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Section 2: Site Assessments and Investigations

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Definition and Purpose

A site assessment or investigation is defined as the process of identifying the presence or likely presence of any hazardous materials on a property, where conditions indicate a release or threatened release of hazardous materials into structures on the property or into soils, groundwater, or surface water on the property.

The purpose of a site assessment or investigation is to gather information about the project area and determine the potential for and/or extent of impacts to the project area from hazardous materials, for us in TxDOT’s decision making process.

According to the Council on Environmental Quality (CEQ), which is responsible for implementing National Environmental Policy Act (NEPA), the requirements of NEPA should be integrated with other planning and environmental review procedures. Therefore, environmental studies established to meet appropriate inquiry or due diligence requirements under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), or to determine appropriate hazardous material management and disposal plans, should be combined with the NEPA process.

FHWA provides general guidelines for identification of hazardous material sites. A copy of this guidance can be found on the Hazardous Materials Environmental Compliance Toolkit:

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Types of Site Assessments

TxDOT uses the following three types of hazardous materials site assessments:

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  • Initial Site Assessment (ISA) – This is a non-intrusive assessment for identifying and evaluating hazardous materials and waste sites that could potentially impact a roadway project.
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  • Phase I Environmental Site Assessment (ESA) – This is a non-intrusive, generally site-specific assessment. The Phase I ESA is conducted in accordance with American Society for Testing and Materials (ASTM) E 1527 standards.
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  • Phase II Environmental Site Assessment (ESA PH II) – This is an intrusive assessment conducted to confirm the presence of soil or groundwater contamination or waste through the collection and analysis of representative site samples.
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Initial Site Assessment (ISA)

The ISA is the primary site assessment tool for investigating TxDOT projects for the possible presence of hazardous materials, and is used during the advanced planning phase. The ISA process is very similar to the Phase I ESA process, but the primary difference is the ISA typically covers multiple parcels of land for a project corridor, as opposed to the single parcel for business development typical for an ASTM Phase I ESA.

TxDOT uses the ISA to evaluate property that may be affected by contamination. The purpose of an ISA is to gather as much information about the possible presence of contamination within the proposed project limits. The project limits would include the existing or proposed right-of-way and easements, including areas stretching from surrounding or adjacent properties. The ISA is a non-intrusive assessment; the information is gathered without actually collecting and testing soil or groundwater samples. Information gathered from an initial site assessment should also be considered in alternative analysis and selection.

The steps of the ISA consist of the following:

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  1. Reviewing project design and right-of-way requirements
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  2. Identify project activities such as excavations or dewatering
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  3. Reviewing existing and previous land use
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  4. Reviewing regulatory agency databases and files
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  5. Performing project site visits or field surveys
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  6. Conducting interviews
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  7. Determining the need for further investigation, considerations and/or coordination
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  8. Determining the likelihood for hazardous materials impacts to the proposed project

While professional judgment is used to determine the appropriate level of investigation for each component of an ISA dependent upon the project's design and right-of-way requirements.

The ISA should be performed as early as possible in project development, preferably prior to schematic development. If design and right-of-way requirements change, the entire ISA or some individual components may require re-evaluation to determine whether the findings are still valid. Any new information or changes to the project requirements should be examined to determine if further assessment, research, or investigation for hazardous materials is needed.

The latest version of the ISA report form can be found on the Hazardous Materials Environmental Compliance Toolkit

Project Requirements: Information about the general, approximate or anticipated project design, and right-of-way requirements should help when evaluating the chances of encountering hazardous material contamination. Design and right-of-way requirements may also be used to determine the appropriate level of inquiry for the ISA. The information can also be used to identify areas requiring additional research or consideration during the subsequent stages of project development. Priority can be assigned to the area(s) most likely to encounter hazardous material contamination.

