SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
NON-AQUEOUS PHASE LIQUID CLEANUP ALLIANCE MEETING
Hilton San Diego Gaslamp Quarter
San Diego, CA
February 14-15, 2005
WELCOME AND OPENING REMARKS
Mark Lyverse, ChevronTexaco Energy Research and Technology Company
Bob Maxey, U.S. Environmental Protection Agency (EPA)
Mark Lyverse and Bob Maxey, co-chairs of the Non-Aqueous Phase Liquid (NAPL) Cleanup Alliance, welcomed attendees (see Attachment A) to the meeting. Maxey provided a quick overview of the agenda and recognized two guests attending the meeting. They were Eva Romero-Giron Garcia, a research engineer with the Technology Center of the Soil and Groundwater Remediation Group, Repsol YPF, Madrid, Spain, and Robert Disney, environmental scientist, North Dakota Division of Waste Management. Maxey noted that the Alliance’s Module 1 training presentations have been well received and that a few presentations are scheduled for the coming months. Lyverse noted that the Alliance has made good progress on its three major products: (1) developing a decision-making framework, (2) developing the light non-aqueous phase liquid (LNAPL) training program, and (3) investigating and remediating a ChevronTexaco site in Casper, Wyoming. He said that the mix of representatives from regulatory agencies, industry, and academia that has participated in the evolution of these projects has provided the critical mass needed to increase recognition that we need to manage NAPLs better than in the past and that the Alliance is providing the tools to help accomplish this.
INSTALLATION RESTORATION (IR) AT NAVAL AIR STATION (NAS) FALLON, NV
Joseph Farry, Navy Remedial Project Manager (RPM), discussed free product removal efforts several IR Sites on NAS Fallon, which is about 70 miles southeast of Reno, NV (see Attachment B). NAS Fallon is in the Carson Desert Hydrographic Area. The elevation is about 4000 feet above mean sea Level, and the station receives about 5 inches of precipitation per year. The station is underlain by an ancient lake bed of clayey sands and sandy clays with silt. A shallow groundwater aquifer at 7-11 feet below ground surface (bgs) is bounded by a clay confining layer at 20-25 feet bgs. Flow is to the southeast at 10-30 feet per year. The average hydraulic conductivity is about 2.5 feet/day. The station is abuts agricultural fields and is cut by irrigation drains that empty into the Stillwater Wildlife Refuge. Of primary concern is the potential f or contaminant plumes on the station to move toward these drains increasing risk to wetland areas.
Of the original 29 IR sites on NAS Fallon, 20 already have been closed, with two additional site closures pending. The seven active sites are targeted for remediation and interim source removal. Contaminants include a variety of petroleum fuels—e.g., JP-4 JP5, JP8, diesel, aviation gasoline (avgas), and motor vehicle gasoline (mogas). Several product removal methods and technologies have been used for varying periods of time at the station in order to provide data for cost and effectiveness comparison and to develop some “rule of thumb” guides for choosing the most cost-effective technique for specific site conditions. Farry’s presentation focused on technology/method comparisons at three sites on the station:
Analysis of these evaluations enabled the Navy to develop the following “rules of thumb” for choosing the most cost-effective technology:
Farry cautioned that the following factors must be considered in using these “rules of thumb” to avoid misleading conclusions:
SIX-PHASE HEATING PROJECT AT NAS ALAMEDA POINT, CA
Rudy Millan, Shaw Environmental, discussed pilot- and full-scale applications of six-phase heating at Sites 4 and 5 at NAS Alameda Point, CA, for dense non-aqueous phase liquid degradation in situ. Six-phase heating is an aggressive technique for volatilization and mass removal of volatile organic compounds (VOCs). It involves splitting conventional three-phase electricity into six separate electrical phases to heat the subsurface evenly, using electro-resistive heating to generate steam. Each phase is delivered to a single electrode, and electrodes are placed in a hexagonal pattern. A vapor extraction well, which removes the contaminants, air, and steam from the subsurface, is located within the hexagon. The system requires specialized equipment and from 0.5 to 3 megawatts of electric power.
Six-phase heating was pilot-tested at NAS Alameda Point IR Site 4 in 2002 and 2003 to remove DNAPL contamination that had accumulated as a separate layer below the water table. The objective of the pilot study was to determine whether six-phase heating would be viable for enhanced in situ degradation and whether temperatures could be limited to 70°C in order to protect 12kV power lines at the site. The pilot used state-of-the-art electrodes, drilled to a depth of 35 feet and placed 20 feet apart. Four and a half months were required to heat the subsurface to 70°C, and the temperature was maintained for 2.5 months. While the pilot provided evidence that utilities can be protected, the cost of the electrodes ($4,000 to $5,000 each) proved to be a limiting factor, and data from the test did not support enhanced degradation.
