BPM006010_Attach12_Method.Approach_MatrixNEWorld.pdf

Request for Proposal

Solicitation No. BPM006010

ASRAC Assessment and Remediation of Hazardous Substances

Arizona Department of Environmental

Quality (ADEQ)

1110 W. Washington Street

Phoenix, AZ 85007

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22

Attachment 12 – Method of Approach

The Offeror shall provide a narrative response to each section that demonstrates their understanding of the Scope of

Work requirements and describes the company’s overall method of approach for providing the Service(s) stated in this

Solicitation.

Offeror shall provide a response either after each question or in a separate document entitled: “Attachment -

Method of Approach.” If a separate document is used, please clearly designate each section and double-check to ensure that each question has been answered. If any information provided is considered CONFIDENTIAL by

Offeror, the information must be specifically included in the Confidential Information Designation Attachment and related documentation to be assessed for confidential treatment under A.A.C. R2-7-103.

Responses shall be limited to one (1) page per question. Response to Question #5 may be up to two (2) pages, in font size 10 pt or greater.

Question 1: Describe your company’s quality control/quality assurance process for reviewing proposals and technical documents prior to submission to ADEQ. What deliverables can ADEQ review to verify QA was completed? If ADEQ finds a quality issue, who, other than the PM, is the point of contact for a remedy?

Question 2: Describe the methods and criteria your company would propose for confirming that a soil vapor extraction system located at a former dry cleaner in downtown Phoenix could be turned off and demobilized from the site. Consider both vapor and direct exposure. How does the Arizona “Soil Rule” apply at closure?

Question 3: Provide a table for a sampling and analysis plan for the implementation of an in situ enhanced reductive dechlorination program for a period of 12 months. Assume the program includes two injection wells (IW-01 and IW-02), four performance monitoring wells (one well [PW-01] located 10-feet upgradient of the injection wells with the remaining three wells located 10- [PW-02], 20- [PW-03], and 30-feet [PW-04] downgradient of the injection wells), and one injection utilizing emulsified vegetable oil. Sample and analysis plan should include what parameters are to be collected for the design of the implementation and for remedy performance monitoring.

Question 4: Describe the multiple lines of evidence necessary to evaluate monitored natural attenuation (MNA) in a typical Arizona aquifer and your experience with the viability of MNA in the deep aquifers of Arizona (focusing on chlorinated solvents), including the limits on MNA in our hydrogeologic settings? Provide key references where appropriate (does not count against page limit). Describe why low-flow sampling would be preferable over passive sampling in MNA evaluation.

Question 5 (RESPONSE to this Question may be up to two (2) pages): Describe the in situ technologies you have used and provide a critical evaluation of successes and failures. What would useful data quality objectives be for the various in situ technologies you have used (plume control, source remediation, mass reduction)? What site characterization data and steps are needed to fully evaluate the applicability of specific in situ technologies?

Question 6: ADEQ is focusing more on statistical techniques to both monitor long term performance of remedies, including MNA and optimize remediation and monitoring programs. Describe how the Air Force Center for Environmental

Excellence (AFCEE) MAROS process can be used for these types of programs. What steps and metrics would you use to optimize a monitoring well network on a large PCE plume over a ten year period that includes both MNA and pumping from existing production wells for municipal or agricultural use?

Request for Proposal, Solicitation No. BPM006010 ASRAC Assessment & Remediation of Hazardous Substances Attachment 12 – Method of Approach (Cont.)

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22

Question 1: Describe your company’s quality control/quality assurance process…(1 page limit).

Offeror Response:

To ensure preparation of quality proposals and technical deliverables, Matrix follows our company Quality Assurance /

Quality Control (QA/QC)

Program, which is based on our policy that no project deliverable is issued without a thorough QA review from multiple technical experts. For each deliverable generated, Matrix will prepare a

Project Review Checklist that will accompany the document from initial and subsequent draft stages to the final review stage. As the document works its way through our internal review process, each reviewer will initial and date the checklist to denote who performed the review and when it occurred. Our QA/QC process goes beyond our deliverables - it also pertains to the notes and forms Matrix staff record when documenting field activities including groundwater monitoring; well drilling and installation; tracer studies; in situ treatment injections; post-treatment monitoring; and monitored natural attenuation (MNA).

Matrix believes good field notes are the foundation of a successful project technical deliverable. Our senior staff work closely with our young professionals to ensure all on the Matrix Project Team understand the project goals and data collection needs. Prior to fieldwork, the Matrix project manager (PM) will create a Work Order describing each task and a list of the appropriate field forms. The Work

Order and field forms will be distributed during a meeting with field staff prior to the scheduled field work. During performance of field activities, Matrix field staff will communicate frequently with the PM, especially at the beginning and end of each day. As laboratory reports with results of sampling activities arrive, each lab report is reviewed to make sure the correct analytes were quantified, holding times met, required detection limits achieved, proper units reported, and laboratory QC was completed. If errors or discrepancies are found, then Matrix will promptly ask the lab to correct the problem(s) and issue a revised analytical report. This process ensures that before a technical deliverable is submitted, the associated lab reports are complete and sample QC protocols have been met.

