. This ET cover also does not prevent future releases of these compounds to the subsurface from the shafts at MDA H.”
There is a contradiction in the practice of NMED to protect human health and the environment between the selection of only a soil cover for the MWL dump and the acknowledgement of NMED for MDA H that the soil cover is not protective for the plumes of VOCs and tritium for releases at this time or for future releases.
Hakonson states1 that “Controlling aqueous transport of volatile contaminants [with a soil cover] does not necessarily control vapor phase transport. In fact, maintaining low soil moisture content of cover and backfill soils to reduce aqueous phase transport may be associated with increases in vapor phase transport of volatile contaminants (Jury, 1987).”
Similarly to LANL MDA H, the soil cover at the SNL MWL does not address the VOCs and tritium that are currently present beneath the dump in far greater amounts than at MDA H. The soil cover will also not prevent the future releases of those contaminants to the subsurface beneath the MWL. The shafts at MDA H, are similar to the unlined pits and trenches at the MWL. However, NMED is requiring much more protection for MDA H with far less contaminants in volume and type than for the MWL. No encapsulation of MWL pits and trenches and no soil-vapor extraction system are required at the MWL. NMED must provide equal protection for similarly situated dumps and communities. At MDA H (p.12),
“NMED therefore has determined that it is appropriate to implement Alternative 3b (complete encapsulation of the shafts), along with a soil-vapor extraction system, at MDA H to prevent biointrusion and eliminate the VOC contaminant source detected in soil pore gas so that the drinking water resource can be conservatively protected.
“Alternative 3b will isolate the shafts from the environmental media to offer the greatest protection against potential intrusion of plants and animals, and accidental human access. This complete encapsulation alternative will prevent water from entering the shafts, and thus minimize the potential for contaminant migration into the surrounding tuff through aqueous phase transport.”
Also at MDA H, NMED is requiring that (p.13)
“To conservatively protect the regional groundwater from contamination by VOCs in soil pore gas, the Permittees will be required to operate the SVE [Soil-Vapor Extraction] until VOCs in soil pore gas are reduced to levels at which any of the detected VOCs, in contact with groundwater, theoretically could result in concentrations above half of the lower of the respective MCLs or Water Quality Control Commission (WQCC) standards. For example, TCE in soil pore gas must be reduced to a concentration below 1100 μg/m3 in vapor phase to meet the established criteria. Installation of a SVE system will require the installation of vapor monitoring extraction wells in the vicinity of MDA H and extending the depth of existing boreholes to the Otowi member of the Bandelier Tuff.” (Emphasis supplied).
At the SNL MWL, NMED is leaving poorly understood soil gas contamination with VOCs and tritium unmonitored beneath a soil cover that increases the potential for the volatile contaminants to contaminate the groundwater. The level of PCE contamination measured in the soil gas below the MWL required that an active soil vapor extraction (SVE) should have been installed 15 years ago. The SVE system was never installed and is not in the LTMMP as it should be.
At MDA H, “NMED questions the long-term reliability of the engineered ET [evapotranspiration] cover in preventing the intrusion of deep-rooting plants and burrowing animals. According to the conceptual design of the engineered ET cover for MDA H, the total depth of the cover is approximately 4.5 feet over the existing surface layer. Based on the Permittees’ findings at MDA H (LANL 2005), the site specific deep-rooting plants can extend roots to depths as deep as 23 feet (7 meters), and local burrowing animals can excavate to depths deep to 10 feet (3 meters).” (Emphasis supplied).
The depth of the soil cover proposed for the SNL MWL is 4.25 ft (MWL Design Report, 1999, p.3). At the MWL, Hakonson reports that many species of ants burrow beyond depths of 5 ft and three species can burrow to depths beyond 5 meters (16.4 feet). (p.37). Hakonson states, “The mixture of grasses that SNL/NM intends to use in reseeding the MWL is lumped within the herbaceous plant category. These data show that deep root habits are quite common in woody and herbaceous species across most of the terrestrial biomes, far deeper than the traditional view has held up to now. The implications for the MWL are that no matter what vegetation is planted on the landfill, if moisture penetrates beneath the ET cover, roots can be expected to follow.” (P. 31-32).
The monitoring at the SNL MWL never produced reliable data for the detection of any contamination (including the VOCs PCE and TCE) at the water table or in the deeper permeable groundwater zones below the MWL. There are other RCRA regulated units at SNL where VOC groundwater contamination with VOCs and other RCRA hazardous wastes is a concern but the required groundwater monitoring was never installed. One example is SWMU 101, Building 9926 Explosive Contaminated Sumps and Drains where PCE contamination was measured in soil gas samples. The nearest groundwater monitoring well is approximately 0.5 mile away. RCRA Subpart F requires a network of monitoring wells as close as possible to SWMU 101 and certainly within a distance not greater than 50 feet away.