Another pilot test at IR Site 5 involved 20-foot hexagonal arrays of electrodes, set at shallow (0-18 feet bgs) and deep (18-30 feet bgs) horizons. Conventional electrodes were set shallow and deep, and sheet-pile electrodes were set shallow as well. The electrode sets were connected in parallel. Vapor extraction also was applied.
Based on the pilot results, six-phase heating was implemented at full scale for a 1/3-acre plume at the site over a period of three months. In this application, electrodes were placed at depths of 20 feet bgs or less, and three power control units applied 1.5 megawatts of power to multiple cells. Using multiple cells allowed site managers to take advantage of inter-cell “crosstalk—that is, they were able to heat areas between and around the cells themselves. The application resulted in reducing DNAPLs in groundwater to 100 parts per billion, exceeding the goals of 10 parts per million.
The pilot tests and the full-scale application of six-phase heating afforded the Navy the opportunity to build its own six-phase heating equipment, which is now scheduled for use at other plumes on the station. In addition, the equipment will be made available to other Navy sites in the future.
NAS NORTH ISLAND, SAN DIEGO, CA
Michael Pound, Navy RPM, briefed participants on LNAPL remediation efforts at two sites at NAS North Island in San Diego (see Attachment C). Industrial Restoration (IR) Site 9 is the former chemical waste disposal area at the station. The disposal area was operated between the late 1940s to the mid-1970s. After the original site assessments, conducted between 1983 and 1994, an interim removal action was initiated in 1997 using soil vapor extraction (SVE) at 3,000 cfm. An atypical response from the SVE prompted Navy officials to conduct further characterization of the site in 1998. The Site Characterization and Analysis Penetrometer System (SCAPS) and LASER Induced Fluorescence (LIF) were used and resulted in discovery of a large volume of free product underlying IR Site 9. This free product consisted of petroleum products—diesel fuel, JP-5 jet fuel, and aviation gasoline (AVGAS)—with dissolved chlorinated solvents, including trichloroethylene (TCE) up to 20%, trichloroethane (TCA) up to 7%, and minor amounts or dichloroethylene (DCE). Depth to groundwater at the site is approximately 10 feet below grade. The LNAPL extends horizontally across the site with an affected area of approximately 81,000 square feet.
The Navy conducted a 7-month pilot test of steam injection to enhance the SVE in 1999, effectively mobilizing the LNAPL and the dissolved-phase TCE. More than 2,000 gallons of free product was removed during the pilot and disposed offsite. Based on findings from the pilot, the Navy proceeded to full-scale implementation of thermally enhanced operations in May 2002. The system consisted of gravity separation, on-site storage, and off-site disposal of LNAPL; a 1,200 scfm SVE system; and biological treatment of groundwater, with carbon polishing, and discharge to the publicly owned treatment works (POTW). In October 2002, steam injection also was initiated. Over 26 months, the system successfully removed about 300,000 lbs of free product.
In order to optimize the system, the Navy conducted new SCAPS and LIF investigations. These investigations provided data on areas where mobile and immobile NAPL had been reduced or eliminated and evidence suggesting that lighter fuel components had been lost in most areas. In addition, investigation results indicate that, while NAPL remains in most areas, it is not mobile. The Navy expects to continue optimized full-scale mass removal and evaluate whether the current non-time critical removal actions with respect to cost and continuing effectiveness.
NAS North Island Operable Unit 19 is a light non-aqueous phase liquid (LNAPL) plume in the vicinity of Buildings 379, 397 and 472 at NAS North Island. The plume is composed primarily of JP-5 with commingled stoddard solvent and TCE. The JP-5 is relatively un-weathered and clear. Depth to groundwater is about 22 feet bgs. The LNAPL resides in the capillary fringe and extends horizontally under Buildings 379 and 397 with an affected area of approximately 160,000 square feet. LNAPL gauging and LNAPL mobility/recoverability modeling suggest the plume is relatively stable with minimal spreading noted.
Following this presentation, Pound conducted a site tour of NAS North Island for all participants.