For each deliverable including proposal and technical documents, Matrix will assign a senior technical staff member as the QA/QC officer and with the assistance of other senior reviewers, will verify that each deliverable meets company standards for overall quality, and technical accuracy of text, tables, figures, and appendices. This includes but is not limited to review of text for technical accuracy and grammar, review of tables for data accuracy and clarity of content, review of figures for accuracy and agreement with narrative text presented in the attendant letter, memorandum, or report. Role expectations and responsibilities for each project phase are summarized in the table above.

This ASRAC submittal, with all of its many components, exemplifies our QA/QC process described above. For future proposal and technical documents, our Project Review Checklist identifying the primary author, senior reviewers and/or registered professionals reviewing specific elements of the document, including data, text, tables, figures, and appendices will accompany each submittal. Draft versions of the documents will be submitted to ADEQ for review and comment. Upon receipt of ADEQ’s comments, Matrix has found it is helpful to have a conference call with the ADEQ PM to ensure their comments are fully understood. The final version of the document will include a final QA review to verify that ADEQ’s comments have all been satisfactorily addressed. To provide some historical context to our QA process, listed below is a small subset of past deliverables submitted for a variety of ADEQ projects, including ASRAC, which ADEQ can review to confirm that Matrix’s QA/QC program was completed.

• 50% Engineering Design Report (Draft) ASRAC Miracle Mile WQARF Site, Tucson, AZ, dated June 18, 2021

• Feasibility Study Miller Valley Road and Hillside Avenue WQARF Registry Site, Prescott, AZ, dated January 11, 2022

• MCL Assumptions Report – Arsenic Aquifer Water Quality Standards Technical Support, dated July 31, 2023

• Well Installation, Groundwater Sampling, Clean Water Injection Test, Early Response Action for Enhanced In Situ

Bioremediation of Chlorinated VOCs in Groundwater, Miller Valley Rd and Hillside Ave WQARF Site, dated August 18, 2023

• State-Based AWQS Report – Arsenic Aquifer Water Quality Standards Technical Support, dated August 24, 2023

If ADEQ finds a quality issue on future documents submitted per this ASRAC contract, Mr. Harry Brenton, RG (480-322-1474, hbrenton@mnwe.com) will be the Point of Contact to resolve the issue, identify a satisfactory path forward, and develop additional procedures to ensure the error is not repeated.

Attachment 12 – Method of Approach (Cont.)

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22

Question 2: Methods and criteria for confirming a soil vapor extraction system at a former dry cleaner…(1 page limit).

Offeror Response: Our answer to this question presumes the site is capped with existing asphalt cover, buildings are present, the SVE manifold is constructed to allow for collection of samples from each well and an overall aggregate, and high resolution site characterization has been conducted to 1) define the vertical and horizontal distribution of chlorinated ethene contamination, 2) locate the depth and extent of the greatest amount of contaminant mass, 3) identify the stratigraphy of the vadose zone containing the contaminant mass, 4) qualify the amount of contaminant mass associated with each type of deposit, 5) understand depth of groundwater, levels of groundwater contamination, flow directions, seasonal fluctuations and 6) identify the distance to nearest receptors.

During SVE system operation, influent soil vapor samples are typically collected at monthly intervals in each well and an overall aggregate to track the relative progress of chlorinated ethene removal. As cumulative contaminant mass recovery increases, the contaminant removal rate will decrease over time.

Eventually the chlorinated ethene recovery rate will approach an asymptotic condition. Recognition of this asymptotic recovery rate condition is a potential indicator that mass removal is complete. Once reached, the SVE system should be turned off for one month of “rebound testing” to determine to what extent matrix back diffusion is occurring and/or if operations have successfully reduced contaminant concentrations to levels warranting system shut down.

Upon restart, field screening and influent sampling is again conducted to determine if contaminant removal rates have increased, decreased, or remained similar to pre-shutdown rates. If no rebound occurs, and a decreased contaminant mass recovery is indicated, then the SVE operations have been successful in removing contaminant mass.

At this point, soil vapor and soil data are needed to verify mass removal.

