Due Diligence & Audits

For over 20 years, NTG Environmental has performed environmental due diligence and compliance audits for our clients to understand their potential liability and remediation needs prior to completing a transaction. With our expertise in local, state and federal regulations, NTG Environmental’s scope for an environmental due diligence assessment can begin with an initial screening of potential liabilities and concerns to a full-scale, in-field review including interviews, field reconnaissance and corporate record review. Our experienced staff is well versed in working with regulatory agencies to obtain records related to the areas of interest and understanding what liabilities may exist based on the findings.

Environmental Due Diligence Assessments

When ownership has the potential to change, Environmental Due Diligence Assessments help manage our client’s liability. Additionally, Environmental Due Diligence Assessments can be of value in identifying, evaluating, and mitigating environmental issues associated with mature operating assets where environmental regulations and industry best practices have changed over the history of the asset.

The goal of an Environmental Due Diligence Assessment is to gather a sufficient amount of data to interpret an asset’s historical background. This information can provide reassurance that environmental impacts are unlikely, provide enough information to outline a Phase II Environmental Site Assessment due to potential or existing impacts, or assist in developing remedial action plans on an impacted site.

Third Party Environmental Audits

Third Party Environmental Audits allow our clients to understand the potential liabilities associated with their use of a given waste storage, disposal, or waste transportation facility, the permit limitations to which a given facility is restricted, and the facility’s compliance with applicable regulations.

Asset Retirement Obligation (ARO) Evaluations

NTG Environmental relies on technical expertise from our multidisciplinary staff to provide support in estimating costs associated with the plugging and abandonment of wells, removal of production equipment and storage vessels, and land restoration. Restoration costs are determined by investigating an asset’s historical conditions and uses and extrapolating costs from select asset characterizations. Cost for closure is tailored to meet the applicable local, state, and federal laws.

Pre-Drill Environmental Site Assessments

Pre-Drill Environmental Site Assessments are performed before site construction. These assessments allow operators to avoid environmentally sensitive areas, determine the proximity to any water bodies or wetlands, and provide background or baseline data for planning purposes. These assessments can be performed from a desktop perspective for an initial screening of potential liabilities to a full-scale in-field review where soil and/or water samples are collected and analyzed by an accredited environmental laboratory to understand the baseline conditions. This information can also be used to create spill management plans, prepare environmental protection plans, and plan for sediment and erosion concerns.

Case Studies


Panola County, TX

NTG Environmental performed an Environmental Due Diligence Assessment on 550 oil/gas wells and associated surface facilities. Our field and regulatory review revealed an environmental risk above $5 million at one of the surface facilities. Using findings from the assessment, NTG Environmental’s client was able to negotiate, and remove the surface facility from the transaction, enabling them to retain the remaining oil/gas wells and remaining assets without the significant environmental risk posed by the one surface facility.


Refugio County, TX

NTG Environmental performed an Environmental Due Diligence Assessment on 20 oil/gas wells and associated surface facilities. NTG Environmental’s field and regulatory review revealed low environmental risk associated with the assets.  Using findings from the assessment, NTG Environmental’s client was able to obtain additional financing to further field development.

Water Quality
& Natural Resources

Our respected team of soil scientists, biologists and environmental scientists are recognized experts in completing biological and natural resource surveys, wetlands determinations, site assessments, and other NEPA compliance support for private and public sector clients throughout the US.

Wetland Determinations

Section 404 of the Clean Water Act prohibits unpermitted filling of “jurisdictional waters of the United States,” but a permit can take more than a year to process. NTG Environmental aids our clients by pre-assessing proposed well pad and surface facility locations as well as pipeline corridors to identify wetland areas that require a permit and/or confirm the absence of wetlands. Diagnostic characteristics of wetlands include hydrophytic vegetation, hydric soils, and wetland hydrology as defined by the US Army Corps of Engineers (USACE). Wetland determinations allow our clients to avoid and/or minimize impacts to potential jurisdictional wetlands prior to commencing construction activities. When regulatory approval is required, NTG Environmental will prepare and submit applicable delineation reports and mitigation plans along with permit applications to the USACE. We act as a liaison between our client and regulatory officials to obtain permits in an efficient manner.