FORMER FUEL FARM, NAVAL AIR WEAPONS STATION (NAWS), CHINA LAKE, CA
Michael Cornell, Navy RPM, briefed participants on NAPL cleanup efforts at NAWS China Lake (see Attachment D). The former fuel farm at Armitage Field, located aboard the Naval Air Weapons Station in China Lake, CA, operated for more than forty years. The area is approximately 450 by 400 ft, and is bordered by a parking lot to the north, undeveloped land to the south and east, and base facilities (Airfield and Hangars) to the west.
The former fuel farm consisted of four 50,000 gallon concrete-reinforced underground storage tanks (USTs) and two 100,000 gallon USTs. An estimated one million gallons of LNAPL, principally jet fuel, were released into the subsurface during the operational period of the fuel farm. The past practice of disposal of off-specification fuels into 10 drywells and possibly leaking fuel lines or transfer stations likely contributed to the release of LNAPL, and the dissolved-phase groundwater contamination.
The Navy has initiated numerous investigations at the former fuel farm. The six USTs were removed, and the Navy developed a Mobile Product Recovery System to skim the free-phase fuels from the subsurface. In 1998, the Navy contracted with the IT Group to evaluate the performance of multiple remedial systems with the goal of maximizing the free product recovery rates and minimizing the amount of extracted groundwater. This was accomplished by performing pilot tests and screening various remedial designs, including: free-product skimming, vacuum-enhanced product pumping, total fluid recovery, soil vapor extraction and tests on various product recovery skimmer pumps. Vacuum-enhanced skimming producing the best results. Additionally, cone-penetrometer (CPT) testing was used to optimize placement of the extraction wells away from zones of high clay content and cemented sands. Eleven wells were constructed in zones that averaged over three feet of free-product per well. This zone was generally within the most saturated free-product zone of the plume.
After vacuum-enhanced skimming was demonstrated in the field, the Navy contracted with the IT Group to complete the design and construction a full-scale system. The full-scale vacuum-enhanced skimming system was installed in 2000. The system includes:
To date, the system has recovered more than 33,000 gallons of free-phase LNAPL and 14,000 gallons of product from the vapor phase.
BIOBARRIER PROJECT, NAVAL BASE VENTURA COUNTY, PORT HUENEME, CA
Karen Miller, Naval Facilities Engineering Service Center (NFESC), discussed an ongoing full-scale cleanup using in situ bioremediation to treat methyl tertiary butyl ether (MTBE) and tri butyl alcohol (TBA) in groundwater at the Naval Base Ventura County (NBVC) in Port Hueneme, CA (see Attachment E). Geology at the site consists of shallow sand semi-perched and unconfined aquifer bounded on the bottom by a clay aquitard, through which groundwater flows at a velocity of 0.10 to 1.00 foot per day. At a depth of 10-20 ft bgs, the 5,000- by-500-foot dissolved MTBE plume, which originated from a smaller BTEX (benzene, toluene, ethylbenzene, and xylene) plume that originates from sands contaminated with residual NAPL.
The original in situ bioremediation system consists of a 500-foot-wide “biobarrier” that acts as a passive flow-through system and was installed just downgradient of the NAPL plume. Contaminated groundwater, containing dissolved MTBE and TBA, travels through the biobarrier and biodegradation is enhanced by injection of various combinations of oxygen, air, and conditioned microorganisms. Oxygen gas and bioaugmented sections are located in the central core of the dissolved contaminant plume, and air injections are used on the edge of the plume. Operation of the system began in Fall 2000.
Initial MTBE and TBA concentrations in the groundwater plume were greater than 10,000 μg/L in the center of the plume. After 18 months, contaminant concentrations were reduced to less than 5 μg/L in monitoring wells downgradient of the biobarrier and extending across the width of the plume. No significant differences in performance were observed for the differently operated sections of the barrier. Dissolved oxygen increased from a pre-injection concentration below 1 mg/L to 10-35 mg/L throughout the treatment zone, thereby increasing the potential for aerobic biodegradation to occur. In addition, increased dissolved oxygen levels upgradient of the treatment zone, due to dispersion of the injected gas, appear to have caused upgradient reductions in MTBE concentrations. Peripheral monitoring wells have not shown an increase in contaminant concentrations, indicating that groundwater is flowing through and not around the biobarrier.
The biobarrier system includes 252 gas injection wells, 174 monitoring wells, 25 satellite gas storage tanks, 154 solenoid valves, a 240-ft3/hour-capacity oxygen generator, automated timer circuits, and associated piping and electrical lines. The total installation cost of this equipment was $435,000. Initial year (FY 01) operation and maintenance (O&M) costs were $75,000 and are expected to continue for a service life of 40 years. A preliminary cost comparison with an existing pump-and-treat system at this site suggests savings of more than $34 million over the project life. The state regulatory agency has approved continued use of this biobarrier and installation of a additional biobarriers approximately midway down the MTBE plume and at the toe of the plume as the final remedy for the MTBE plume.