Installation of permanent soil vapor probes installed to 5 feet below ground surface (ft bgs) in the area where the highest historical chlorinated ethene concentrations have been observed during the site characterization process to determine shallow soil vapor conditions and to assess vapor intrusion potential and direct exposure at hypothetical site structures. The quantity and distribution of soil vapor probes is dependent on a variety of factors including the areal extent of the chlorinated ethene plume, but likely requires at least three and up to

15 probes for a typical dry cleaning site. During sample collection, soil vapor probes are allowed to equilibrate to subsurface conditions, purged of three internal volumes, and collected into laboratory-prepared summa canisters for analysis of volatile organic compounds

(VOCs) using EPA Method TO-15. The laboratory analytical data are compared to EPA Region 9 Regional Screening Levels (RSL) for

Resident Air. VOCs detected at concentrations above 10% of their respective carcinogenic or non-carcinogenic RSL are selected for further Tier 3 evaluation using the Johnson and Ettinger (J&E) Model. If the calculated cumulative Excess Lifetime Cancer Risk (ELCR) is less than 1x10-4 and the hazard index (HI) is less than 1, then the Tier 3 evaluation demonstrates the vapor intrusion exposure pathway is incomplete and no further SVE remediation response is necessary. If the Tier 3 evaluation outputs exceed ELCR and/or HI thresholds, additional contaminant mass removal is needed, and additional J&E Model simulations are required post-remediation.

When considering removal of an SVE system, confirmation soil data must be collected to verify that soil concentrations do not exceed their respective Residential Soil Remediation Levels (rSRL) promulgated under Arizona’s “Soil Rule” (Arizona Administrative Code

[AAC] Title 18, Chapter 7, Article 2). If confirmation soil samples demonstrate the chlorinated ethene concentrations are below their respective rSRLs, no further soil remediation response is necessary. The “Soil Rule” includes two risk tiers where meeting the 10-6 risk threshold is required when the current, or currently intended future site use is a childcare facility or school where children under the age of 18 are reasonably expected to be in frequent and repeated contact with the soil. If current, or currently intended future site use does not meet this description, remediation to the less stringent 10-5 risk threshold is acceptable.

Confirmation soil data are also used to determine the leaching potential of contaminated soil to groundwater, as the results must demonstrate that residual concentrations in soil cannot cause, or threaten to cause, a violation of , aquifer water quality standards

(AWQS). The leaching potential of each contaminant of concern (COC) is determined by comparing the confirmation soil sample results to minimum Groundwater Protection Levels (GPL) which are based on a “worst-case” scenario where the entire soil profile is contaminated from ground surface to the groundwater interface. If confirmation soil sample concentrations do not exceed a minimum

GPL, no further action is needed. If a minimum GPL is exceeded, alternative GPLs are calculated using the ADEQ GPL Model or a commercially available vadose zone model such as SESOIL. Alternative GPLs are calculated for each COC based upon the depth of

COC incorporation (defined as the deepest depth at which the minimum GPL is exceeded), lithology, and depth to groundwater.

Attachment 12 – Method of Approach (Cont.)

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22

Question 3: SAP for implementation of an in situ enhanced reductive dechlorination program…(1 page limit).

Offeror Response: Table 1. Sampling & Analysis Plan for In Situ Enhanced Reductive Dechlorination (ISERD) Program

PW-01^ PW-02 PW-03 PW-04

10 ft up-gradient

10 ft down-gradient

20 ft down-gradient

30 ft down-gradient

Monitoring Parameter Purpose of Parameter Wells

Dissolved Oxygen, Oxidation

Reduction Potential, pH, conductivity, temperature

Determine if anaerobic conditions have been established and pH between 6-8.

All Wells A Q M-Q Q Q

VOC using EPA Method 8260B All Wells A Q M-Q Q Q

Dissolved Gasses: methane, ethane and ethene All Wells A Q Q Q Q

Chloride All Wells A Q Q Q Q

Total Organic Carbon Required for microbial growth.

All Wells A Q M-Q Q Q

Volatile fatty acids

Biodegradation by-product of carbon substrates

All Wells A Q M-Q Q Q

Alkalinity Shows buffering capacity All Wells A Q M-Q Q Q

Dissolved Oxygen All Wells A Q M-Q Q Q

Nitrate as N* All Wells A Q M-Q Q Q

Sulfate* All Wells A Q M-Q Q Q

Manganese* All Wells A Q M-Q Q Q

Dissolved Ferrous Iron (Fe2+)* All Wells A Q M-Q Q Q

Hydrogen Sulfide (if high sulfur in GW)

Interferes with reductive dechlorination.

All Wells A -- -- -- --

Ammonia IWs A -- Q SA SA

Nitrogen, Total Kjeldahl IWs A -- Q SA SA

Total Phosphorus as P IWs A -- Q SA SA

Phospholipid Fatty Acids Microbe information IWs A -- SA SA SA

Key microbes: e.g.