Even though specific details may not be available during the early stages of project development, the following design and right-of-way requirements and information related to the limits of the entire project should be obtained and reviewed, if applicable:

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  • Existing or proposed location of geotechnical borings, or soil cores, and associated drilling logs
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  • Proposed location and depth of borings, columns, piers, or drilled shafts
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  • Locations and depths of excavations, such as vertical alignment, or profile changes, cuts, trenches, and/or storm sewers
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  • Anticipated de-watering requirements and depth to groundwater level
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  • Displacement, structure removal or structure modification requirements
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  • Locations of proposed right-of-way acquisition and easement requirements
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  • Locations and types of known encroachments
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  • Locations, depths, and types of proposed utility and pipeline adjustments
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  • Timeframes and contracting decisions for any proposed utility adjustments (prior to construction, during construction, joint bids)
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  • Documentation and/or findings of any related environmental assessments, testing or studies previously performed

Generally, when additional right-of-way acquisition, easements, displacement, structure removal, structure modification, underground utility adjustments, pipeline adjustments, column, pier, drilled shafts and excavation are not required, the project should have a low potential for encountering hazardous material contamination during construction.

Although shallow, contaminated soil may require special considerations during typical grading practices, excavations are more likely to adversely impact the environment and human health and possibly delay construction. The following are examples of project requirements at the highest risk of encountering hazardous material contamination during construction:

Projects requiring excavation within confined spaces and/or limited means of entry may require investigation to identify any special considerations necessary to ensure worker health and safety during construction. It is especially important to determine the potential for encountering contamination on projects that require de-watering. Drainage or de-watering of contaminated groundwater can adversely impact human health and the environment, as well as off-site corrective action activities that may be underway, if not handled properly. Preliminary project requirements for de-watering should be determined as early as possible. If the project requires de-watering, then further research or investigation may be necessary to confirm whether the groundwater is contaminated.

Projects requiring the displacement of either commercial or industrial businesses, such as retail service stations with underground storage tanks, have a high potential for hazardous materials.

Projects requiring bridge, building or other structure removal/modification may require asbestos or lead-based paint inspection surveys (sampling and analysis) to determine proper abatement, waste disposal, and contractor safety considerations according to applicable regulations.

Existing and Previous Land Use Information: Review of existing and previous land use information helps to identify earlier uses or occupancies likely to have led to hazardous material contamination. The review of land use information should address not only potential sites within the proposed project limits (including sites within both the existing and proposed rights of way); they should also assess the potential for contamination migrating from adjacent or surrounding properties.

Concerns may exist from land uses that previously existed on the property. Incorporating ASTM standards, property uses should generally be identified from the present back to the first developed use or 1940, whichever is earlier. The year 1940 reflects the increased levels of industrial development, chemical manufacturing and waste generation that occurred prior to and following World War II. Sources of contamination can exist from operations prior to 1940; therefore, research prior to 1940 may be necessary to reach a higher confidence level if the project requires significant excavation, de-watering or right-of-way acquisition.

In general, projects within or adjacent to undeveloped, agricultural cultivated fields, ranch, pasture and residential areas have a low potential for hazardous material contamination. Existing rights-of-way could have possible concerns not identified during earlier acquisition or corridor preservation. Many older roadway intersections may have abandoned gasoline stations and unregistered underground storage tanks. Previous land use of some existing rights-of-way may have also included previous chemical storage, manufacturing, or industrial properties. A few examples of land uses that typically generate, treat, store, or dispose of hazardous waste, hazardous substances, hazardous materials, petroleum products, or solid waste include:

Visual evidence of previous land use may be difficult to identify from only site visits and field surveys. The readily available TxDOT sources of land use information listed below should be reviewed for all projects:

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  • United States Geological Survey (USGS) 7.5 minute topographic maps:
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  • Past and present aerial photographs:
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    • sources of aerial photographs include TxDOT, municipal/county planning offices, soil conservation field offices and Council of Governments web sites

United States Department of Agriculture (USDA) Soil Conservation Surveys:

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  • sources of soil surveys include TxDOT and soil conservation field offices and web sites
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  • Right-of-way maps and files:
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  • TxDOT Temporary Use of Right-of-Way Agreements:
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    • sources of temporary use agreements include TxDOT district maintenance sections
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  • Affected property owner notifications from the TxDOT district office, area office, or maintenance sections, and/or district environmental coordinator

