2017 Excellence in Environmental Engineering and Science® Awards Competition Winner

Grand Prize - Small Projects

Innovative Approach for Implementing Performance-Based Remediation Project

Entrant: HydroGeoLogic, Inc.
Engineer in Charge: Roy Evans, P.E. and Varut Guvanasen, Ph.D., P.E.
Location: Former Fort Ord, California
Media Contact: Dr. Peter S. Huyakorn, HydroGeoLogic, Inc.

Entrant Profile

HydroGeoLogic, Inc. (HGL) is a prominent independent, employee-owned environmental engineering and water resource services firm. Established in 1987, HGL has extensive experience providing hazardous, toxic, and radioactive waste site characterization, remedy design, construction, operation and maintenance, and optimization, as well as mine reclamation and Military Munitions Response Program services. With over 300 employees, HGL has earned a spot in Engineering News-Record's top 200 environmental firms' rankings since 2006.

Fort Ord is a former U.S. Army base encompassing more than 28,000 acres in Monterey County, California. Closed by Congress in 1994, the base has been undergoing cleanup with oversight by federal and state regulatory agencies. In December 2003, HGL was contracted by the U.S. Army Corps of Engineers to conduct a Performance-Based Remediation with the objective of Site Closure at Operable Unit (OU)-1. The Fort Ord Natural Reserve encumbered a large part of the OU-1 plume, and special precautions were taken to minimize impacts on the eleven listed plant and six listed animal species.

Contamination at OU-1 resulted from releases of solvents and fuels during fire response training. Upon initiating work on the contract, HGL discovered that the pre-contract-award groundwater site characterization had underestimated the extent of affected groundwater. HGL's innovative management approach in conjunction with advanced optimization technology was used to minimize remediation system costs and reduce the cleanup time. HGL's optimized site exit strategy achieved remedial-action completion in 2014 and obtained regulatory concurrence in 2016, before 2017 as estimated in the Record of Decision.

Project Description

Fort Ord is a former U.S. Army post in Monterey County, California, that operated from 1917 until 1994. Fire training activities conducted from 1962 to 1985 resulted in releases of volatile organic compounds to groundwater. In 1990, Fort Ord was added to the National Priorities List. The U.S. Army Corps of Engineers Sacramento District (USACE) and the Army Base Realignment and Closure (BRAC) Office oversee environmental cleanup activities to restore the property to beneficial use. The former post is located on Monterey Bay and contains critical habitat for the endangered Sand Gilia and threatened Monterey Spineflower. Parts of former Fort Ord have been either designated as a National Monument or transferred to the University of California Natural Reserve System (UCNRS) for the study and protection of the unique habitats of these threatened and endangered (T&E) plants.

In 2003, HGL assumed management of remedial actions (RAs) under a Performance-Based Remediation (PBR) contract to address groundwater contamination related to the former fire training area (Operable Unit 1 [OU-1]). Remedial action objectives (RAOs) included (1) restoring groundwater quality beneath 130 acres of the Fort Ord Natural Reserve (FONR) to cleanup goals identified in the 1995 Record of Decision (ROD), and (2) preventing off-post plume migration. The RA selected in the ROD consisted of groundwater extraction and treatment (P&T). The cost of the PBR contract and subsequent task orders was approximately $6.4M (approximately $1.9M capital expenditure and $317K/year operating budget for 14 years).

The project consisted of optimization of groundwater remedial system design and operation that resulted in attainment of site remedial goals and RA completion three years before the 2017 date estimated in the ROD. RAOs were achieved despite the after-contract-award discovery that the plume extended off site approximately 1,400 feet beyond the previously estimated limit of 2,400 feet. The off-post plume was addressed separately. The Fort Ord remedial optimization project attained RAOs, preserved critical habitat, and minimized adverse impacts on adjacent groundwater contaminant plumes. HGL achieved the groundwater RAOs in 2014, completed attainment monitoring in 2015, and obtained RA-completion concurrence from California regulatory agencies in 2016. HGL is currently supporting the USACE/BRAC team in obtaining federal regulatory approval to close the site.

HGL employed an integrated approach to address the technical and management complexities. Technical and management complexities included previously underestimated plume length, off-post plume migration, requirements to expand the existing remedial system, the presence of an adjacent carbon tetrachloride (CTET) plume, and critical habitat. The integrated technical approach included use of groundwater models, a cloud-based parallelized computational optimization methodology, ongoing adjustment of pumping schedules based on performance monitoring, and construction practices minimizing impact on habitat.

As field investigations showed that the OU-1 plume had extended beyond the previously estimated limit, the remedial design and implementation schedule had to be altered to prioritize plume control to prevent further off-post migration. HGL used the 3-dimensional MODFLOW- SURFACT® groundwater mass-transport model to characterize the OU-1 plume. The model was used to identify and mitigate potential impacts from OU-1 RAs on migration and remediation of the nearby CTET plume. The model also was used to optimize the long-term operation of the remedy, to reduce costs, maximize mass removal, and maintain the cleanup schedule. Impacts to air quality were eliminated by using granular activated carbon to treat extracted groundwater. The aquifer water balance was preserved by returning treated water to the aquifer through infiltration trenches and injection wells. Biological mapping results were incorporated into the remedial design to select locations for extraction wells and treated-water recharge facilities that avoided rare plant populations. To preserve the seed banks of T&E plants in sensitive areas, the top six inches of soil removed during construction was segregated, saved, and applied as surface topping during post-construction restoration. Temporary mats were also placed on roadways to protect seed banks and dormant plants from heavy equipment traffic. Construction activities were limited to late June through early October to avoid disturbing rare plants and habitat during critical periods.