Dehaloccoides, Dehalogenimonas, Dehalobacter

Microbes capable of reductive dechlorination and can convert PCE to ethene

IWs A -- Q Q Q

Key gene targets: tceA reductase, VC reductases

Key genes for TCE and VC biodegradation IWs A -- Q Q Q

Bromide Tracer for groundwater flow direction IWs -- Q M-Q Q Q

Compound Specific Isotope

Analysis

Indicates compound transformation pathway IWs + -- + + +

Notes: * = If the concentration of this parameter is below a level that would inhibit reductive dechlorination, then it can be removed from the sampling program.

^ = Assuming upgradient is clean; quarterly or semi-annually depending on flow velocity

= Only if we want to demonstrate biodegradation reaction

-- = Not analyzed

PW = monitoring wells IW = injection well Q = quarterly A = annually

M-Q = monthly for first quarter then quarterly SA = semi-annually DHC = Dehaloccoides

Major nutrients required for microbial growth

Implemen-tation

Design

Remedy Performance Monitoring Note: Groundwater level measurements will be collected prior to program implementation and on a monthly basis thereafter to understand groundwater mounding and determine any changes in flow direction.

Monitor contaminant concentrations and reductive dechlorination end products.

Electron acceptors can interfere with reductive dechlorination

Microbial Parameters:

Additional Potential Parameters:

IWs

(IW-01

and

IW-02)

Nutrient Information:

Analytical Parameters:

Frequency of Sampling

Field Parameters

Electron Acceptors:

Attachment 12 – Method of Approach (Cont.)

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22

Question 4: Evidence necessary to evaluate monitored natural attenuation (MNA) in a typical AZ aquifer …(1 page limit).

Offeror Response:

Aquifer systems in Arizona are complex and reflective of AZ’s three distinct physiographic provinces.

The provinces exhibit diverse hydrogeologic settings with unique groundwater flow and contaminant transport characteristics ranging from primary porosity and flow through porous media within the alluvial aquifers of the Basin and Range to secondary porosity and flow through fractures and dissolution cavities within the bedrock aquifers of the Colorado Plateau. As such, to determine the role MNA can play in meeting site remediation goals, a thorough and detailed understanding of aquifer characteristics must be developed to provide insight into the natural mechanisms of contaminant control and destruction to identify the various processes of natural attenuation through biodegradation, sorption, dispersion & dilution, and chemical reactions. Detailed characterization efforts are needed to understand the subsurface stratigraphy, mobile versus immobile porosity of aquifer materials, mass and distribution of chlorinated solvent contamination, the geochemical and microbial makeup including key enzymes of the aquifer and aquifer sediments, the behavior, and pathways of advective contaminant movement within the aquifer, and long-term contamination and groundwater level trends in monitor wells. These data can then be used to develop a Conceptual Site Model to be used as a framework to evaluate whether natural attenuation of contaminants is occurring and collect additional data, if necessary, to support the lines of evidence presented below.

The First Line of Evidence is a reduction in contaminant concentrations in key monitor wells. This is evaluated by reviewing trends in contaminant concentrations in the context of the subsurface stratigraphy to show reduction in mass is occurring and identify the potential presence of matrix back diffusion. This can also include the use of the BIOCHLOR model, Mann-Kendall trend evaluation and linear regression analysis to demonstrate plume reduction and stability. BIOBALANCE toolkit can be used to determine mass balance calculations (Kamath et al., 2010). The Second Line of Evidence are changes in concentrations and distributions of geochemical and biochemical indicator parameters identified during site characterization activities. A Third Line of Evidence can be conducted through laboratory testing or in situ microcosms (ISMs), which have the major benefit of evaluating the geochemical and microbial parameters under in situ conditions as opposed to extracting native aquifer materials and conducting a lab study. If the first two lines of evidence are insufficient to support a determination that natural attenuation is occurring, then the third line of evidence is appropriate.

Recent tools, such as microbial finger printing, microarrays, enzyme activity probes, fluorescence in situ hybridization and quantitative polymerase chain reaction can provide evidence concerning if natural attenuation is successfully occurring in a plume (ITRC, 2013 and

2020). Biochemical pathways can now be determined via compound specific isotope analyses (CSIA), such as using targeted 14C assays and isotope fractionation (Antelmi et al., 2021). BioPic is a decision framework spreadsheet tool that provides guidance concerning the natural attenuation of chlorinated solvents and other compounds, such as 1,4-dioxane (Adamson et al., 2022).

The viability of using MNA to address chlorinated solvents in deep aquifers in Arizona can be challenging due to: 1) the lack of key geochemical and microbial populations needed for MNA to occur in deep groundwater and aquifer materials, and 2) pumping stresses from production wells typically screened in the deeper aquifer units. As such, the viability of using MNA in deeper aquifers must be based on a detailed understanding of the subsurface geology, geochemical characteristics and microbial characteristics described above.