Older TxDOT schematics developed for public meetings and hearings may identify former businesses, buildings and improvements in the proposed alignment. TxDOT aerial photograph archives should also be reviewed for photographs along or near the project limits. TxDOT right-of-way files and possibly local entity acquisition files may have listed purchased and retained items. This information may identify the type of business in operation at the time of acquisition. As built plans, which verify construction activities including fill, cuts and structure removal, may also provide information either identifying concerns or developing requirements for further investigation. Any temporary use agreements for monitoring well and remediation systems should be reviewed for the project limits to determine the level of contamination, potentially responsible parties and points of contact. Districts may also receive written notification from adjacent landowners or responsible parties of contamination on the existing right of way.

Reviewing additional land use resources may not be necessary, depending upon the project requirements and whether readily available sources (as discussed above) are sufficient. Additional research should be considered for commercial parcels that have been abandoned or appear undeveloped within urban, commercial and industrial areas; lending institutions or the private sector may have been wary of investing or developing potentially contaminated property.

Additional land use information may be found through the following sources:

A title records search is generally not practical for an ISA in the advanced planning stage. However, if the prior land use at the site of the proposed project is dubious, then research of the title records should be considered. Research on title records (chain of title) can provide valuable information including environmental liens or deed recordation of contamination, and closure requirements. Additionally, the names of previous property owners may suggest the types of land use or previous operations on the property. Any title searches should be discussed and coordinated with district right-of-way staff.

Regulatory Agency Databases and Files: The purpose of the regulatory agency database and file review is to identify known sources of contamination and involvement with registered or regulated sites. The Texas Commission on Environmental Quality (TCEQ) and EPA provide regulatory database information under the Texas Public Information Act and Freedom of Information Act, respectively.

Recommendations for regulatory database searches and the minimum suggested search distances are identified in the ASTM standards. Additional information about individual data-bases and obtaining databases directly from the regulatory agencies or list searches from commercial vendors is provided in Chapters 2, 3 and 4 of Hazardous Materials in Project Development

The database search should address the regulatory status of any site within the proposed project limits, both existing and proposed right-of-way, as well as potential sources of contamination from adjacent or surrounding properties. In general, emphasis should be on sites within or directly adjacent to the proposed project limits unless excavation, de-watering and/or utility adjustments have been proposed. The minimum search distance should be sufficient to evaluate alternatives, minor shifts in the alignment and other possible re-design options to avoid hazardous material involvement. For proposed project limits covering several miles and/or with a high density of commercial or industrial facilities, it is generally more cost effective or timely to plot the sites of a database search (list search) using geographic information system (GIS) mapping.

In some cases, the minimum search distance could change depending upon local geologic or hydrogeologic and land use conditions. However, there are problems with reducing the minimum search distance. Some larger facilities may have office addresses registered at the outer limits of the minimum search distance, although the hazardous material or chemical storage operations associated with these facilities may be within or adjacent to the proposed project limits. The minimum search distance should be reduced on a case-by-case basis. The justification for each reduction must be reasonable, well-documented and dependent upon project excavation and right-of-way acquisition requirements.

Caution should be used when interpreting the list search information. Even sites not listed as regulated or registered may be contaminated from improper hazardous material handling or disposal. Once obtained, the list search should be field-checked for possible unmapped data and incorrect addresses. If asked, most commercial vendors will provide additional services to reduce the number of unmapped sites. A single database should not be used as the sole source of information about a release or regulated site. Information in one database should be checked against as many sources as practical. Additionally, regulatory databases information is constantly updated and revised; therefore, the date of the database search is very important. A list search may need to be updated throughout project development.