A second example is SWMU 154 where High Explosive (HE) and VOC liquid wastes were disposed of in two 23-ft deep seepage pits known as "the west HE drain system. The seepage pits received liquid wastes for 40 years from 1965 to possibly 2005, the year the seepage pits were backfilled with clean, native soil. The only monitoring well for SWMU 154 is located 300 feet away from the seepage pits. SWMU 154 is not in compliance with the groundwater monitoring requirements of RCRA Subpart F.
A third example is SWMU 196 where poorly characterized radioactive and hazardous liquid wastes were discharged to a large cistern, a vertical concrete cylinder 25-ft in diameter installed from 3-ft above ground to a depth of 22 ft bgs. RCRA liquid wastes including total petroleum hydrocarbons, VOCs, SVOCs and metals (and also radionuclides) were discharged into the cistern for 12 years from 1978 to 1989. There are no groundwater monitoring wells to investigate groundwater contamination below the cistern. RCRA Subpart F requires a network of monitoring wells at SWMU 196.
The three SWMUS are among a population of many SWMUS that are being proposed for No Further Action status by DOE and NMED without establishment of RCRA requirements for groundwater monitoring.
There currently is no monitoring at the MWL of the “Groundwater” as defined by the Consent Order. (p.15). The Consent Order (“CO”, April 29, 2004) defines groundwater as follows:
“Groundwater means interstitial water which occurs in saturated earth material and which is capable of entering a well in sufficient amounts to be utilized as a water supply.”
The fact that groundwater is not monitored at the MWL is evidenced from the monitoring reports that cite poor production of the MWL wells and samples being collected days later from the water that trickles into the wells after they are pumped dry.
At the Sandia MWL, wells MWL-MW4, MW5 and MW6 need replacement under the CO because they have all failed for their intended purpose. The pertinent part of the CO is pasted below:
"In the event of a well or piezometer failure, or if a well or piezometer is any way no longer usable for its intended purpose, it must be replaced with an equivalent well or piezometer. In constructing a well or piezometer, Respondents shall ensure that the well or piezometer will not serve as a conduit for Contaminants to migrate between different zones of saturation." (P. 63, CO Sec. VIII.A.).
Monitoring Well MW4. The purpose of well MW4 was to investigate contamination at the water table beneath Trench D. However, the top screen in well MW4 was installed too deep below the water table, and the well has never met its important purpose to investigate contamination at the water table. The bottom screen in well MW4 is installed across the contact of the AF sediments with the ARG strata. The position of NMED is that well screens shall not be installed across formations with contrasting hydraulic properties or markedly different hydraulic head but this is the setting for the bottom screen in well MW4. In addition, the available information indicates that well MW4 is allowing cross-contamination between the top and bottom screen. There is an immediate need to plug and abandon well MW4, and install a new monitoring well to characterize groundwater contamination at the water table beneath Trench D.
Monitoring Well MW5 is located west of the MWL, but the well screen is installed across the contact of the AF sediments with the ARG strata which, as explained above, is in violation of NMED requirements for monitoring wells. In addition, a mistake in well construction contaminated the screened interval with the bentonite clay grout that was used for back-filling and sealing the annular space between the well casing and the borehole wall. The grout accidentally filled the lower part of the screen. There is an immediate need to plug and abandon well MW5. The failure to do so is a violation of the CO.
Monitoring Well MW6. MW6 is in the productive groundwater zone but is more than 500 ft distant to the northwest corner from the dump. No monitoring well is located at the point of compliance to monitor the “groundwater” as defined by the Consent Order. RCRA Subpart F also requires monitoring the productive groundwater zone as close as possible to the western and southern boundaries of the buried wastes in the MWL.
The SNL 2007 Annual Groundwater Monitoring Report (released by DOE/SNL February 21, 2008) again incorrectly takes credit over the years for sampling with one background monitoring well and five downgradient monitoring wells that have never existed at the MWL. The Report still presents flow direction as being to the northwest, contrary to NMED recent declaration that flow at the water table is to the southwest.
Fate and Transport Model for the MWL
National Academy of Sciences (2000): “Long-Term Institutional Management of
U.S. Department of Energy Legacy Waste Sites” points out that “Stewardship” (covering waste with dirt and instituting institutional controls) of waste sites will be difficult if not impossible to achieve.
The National Academy of Sciences 2007 report - Plans and Practices for Groundwater Protection at the Los Alamos National Laboratory states (p.68):
“Numerical models combine information on geology, geochemistry, infiltration, regional groundwater fluxes and waste discharges in a manner that quantifies understanding of the physical/chemical processes and interactions involved in the transport of contaminants. Information gained during the process of model development provides valuable insight on the validity of the conceptualization implemented in the numerical model. Though many “solutions” are possible, comparison of predicted results to actual measurements [emphasis supplied] provides an estimate of the level of understanding of the flow and transport processes moving contaminants away from their initial disposal locations.”