Each hydrogeologic setting is unique and has characteristics that may limit the effectiveness of MNA. These include: 1) the presence of water production wells and associated hydraulic stresses causing mixing within the aquifer and unanticipated contaminant plume movement, 2) inherently complex fracture flow systems with unknown connectivity, and 3) clay-dominant sediments having sorbed contaminant mass which, through the process of matrix back diffusion, continue to behave as secondary sources of contamination.

No single sampling method is universally applicable to all site conditions. Both low-flow purge sampling and passive sampling have been successfully used to monitor groundwater conditions at a variety of contaminant sites, but these also have their limitations. Studies

(USGS, 2012; USGS, 2020a; USGS, 2020b) have shown that results of these two methods tend to be comparable and are dependent upon aquifer characteristics, analytical suite and the volume of sample required for analysis. In the context of MNA sampling, low-flow purging may provide added benefits for the following reasons: 1) it allows for real-time monitoring of groundwater parameters such as pH, ORP, DO, and specific conductance, 2) samples more accurately represent in situ aquifer conditions, 3) it allows for collection of larger sample volumes to facilitate analysis of a more robust suite of analytes needed to document the effectiveness of MNA, 4) it results in less mixing of stagnant well casing water with aquifer water, and 5) it provides greater control over sample collection, resulting in higher precision and accuracy. This is particularly important when evaluating changes over time and conducting statistical analysis of the data using software programs like Monitoring and Remediation Optimization System (MAROS).

Attachment 12 – Method of Approach (Cont.)

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22

REFERENCES

Adamson, David T., John T. Wilson, Charles J. Newell, Brian A. Strasert, Phillip C. Blanc, David L. Freedman, Carmen Lebron, and

Anthony Danko. "State of the practice worldwide: Development of a quantitative framework for evaluating natural attenuation of 1,1,1-TCA, 1,1-DCA, 1,1-DCE, and 1,4-Dioxane in Groundwater. "GROUND WATER MONITORING AND

REMEDIATION 42, No. 4 (2022): 78-84.

Antelmi, M., Mazzon, P., Höhener, P., Marchesi, M., & Alberti, L. (2021). Evaluation of MNA in a chlorinated solvents-contaminated aquifer using reactive transport modeling coupled with isotopic fractionation analysis. Water, 13(21), 2945.

ITRC, 2013. Environmental Molecular Diagnostics, New Site Characterization and Remediation Enhancement Tools.

ITRC, 2020. Environmental fate, transport and investigation strategies: 1,4-Dioxane.

Kamath, R., Looney, B. B., Newell, C. J., Adamson, D. T., & Vangelas, K. M. (2010). Closing the mass balance at chlorinated solvent sites: Sources and attenuation processes. Remediation Journal: The Journal of Environmental Cleanup Costs, Technologies &

Techniques, 20(2), 61-75.

USGS, 2012. Comparison of No-Purge and Pumped Sampling Methods for Monitoring Concentrations of Ordnance-Related

Compounds in Groundwater, Camp Edwards, Massachusetts Military Reservation, Cape Cod, Massachusetts, 2009-2010.

USGS, 2020a. A Comparison of Groundwater Sampling Technologies, Including Passive Diffusion Sampling, for Radionuclide

Contamination.

USGS, 2020b. Passive Sampling of Groundwater Wells for Determination of Water Chemistry.

Attachment 12 – Method of Approach (Cont.)

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22

Question 5: Describe in situ technologies you have used…critical evaluation of successes and failures…(2 page limit).

Offeror Response:

IN SITU BIOREMEDIATION (ISB) involves the application of biostimulation (injection of electron donor or electron acceptor (e.g., oxygen) to create an environment where conditions are more favorable for existing microbial consortia to biodegrade compounds of concern (COCs) and/or bioaugmentation (injection of non-native microbes capable of biodegrading COCs under anaerobic and/or aerobic conditions to reduce contaminant mass via metabolic and/or cometabolic processes. Matrix has employed this technology on multiple petroleum hydrocarbon and chlorinated solvent release sites through the use of temporary direct push probes or injection wells.

Matrix used sonic borings and depth-specific sampling to understand the stratigraphy, define the extent and mass COC distribution and determine key soil and groundwater parameters. We have also employed recirculation wells to enhance the distribution of amendments and have used tracers, such as bromide and rhodamine to establish the radius of influence (ROI) of the injected amendments. We prefer permanent wells since they allow for injection of additional amendments, if needed, to maintain and sometimes alter geochemical conditions to biodegrade different types of contaminants. For example, PCE and TCE could be anaerobically biodegraded first, and if

1,4-dioxane was also present in the groundwater, the remedy could be transitioned to an aerobic one and then inject a microbe, such as

Pseudonocardia dioxanivorans, which is capable of aerobically biodegrading cis-1,2-DCE, vinyl chloride, and 1,4-dioxane.

