Section 2: Site Assessments and Investigations

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Definition and Purpose

A site assessment or investigation can be 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 use in TxDOT’s decision-making process.

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Outside Guidance and Standard Practices

According to the Council on Environmental Quality (CEQ), which is responsible for implementing the National Environmental Policy Act (NEPA), the requirements of the 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.

The FHWA, American Association of Highway Transportation Officials (AASHTO), National Highway Institute (NHI), National Cooperative Highway Research Program (NCHRP) and ASTM International provide guidance for conducting environmental studies and investigations for hazardous material contamination. FHWA Interim Guidance provides only general guidelines for identification or site assessment. A copy of this guide is provided in Chapter 1 of the web document Hazardous Materials in Project Development: Additional Guidance. AASHTO also outlines a general procedure and terminology to identify and assess projects throughout project development. This policy and resolutions that are not copyrighted are outlined in Chapter2 of Hazardous Materials in Project Development: Additional Guidance. The United States Department of Transportation (DOT) has provided preliminary information on brownfields. This information is provided in Chapter 3 of Hazardous Materials in Project Development: Additional Guidance.

The ASTM standard practices and guides include:

  • ASTM E 1528-06 - Standard Practice for Limited Environmental Due Diligence: Transaction Screen Process (Transaction Screen)
  • ASTM E 1527-05 - Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process (Phase I ESA)
  • ASTM E 1903-97 (2002) - Standard Guide for Environmental Site Assessments: Phase II Environmental Site Assessment Process (Phase II ESA).

The ASTM Standard Practices and Guide were developed for commercial real estate transactions to provide guidance on industry standards. To specifically address transportation or corridor projects, additional services or modifications to the ASTM Standard Practices are needed. During the advanced planning stage, the ASTM Transaction Screen is more practically used as a documentation tool for an individual site or parcel. The ASTM Transaction Screen is only sufficient when:

  • interviews with the property owners and/or operators are practical
  • right of entry can be obtained
  • knowledge of the site and/or initial surveys do not indicate concerns.

A brief overview of the ASTM Standard Practices or Guide, including information on how to obtain the copyrighted practices, is provided in Chapter 4 of the web document Hazardous Materials in Project Development: Additional Guidance.

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Types of Site Assessments

TxDOT utilizes two types of site assessment standards:

  • Phase I Environmental Site Assessment or Initial Site Assessment (ISA) – a non-intrusive assessment
  • Phase II Environmental Site Assessment (ESA) – an intrusive assessment.
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Phase I or Initial Site Assessment (ISA)

TxDOT uses the initial site assessment (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, including that stretching from surrounding or adjacent properties. The ISA is a non-intrusive assessment; the information can be gathered without actually collecting soil or groundwater samples to help determine the likelihood of encountering hazardous material contamination on the project. Information gathered from an initial site assessment should also be considered in alternative analysis and selection.

The components of the ISA include:

  • reviewing project design and right-of-way requirements
  • reviewing existing and previous land use
  • reviewing regulatory agency databases and files
  • performing project site visits or field surveys
  • conducting interviews
  • determining the need for further investigation, considerations and/or coordination.

Professional judgment should be used to determine the appropriate level of investigation for each component of an ISA. The appropriate level of investigation for an ISA will depend 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. Because the duties are similar, the ISA can be incorporated into the site visit, field surveys and land use research required for other environmental studies in the NEPA process. 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. To be cost effective, components of the assessment and investigations may be performed in phases as the design requirements are finalized during project development.

Similar to the ASTM Transaction Screen questionnaire, a checklist or worksheet can be completed to document the findings of the ISA. An example worksheet is presented in Chapter 1 of the web document Hazardous Materials in Project Development: Environmental Site Assessments. Alternatively, a separate report can be generated. Documentation of the ISA should be forwarded to the district right-of-way, design and construction staff, as appropriate. Section 4 of this chapter and Chapter 1 of the web document Hazardous Materials in Project Development: Environmental Site Assessments provide information on how to summarize the findings of an ISA in the document required for environmental clearance.

