Groundwater Treatment / FP Recovery

Groundwater Extraction and Treatment for Source Control and Containment

The two most common objectives of groundwater pumping include removal of dissolved and/or phase separated contaminants from the subsurface and containment of contaminated ground water to prevent migration.

Precision technical staff determine the applicability of groundwater pumping during the process of performing a thorough site characterization. Site characteristics, such as hydraulic conductivity, are used to determine the range of remedial options possible. Chemical properties of the site and plume are established to characterize transport of the contaminant and evaluate the feasibility of ground water pumping. To determine if ground water pumping is appropriate for a site, one needs to know the history of the contamination event, the properties of the subsurface, and the biological and chemical contaminant characteristics. PES project members identify the chemical and physical site characteristics; define the ground water contaminant plume in three dimensions, and determining aquifer and soil properties necessary in designing an effective ground water pumping strategy.

Once the decision to implement groundwater extraction methods is made based on site specific data, the following decision process is performed by PES project management to map a pathway to site closure.

The first step of any remediation project consists of defining the remedial action objectives to be accomplished at the site. This involves gathering enough background site information and field data to make assessments of remedial requirements and possible cleanup levels. The first determination is whether cleanup or containment will be the most appropriate remedial action. If cleanup is chosen, the level of cleanup must be determined. If containment is chosen, ground water pumping is used as a hydraulic barrier to prevent off-site migration of contaminant plumes.

The next component consists of the design and implementation of the ground water pumping system based on data evaluated in setting the goals and objectives. The criteria for well design, pumping system, and treatment are dependent on the physical site characteristics and contaminant type. Actual treatment may include the design of a train of processes such as gravity segregation, air strippers, carbon systems tailored to remove specific contaminants.

The third essential component of any ground water extraction system is a ground water monitoring program to verify its effectiveness. Monitoring the remedial process with wells and piezometers allows the operator to make iterative adjustments to the system in response to changes in subsurface conditions caused by the remediation.

The final component is determining the termination requirements. Termination requirements are based on the cleanup objectives defined in the initial stage of the remedial process. The termination criteria are also dependent on the specific site aspects revealed during remedial operations.

Our experience includes the design, installation, operation and optimization of:

• Conventional Groundwater Extraction using down well pneumatic and/or electric pumps
• Vacuum assisted Groundwater extraction
• Total Fluid (Multi Phase) Extraction
• Air stripper tray and packed Towers
• Granular Activated Carbon Treatment
• Advanced Oxidation
• Chemical Augmentation
• Free product Recovery

Case Study

Dual Pump (LNAPL & Groundwater Recovery), Multi-Well Groundwater Pump and Treat, Large Scale Soil Vapor Extraction and Air Sparging
 
Project Name: Former Service Station
Location: Upstate, NY

Impact Characterization:  Mixed fuels, primarily gasoline/kerosene, resulting from activities associated with the operation of a former retail gasoline storage/sales facility.  Petroleum impacts to both the subsurface soil and groundwater regimes.  Contamination was documented beneath the site proper as well as at several adjacent properties due to prolonged groundwater transport.

Technical Overview: This project resulted from one or more historic releases associated with former retail fuel storage/dispensing activities at the subject site.  PES’s initial response involved a complete assessment of subsurface conditions to refine the comprehension of the initial definition of the contaminant plume.  The assessment included the definition of contaminant type/spatial distribution, geologic/hydrogeologic subsurface parameters, aquifer analysis, and baseline transport characteristics (groundwater/contaminant dispersion profile).  The initial assessment and subsequent testing established a substantial negative environmental impact that included the existence of light non-aqueous phase liquid (LNAPL)/free product contamination.  Impacts in the subsurface involved both vadose and phreatic aquifer components starting at depths of twenty feet below grade.  The documented adverse impact extended from the site proper to adjacent third party parcels.  PES developed a remedial feasibility plan presenting groundwater pump and treat technology to gain hydraulic control over the expanding plume and a combination of soil vapor extraction and air sparging to address the absorbed and dissolved phase impacts. The remedial feasibility plan was submitted to the NYS DEC and subsequently approved and implemented.   