• Successes – After conducting clean water injection at a site in AZ, Matrix determined it would be very challenging to inject an emulsified oil into the aquifer. The remedy was modified by switching the carbon source to one which was more highly soluble, injecting under pressure, and using a nearby extraction well as a recirculation point. This resulted in higher than expected injection volumes in a shorter time frame. Failures – At one ISB site we noticed a reduction in biodegradation rates of COCs and determined that volatile fatty acids were being produced lowering the pH of the groundwater. Matrix modified the remedy to include a buffering agent with the carbon source injection to maintain optimum pH levels, which met the ROs but slightly increased remediation time.

At another site, arsenic was mobilized under anaerobic conditions and was observed in nearby monitor wells. Since arsenic precipitates under aerobic conditions outside the reactive zone, it was not considered a risk to downgradient receptors.

• Remedial Objectives (ROs) include source area and downgradient mass reduction, conditioning the aquifer for transition to future

MNA, and site closure. Data Quality Objectives (DQOs) for ISB projects begin by clarifying the objectives and then defining the types of COCs, target treatment goals, the area to be treated, hydrogeologic conditions, geochemical conditions, and microbial key indicators (e.g., Dehalococcoides and key enzymes) in the groundwater to determine effectiveness of the ISB system. The DQOs for each project include defining acceptable levels of decision errors and the development of plans and contingencies to optimize the remedy as needed. The DQOs are continually evaluated by collecting data during routine monitoring and sampling.

IN SITU AIR SPARGE (AS) is a groundwater remediation technology where pressurized air is injected into the saturated zone through

1) in situ air stripping of dissolved volatile organic compounds (VOCs) into recoverable vapor phase, and 2) increased oxygen to the saturated zone to stimulate enhanced aerobic biodegradation. Matrix has successfully employed this technology on multiple petroleum hydrocarbon and chlorinated solvent sites to remove source area contaminant mass. Matrix used sonic borings and depth-specific sampling to understand the stratigraphy, define the extent and mass COC distribution, and determine key soil and groundwater parameters. This facilitated remedial designs, so wells were properly placed and constructed with short discrete screened intervals below contaminant mass. Prior to designing full scale systems, pilot tests are typically conducted to verify the AS remedy. On all AS systems

Matrix has used, SVE was also conducted to remove the volatized COCs for treatment using thermal or catalytic oxidation or granular activated carbon.

• Successes – Matrix has been very successful reducing high concentrations of COCs with AS systems operating in conjunction with

SVE systems. At an AZ site, Matrix optimized system operations by adjusting and increasing air flow to select wells to address areas with higher concentrations and utilized pulsed AS cycles to optimize VOC extraction rates. This resulted in a significant reduction of mass to meet ROs in a relatively short time frame and achieved site closure. Failures - Working with the local power company at another AZ site, Matrix encountered unanticipated delays getting an adequate power drop to energize the blowers and treatment unit. While power was ultimately supplied, it delayed the start of the project by 2 months.

• ROs include source area and downgradient mass reduction, conditioning the aquifer for transition to future MNA, and site closure.

DQOs for AS projects involve defining the types of COCs, target treatment goals, the area to be treated, hydrogeologic conditions, ROI, geochemical and microbial conditions in the groundwater to determine effectiveness of the AS system. DQOs also include defining acceptable levels of decision errors and the development of plans and contingencies to optimize the remedy as needed. The

DQOs are continually evaluated by collecting data during routine monitoring and sampling.

IN SITU SOIL VAPOR EXTRACTION (SVE) is a soil remediation technology in which contaminant mass is extracted to eliminate a source of VOCs from the vadose zone. The rate and degree of mass removal through SVE operations are a function of the contaminant properties (Henry’s Law constant, vapor pressure, and adsorption coefficient), subsurface temperature, soil properties (grain size, moisture content, and permeability), and heterogeneity. Matrix has employed this technology on multiple petroleum hydrocarbon and chlorinated solvent release sites. Matrix used sonic borings and depth-specific sampling to understand the vadose zone stratigraphy, define the extent and mass COC distribution, and determine key soil parameters. This facilitates remedial designs where wells are properly placed and constructed with screened intervals throughout areas of high COC concentrations. Prior to designing full scale systems, pilot tests are typically conducted to verify the SVE remedy, understand mass removal rates and ROI, and proper emission

Attachment 12 – Method of Approach (Cont.)

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22 controls. Typically, our SVE systems utilize vertical wells, but we have also designed systems where horizontal wells were needed due to onsite structures. Properly designed vacuum blowers, capable of extracting vapors at suitable flow rates and routing vapors through a treatment system using thermal or catalytic oxidation or granular activated carbon result in a more effective remedial system.

