SOW_3-yr_TBC_Groundwater_Monitoring_2.docx

SCOPE OF WORK

Three (3) Year Groundwater Monitoring Project Tuba City Headquarters Operational Units (OU) 1, 2, 3, Bureau of Indian Affairs-Western Navajo Agency Tuba City, Arizona

1.0 Introduction:

The Bureau of Indian Affairs (BIA), Branch of Environmental Management (BEM) requires the services of a professional and experienced environmental firm to continue the groundwater monitoring at the Tuba City Headquarters Operational Units (OUs). The three operational units are designated as OU-1, the former Tuba City Motors property, OU-2, the former Heating Plant property, and OU-3, the Department of Transportation Maintenance Yard (DOT) property (Figure 1). These three sites were selected for groundwater monitoring based on an investigation related to the 1999 boiler explosion at OU-2. All three of the OUs are in adjoining parcels centrally located in the Tuba City community.

The work to date includes the ongoing collection of groundwater samples from 60 monitoring wells and the installation of an in-situ bioremediation system at OU-1 and OU-2. Sampling data is used to determine the groundwater quality at the site to support remedial actions. The remedial work for all three OUs includes the review and submittal of the groundwater data and reports to BEM and regulatory agencies for approval.

1.1 Project Location:

The Tuba City Headquarter and Operational Units 1, 2, and 3 are located in Tuba City, Arizona (Figure 2). The project site is centrally located near the northwestern corner of the intersection of Oak Street and Edgewater Drive, and is bordered by Birch Avenue to the north, Edgewater Drive to the South, and encompasses both sides of Oak and Pine Streets. Oak Street bisects the OUs from north to south, as does Pine Street. Project elevation is approximately 4,945 feet above mean sea level, and topography slopes gently toward the southeast. The nearest naturally occurring surface water is Pasture Canyon Reservoir located approximately 1 mile to the east. (E.W. Wells Inc. 2015)

1.2. Background:

In 1999, a boiler explosion occurred at the BIA Heating Plant (OU-2) which resulted in a release of an unknown amount of heating oil from an aboveground storage tank (AST), drum storage area, and associated buried piping. BIA Branch of Environmental Management (BEM) conducted a site characterization by installing monitoring wells. The result of the groundwater monitoring sampling data showed contamination to the groundwater and determined other sources of releases expanding beyond OU-2. The site characterization of OU-2 expanded to OU-1 and eventually to OU-3. The research of the areas beyond OU-2 revealed a historical presence of an underground storage tank (UST) at OU-1, as well as OU-3 AST and drum storage area impacted the groundwater. Both UST at OU-1 and the AST and drum storage area at OU-3 have since been removed.

Approximately 7,000 gallons of liquid hydrocarbons (LHC) and dissolved-phase liquids were reportedly recovered during the initial remedial actions at OU-2. The 2011 groundwater monitoring report prepared by Terranext, Inc., indicated that LHC was present in monitoring well MW-20 located directly downgradient from OU-2. The groundwater monitoring results indicated petroleum constituents were present in groundwater beneath OU-3. The highest benzene concentration in groundwater was reported in MW-4. This concluded potential multiple petroleum release locations at OU-1, OU-2, and OU-3. Concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX) were slightly above the U. S. Environmental Protection Agency (EPA) Preliminary Remediation Goals (PRGs), now called Regional Screening Levels (RSLs) for groundwater ingestion (Terranext, 2011).

In 2018, Division of Environmental Management hired a contractor to begin the excavation of the OU-3 area to place remediation piping within the Roads Maintenance Yard. During the excavation to place the piping, an asbestos containing material (ACM) waste pile was discovered and inadvertently mixed with the overburden soil from the excavation. The overburden material could not be re-used to backfill the excavated area and had to be removed from the site as hazardous waste. The contractor had to dispose of approximately 5,000 yd3 of contaminated soil which left the excavated open exposing the piping and monitoring wells for more than a year. The waste pile was not removed by the contractor.