Wildlife Habitat Assessment

NTG Environmental’s wildlife biologists have extensive knowledge and experience managing threatened, endangered, or special status wildlife species issues for both private landowners and oil/gas operators. NTG Environmental conducts threatened/endangered species surveys and monitoring activities, as well as provides management recommendations and options. Other threatened/endangered species related services include assistance in preparing formal cooperative agreements with state and federal agencies and obtaining permits for the removal of a protected species from an area of interest.

Baseline Water Supply Sampling

With the potential for environmental impacts associated with oil and gas exploration and production activities, the industry is becoming proactive in determining baseline conditions in areas where regulations do not yet exist. Baseline water supply sampling provides our clients with documented water supply quality prior to their activities commencing and enables detection of possible changes over time to water supplies in their areas of operation.

Spill Prevention Control and Countermeasure (SPCC) Plans

Spill Prevention Control and Countermeasure (SPCC) regulations aid facilities in preventing discharges of oil into navigable waters or adjoining shorelines and mitigating discharges promptly, should they occur. A key element of SPCC regulations requires facilities to develop, maintain and implement an oil spill prevention plan, referred to as a SPCC Plan. Not all facilities are subject to SPCC regulations and NTG Environmental can help clients determine their applicability. SPCC plans require certification by a Professional Engineer and are reviewed annually with recertification every five years. Other services offered include annual inspections and SPCC training for field personnel.

Stormwater Discharge

The Clean Water Act and associated federal regulations may require operators that clear, grade, and excavate locations to obtain coverage under the US EPA or an authorized state agency’s permit for stormwater discharges. As part of the permitting process, a Stormwater Pollution Prevention Plan (SWPPP) may be required to reduce pollutants in stormwater runoff leaving a site. NTG Environmental can evaluate a site’s applicability to the regulations and prepare permit applications with all supporting documentation.

Case Studies


Oklahoma and Texas

NTG Environmental developed and is continually updating a database of water supply sources and analytical results within 0.5-mile radius of a client’s current and proposed assets. The database enables our client to be proactive in understanding the water supply quality in their areas of operation.


McMullen County, TX

During field reconnaissance for a Pre-Drill Environmental Site Assessment, NTG Environmental personnel observed the Texas Tortoise (Gopherus berlandieri), a state-listed threatened species, at the proposed well site. In order to prevent unnecessary delays to our client’s drilling schedule, NTG Environmental applied for a Scientific Research Permit through the Texas Parks and Wildlife Department’s Wildlife Permits Office in Austin, Texas. State-listed species may only be handled by individuals with a Scientific Research Permit obtained through the TPWD. Within three weeks, NTG Environmental returned to the proposed well site with an approved TPWD permit to safely relocate the tortoise(s). Our client experienced minor delays, but was able to use the proposed location without impacting protected wildlife.

Site Assessment
Remediation & Site Closure

NTG Environmental performs site investigations for residential, commercial, and industrial sites to obtain the data necessary to assess risks and create remedial design plans. When remediation and site closure are required, our experienced team employs proven remedial technologies that are both effective and cost efficient.

Phase I/II Environmental Site Assessments (ESAs)

NTG Environmental applies scientific and defensible assessment and remediation techniques to meet regulatory requirements, manage client liabilities, and minimize costs over the lifecycle of an asset. Our ESAs meet the US Environmental Protection Agency’s All Appropriate Inquiries criteria and associated ASTM E 1527-05 and ASTM E 1903-11 standards.