• Successes – Matrix has been very successful at reducing high concentrations of COCs with SVE systems to remove source area mass. At an AZ site, Matrix optimized system operations by adjusting and increasing vacuum to select wells to address areas with higher concentrations and using pulsed SVE cycles between wells to optimize VOC extraction rates. This resulted in a significant reduction of mass to meet ROs in a relatively short time frame and achieved site closure. Failures – At another AZ site characterized using percussion hammer drilling methods and depth-specific sampling at 10 foot intervals, higher than expected VOC mass recovery occurred presumably due to COC concentrations that were biased low due to the use of air as the drilling fluid and unaccounted for COC mass between sample points. This resulted in extended treatment times and increased costs to operate the treatment system to achieve ROs.

• ROs include source area mass reduction, mitigation of COCs migrating to groundwater, and site closure. DQOs for SVE projects involve defining the types of COCs, target treatment goals, the area to be treated, vadose zone conditions, ROI, and vacuum flow rates to determine SVE system effectiveness. DQOs also include defining acceptable levels of decision errors and the development of plans and contingencies to optimize the remedy as needed. The DQOs are continually evaluated by collecting these data during routine system operation and maintenance visits.

IN SITU CHEMICAL OXIDATION (ISCO) is a groundwater remediation technology that involves injection of an oxidant into the subsurface, the most common of which are permanganate, persulfate, and hydrogen peroxide. Matrix has employed this technology to reduce dissolved phase petroleum hydrocarbon contamination in groundwater through the use of temporary direct push probes or injection wells. We have also employed recirculation wells to enhance distribution of the amendments. Matrix has used sodium persulfate and hydrogen peroxide based oxidants to treat the source area and downgradient areas associated with former UST facilities.

Matrix used sonic borings and depth-specific sampling to understand the subsurface stratigraphy, define the extent and mass COC distribution and determine key soil and groundwater parameters. This facilitated a remedial design where wells were properly placed and constructed with screened intervals throughout areas of highest COC concentrations. Pilot studies were conducted to select an appropriate oxidant, dosing, and activation agent based on the COCs present, estimates on injection rates and ROI. Matrix has also applied a hydrogen peroxide-based oxidant to the bottom of a UST excavation where contamination was found to facilitate ISCO of

COCs prior to site characterization.

• Successes – At an AZ site where injections of sodium persulfate were completed, post-injection groundwater monitoring indicated that source groundwater concentrations decreased between 66 and 94% for the targeted COCs after four quarterly sampling events.

Ongoing monitoring events will continue for future MNA. Failures - One of the biggest challenges with ISCO is the ability to effectively distribute the required amendments into the groundwater in order to come into contact with the COCs. Unintended consequences can occur. At a site in northern AZ that Matrix inherited from another consultant, historical ISCO injections completed by others resulted in the horizontal migration of contaminant mass. Our work identified this was due to inadequate site characterization and misinterpretation of the subsurface geology.

• ROs include source area and downgradient mass reduction, conditioning the aquifer for transition to future MNA, and site closure.

DQOs for ISCO projects begin by clarifying the objectives and then defining the types of COCs, target treatment goals, and the area to be treated, hydrogeologic conditions, and geochemical conditions in groundwater to determine the effectiveness of the ISCO system. The DQOs for each project include defining acceptable levels of decision errors and the development of plans and contingencies to optimize the remedy as needed. The DQOs are continually evaluated by collecting data during routine monitoring and sampling.

SITE CHARACTERIZATION DATA AND STEPS NEEDED TO EVALUATE - The primary challenge of any in situ treatment technology is to effectively deliver amendments to or extract from where COC mass is located. As such, in order to make decisions regarding the role any in situ technology can play in meeting site remediation goals, a thorough and detailed understanding of vadose zone and aquifer characteristics must be developed to provide insight into any existing natural mechanisms of contaminant control and destruction to guide the remedial efforts to work in concert with native processes. Detailed site characterization efforts must occur in order to 1) establish a thorough understanding of subsurface stratigraphy, 2) define mobile versus immobile porosity of aquifer materials,

3) define the horizontal and vertical distribution of COCs, 4) determine the geochemical (cations, anions) and microbial makeup including key enzymes of the aquifer and aquifer sediments, 5) identify behavior and flow paths of advective contaminant movement within the aquifer, 6) evaluate long-term contamination and groundwater level trends in monitor wells, and 7) identify and mitigate threats to nearby receptors. Additionally, in ISB and ISCO applications, understanding how aquifer dynamics may change from mounding and key groundwater characteristics described above is necessary to develop injection protocols including identification of buffering agents to maintain optimum pH levels, and in AS and SVE applications, understanding air flow and vacuum rates, radii of influence, and mass recovery estimates will help develop and facilitate in situ remedial design strategies. Compound specific isotope analysis (CSIA) is also recommended for sites where degradation pathways need to be better understood. Collectively, these data can then be used to develop a robust Conceptual Site Model as a framework to evaluate different in situ remedial technologies through an

Early Response Action pursuant to R18-16-405 and through the RI/FS process pursuant to R18-16-406 and -407.