In March 2020, another contractor backfilled the excavated pit and replaced the damaged remediation piping. No repairs were made on the monitoring wells that were damaged. During this period, the semi-annual groundwater monitoring continued under a contract with E.W. Wells.

Groundwater monitoring has been conducted at the site by several different contractors and consultants, beginning soon after the fuel release at OU-2 in 1999. The latest semi-annual sampling event occurred in December 2023. As reported by the latest contractor, several issues have been consistently noted. Several of the flush mounted groundwater monitoring wells are either covered, destroyed, or damaged. Monitoring wells (MW-20 and MW-227) has a floating layer of fuel oil. Naphthalene is continually detected across the site exceeding the NNEPA cleanup standards.

Semi-annual reports through May 2023 have been submitted for review and comments to regulatory agencies. A review of monitoring data was presented to the USEPA Region IX and NNEPA.

1.3 Geology

The geology at the site consists of primarily sandy silts and clayey silts, which are transitional both laterally and vertically in various locations, with lenses of silty fine sands. These soils extend to depths of between approximately 10 –15 feet below ground, at which point bedrock is present. (Terranext, 2011) (E.W. Wells Inc.)

The principal aquifer beneath Tuba City, AZ is the weakly cemented and variably permeable Navajo Sandstone, which is referred to as the N-Aquifer. Near Tuba City, springs emerge along the contact between Navajo and underlay Kayenta Formation in Pasture Canyon and Moenkopi Wash. (Peterson et.al, 1979)

TASK I - Pre-Work Submittals Pre-work submittals shall be submitted to the Navajo Region BEM within thirty (30) calendar days from the Notice to Proceed.

A. The contractor shall provide a site-specific Health and Safety Plan (HASP) to address worker protection in accordance with 29 CFR 1910.120. The HASP shall contain certifications/licensures of workers and identify all appropriate PPE for known and potentially occurring environmental and biological hazards at the site. Biological hazards include venomous insects, snakes/reptiles, and mold that maybe encountered during work. In addition, the plan shall address precautions for human health hazards such as the Covid-19 virus.

B. The contractor shall prepare a workplan with work schedule for sampling with a quality assurance/quality control plan for groundwater monitoring.

TASK II - Conducting the Groundwater Sampling I. The contractor shall furnish the necessary personnel, materials, equipment, services, and facilities to successfully perform the groundwater sampling at the Tuba City site for a three-year period.

II. The contractor shall conduct semi-annual groundwater monitoring events for each year to record and monitor the conditions of the groundwater. Originally sampling events occurred quarterly, however due to the arid weather conditions and the lack of rain only two sampling is required per year. Therefore, the contractor shall ensure a sampling event occurs in every semi-annual period and maintain a contingency plan for unforeseen events.

III. The contractor shall make every effort to ensure all groundwater monitoring wells are sampled. The contractor shall attempt to locate and sample all monitoring wells that are covered. A list of all damaged and destroyed wells along with photos shall be submitted to BEM for review. When free floating oil is found in the groundwater monitoring wells, the product shall be removed via bailing if necessary. Sampling of all monitoring wells helps to determine a course of action for remediation.

Work:

I. The contractor shall sample the 60 monitoring wells within the areas of OU-1, OU-2 and OU-3 following the measurements of field parameters. The sampling is conducted to determine the operation and effectiveness of the treatment of the infiltration units.

II. The contractor shall coordinate with the Navajo Region-BEM, Division of Transportation, and the Bureau of Indian Education, Facility Manager to schedule field work for groundwater sampling at the site to minimize interruptions to services and traffic in the area. The contractor shall notify the departments of scheduled visit at least two weeks prior via email.

III. Contractor shall review the existing data files and reports describing previous investigation and sampling results for the three (3) OUs, and prepare a plan related to sampling procedures, laboratory analysis, and quality assurance /quality control (QA/QC) issues. Contractor is to coordinate with selected laboratory to obtain the appropriate sampling equipment and containers.