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:

  • existing or proposed location of geotechnical borings or soil cores and associated drilling logs
  • proposed location and depth of borings, columns, piers or drilled shafts
  • locations and depths of excavations, such as vertical alignment or profile changes, cuts, trenches and/or storm sewers
  • anticipated de-watering requirements and depth to groundwater level
  • displacement, structure removal or structure modification requirements
  • locations of proposed right-of-way acquisition and easement requirements
  • locations and types of known encroachments
  • locations, depths and types of proposed utility and pipeline adjustments
  • timeframes and contracting decisions for any proposed utility adjustments (prior to construction, during construction, joint bids)
  • 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:

  • significant excavation or cuts greater than three (3) feet
  • vertical alignment changes
  • underpasses
  • trenching
  • tunneling
  • storm sewers
  • pipeline and underground utility installation or adjustments
  • confined spaces
  • de-watering.

Projects requiring excavation with 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 building or 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 of 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:

  • automotive or engine salvage, repair and maintenance facilities
  • manufacturing, industrial or processing facilities such as creosote plants, coal tar gas plants and electroplating facilities
  • oil depots and refineries
  • aboveground and underground petroleum storage tank facilities
  • service industries such as oil and gas equipment service, dry-cleaning, laundry, photographic processing, printing and analytical laboratory operations
  • rail or switching yards
  • landfills, disposal and recycling facilities
  • oil and gas exploration facilities such as wells, separation tanks and circulation pits
  • military bases.

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:

  • United States Geological Survey (USGS) 7.5 minute topographic maps:
    • Sources of topographic maps include TxDOT, USGS and online at
  • Past and present aerial photographs:
    • 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:
    • Sources of soil surveys include TxDOT and soil conservation field offices and web sites.
  • Right-of-way maps and files:
    • Sources include TxDOT district right-of-way sections.
  • TxDOT Temporary Use of Right-of-Way Agreements:
    • Sources of temporary use agreements include TxDOT district maintenance sections.
  • 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:

  • Fire insurance or fire hazard maps
    • City atlases produced by private fire insurance companies (for example, Sanborn Maps) show potential fire or explosion concerns, including tanks or chemical vats. (Also available online through the Texas State Library and Archives Commission.)
    • Sources include local libraries, historical societies, commercial services and fire insurance companies.
  • Building department records
    • Local jurisdiction records show approvals to construct, alter or demolish improvements on the property.
    • Sources include municipal and county building departments.
  • Local street or city directories
    • Directories published by private or governmental sources show ownership, occupancy and uses of sites referenced by street address.
    • Sources include libraries of local governments, historical societies, colleges and universities.
  • Property tax files
    • Local jurisdiction files include records such as past ownership, appraisals, maps, sketches and photographs.
    • Sources include county appraisal offices.
  • Recorded land title or deed records
    • Local jurisdiction records include information regarding fee ownership, leases, land contracts, easements, liens and other encumbrances on or of the property.
    • Sources include private title companies, municipal/county recorder and/or clerk offices.
  • Zoning and land use maps or records
    • Local jurisdiction maps show use(s) permitted by the local government.
    • Sources include municipal and county planning departments.
  • Site plans
    • Maps show locations of buildings, tanks, fill areas and monitoring wells.
    • Sources include regulatory agency files and property owners.

Sanborn fire insurance maps, which date from the mid-1800s to the 1950s, have been completed for most cities in Texas. Additional information on obtaining or reviewing Sanborn maps is provided in Chapter 5 of the web document Hazardous Materials in Project Development: Environmental Site Assessments.

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 more 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 the Environmental Protection Agency (EPA) provide regulatory database information under the Texas Public Information Act and Freedom of Information Act, respectively.

Table 2-1 identifies the federal and state regulatory agency databases and their minimum search distances based on requirements identified in the ASTM standards. Other databases also exist. Additional information about individual databases 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: Additional Guidance.