Attachment 12 – Method of Approach (Cont.)

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22

Question 6: Describe how AFCEE MAROS process can be used….(1 page limit).

Offeror Response: Matrix successfully used the Monitoring and

Remediation Optimization System (MAROS) Software to complete Long

Term Monitoring Optimization (LTMO) at Superfund site in Arizona with a large diffuse chlorinated solvent plume having 20 years of data from over 190 monitoring locations (including extraction, monitoring, and production wells) that defined the horizontal and vertical extent of contamination. The application utilized both spatial and temporal data sets of contaminant constituents from each well within the network to facilitate informed professional decisions, including providing recommendations for optimizing the sampling frequency and improving the efficiency and accuracy of the monitoring network to better track changes in contaminant movement, total dissolved mass, and center of mass. In this context, MAROS also helped identify threats to municipal and irrigation production wells, refined the limits of the contaminant plume, and assessed hydraulic capture to monitor remediation performance in response to changes in plume dynamics.

The hypothetical site to optimize a monitor well network on a large tetrachloroethylene (PCE) plume that includes MNA with additional hydraulic stresses from pumping existing production wells presents challenges due to ever changing aquifer and subsequent plume dynamics caused by aquifer stresses from pumping. Prior to implementing MAROS and conducting any LTMO evaluation, it is important to discuss and agree upon monitoring objectives with all stakeholders/agencies so the program can be optimized using agreed upon remedial objectives, such as monitoring frequency to ensure plume reduction and protection of water supplies. The steps necessary for LTMO include 1) Development of a working Conceptual Site Model (CSM) describing the detailed subsurface stratigraphy, aquifer characteristics and identifying data gaps and uncertainties. The monitor well network needs to delineate the horizontal and vertical extent of the PCE contaminant in the subsurface and demonstrate plume stability through hydraulic capture analysis, 2) Import/input data -

Excel spreadsheets should be developed for import into MAROS with specificity with respect to well names, constituent names, sample dates, analytical results, data flags, and detection limits. For proper analysis, MAROS requires data from at least four wells, with data for each well including at least four measured concentrations over six sampling events. Clustered wells should not be used as optimization methods are two-dimensional. The Site Details module allows input of the site-specific information including aquifer parameters, plume length and width, distance to the receptors, and monitoring objectives for each individual monitoring well. Data consolidation (including non-detect and duplicate sampling handling) may be performed prior to import into MAROS, after entering the site details, or during the Plume Analysis or Spatial Analysis modules; and 3) Perform analysis in MAROS.

The individual well analysis uses the Mann-Kendall test and linear regression analysis to determine trends in PCE concentrations, and

T-Test analysis to determine if concentrations have statistically attained the clean-up goal (includes an estimation of the number of samples required to demonstrate attainment). Well scoring combines the statistical metrics to evaluate the individual wells in terms of attaining the monitoring objectives. Moment analysis can be used to evaluate the effectiveness of the remedial actions over time by estimating trends in the mass of PCE remaining, the location of the center of mass, and the spread of the contaminant. During Plume

Analysis, the wells can be manually grouped (e.g., corresponding to specific remedy locations) so the analysis may be performed to evaluate movement of contaminant mass in the context of MNA to protect production wells. Based on results of the moment analysis, adjustments to the remedial actions may be recommended to better optimize treatment. The Sampling Optimization module of MAROS can be used to eliminate redundant sampling locations (as determined by evaluating the amount of information each well provided toward describing the spatial distribution of the PCE) and determine the lowest sampling frequency at each well location. Additionally, the Sampling Optimization module includes a data sufficiency analysis to examine the cleanup status and significance of concentration trends at each well location. These analyses allow recommendations regarding future sampling frequency, locations, and density to optimize the current site monitoring network while maintaining adequate delineation of the plume. The Delaunay Triangulation (black lines) and Voronoi Diagram (blue lines), used for both the plume analysis and sampling optimization, divide two-dimensional space to assign a monitoring area to each well. The letter in the centroid

(center of mass) of each Delaunay Triangulation is the level of the estimated Slope

Factor value used to estimate error in the area (S=small, M=medium, L=large, and

E=extremely large) which suggests a level of uncertainty in plume analysis. If, for example, an area was identified as L or E, an additional monitor well may be needed near the center of mass.

The quantitative results from the MAROS runs should be evaluated qualitatively and discussed with stakeholders/agencies prior to implementation to determine if additional sampling frequency beyond the MAROS recommendations would be required to meet project goals and objectives. A large PCE plume such as the hypothetical site discussed here should be periodically evaluated using MAROS to ensure remedial objectives continue to be met and municipal and irrigation supply wells are protected.