V. The scope of work requires the contractor to sample the current 60 monitoring wells up to 20 feet deep, plus 5 duplicates samples using standard environmental monitoring low-flow sampling techniques. Contractor shall conduct the measurement of field parameters before taking samples. Field measurements consist of depth to water, conductivity (EC), pH, temperature, dissolved oxygen (DO), and oxidation reduction potential (ORP) using a peristaltic pump and a low flow, flow through monitoring cell.

1) Sampling handling:

Sample containers shall be sealed at the time of collection with an adhesive label placed over the lid and threads. Sample container shall be bubble wrapped for protection and placed on ice in a cooler for shipment to the laboratory.

2) Laboratory Sample Analyses:

The analytical methods were selected to provide data of necessary quality to meet the project data quality and to maintain consistency and comparability with data from previous sampling conducted. Groundwater samples shall submit under standard chain-of-custody protocol.

All ground water samples are to be analyzed by an Arizona-state certified laboratory for the following approved Environmental Protection Agency (EPA) analytical methods:

· 8015 GC/FID-Gasoline Range Organics (GRO)

· 3511 GC/FID –Diesel Range Organics (DRO) and Oil Range Organics (ORO)

· 8021 - Benzene, Toluene, Ethylbenzene and Xylenes (BTEX) (AZ Method 8015AZ/8260)

· 8270SIM- EPA method -Polycyclic aromatic hydrocarbons (PAHs) by EPA.

3) Quality Control Samples:

The primary goal of the sampling and analysis program is to obtain accurate and representative environmental samples and to provide defensible analytical data. A program to evaluate field and laboratory data was developed to ensure achievement of this goal. The field data quality will be assessed through the collection and analysis of field QC samples on a regularly scheduled basis. Laboratory data quality will be assessed using QC samples analyzed in accordance with each laboratory’s QA requirements and referenced analytical method protocols to ensure that laboratory procedures and analyses are conducted properly.

4) Field Sampling Quality Control Field parameters shall be measured and documented on the sample collection forms during each groundwater monitoring event. Field quality assurance and control (QA/QC) activities shall consist of the following:

· Following standard sampling procedures

· Maintaining proper sample handling and documentation

· Calibrating and maintaining field instruments; and

· Collecting field QA/QC samples.

Field equipment shall be operated, maintained, calibrated, and standardized in accordance with manufacturer’s recommendation procedures. Field QA/QC samples shall be collected to evaluate the precision, accuracy and representativeness of the field sampling effort and shall include trip blanks, duplicates, and MS/MSD samples. The duplicate samples (not including MS/MSD samples) will be blind samples; the sample location will not be used on the sample label. It should be noted the decontamination or equipment blanks are not proposed for this project since disposable sampling equipment will be used.

5) Trip Blanks are provided by laboratory are to be stored with the samples in each sample cooler throughout the sampling event. Trip blanks are analyzed by the laboratory to determine if the samples are contaminated during storage or transport.

6) Duplicate Samples are collected in the field at precisely the same time and location as another sample. In practice, the duplicate is often a “split sample”. One (1) duplicate groundwater sample for each quarterly monitoring event shall be collected and submitted to analysis according to the EPA methods 8021 (BTEX and MTBE), 8015 (GRO, DRO, TPH and 3511 (GRO).

7) Matrix Spike/Matrix Spike Duplicate Samples – a matrix spike is sample with a known amount of the target analytes added to it before analysis to determine the accuracy of laboratory procedures and efficiency of any extraction steps. One (1) MS/MSD groundwater sample for each quarterly monitoring event shall be collected and submitted annually according to EPA method 8021 (BTEX and MTBE).

TASK III- Reporting

1) A groundwater monitoring report shall be prepared at the end of each monitoring event using the sampling results:

a. The contractor shall prepare a report to document all activities associated with the groundwater sampling project to Navajo Region BEM, Navajo Nation Environmental Protection Agency, and the U. S. Environmental Protection Agency Region IX. The report shall summarize the groundwater conditions, a summary of the field activities, and figures illustrating site features. Figures shall be generated showing the site location, configuration, monitoring well locations, groundwater elevations, flow direction and hydraulic gradient.

