Cleanup Authority: Department of Defense (DoD)
Contacts:
Principal Investigator
Tony Lieberman
Solutions-IES, Inc.
1101 Nowell Road
Raleigh, NC 27607
Phone: 919-873-1060, Ext. 117
Email: tlieberman@solutions-ies.com
Co-Principal Investigator
Robert C. Borden
Solutions-IES, Inc.
1101 Nowell Road
Raleigh, NC 27607
Phone: 919-873-1060, Ext. 123
Email: rcborden@solutions-ies.com
Project Manager
Sheri L. Knox
Solutions-IES, Inc.
1101 Nowell Road
Raleigh, NC 27607
Phone: 919-873-1060, Ext. 174
Email: sknox@solutions-ies.com
Contracting Officer Representative
Bryan Hare
Naval Facilities Engineering Service Center
1100 23rd Avenue, Code 411
Port Hueneme, CA 93043
Phone: 805-982-1795
Email: bryan.harre@navy.mil
Environmental Restoration Program Manager
Andrea Leeson
ESTCP
901 Stuart Street, Suite 300
Arlington, VA 22203
Phone: 703-696-2118
Email: andrea.leeson@osd.mil |
Results: Indian Head Demonstration:
Results from the Tier 1, 2, and 3 evaluations are summarized below: - The Tier 1 and 2 evaluations showed that groundwater conditions are conducive to perchlorate biodegradation beginning in the nutrient-rich shallow groundwater beneath the Littoral Zone and continuing out into Mattawoman Creek. However, complex hydrogeology and the potential impact of the mixing and dilution activities made additional research (Tier3) necessary to evaluate site conditions and MNA.
- The Tier 3 evaluation indicated that the first-order biodegradation rate constant ranged from 0.12 to 0.63 per day. The results support the information obtained in Tier 1 and 2 and provide additional evidence for the natural attenuation of perchlorate at the site.
Source Area Demonstration:
Results from the Tier 1, 2, and 3 evaluations are summarized below:- The Tier 1 and 2 evaluations showed that groundwater conditions are minimally conducive to biological degradation of perchlorate until closer to discharge into Little Elk Creek. Non-biological attenuation mechanisms have resulted in decreases in perchlorate concentrations over distance. Perchlorate mass flux in the intermediate zone declined significantly during groundwater flow from Transect 1 to 3. However, there is a substantial increase in the shallow zone mass flux in Transect 3 as groundwater migrates from the intermediate to the shallow zones near Little Elk Creek. Total mass flux declines from an average of 28 grams per day (g/d) to 18 g/d of perchlorate from Transect 1 to 3.
- Tier 3 evaluation results indicated that the first-order biodegradation rate constant was 2.9 per year.
|
Cost Factors: Indian Head Demonstration:
The total cost of the Indian Head test demonstration was approximately $509,100. Primary cost elements are described below: - Technical Demonstration Plan, White Papers/Design: ~$51,300 (10%)
- Additional Characterization: ~$103,600 (20%)
- Performance Monitoring & Data Acquisition for Tiers 1 & 2: ~$209,300 (41%)
- Tier 1 and 2 Data Evaluation: ~$14,900 (3%)
- Tier 3 Data Acquisition and Evaluation: ~$60,000 (12%)
- Technical Reporting: ~$70,000 (14%)
Manufacturing Site Demonstration:
The total cost of the Manufacturing Site test demonstration was approximately $292,900.
Primary cost elements are described below:- Technical Demonstration Plan, white papers/design: ~$17,000 (6%)
- Additional characterization: ~$45,000 (15%)
- Performance monitoring and data acquisition for Tiers 1 & 2: ~$101,900 (35%)
- Tier 1 and 2 evaluations: ~$21,000 (7%)
- Tier 3 data acquisition and evaluation: ~$58,000 (20%)
- Technical reporting: ~$50,000
|
Description: Two field demonstrations were conducted to evaluate the effectiveness of MNA for the remediation of perchlorate-contaminated groundwater. The demonstrations were conducted near Building 1419 at Indian Head NSWC in Indian Head, MD (Indian Head Site), and at the TCE/Perchlorate SWMU field site at a manufacturing facility in Maryland. The purpose of the demonstration was to evaluate the tools needed to evaluate whether MNA can be an effective remedy for managing the environmental impacts of perchlorate contaminated groundwater at specific sites. Both demonstrations were implemented following a three- tiered approach to develop multiple lines of evidence related to perchlorate MNA.