Pilot testing was performed to generate site-specific data to allow for a full-scale remedial system design.  The resulting pump and treat remedial corrective action incorporated four six-inch diameter forty foot deep groundwater recovery wells with down-well separate dual pumping (free product and groundwater) capability at one location and a groundwater treatment system consisting of a coalescing plate oil/water separation, low profile air stripper, 1400-pounds of activated carbon polish all capable of treating the impacted groundwater to allowable discharge standards at a rate of 40 gallons per minute. 

The resulting soil vapor extraction and air sparge remedial system incorporated nine nested sparge and ventilation wells, a 15 horsepower vapor extraction blower capable of inducing airflow of more than 3,000 feet per minute and a 15 horsepower sparge compressor. 

Each of the remedial system wells were properly installed by Aquifer Drilling and Testing, Inc., (ADT) under the supervision of PES geologic staff, utilizing hollow-stem auger drilling and standard split spoon soil sampling methodologies.  Each system was designed, constructed, installed (including the safety interlocks and remote monitoring telemetry), operated and maintained by PES.  Both pump and treat and soil vapor extraction/air sparge systems are each housed in mobile trailers thereby eliminating cost associated with enclosure construction and/or demolition.

Site Progression Specifics:  The site reached its primary remedial goals and the active remedial program was terminated by the local regulatory.

Total Fluid Extraction – (process overview)

Total Fluid Extraction (TFE), also known as multi-phase extraction, vacuum-enhanced extraction, or sometimes bioslurping, is a technology that uses a high vacuum system to remove various combinations of contaminated ground water, separate-phase petroleum product, and hydrocarbon vapor from the subsurface. Extracted liquids and vapor are treated and collected for disposal, or re-injected to the subsurface (where permissible under applicable state laws).

In DPE systems for liquid/vapor treatment, a high vacuum system is utilized to remove liquid and gas from low permeability or heterogeneous formations. The vacuum extraction well includes a screened section in the zone of contaminated soils and ground water. It removes contaminants from above and below the water table. The system lowers the water table around the well, exposing more of the formation. Contaminants in the newly exposed vadose zone are then accessible to vapor extraction. Once above ground, the extracted vapors or liquid-phase organics and ground water are separated and treated. TFE for liquid/vapor treatment is generally combined with bioremediation, air sparging, or bioventing when the target contaminants include long-chained hydrocarbons. Use of dual phase extraction with these technologies can shorten the cleanup time at a site. It also can be used with pump-and-treat technologies to recover ground water in higher-yielding aquifers.

Case Study

Large Scale Subsurface Investigation, Remedial Feasibility Study, Design, Install, Operate and Maintain Total Fluid, High Vacuum Extraction In-Situ Remedial System

Project Name: Former - Major Oil Bulk Storage Facility
Client: Major Oil.
Location: Capital District, New York

Impact Characterization: - The subject site and surrounding properties have been impacted by various petroleum fuels, including various grades of gasoline, fuel oil and kerosene.  For clarity in the subsequent discussion - the source site is designated the site proper.  Documented impacts resulted from former activities associated with the site proper that included operation as a major oil storage facility (MOSF).  Initial off site investigations discovered petroleum contamination impacts to the shallow soil and local groundwater regimes.  Subsequent investigations conducted on the site proper indicated significant impacts including thickness of light non-aqueous phase liquid (LNAPL) that varies from 1 to 5-ft, high concentrations of dissolved phase constituents in groundwater and a substantial degree of adsorb phase contaminates residing in the local overburden material.  Total impacted area covers approximately 2 acres.

Technical Overview: - PES was initially retained by a government agency to conduct a supplemental site investigation in an attempt to delineate and identify the source of petroleum-impacted groundwater discovered at off site locations.  PES drafted a work plan and secured off site access at two adjoining parcels of land that were identified as potential source areas from a critical review of Sanborn maps that were obtained as part of a phase 1 site assessment.

Following review and approval of the work plan by the NYSDEC and negotiation of site access with adjacent landowners PES commenced the investigation by installing nine (9) soil borings and seven (7) groundwater-monitoring wells.  Investigative depths reached 24-feet beneath the relative ground surface.  Soil borings and monitoring wells were installed utilizing PES’s direct push soil probe.  PES geotechnical staff performed oversight and direction of all drilling activities including continuous macro core sampling.  The results of this initial investigation concluded that significant impacts were present at the site proper.  Hydrogeologic assessment data indicated the site proper to be hydraulically up-gradient of the Spare Room II.  This information documented the site proper as the source location for the petroleum impact to the local groundwater.  Initial findings documented LNAPL and dissolved phase contamination consisting of greater than 100ppm of total STARS list VOC’s detected in groundwater.