The report shall include the results of analysis of each sample, a groundwater flow map using depth to water measurements, groundwater contour maps showing the extent of impacts above the Navajo Nation Environmental Protection Agency (NNEPA) target cleanup levels, and all laboratories and supporting information.

b. The contractor shall prepare a cover letter to the regulatory agencies for submittal with the groundwater monitoring report. The cover letter shall include a summary of data, conclusions, and recommendations (if necessary) for the BEM and regulatory agencies. The cover letter shall be submitted to the BEM for review and approval.

c. The contractor shall provide the draft report to the BEM and the regulatory agencies within 30 days of the end of a sampling event. Draft report shall be submitted to the BEM and regulatory agencies for review and comments. BEM will review the draft report within 5 days and provide any comments (if necessary) and return the document to the contractor.

d. Once comments are received from the BEM and regulatory agencies, the contractor shall schedule a meeting via MS Teams with the BEM and regulatory agencies to discuss the comments and the progress of the sampling for the draft annual groundwater sampling report.

e. When the draft is approved by BEM, the contractor shall prepare one (1) final copy and two (2) electronic file copies in Microsoft Word /AutoCAD format; one in read-only format and one in write version marked FOR BIA USE ONLY.

f. BIA shall be the owner of all documents prepared by the contractor. The contractor shall not copyright or write protect any documents or utilize any data from the project without consent from the GOVERNMENT.

2) The contractor shall prepare an annual report with a narrative describing the work performed and all results of the sampling events. The contractor shall provide recommendations for system changes or improvements. In the event, the system shows that the contamination is remediated, the contractor shall document the findings and sign the report certifying the project has been completed in accordance with the regulatory requirements and system design.

a. The contractor shall provide the draft report to the BEM and the regulatory agencies within 30 days of the end of a sampling event. Draft reports are provided to the BEM and regulatory agencies for review and comments. BEM will review the draft report within 5 days and provide any comments (if necessary) and return the document to the contractor.

b. Once comments are received from the BEM and regulatory agencies, the contractor shall schedule a meeting via MS Teams with the BEM and regulatory agencies to discuss the comments and the progress of the sampling for the draft annual groundwater sampling report.

c. When the draft is approved by BEM, the contractor shall prepare one (1) final copy and two (2) electronic file copies in Microsoft Word /AutoCAD format; one in read only format and one in write version and marked FOR BIA USE ONLY.

d. The BIA shall be the owner of all documents prepared by the contractor. The contractor shall not copyright or write protect any documents or utilize any data from the project without consent of the GOVERNMENT.

INSTRUCTIONS, CONDITIONS, AND NOTICES TO CONTRACTORS

Special Conditions The contractor shall obtain all necessary drilling and other use permits if required.

The contractor shall adhere to all applicable tribal laws and regulations and payment of the Navajo Nation Tribal and Arizona Gross Receipts.

The contractor is responsible for any utilities that are damaged during work and shall repair them immediately at no cost to the Government.

Barring complications in site access or other site-specific factors. Contractor shall conduct bi-annual groundwater sampling for each year of Period of Performance.

As the data is developed and presented, the contractor is expected to provide a timely and quality response to issues raised by the regulators on the sampling data. All contact with the public, private or regulatory community shall be made through the BIA Navajo Region. No information may be released without the written consent of the BIA Navajo Region.

Requirements Pre-work Conference Monthly status reports to BEM-COR Submittals of 90% and final documents for sampling data/reports/recommendations for:

Date of Award - December 31, 2024 (1st Year) January 1, 2025 – December 31, 2025 (2nd Year) January 1, 2026 – December 31, 2026 (3rd Year) Reference Material Contractor may review any previous work report for this site available from NRO BEM.

Place of Performance: Tuba City, Arizona Period of Performance: The period of performance will begin from Date of Award through December 31, 2026. This is three-year project for groundwater sampling to monitor the progress of cleanup of the petroleum contaminated soils that is impacting groundwater within the OU-1, OU-2, and OU-3.