Preliminary Investigation

A preliminary investigation is a historical search of the past uses of the site and on-site activities. The purpose of a preliminary investigation is to collect and review existing information to determine the possibility of contamination or pollution. It is primarily a document review activity, and while the site is visited, no sampling occurs. A Preliminary investigation is usually performed by an environmental consultant but it is not required by law. The historical search can include:

  • identifying past owners and the property uses during time of ownership
  • reviewing of governmental records to identify past use and the use or disposal of hazardous substances at the site
  • reviewing of state and federal databases that list regulated environmental activities (e.g., CERCLIS, RCRA, CAA and NPDES records and state records of emergency removal)
  • interviewing of past property owners and employees
  • reviewing of aerial photographs of the site
  • visiting the site, adjoining properties, buildings and infrastructure

Site Reconnaissance - What to look for?

The objective of the site reconnaissance is to visually and physically observe the property and any structure(s) located on the property in order to determine the likelihood of environmental impact to the property. The entire site must be observed, both inside and outside. If there are any areas that are not accessed, they must be specifically identified in the report.

Site Overview

A sketch or map of the site layout is helpful. Items to be noted on the map are location of contamination, buildings (current and past), land cover, topography, adjacent neighbors, and site utilities.

A description of the structures or other improvements on the property must be noted during the site visit including number of buildings, number of stories each, approximate age of buildings, and construction type of each building.

The topography of the site and the surrounding area should be noted at the site of the site visit. If any information shows there are likely to be hazardous substances or petroleum products onsite or that may migrate from offsite, the topographic observations must be analyzed in connection with the geologic, hydrogeologic, hydrologic, and topographic information obtained from record reviews, interviews, or site observations. This analysis will evaluate whether hazardous substances or petroleum products are likely to migrate to the property, or within or from the property, into soil and groundwater.

Public thoroughfares (roads) adjoining the property should be identified during the site visit. In addition, note any roads, streets or parking facility on the subject property should be described. The source of potable water for the property must be identified during the site walk through. The sewage disposal system for the site must also be determined during the site reconnaissance. If the sewage disposal system is an onsite septic system, an inquiry into the age of the system, and its maintenance should be completed. The means of heating and cooling the buildings on the property, including the fuel source, must be identified during the site reconnaissance. These systems can include but are not limited to heating oil, gas, electric, or radiators from steam boiler fueled by gas.

Site Conditions

One of the main determinants of whether potential environmental impact will be present is the current and past usage of the site and the surrounding properties. The current use of the property as noted during the site visit should focus on the likely use, treatment, storage, disposal or generation of hazardous substances or petroleum products. During the site reconnaissance it is also imperative to observe adjacent properties in an attempt to determine if any potential environmental conditions exist on the site which could ultimately impact the subject property. The observations about the adjacent properties and the surrounding area should be made from the subject site or from a public right-of-way. Due to legal issues, no entry onto another person's piece of property is advisable. Past uses of the subject site, adjacent properties and the surrounding area can be determined either via historical document review, interviews or visual observations.

Common Features

The following is a short list of common features found at many sites under consideration:


The final preliminary assessment report may contain one or more of the following items:



  • Objectives of the property assessment
    Client (owner/operator, 'Voluntary Party')


  • Present owner (length of ownership)
  • Current use
  • Proposed land use (residential, commercial, industrial)
  • Ownership history (length of ownership)
  • Operations history
  • Past physical features

Property Overview

  • Property location - address and legal descriptions as shown on tax records
  • Site features - that at a minimum describes buildings, fill areas, drainage patterns, surface cover, and adjacent property uses
  • Parcel Size - in standard units of measurements square feet, acres and etc.
  • Survey (or equivalent) of property boundaries - With permanent horizontal and vertical bench mark established
  • Land use and Zoning within 0.5 miles of the property (or professional judgment)

Geographic and Physiographic Features

  • Groundwater use
  • Location of existing and abandoned water supply wells in the area including potable and non-potable (including available well logs)
  • Surface water distances, uses, location, and classification
  • Wetlands
  • Environmentally sensitive areas

Property History

  • Products
  • Waste inventory
  • Waste disposal processes and recycling or reuse
  • Bulk storage tanks
  • Chemical and waste storage areas
  • Disposal Sites

Regulatory History

  • Present activities of owner/operator
  • Permits
  • Inspections
  • Hazardous Substance/Hazardous Chemical Inventory
  • Regulatory compliance history

Environmental Investigations and Cleanups

  • Environmental cleanups
  • Environmental assessments

Physical Reconnaissance

  • Investigators
  • Contacts/Interviews
  • Limiting site conditions
  • Current site activities
  • Buildings
  • Grounds
  • Areas of concern including
    • above or below ground pump stations
    • sumps, pits
    • rail or truck loading/unloading docks or areas
    • storage pads and areas including drum and waste storage
    • dumpsters
    • chemical storage cabinets or closets
    • storage tanks and associated piping (underground and above ground)
    • silos
    • transformers and capacitors
    • storm water retention ponds and fire protection water ponds
    • air vents and ducts
    • roof drains
    • stained areas - pavement, soils, wall, and etc.
    • stressed or no vegetation
    • drainage depressions
    • pools of liquid
    • areas of fill material
    • areas where chemicals were mixed and loaded
    • areas where machinery was washed and tanks were rinsed

Property (or Site) Maps

  • property location
  • property survey
  • all buildings and structures
  • all utilities and underground services
  • all known past buildings and structures
  • storage areas
  • water supply wells
  • photo documentation of areas of concern
  • adjacent and offsite activities

Next Steps

Once a preliminary investigation is completed and the past uses of the property (e.g. types of industry) have been defined, it is possible to develop a short list of possible contaminants. Refer to Pollutants for more information. If contamination is suspected, a sampling and analysis should be conducted.

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