PES documented the findings in a comprehensive investigation report that concluded the site is tidally influenced from the adjacent Hudson River, local geology consisted of silt, sand and gravel underlain by black shale bedrock, groundwater flow was confirmed to flow off site and ultimately that the most likely source of the petroleum impacts documented in the area were a result of the property formerly utilized for Bulk Petroleum storage/dispensing.  Recommendations included in the report included additional subsurface investigation work to further delineate the plume limits, contaminant profile and magnitude.

PES completed a work plan to perform the recommended supplemental subsurface investigation of the site proper that included the installation of additional SBs and MWs in a 40’X40’ grid pattern to complete a comprehensive assessment of subsurface conditions.  The fact that the site previously possessed multiple possible sources in the way of underground/aboveground tanks and associated piping dictated the need for the detailed grid pattern-drilling program.  Additional work tasks included a preliminary, private utility mark out, subsurface geophysical survey to ascertain the existence of USTs and piping that were depicted on a historical map of the former MOSF and a site survey that was completed by a NYS licensed land surveyor.  The professional survey work was required to document accurate locations of installed monitoring wells, elevations and relevant surface features.

Upon approval of the supplemental work plan PES commenced additional investigative work by completing a private utility mark out on the property and then installing 82 soil borings and an additional 28 groundwater monitoring wells over the approximate 5 acre site. 

The results of the investigation successfully delineated the limits of the contamination previously discovered and identified two additional areas of concern, in which significant (4-5-feet) of LNAPL were documented.  Additionally, a subsurface geophysical ensued, in which an underground storage tank (UST) associated with former site operations was identified.

With the comprehensive site investigation completed a critical technical review was performed utilizing all available information collected from the site.  The review focused on the three identified target areas of concern.  Particular attention was paid to geological and hydrogeological data collected and a recommendation for pilot testing to determine the site-specific affects of high vacuum, total fluid extraction (HVTFE) was recommended.  Authorization was granted and PES proceeded to complete the pilot test study to evaluate proposed remedial method feasibility and obtain preliminary bench-scale design parameters.  The bench scale design data was subsequently used to develop a full-scale remedial corrective action plan using HVTFE as a cost effective strategy for containment/reduction of the LNAPL and dissolved phase plumes.

For purposes of the pilot study five six-inch diameter wells were installed at various locations throughout the site.  The remedial test wells were installed by Aquifer Drilling and Testing (ADT) in concert with PES geological staff supervision.  ADT performed all required drilling using hollow stem auger methods coupled with continuous split spoon sampling procedures.  ADT drilling staff was tasked with proper drilling, construction, design and development of the test remedial wells.  In general test locations were selected due to their spatial relationship with respect to both existing (historic) monitoring points and the geographic occurrence within the documented plume. A vacuum truck was then utilized to create a vacuum within each pilot test well. 

Testing involved variable vacuum application and stepped draw down limits procedures.  PES recorded all site-specific design data/parameters.

The results of the pilot test study concluded that the proposed remedial action would be capable of achieving the required design flow and vacuum at the site necessary to achieve site-specific remedial goals.

PES used the site specific design data to develop a comprehensive corrective action plan (CAP) for the site, utilizing high vacuum total fluid extraction (multi phase extraction) for mitigation of petroleum impacts.  The plan summarized investigative and pilot test results, conceptual design of the remedial system and system and site monitoring plans.  Associated project budgets and implementation schedules were developed as part of the comprehensive corrective action plan. 

Upon receipt of CAP approval from the Department, PES/ADT implemented the CAP by installing 18, large diameter (four-inch) groundwater extraction wells in an array that covered areas of concern in the northern plume.   In association with the 18 recovery wells, PES installed 2,000 (+) linear feet of subsurface piping at depths below the projected frost penetration.  In addition provisions were made to supply primary and secondary electrical service including a 25 KVA transformer sub-station and containment pad.   The required remedial trenching generated approximately 400 tons of petroleum-impacted soil.  PES arranged all aspects of the soil transport/proper disposal - including loading.