Based on the success of the original biobarrier project, NBVC, with technical support from NFESC, has awarded a contract for the installation and operation of the mid-plume and toe biobarriers. The installation and operation was based on the original biobarrier technology for the treatment of MTBE and related oxygenates in the groundwater. The combined length of the two new barriers is approximately 900 feet, with oxygen injection points spaced every four feet. The construction of the mid-plume and toe barriers was completed summer 2003 and may reduce the overall remediation time by two thirds.
Based on the original biobarrier data, the project team decided to use oxygen injection in combination with the in situ bacterial colonies for both the mid-plume and toe biobarriers. As demonstrated by sampling data, six months was required to build up sufficient microbial populations and since Spring 2004, the mid-plume and toe biobarriers have provided for the effective and comprehensive degradation of the MTBE contaminants in groundwater to below target concentration. State regulators have been petitioned to cease the operations of the containment system.
STATUS – LNAPL TRAINING MODULE 2
Harley Hopkins, American Petroleum Institute (API), briefed participants on the first draft slides for Module 2. The purpose of the module to help people understand how the new understanding regarding LNAPL behavior and characteristics, which has developed over the decade and is the focus of the Alliance’s Module 1 training, can improve how LNAPL management and remediation decisions are made both by site owners and by regulators with different regulatory frameworks. The module 2 draft mirrors the Alliance’s Decision-Making Framework document, which has just been finalized.
Hopkins showed the draft slides and asked for participant comments on items that should be changed to improve the presentation. The following comments were made:
Mark Lyverse remarked that those who present this module in a given location will need background on NAPL drivers in that location, so they can set up a useful discussion. Bob Maxey suggested engaging EPA personnel right away, so that they are involved in further development of the module. This would help minimize the potential for problems later. Greg Fletcher, Suncor, suggested that the module should stress that we are advocating a safe and responsible approach. Jim Higinbotham, ExxonMobil, added that the module must emphasize that this is based on sound technical information. Ali Tavelli, Wyoming Department of Environmental Quality, said that the intention is to stress that one must know/understand the problem well in order to make good decisions. While the decisions will vary, because sites vary, we need to come to agreement on how to get the right data, so we will all the best information for decision-making. Mark Lyverse added that the module needs to say that better site characterization can help managers look at aggressive technology options as well as containment options. Also, it needs to acknowledge that this means investing more dollars up front.
Hopkins asked that anyone wishing to join the team developing Module 2 provide their names to Carolyn Perroni, EMS.
STATUS – NAPL DECISION-MAKING FRAMEWORK AND LNAPL TRAINING MODULE 1
Ellen Rubin, U.S. EPA Technology and Field Services Division (TIFSD), indicated that the Alliance’s NAPL Decision-Making Framework and Module 1 training have been completed and will be posted on the NAPL Alliance web site shortly. She asked those who want to receive bulk hard copies (10 or more) of the Framework document to e-mail her and let he know the quantity needed. Each participant was provided with a CD-version of the Module 1 training; Ellen will have a limited number of additional copies if anyone needs them.
Jim Higinbotham asked that a list of all those who reviewed the Framework and the Module 1 package be sent to the Core Team for reference.
STATUS – NAPL CASE STUDIES
Rubin said that the case study of the Chevron Cincinnati LNAPL site has been completed, and RETEC is finalizing the case study of BP’s Sugar Creek site. She will provide all Core Team members with a copy of each completed, and both case studies will be posted on the NAPL Alliance web site.
Ali Tavelli suggested that Rubin send copies of the case studies, the Framework document, and the Module 1 training to the Association for State and Territorial Solid Waste Management Officials (ASTSWMO) and ask the association to publicize the products to its membership.
Rubin encouraged all participants to notify her about other NAPL sites that might make informative case studies. The following sites were mentioned as possible case study subjects:
CHEVRONTEXACO CASPER PROJECT UPDATE
Todd Creamer, TriHydro, Inc., explained that, as part of the remedy evaluation process for the site under the Wyoming voluntary remediation program, the Casper Project Team has hosted presentations from vendors of three types of technologies for aggressive source term technologies. Vendors were Surbec and Intera for surfactants, MECx and Isotech for chemical oxidation, and TRS for six-phase heating. The team analyzed the data from each presentation and developed a cost/acre (for a pilot test) comparison. The team also looked at 19 case studies from 1997-2002 involving the use of chemical oxidation, resistive soil heating, water flood, steam flood, and surfactant/cosolvent flood. Case studies included those involving both LNAPL and DNAPL. Analysis of the case studies has provided data for comparison of cost/cubic yard, cost/pound of contaminant removed, and fraction of contaminant removed.