The list search data should be compared with preliminary right-of-way and design requirements to determine involvement with registered or regulated sites. For example, proposed displacements, structure removal, tank removal, and/or excavation requirements should be determined for each identified regulated site within the proposed project limits. If proper containment and waste management practices are followed, any site registered as Registered Petroleum Storage Tank (RPST) or Resource Conservation and Recovery Act (RCRA) Generator is not necessarily contaminated. However, these sites may require additional considerations for tank removal or waste disposal if proposed right of way is required from them.

Caution should also be used when interpreting the reported status of a site. Sites with “case closed” status may still have contaminated soil or groundwater. Corrective action of contaminated areas underneath buildings may not have occurred due to safety or structural integrity concerns. Additionally, health-based or risk-based closures may allow some contamination to remain in place if contaminants are under certain regulatory levels or if proper deed record requirements are met. Unfortunately, risk-based remediation closures performed by private parties may not have adequately addressed potential impacts due to highway construction or related construction worker exposure.

It should also be noted that the information contained in databases may be insufficient to determine the chances of encountering contamination. Additional information from regulatory agencies or property owners may be necessary to determine right-of-way acquisition, property management, design or construction considerations for registered or regulated sites. Investigation reports and correspondence contained in the case files can be reviewed at regulatory agency regional and/or central records offices. As discussed below, federal and state regulatory agencies can also provide details on site status and enforcement actions. To review regulatory files or discuss site status with a regulatory agency, identification numbers or facility information contained in the regulatory databases is often required.

Project Site Visit or Field Surveys: Some potential hazardous materials concerns may not be identified in the land use or regulatory database research. The purpose of a project site visit/field survey is to visually observe the existing and proposed right-of-way, the periphery of the project limits and structures located within the project limits for possible concerns. A project site visit/field survey should also include observations of surrounding and adjacent land use. A project site visit/field survey should be conducted following or in conjunction with a preliminary review of available project plans, topography maps, aerial photographs, and regulatory database lists.

Windshield surveys, observations from public land or having concerns about existing right of way on adjacent properties are typically not sufficient for the initial site assessment, especially if right-of way acquisition is required. However, an initial windshield survey can be helpful depending upon the project requirements, length of the proposed project limits, land use and whether right of entry is permitted. If right of entry cannot be obtained, then additional individual site surveys should be considered for subsequent stages of project development. A windshield survey one-quarter to one mile from the proposed project limits should also be performed to determine the potential for contamination migration to the proposed project from surrounding properties.

Possible concerns to note during the project site visit or field survey include, but are not limited to, the following:

Field notes should be taken during the project site visits/field surveys. Photographs should be taken of any suspected or potential environmental contamination. The locations, distances and compass orientations/directions of photographs and environmental concerns should be noted on available maps or site plans.

Interviews: The purpose of conducting interviews is to confirm any concerns about the existence of potential hazardous material contamination. Individuals to consider for interviews include:

Property owners, operators and/or employees can provide valuable information about operations and activities that may have involved hazardous materials. Local residents, including TxDOT area maintenance office staff, may be aware of current or former operations on a parcel of land and may be able to describe situations warranting further investigation. TxDOT staff may also know of contamination problems that have required ongoing maintenance.

Depending upon the length of the project and/or number of parcels, interviews with property owners, operators, employees and local residents may not always be practical during the advanced planning stage of project development. Interviews concerning specific sites of concern with TxDOT staff, local entities or regional regulatory agencies may be more feasible. Regional and local regulatory or emergency response agencies include local fire departments, city or county environmental health departments, and regional TCEQ offices. If railroads or oil and gas facilities exist along the proposed project limits, district offices of the Railroad Commission of Texas (RRC) offices can also be contacted. The following is a list of local and regional regulatory and emergency response agencies, or planning departments and the types of information available from each:

Municipal and local fire department administration

Some caution should be taken when considering the information obtained during interviews. Memories fade and people interviewed may not always be forthright. Therefore, the initial site assessment should not rely solely upon information obtained from property owners, operators, employees, or the public.

The names, addresses, and phone numbers of all individuals interviewed should be documented with the dates and times of the interviews. Memoranda to the project file, completed records of communication forms, and letters confirming the information discussed should also document conversations.