Once all remedial system appurtenances and electrical connections were installed a trailer-mounted HVTFE system consisting of two (2) 20-horsepower liquid ring vacuum pumps, moisture separator, commercial-grade coalescing oil-water separator, bag filtration units, low profile air stripper, granular activated carbon treatment and 500-gal aboveground storage tank (for recovered LNAPL) was installed at the site. 

The remedial system was constructed in a trailer such that it can be mobilized to the three separate areas of concern that are to be remediated with a single site-specific remedial system.

In addition to governing system design, installation and operations, PES was also responsible for set up and coordination of site access through the property owner, electrical and discharge permits/service provided by the local municipality, procurement of building permit and attending public meetings.

Site Progression Specifics: - PES was involved at the inception of this large scale investigation and remedial project and has successfully governed the course of the work to reach a point of active remediation to the benefit and satisfaction of the local regulatory community (NYSDEC) the responsible party and the local community (through public meetings, etc.)

The PES/ADT team performed a majority of the work, including all trenching, piping, well installation, UST closure activities and contaminated soil, storage, handling, transportation and disposal utilizing properly trained and skilled PES personnel and equipment.  When additional expertise within a particular field/service (i.e.; electrical, geophysical and location/elevation survey, etc.) were required, subcontracting services were acquired by PES, whereby PES acted as general contractor with sole oversight responsibilities for work completed on the project.  General contracting duties included subcontractor set up and payment, scheduling and on-site supervision of subcontractor field activities and the procurement of equipment and materials necessary to complete the project in a comprehensive manner.  PES project management and on-site field supervisors ensured that the work was completed efficiently, on time, within budget and in accordance with the site specific CAP.

Major site construction activities (remedial system installation) commenced in September 2007 and were completed in December 2007.  The HVTFE system was placed on-line in March 2008.    PES continues to implement the remedy through operation and maintenance of the system.

This work was performed under a time and materials contract with project budgets produced for major site events for the Department.  Work for GPC has been completed subject to a comprehensive budget.  PES/ADT have consistently performed required work within the time and budget framework for this site to the satisfaction of the client(s).  When the responsibility of the project transitioned from the Department to GPC the Department representative stated “Precision Environmental Services did excellent work for the Department on a very complex site.  I appreciate the way [PES staff] supervised the work done on this site and look forward to working with [them] and [PES] in the future.”

Case Study

Large Scale General Construction, Groundwater Extraction and Remediation, Bedrock Drilling

Project Name: Hazardous Waste Landfill
Client: Government Agency
Location: Up-State, New York

Impact Characterization: - The subject Site is a class 2 inactive hazardous waste disposal site located within a 19.6-acre permanent easement obtained by the regulatory agency.  The Site was reportedly involved in salvage/ disposal of industrial fluid waste from 1952 to 1968.  The site was later utilized as a waste oil transfer station.  These activities resulted in the disposal of hazardous waste, including solvents, waste oils, polychlorinated biphenyls (PCBs), scrap materials, sludges, and solids at the site during its period of operation.   The unlined nature of the landfill resulted in contaminant releases to the surrounding areas, including into the local bedrock aquifer occurring beneath the subject site.

The regulatory agency retained an engineering firm to provide design services related to the remediation of the project site.  In order to obtain information necessary to complete the design of the final remedial alternative for the site, an investigation of the off-site bedrock aquifer needed to be completed.  To accomplish the bedrock study site facilities/infrastructure needed to be designed, constructed and maintained.

Additionally, services were needed to manage the handling, transportation and subsequent off-site disposal of extracted groundwater and leachate collected from the previously installed (by others) on-site leachate collection system.

Technical Overview: - PES was tasked with providing the oversight engineers with construction, field management and remedial services.  The principle features of the work to be performed by PES included: 1. - Installation of a gravel access road with turnaround and main entry gate/fencing within the subject Site; 2. – Installation of a frac tank and associated appurtenances; 3, - Clearing and removal of trees and other site preparation activities; 4 – Installation of one new bedrock extraction well; 5. – Installation of three electric piston extraction pumps and associated electrical equipment on one new and two existing bedrock extraction wells; 6 – Installation of over 3,500-feet of double-walled, High Density Polyethylene (HDPE) piping system and associated appurtenances; and 7 – operation and maintenance of the installed off-site pumping system.