SNL has never put in monitoring wells at the identified hot spots for PCE and TCE at the MWL to verify the accuracy of its fate and transport model.
Drilling MWL wells with “mist” is not appropriate.
In a June 19, 2007 letter from Mr. Bearzi to SNL it states (page 5, Section 5.2.1): “The permittees shall log the depth of the first encounter with regional groundwater and the depth of any perched groundwater will be logged during drilling.”
In a July 2 2007 letter from James Bearzi to SNL for replacement of MWL-MW 1 and MW3, it states, “The mud rotary drilling method shall not be used to install the wells.” Our position is that the ARCH drilling method using an undefined amount of water as a mist is the same as the mud rotary method because using water to drill through clay-rich sediments will create "drilling muds" that will invade the zones that are important to monitor with the clay-rich muds produced by the fluid-assisted ARCH drilling method.
In the August 10, 2007 Workplan for MWL-MW7 and MW8 sent to James Bearzi by SNL it states: “Minimal water (but no other foams/liquids) in the form of “mist” may be introduced into the borehole to aid in the removal of cuttings.”
Section 3.5.3 of the LTMMP should include the drilling methodology to be used for installing monitoring wells. It should state specifically that no drilling methods with water or water-based fluids (i.e., bentonite clay or organic fluids or -foams) shall be allowed for any of the boreholes for the groundwater monitoring wells. Those fluid-assisted drilling methods should not be used at any location because the boreholes are to be used to investigate the existence of perched zones. The only drilling methods that meet the NMED requirement to investigate perched zones and the first encounter with regional groundwater are the air- rotary reverse circulation under reamer casing advance or sonic. The sonic drilling method was used to install well MWL-MW4 at the MWL. The air rotary casing hammer (ARCH) drilling method should not be used in any of the boreholes because the history is that circulation of water is necessary to recover the cuttings and the circulation of water produces drilling muds that invade the zones that are important to monitor.
Prior data from ARCH drilling with “misting” at monitoring well MWL-MW5 shows that the misting resulted in slugs of mud that invaded the screened interval. The perched zones of saturation and the water table cannot be accurately identified nor can reliable sampling be obtained if water, even as a mist, is used for drilling. An additional important reason to use no water during drilling is that the in situ groundwater in the perched zones and from the water table of the regional zone of saturation should be sampled from the borehole for the full analytical suite including VOCs, Semi-VOCs, tritium and RCRA trace metal suite. Tritium should also be analyzed at the low detection limits of the University of Miami as is done for LANL. In the past year, the dry air-rotary reverse circulation underreamer casing advance drilling method was used for monitoring wells R-35a, R-35b and R-36 at LANL.
FLUTe wells shall not be used for monitoring soil gas at the SNL MWL. FLUTe membranes are inappropriate for their known properties to absorb the contaminants of concern.
Permanent installation of multiple port wells is required for monitoring the unsaturated zone beneath the MWL. The location and installation of the unsaturated zone wells at the MWL must be at locations within and immediately along the boundary of the MWL.
The monitoring wells MW4, MW5, and MW6 need to be replaced.
The nickel and chromium contamination measured at well MW1 requires a new monitoring well with a PVC screen at a location south of MW1 as close as possible to the northern side of the MWL
The southwest direction of groundwater flow at the water table below the MWL requires installation of a monitoring well along the southern side of the classified area and along the southern side of the unclassified area.
All new groundwater monitoring wells installed outside the MWL dump shall be installed as close as possible to the boundary of the buried wastes.
Well MW4 must be plugged and abandoned and replaced with a new angle well installed at an appropriate location inside the MWL to monitor contamination at the water table below Trench D.
Two monitoring wells shall be installed at locations within the MWL where high levels of PCE and tritium are known to be present. The wells shall monitor contamination at the water table. The two wells are essential for confirmation of the MWL Fate and Transport Mode.
DOE/SNL should be informed by NMED that the claims of the 2007 Annual Groundwater Monitoring Report are not accurate and that an appropriate monitoring network must be installed at the MWL and the SWMUs.
Only the dry air-rotary reverse circulation under reamer casing advance or sonic drilling methods should be used for drilling boreholes through the unsaturated zone and into the regional aquifer at the MWL. The ARCH drilling method with water as a mist to recover cuttings is not appropriate at the MWL.
In addition to considering these concerns for present action, please submit this letter for the Long Term Monitoring and Maintenance Plan, the SNL Draft RCRA Permit, 26 SWMUs for NFA Status and 5 SWMUs for NFA Status.
David B. McCoy, Executive Director
Citizen Action New Mexico
Albuquerque, NM 87196-4276
Robert Gilkeson, Registered Geologist
PO Box 670
Los Alamos, NM 87544
1 Review of Sandia National Laboratories/New Mexico Evapotranspiration Cap Closure Plans for the Mixed Waste Landfill, T.E. Hakonson 2/15/02, p. 28.