We perform small and large-scale Phase II ESAs ranging from isolated releases to field-wide environmental impact investigations whether impacts are from a recent spill or historical releases. Characterization strategies include the use of a variety of sampling methods including hand augers, direct-push probes, and hollow stem auger and mud rotary drilling rigs. Services include the following:

  • Soil and groundwater investigation
  • Risk assessment and identification of cleanup objectives
  • Cost and feasibility evaluations for potential remediation technologies

NTG Environmental specializes in using the most efficient and cost-effective remediation strategies to address soil and groundwater impacted by petroleum hydrocarbons, produced water, and NORM. Services include the following:

  • Remediation strategy implementation and oversight (enhanced bioremediation, soil vapor/dual phase extraction systems, on-site land treatment, off-site disposal, monitored natural attenuation, in-situ leaching, etc.)
  • Soil, groundwater, and remediation system monitoring and performance review
  • Regulatory agency and stakeholder negotiation and concurrence for “No Further Action”
Pit Closure

We characterize reserve pit contents and develop closure options associated with the final disposition of those contents. Our approach ensures that applicable regulatory standards are met while also substantially minimizing or removing potential future environmental liability associated with the pit. We use site-specific criteria to tailor the sampling and closure approach according to the drilling program and the operator’s level of acceptable risk.

Case Studies


Cameron Parish, LA

NTG Environmental conducted a comprehensive Phase II ESA following a well blowout that released 280 bbls of condensate; 500,000 bbls of brine; and 420 yd3 of produced sand, resulting in impacts to 2 upland acres and 30 coastal wetland acres. NTG Environmental remediated the impacted area with conventional and innovative strategies, including the homogenization of amendments (gypsum, fertilizer, lime, sulfur, etc.) with a track-hoe mounted Fecon® unit, construction of French drains, and onsite treatment and discharge of extracted groundwater. Concentrations of oil & grease, electrical conductivity, exchangeable sodium percentage, barium, and pH (among others) were brought into compliance under applicable LDNR regulations within 18 months of treatment for a total cost of $8,911 per acre.


Webb County, TX

NTG Environmental employed a wind and solar powered aeration unit to perform enhanced biodegradation via oxygenation of more than 500 yd3 of petroleum hydrocarbon impacted soils. Project constraints included a limited budget, minimum available land, and a remote location. Benzene concentrations decreased from 13 mg/Kg to < 0.026 mg/Kg (the regulatory limit) in three months.

Air Quality

NTG Environmental offers comprehensive air quality permitting, monitoring, and compliance services to meet the ever-changing regulatory requirements on upstream and midstream oil and gas operators.

NTG Environmental’s experienced air quality staff helps owners and operators stay in compliance with federal and state air regulations, including New Source Performance Standards (NSPS), National Emission Standards for Hazardous Air Pollutants (NESHAP), and the mandatory greenhouse gas reporting rule

Air Permitting

NTG Environmental can address air quality issues for new facilities or expansion and modification of existing ones. There are state and federal programs that consist of technical requirements such as emission quantification and air dispersion modeling, compliance assurance, and testing and monitoring requirements. We work hard to streamline the air permitting process by reducing unnecessary requirements and eliminating agency-processing delays due to insufficient or incorrect documentation. Our staff is experienced in the following air permitting projects:

  • New Source Review (NSR) permit applications
  • Federal NSR Prevention of Significant Deterioration (PSD) and nonattainment permit applications
  • Federal operating permit (Title V) applications
  • State minor source permit applications
  • Permit by Rule (PBR) and standard permit registrations
  • Permitting strategies
Air Quality Audits & Compliance Assistance

We assist our clients through the development of monitoring and testing plans, conducting on-site evaluations/audits to determine applicability of and compliance with regulations, and preparing compliance determinations for record keeping purposes. Our air quality compliance services include the following:

  • Air dispersion modeling
  • Maintenance, Startup & Shutdown (MSS) activities
  • Coordinate sampling / stack-testing
  • Greenhouse gas reporting
  • Air emission inventories
  • Emissions Cap and Trade Program

Environmental, Health, & Safety

NTG Environmental understands the challenges associated with navigating the ever-changing environmental, health and safety best management practices and understands the risks that businesses face today. By applying experience, innovation and technical expertise, we are able to partner with our clients to establish corporate-level H&S policies and procedures that improve efficiency, reduce liability, and proactively address their EHS responsibilities.  NTG Environmental provides facility-level and corporate-level outsourcing and support during peak times, on a scheduled basis, or to temporarily fill vacancies.