PES began the project by first installing the access road and turnaround at the site in August 2007.  The timing of this construction aspect was such that it allowed implementation of the required work in ideal (dry) weather conditions.  This was essential considering the access road was to be installed over top of a previously installed clay cap. 
The completion of this particular phase of the project was also scheduled first as it provided a staging area for the additional site work.

Once the roadway and turnaround were complete the base for the frac tank was completed in the same fashion and the frac tank was placed at the site.  Completing the access road allowed for the staging of materials and other construction equipment necessary to efficiently complete other critical work tasks.

To allow off-site access to existing and newly installed bedrock extraction wellhead areas, PES cleared approximately 700 linear feet of wooded terrain and installed an improved access road consisting of shale bedding material.  Once access to the drilling area was achieved the installation of the bedrock extraction well commenced.

Bedrock extraction well installation procedures involved the construction and installation of temporary decontamination facilities, drilling through approximately 85-feet of unconsolidated overburden material and setting a 12-inch steel surface casing in competent bedrock, all of which was completed by Aquifer Drilling and Testing, Inc. (ADT) with geotechnical oversight performed by PES.  During the well drilling/installation process, PES geological staff collected 240 feet of continuous HQ rock cores.   The resulting small diameter rock core borehole was subsequently reamed out to achieve the final designed borehole diameter of 9-7/8-inches.  Six (6)-inch diameter PVC well screen and riser were installed to complete the extraction well to design specifications.

In an effort to expedite overall progress on the project, PES commenced the installation of the double-walled HDPE piping beginning in the landfill while simultaneously completing the installation of the extraction well.

Installation of the HDPE piping involved joining the pipe by thermal butt-fusion to produce a homogenous, sealed, leak tight system.  PES personnel involved in the pipe fusing process were specifically trained by factory representatives to ensure high levels of QA/QC.

To document the integrity of the installed subsurface utilities and to ensure that piping and fittings were tight, all piping, valves and fittings were pressure tested in sections as the work progressed.  In addition, completed respective utility runs were tested in their entirety following full installation.

To accommodate various system components several precast concrete structures were placed in conjunction with the subsurface piping system(s).  Three air release chambers, one valve vault and five electrical utility vaults were set at locations in accordance with design documents.

Following successful installation and testing of the piping system, subterranean vaults and appurtenances, three electric piston extraction pumps and corresponding control circuitry were installed in respective groundwater extraction wells. 

The well discharge was then connected to the HDPE subsurface piping with stainless steel piping, valves and appurtenances. 

Data loggers were then installed/utilized in five wells to allow for aquifer performance data collection.  The secured data was used to establish/confirm physical parameters of the bedrock aquifer as well as accurately determine aquifer responses to active groundwater extraction.

Once active pumping commenced, PES personnel performed operation and maintenance of groundwater extraction activities and monitored water storage availability with respect to frac tank capacity.  PES also coordinated(s) for transport and disposal of extracted groundwater and water accumulated within the on-site leachate collection system.

Site Progression Specifics: - PES and ADT performed a majority of the work, including all trenching, piping and well installation activities, utilizing properly trained and skilled personnel and equipment.  When additional expertise within a particular field/service (i.e.; electrical) was required, subcontracting services were acquired by PES, whereby PES acted as general contractor with sole oversight responsibilities for work completed on the project.  General contracting duties included subcontractor set up and payment, scheduling and on-site supervision of subcontractor field activities and the procurement of equipment and materials necessary to complete the project in a comprehensive manner.  PES project management and on-site field supervisors ensured that the work was completed efficiently, on time, within budget and in accordance with the design specifications.

Major site construction activities commenced in August 2007 and were completed in October 2007.  The pumping system was placed on-line in March 2008.  Since start up, over 50,000 gallons of impacted groundwater have been extracted from the bedrock aquifer.  PES continues to implement the off-site remedy through operation and maintenance of the groundwater pumping system(s).  The implemented remedial action continues to produce valuable data for the engineering firm to facilitate the completion of their comprehensive site investigation and ultimately determine an effective long-term