Ali Tavelli commented that discussions with the vendors and the case study review has resulted in the team’s realization of the huge importance of natural attenuation, but it is not clear how to quantify this for NAPL. Mark Lyverse said that ChevronTexaco has been surprised how much mass loss they have seen in the vapor phase. He was not convinced that any of the vendor technologies could get all of the NAPL out of the smear zone, and it is very likely that the company would still be required to do NAPL management at the river.
Before moving further in the remedy selection process, the team is building out the conceptual site model (CSM). This includes looking at ambient environmental data, such as the North Platte River stage and discharge, climate, bedrock surface, and fluid levels; aquifer data, including CPT-LIF, cores, pump and slug tests, and sedimentology and stratigraphy; water chemistry; NAPL characterization; soil gas; and modeling. The team currently is doing a NAPL partitioning study to detail NAPL impact on groundwater and describe NAPL composition, and vapor and bio-attenuation study to measure vapor mass flux and characterize species in vapor. Creamer and Smith said the team expects to complete the conceptual site model this summer. At that point, the team will look again at technologies that might be applicable for a pilot demonstration.
Brian Smith, Tri Hydro, Inc., briefed the group on techniques being used to visualize NAPL impacts and get a more realistic perspective on the LNAPL smear zone. This involved using LIF data on both intensity and wavelength from 165 push points at the site.
A work plan for the site has been approved by Wyoming DEQ and will be posted on the NAPL Alliance web site. In addition, a NAPL investigation report is in process and will be made available when it has been finalized and approved. Dawn Kaback, Geomatrix Consultants, suggested that the team prepare a fact sheet that could be posted on the web site about the process of developing and building out the CSM and the types of data being collected.
INCREASING STATE PARTICIPATION IN THE ALLIANCE
Ellen Rubin said that EPA is continuing its effort to encourage more state regulators to participate in the NAPL Cleanup Alliance. She asked EPA regional staff for recommendations, and was able to bring Bob Disney, North Dakota. The key is to continue to search for the right people in each state. The Alliance has tried several times to increase state participation, but has had a difficult time attracting the right personnel from the various states. In addition, travel restrictions in many states have been an issue.
David Zabcik suggested that the Alliance focus its efforts only on the few states where there is substantial petroleum industry activity. Ali Tavelli added that it is important to define clearly what the Alliance expects from its state representatives and to delineate what advantages they would get from membership and active participation.
It was agreed that each industry representative in the Core Team would identify one or more appropriate personnel in the states in which they operate. In addition, the EPA Regions that include those states would be asked to sponsor a delivery of the Module 1 LNAPL Training, providing an opportunity for these state representatives, and others, to get familiar with the Alliance. Tavelli offered to participate in these deliveries and to discuss the specific advantages the State of Wyoming has seen in Alliance membership. The group also agreed that expanding participation among federal agencies would be helpful.
WHERE DO WE GO FROM HERE?
Participants discussed the future of the Alliance and how best to move forward to maximize productivity while recognizing that EPA support funds may be limited. The discussion yielded the following suggestions:
Wrap Up and Adjourn
Lyverse and Maxey thanked everyone for their participation and the meeting adjourned.
Attachments A through E
Attachments B through E are available on the Internet. To view these attachments, visit the RTDF home page at http://www.rtdf.org, click on the "NAPL Cleanup Alliance" button, then click on the "Alliance Meetings" button. The attachments are available as part of the February 2005 meeting summary.
Attachment A: Final Attendee List (PDF, 36KB)
Attachment B: Free Product Removal, Case Histories at NAS Fallon and Practical Considerations for
Selecting Removal Methods (PDF, 20.2MB)
Delivered by Joseph Farry
Attachment C: NAS North Island (PDF, 2.5MB)
Delivered by Michael Pound
Attachment D: Site 1 LNAPL Free-Product Recovery. NAWS China Lake (PDF, 853KB)
Delivered by Michael Cornell, Naval Facilities Engineering Command
Attachment E: Demonstration and Installation of MTBE Biobarriers at Naval Base Ventura County, Port
Hueneme, CA (PDF, 1.5MB)
Delivered by Karen Miller, Naval Facilities Engineering Service Center