Vapor Intrusion: How to Negotiate Off-Site Access

Vapor Intrusion (“VI”), or the migration of contaminant vapors from soil and groundwater into overlying structures, has been a significant topic in the environmental world for over 20 years.  Common contaminants associated with VI are volatile organic compounds (VOCs), which include gasoline constituents, such as benzene, and industrial degreasing and cleaning chemicals like tetrachloroethene and trichloroethene (PCE and TCE).  As the science and understanding of VI advances, federal and state regulatory agencies continue to request VI sampling more often.   Since contaminant plumes often spread past a property boundary, it is very common that VI must be investigated in off-site properties, which could be residential, commercial, or industrial.   Most environmental practitioners have an understanding of VI; however, the general public does not.  As such, requesting access from a property owner whose residence or business is overlying a groundwater plume must be done in a thoughtful, sensitive and down-to-earth manner. 

Many federal and state agencies offer guidance and procedures for gaining access to third party properties. These procedures provide helpful step-by-step directions on how to negotiate access, and the agency expects them to be followed and documented during the negotiation process.  Although the procedures are useful, they may not always result in access and can be modified to be more successful. This article provides information on how to strategically approach access negotiations, evaluates effective communication methods, and provides a brief background on conducting the actual sampling to satisfy the homeowner and regulatory agency.

Identify the Buildings Where Vapor Sampling is Necessary

Prior to access negotiations, the number of buildings or residences that potentially could be affected by VI must be determined.  The extent and magnitude of the subsurface contamination relative to the overlying structures will dictate where VI sampling needs to occur.  This is an important first step to understand, because the communication and outreach methods will vary significantly if you are requesting access to one commercial business, 50 residential homes, or a combination of the two.  The regulatory agency should be in general agreement with the location and number of structures where VI sampling is proposed.

Understand the Expected Regulatory Access Negotiation Procedures

After the VI testing area is determined, the next step is to review the federal or state guidance for gaining access to third party properties.  The regulatory agency expects these steps to be followed and documented during the access negotiation process.  The step by step guidance may vary slightly from state to state, but they are all similar and generally include the following:

  1. Desktop Records Review and Reconnaissance – Determine the relevant structural and owner contact information for the property.
  2. In-Person Visits and Door Hangers – Attempt in-person visits during hours when property owners should be present (i.e., evening), and if contact is not made, leave a door hanger with an informational packet that includes the project background, what the owner can expect during the VI evaluation process, and provide an access agreement with a self-addressed stamped envelope to assist in obtaining access.
  3. Telephone Calls – Attempt telephone calls during various time throughout the day, and if necessary, leave a voicemail stating the reason for the call and provide contact information.
  4. Written Letters – If contact has still not been made, mail the same informational packet/access agreement provided in the door hanger.
  5. Regulatory Follow-Up – If unsuccessful in gaining access, document the access attempts performed to the regulator, and depending on the potential risk, they may contact the owner directly.

Determine the Most Effective Communication Methods

It is necessary to understand the state-specific guidance so you can fulfill the steps that the regulator expects; however, it can be useful to change the order of the steps and/or add additional steps to the process.  For instance, providing a written letter to the property owner prior to conducting an in-person visit is an effective way to educate them about the potential VI issue beforehand.  It can also make the in-person visit more successful, because you can start off the conversation referring to the letter that was sent earlier.

Depending on the number of buildings you are requesting access to, effective public involvement is an important part of building trust and cooperation with a community.  An additional step that may be worth adding to the process would be a public meeting.  For example, if you are trying to negotiate access to 50 residential homes, conducting a public meeting may be a more effective and efficient way to educate the homeowners enough to allow access, rather than conducting 50 individual home visits. Although public meetings are not typically part of the regulatory access procedures, agencies understand the value they add, and a representative should be requested to attend the meeting.

Be Prepared to Answer Questions and Educate

Once contact is made with someone, it is important to confirm they are the property owner and are authorized to grant access.  It is necessary to be prepared for any question the owner may ask about the contamination, vapor sampling process, and long-term repercussions.  It is also recommended that a Fact Sheet or similar communication tool be provided.  The Fact Sheet should explain the VI sampling process in layman’s terms and include diagrams and or photos (including the sampling equipment).  Personnel communicating with a homeowner/tenant must be polite and patient. Everyone is unique and will react differently when informed about the reason for the sampling. Based on experience, some of the most common questions you may be asked include:

  • How long has the contamination been present? Who caused it?
  • Does it affect the water I am drinking?
  • I’ve lived here for a while, will the air I’m breathing give me cancer?
  • How will it affect my property value?
  • What happens if my air has detections?
  • Will holes be drilled in my ground to perform the sampling?
  • Will it be necessary to remove certain cleaning products?
  • Will family members or pets need to be moved out of the home during the sampling?

The list of questions can go on and on, and you need to be prepared to discuss anything that may come up.  If necessary, it may be worth discussing hypothetical questions with the project clients and attorneys, to reduce any potential liability.  The ultimate goal of the discussion is to obtain access in order to evaluate the potential VI exposure pathway.  Once the agreement is signed, it is necessary to be flexible and schedule the VI sampling in accordance with the owner’s schedule, which may be in the evening in some cases.   


As explained above, there are many factors that need to be considered when negotiation access for VI sampling. It starts from determining where to sample, followed by understanding what the regulators expect, and determining the most effective communication methods to obtain access.  It is important to have the right team of professionals conducting your access negotiations, performing the sampling events, and evaluating your data.

To learn more about vapor intrusion and negotiating access to conduct VI sampling, click here to register for the webinar on August 5.


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