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Database Abbreviation

Regulatory Database

Minimum Search Distance



National Priorities List (Federal Superfund Sites)

1.6 km (1.0 mi)


Comprehensive Environmental Response, Compensation and Liability Information System

0.8 km (0.5 mi)


Resource Conservation and Recovery Act [Treatment, Storage and/or Disposal (TSD) Facilities]

0.8 km (0.5 mi)


Emergency Response Notification System

Proposed project limits (existing and proposed right of way)


Resource Conservation and Recovery Act (Generators)

Proposed project limits (existing and proposed right of way) and adjoining properties*


Tx Superfund

State Superfund Sites (state equivalent to NPL)

1.6 km (1.0 mi)


Leaking Petroleum Storage Tanks

0.8 km (0.5 mi)


Municipal Solid Waste Landfills (Authorized and Unauthorized)

0.8 km (0.5 mi)


Registered Petroleum Storage Tanks (Aboveground and Underground Tanks)

Proposed project limits (existing and proposed right of way) and adjoining properties*

* Adjoining properties can typically use a minimum search distance of 0.4 km (0.25 mi) from proposed project limits.

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, the information in regulatory databases 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 RPST or 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 levels or if proper deed record requirements are met. Unfortunately, risk-based 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 are often required.

Project Site Visit or Field Surveys: Some potential 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 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 right of entry. 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 or corridors should also be performed to determine the potential of contamination migrating to the proposed project limits from surrounding properties.

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

  • Chemical or waste storage concerns including:
    • underground storage tanks, fill pipes and vent lines
    • aboveground storage tanks
    • electrical and transformer equipment
    • injection wells, cisterns, sumps and dry wells
    • vats, labeled/unlabeled drums, canisters, barrels and bottles
    • spills, stockpiling, surface dumping such as trash, garbage, refuse or rubbish, or half exposed or buried debris
  • Soil concerns including stained, discolored, barren, exposed or foreign soil (fill)
  • Surface water or drainage area concerns including:
    • oil sheen or films on surface water, seeps, lagoons, ponds or drainage basins
    • changes in drainage patterns from possible fill areas
  • Vegetation concerns including dead, damaged or stressed vegetation
  • Biological concerns including dead animals, radioactive materials and medical waste
  • Protected area concerns including security fencing, placarding or warning signs

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:

  • current/former property owners or operators of proposed right of way
  • existing or former employees
  • local residents
  • regional and local regulatory agency staff
  • regional or local emergency response staff.

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. Following is a list of local and regional regulatory and emergency response agencies or planning departments and the types of information available from each:

  • regional TCEQ offices
    • available correspondence, files and permit registration for listed or regulated sites
    • status or specific information about sites.
  • district RRC offices
    • citations, enforcement actions and cleanup status of oil and gas fields and facilities
    • naturally occurring radioactive materials (NORM)
    • oil and gas pipeline spills.
  • municipal and county environmental health departments
    • abandoned or unregistered landfills
    • public complaints
    • spills.
  • municipal and local fire department administration
    • train accidents or derailments
    • spills.

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: Usually, 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. 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 occurring during 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.

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Phase II Environmental Site Assessments or Investigations (ESA)

Several terms for environmental site investigations include both non-intrusive geophysical surveys and intrusive sampling of surface water, soil vapor, soil and groundwater. AASHTO refers to environmental site investigations as “preliminary site investigations” and “detailed site investigations.” ASTM refers to sampling and analysis as a “Phase II Environmental Site Assessment (Phase II ESA).” Depending upon the type of contamination or regulated site involved, other terms for environmental site investigations may apply.

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

  • 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
  • identify and characterize the contamination through sampling and analytical testing
  • determine the horizontal and vertical extents of contamination that might be encountered prior to or during construction
  • assess worker safety and public health exposure concerns
  • determine the regulatory handling, reuse and/or disposal requirements for contaminated media
  • 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.

In general, sampling and analysis should occur prior to environmental clearance for any project that has only one feasible alternative and no proposed right-of-way acquisition. 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 Studies. 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 ESA should be completed and documented in the Final Environmental Impact Statement 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 include those to further determine waste characteristics, hydrogeologic conditions and/or extent of contamination.

For all projects, ESAs 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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