HGL aggressively optimized operation of the P&T remedy from startup in 2006 through termination of active remediation in 2014. RA optimization consisted of development and application of the original and innovative Physics-Based Management Optimization (PBMO®) method to minimize cost and duration of P&T. In 2011, PBMO® was used with the calibrated OU-1 MODFLOW-SURFACT model to evaluate alternative pumping strategies using both existing extraction wells and potential new extraction well locations. The PBMO® process led to regulatory acceptance of reduced pumping rates and corresponding sampling reductions that saved approximately $310K in overall cleanup costs. Operational modifications resulting from implementation of PBMO® results reduced greenhouse gas (GHG) emissions (as calculated from the Pacific Gas & Electric Company estimation tool) by 59,000 pounds per year.

The project accomplishments have provided social and economic advancement through the reduction of potential human-health risks, preservation of critical habitat, reduction in GHG emissions, significant cost savings, and timely attainment of cleanup goals. Annual biological mapping of protected species has not shown any significant impact to plant populations. Concentrations for the contaminants in the off-post groundwater, beneath private property, have been reduced to meet the ROD-specified cleanup goals. In addition, this project served as a pilot project to test the efficacy of HGL's PBMO® global optimization methodology in remediation planning and operations. The method has since been applied to other major Superfund and NPL sites to identify remediation alternatives that offer significant decreases in capital expenditures and in monitoring, operation, and management costs.

The overall work quality is demonstrated by the client performance reviews; regulatory concurrence in March 2016 from the USEPA, the California Department of Toxic Substances Control, and the California Regional Water Quality Control Board (RWQCB) that the cleanup requirements of the ROD had been met; and a commendation issued by the RWQCB in January 2017. HGL's performance to date has been graded by the USACE as "Exceptional" in 27 of the 29 ratings and "Very Good" in the 2 other ratings based on the Government's performance evaluation criteria.

Click images to enlarge in separate window.


Location of Operable Unit 1. Operable Unit 1 (or OU1) is located in the northernmost portion of the former Fort Ord. OU1 comprises the contaminated groundwater plume emanating from a former fire drill area that operated from 1962 to 1985 for the Fort Ord Fire Department. Ten volatile organic compounds were listed as chemicals of concern (COCs) at the site, but TCE is the only COC to exceed the cleanup target since 2008.	Chemical of Concern Plume Based on Pre-2004 Investigations. HGL began work at this site in 2003. The available data at that time showed the chemicals-of-concern plume extent to be within the Fort Ord boundary.

Chemical of Concern Plume Based on Post-2004 Investigations. In 2004, HGL's field investigations showed the chemicals-of-concern plume extended beyond the former Fort Ord boundary. Subsequent Army investigations showed the plume migrated into the adjacent private property (used as cattle pasture) and toward a neighboring residential area.	Sand Gilia, an Endangered Species at the Operable Unit 1 Area. Sand gilia (SG). Federal designation of "endangered". Protective measures for Monterey spineflower and SG were required to avoid costly restoration.

Locations and Extents of Threatened and Endangered Plant Species. Locations and extents of threatened or endangered plant populations identified through biological surveys were used in remedial design to guide placement of extraction and injection wells and avoid populations of threatened or endangered plants as much as possible.	Temporary Mats to Protect Threatened and Endangered Plant Species During Construction. Temporary mats were placed on roadways to protect seed banks and dormant plants from heavy equipment traffic.

Trench Excavation for Water Transmission Lines. A 200-gpm treatment plant was constructed on the northwest former fort Ord boundary. Five extraction wells along the plume axis were added to the four boundary control wells. The trench shown is for the transmission lines that deliver extracted groundwater to the treatment plant and return treated water to the infiltration trenches and injection wells.	Groundwater Flow and Transport Model Grid. HGL recalibrated the groundwater flow and transport model developed during the remedial design phase to simulate the migration of TCE in OU-1 groundwater. Shown in the figure is the model's outline.

Locations of Extraction Wells, Injection Wells, Monitoring Wells, and Infiltration Trenches. The groundwater pumping and treatment system within the former Fort Ord boundary was expanded incrementally from the pilot system in 2006 to the final system in 2011. Shown in the figure are the locations of pumping wells, injection wells, infiltration trenches and monitoring wells. Three extraction wells are located along the northeastern boundary to prevent the TCE plume from leaving the site.	Physics-Based Management Optimization Design Criteria. PBMO Design Criteria which included objective function requirements and constraints

Estimated Trichloroethylene Concentration Distribution at the End of Pumping in 2014. Estimated TCE at the end of pumping in 2014. There is a small TCE plume with concentration between 5 to 8 ppb (green area). The concentration is expected to decay to below 5 ppb when the plume approaches the site boundary. The overall project cost savings estimated by PBMO and input from HGL's subject matter experts was $310,000. The total pumping rate was reduced from approximately 56 gpm to approximately 10 gpm (or a factor of five).	Remediation Activity Completion Concurrence Letter from the California Department of Toxic Substances Control in 2016. Remedial-activity-completion concurrence from California Department of Toxic Substances Control in 2016.

Commendation Letter from the Regional Water Quality Control Board in 2017. A commendation from Regional Water Quality Control Board in 2017.