Determine Need for Further Investigation, Considerations, or Coordination: If no concerns are identified during the ISA, then no further research, coordination, investigations or considerations are necessary. However, for some projects an ISA may not be sufficient; evaluation of the preliminary information obtained during an ISA may indicate the need for further research or investigation (i.e. “unresolved” issues). In general, additional research or regulatory file review should be completed before the next stages of project development begin to resolve whether investigation, additional considerations or coordination are needed.

Limitations in the ISA may warrant more assessment or investigation in subsequent stages of project development. These limitations include, but are not limited to, structures not entered, right-of-entry access denial by property owners and insufficient interviews of property owners or operators for appropriate inquiry.

The need for additional investigation will depend upon the project design and right-of-way requirements. For example, additional investigation may be required for projects with significant excavation or de-watering, structure removal, or right-of-way acquisition of properties with past land uses at high risk of hazardous material concerns.

In general, hazardous materials issues should not prevent a project from receiving environmental clearance. However, these issues must be tracked and resolved during future phases of the project development process or during and after the project’s construction if necessary.

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Phase II Environmental Site Assessments or Investigations (PH II ESA)

The main purpose of conducting a PH II ESA is to determine whether known or possible contamination might be encountered during construction. The information from a PH II ESA may be useful in developing cost-effective preventive action plans or specifications to handle any contamination found. A PH II ESA may also help to determine closure requirements of regulated facilities or contaminated areas. A PH II ESA should include the following activities:

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  • Develop a soil and/or groundwater sampling and analysis plan, such as locations of borings, depths of borings, locations of monitor wells, groundwater gradient, and hydrogeologic or hydraulic testing
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  • Identify and characterize the contamination through sampling and analytical testing
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  • Determine the horizontal and vertical extents of contamination that might be encountered prior to or during construction
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  • Assess worker safety and public health exposure concerns
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  • Determine the regulatory handling, reuse and/or disposal requirements for contaminated media
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  • Recommend a cost-effective preventive action plan to ensure the contamination is not aggravated.

Sampling and analysis can be very expensive. The most cost-effective approaches will vary on a case-by-case basis. Several factors determine when and how to conduct a cost-effective environmental site investigation. For example, the sampling and analysis plan should limit the number of investigations or remobilization. However, multiple or phased investigations may be necessary for some projects or individual sites; detailed information about a project's proposed excavation and de-watering requirements may be needed to develop an adequate sampling and analysis plan. One option is to perform more detailed design activities during advanced planning to facilitate the investigation. Another option is to postpone investigation until the project details are known later in the project development process. It may also be more cost-effective to combine geotechnical testing with environmental testing.

Since a preferred alternative or alignment could change during the environmental process, investigations should be performed after approval of the environmental documentation, public involvement or environmental clearance. To determine whether possible contamination exists on a proposed right of way, investigations depend on property owners providing access or right of entry. If right of entry is refused, the investigation may be postponed until the eminent domain process or until after acquisition.

FHWA has specific guidelines for projects requiring Environmental Impact Statements (EIS). Prior to selection of a project alternative, detailed design activities and additional investigations may be necessary to evaluate the impact and obtain sufficient information for the project decision-making process. Sufficient information is necessary to characterize the site, identify the type and extent of contamination, and estimate disposal, waste management or cleanup costs. It may also be necessary to determine alternative treatment, cleanup, disposal measures, and associated costs. Assuming that right of entry can be obtained, the hazardous materials assessment should be completed and documented in the Final EIS prior to circulation; however, it is not necessary to complete all investigations prior to environmental clearance. If a contaminated site cannot or will not be cleaned up prior to acquisition and it is decided to proceed with the project, then a more detailed site investigation can be performed after clearance. More detailed site investigations may be needed to determine waste characteristics, hydrogeologic conditions and/or extent of contamination.

For all projects, hazardous materials assessment should be completed prior to finalizing the Plans, Specification and Estimates (PS&E). If the analytical testing does not reveal contamination, then there is added support that contingencies or special provisions are not required in the PS&E.


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