In-House Training and Oversight of EHS Program Implementation

NTG Environmental provides safety training to maintain an incident free work environment for your operations. We are prepared to bring all training materials to your office or field location and train your employees on a variety of topics, including:

  • General safety
  • Hydrogen Sulfide (H2S) Awareness
  • SafeLand/SafeGulf
  • OSHA HazWoper and Annual Refreshers
  • OSHA Hazard Communication Standards
  • Spill Prevention Control and Countermeasure
  • Targeted training based on EHS metric report needs
Naturally Occurring Radioactive Material (NORM) Surveys

NTG Environmental provides NORM field surveys using licensed personnel to measure levels of NORM in equipment being used at production leases and other associated oilfield facilities.

Hydrogen sulfide (H2S) Contingency Plans

Hydrogen sulfide (H2S) is an extremely toxic gas that can be encountered in many oil and gas producing formations and can be present at drilling locations, producing wells, tank batteries, production facilities, gas plants, etc. NTG Environmental prepares H2S contingency plans for oil and gas operators that outline actions to take for alerting and protecting the public within a specified area of exposure prior to an intentional release or after an accidental release of H2S. These plans take into account conditions that may be present in given areas of potential exposure and provide contact information for potentially affected individuals and response actions.

Superfund Amendments and Reauthorization Act (SARA) Title III

The US EPA, under Superfund Amendments and Reauthorization Act (SARA) Title III, requires facilities with hazardous chemicals above certain threshold limits to submit Emergency and Hazardous Chemical Inventory Forms, or Tier II Reports, annually to the state and local agencies tasked with emergency planning and response. Tier II reports provide information about the type, quantity, and locations of hazardous chemicals at a specific location.

Case Studies


Bigfoot, TX

An NTG Environmental client requires on-site EHS training for remote field offices and a tracking system for each training session. Based on input from facility managers, NTG Environmental organized a list of relevant training topics and implemented training sessions at each field location. The regular and topical training has improved safety communication with a tracking system for OSHA records.


Houston, TX

Through acquisition and growth, a client had an immediate need to revise and improve its EHS manual. By interviewing safety and facility managers, NTG Environmental was able to draft a concise and applicable EHS manual that is used at all of the client’s locations.


Vinton, LA

Using licensed NORM survey teams, NTG Environmental established a survey grid system encompassing inactive equipment and soils for a facility. The NORM survey results were summarized, mapped, and documented by submittal of a NORM Site Notification Form ­RPD-36 to the Louisiana Department of Environmental Quality.


Guadalupe County, TX

Due to the known high concentration of sour gas and the close proximity of residences in Darst Creek Field, NTG Environmental performed a door-to-door notification visit at all dwellings within the area of exposure for a Client’s oil and gas operations as part of an H2S Contingency Plan. As a result, this public relations effort by the client was well received by the residents in the area.

Compliance & Permitting

NTG Environmental provides a comprehensive list of services to our clients as part of Regulatory Compliance & Permitting from the acquisition of drilling permits to securing the full complement of authorizations, approvals, permits and plans required by agencies.

NTG Environmental also routinely files our clients’ required completion, production and monthly, semi-annual and annual production operations report forms on their behalf.

  • Drilling permits
  • Surface use plans
  • Underground Injection Control
  • Waste (pits/impoundments, treatment and disposal facilities)
  • Land farming
  • Hydrostatic test water discharge
Regulatory Compliance
  • Discharge monitoring reports
  • Federal, state, and municipal emergency response plans, hazardous materials management plans, and waste management plans
Regulatory Services
  • Federal, state, city, and municipality permitting and completion filings
  • Regulatory compliance filings
  • In-house regulatory assistance and training
  • Regulatory compliance audits
  • Monthly production report filing
  • Groundwater protection compliance
  • Rule exception filing