Indian Head Demonstration
Based on site conditions, microcosm studies, site logistics, and cost considerations, the Indian Head site was selected for testing the potential for MNA of perchorate in groundwater. Perchlorate-contaminated groundwater was identified near Building 1419, the former perchlorate clean-out facility. Site investigation results indicated that plume was migrating about 300 to 400 feet toward Mattawoman Creek, a large tributary of the Potomac River. No perchlorate-contaminated wastewater has been discharged from the site since 1996; however, a study conducted in 2001, indicated the presence of a persistent source of perchlorate. Results from the 2001 study showed that the perchlorate flux at the site did not change over time and suggested the possibility of a vadose zone source that would continuously release perchlorate to the aquifer during periods of heavy rainfall. As a result, monitoring results indicated a high temporal variability of perchlorate concentrations in wells located 180 and 125 feet downgradient from the presumed source area. The plume is at least 400 feet wide along the creek bank, and dispersion of the plume has resulted in similar perchlorate concentrations being observed throughout the thickness of the surficial aquifer.
During this demonstration, the monitoring well/ piezometer network was sampled up to five times during the 38-month performance-monitoring period. Trends in groundwater flow, biogeochemical parameters, microbial populations, and perchlorate concentrations indicated that perchlorate attenuates mostly as a result of nonbiological mechanisms near the presumed source and areas downgradient from the source but prior to discharge to Mattawoman Creek. Biodegradation rates were calculated by several methods and were generally reproducible, providing supporting lines of evidence for natural bioattenuation.
Maryland Manufacturing Site
The second demonstration was conducted at a 600-acre manufacturing facility in Maryland. Since the 1930s, the facility has been used for various industrial purposes such as fireworks manufacturing, munitions production, pesticide production, and research and manufacturing of solid propellant rockets. Ammonium perchlorate continues to be used to manufacture and test rocket engines at the facility. The surrounding areas also have a diverse history of industrial activities. Recent site investigations have identified a commingled TCE and perchlorate plume on the east of the manufacturing facility that has attenuated over time. The plume migrates through an intermediate aquifer to Little Elk Creek, which lies almost 3,400 feet east of the presumed source area. From 1997 through 1998, a pump and treat system was used as an interim remedial measure to capture and treat contaminated groundwater from the intermediate aquifer in the vicinity of the source. The pump and treat system has removed over 800 pounds of volatile organic compounds (VOCs) since it was installed. Pre-demonstration groundwater and soil sampling results indicated perchlorate concentrations ranging from 1,200 micrograms per liter (µg/L) near the presumed source to an average of 215 µg/L at a downgradient monitoring well about 30 ft from the creek. TCE concentrations showed an increase from 1,300 µg/L near the source to an average of 2,015 µg/L at a downgradient monitoring well.
During the demonstration, new and existing monitoring wells were sampled up to five times during the 23-month performance monitoring period from May 2006 and April 2008 to evaluate aquifer conditions and how those conditions might affect the potential for natural biodegradation of perchlorate. Trends in groundwater flow, biogeochemical parameters, microbial populations and perchlorate concentrations suggest that perchlorate is attenuating and, in some locations, is biodegrading prior to groundwater discharging to Little Elk Creek. Perchlorate biodegradation rates were calculated, but bioattenuation time frames were measured in decades.
Overall, the field demonstrations indicated that MNA can be used to help address perchlorate-contaminated groundwater. The site conditions favorable to perchlorate biodegradation were defined and tested in the field to confirm their usefulness for future MNA evaluations. The key favorable factors include: (1) mildly to strongly reducing conditions (ORP<+100 mV), (2) the absence of strongly acidic groundwater (pH>5.5), (3) relatively low nitrate concentrations, and (4) the presence of TOC to supply electrons for perchlorate reduction (TOC greater than 4 to 6 mg/L). |