Solving Complex Environmental Problems #4: Using Cutting Edge Science to Avoid Ongoing Remediation

BSTI uses a science-based approach to close a site with LNAPL, save our client money and re-start a stalled real estate transaction.

The Problem

A release from a 30,000-gallon underground storage tank resulted in a body of diesel fuel above and below the water table (commonly referred to as light non-aqueous phase liquid or LNAPL).  This condition created a regulatory compliance problem, a financial burden on the property owner and severely complicated a planned real estate transaction.

Based on a thorough site characterization, BSTI determined that potential mobility of the LNAPL body would be the primary driver to achieving closure with the regulatory agency.  A traditional approach was first adopted that used a product recovery pump to actively remove available LNAPL from the subsurface.  During the recovery process, BSTI tracked recovery rates, in-well liquid levels, and assessed the efficacy of the system.  After several months, diminished returns of product recovery had been established and dissolved contaminants in groundwater remained below screening criteria at downgradient and perimeter monitoring wells. Despite establishing a technical argument for the cessation of LNAPL recovery, the regulator initially requested that additional recovery efforts be deployed based on an antiquated and unscientific “rule of thumb” cleanup criteria of reducing LNAPL thickness to less than 1-inch.  LNAPL thickness has been the prevailing regulatory criteria for the past five decades and remains the closure criteria on the majority of LNAPL cleanup projects.

The Solution

Rather than accede to the regulator’s request for additional LNAPL remedial measures, BSTI employed a science-based approach to clearly establish that the LNAPL remaining at the Site presented an insignificant exposure risk to human health and the environment. Using data collected from the site, as well as following recently developed technical guidance (1), BSTI developed a sound LNAPL conceptual site model (LCSM). The LCSM utilized multiple lines of evidence, including a LNAPL Transmissivity analysis, showing that recovery efforts had indeed reached the point of diminished returns and additional remedial efforts were unlikely to appreciably diminish the remaining LNAPL body at the site. Moreover, an exposure pathway analysis revealed no direct link between the LNAPL and potential receptors. Through the development of a LCSM for the site, BSTI demonstrated an acceptable level of risk for the LNAPL remaining at the site which would avoid a potentially costly and enduring process of continuing to apply additional remedial measures.

BSTI’s request for closure was approved by the regulator and liability relief was granted to the client.

Benefits to the Customer

By avoiding the additional active remediation at the site, BSTI saved its client from venturing into a costly cleanup with an unclear endpoint. Due to the scientific demonstration of a non-mobile LNAPL body at the site and the low levels of dissolved COCs in groundwater, the site was able to be closed by attaining generic cleanup standards. As a result, the client was relieved of adherence to a long-term care and monitoring plan, a deed restriction, or an environmental covenant.  The planned sale of the property took place without lingering environmental concerns.

Illustration of the conceptual release model showing the directional plume of the petroleum release and the location of the primary monitoring well.

For more information, contact Tripp Fischer at .

  • (1) The Pennsylvania Department of Environmental Protection’s Revised Land Recycling Program Technical Guidance Manual (TGM) was finalized on January 19, 2019. The TGM provides guidance for implementing the Chapter 250 regulations promulgated pursuant to the Land Recycling and Environmental Remediation Standards Act (Act 2 of 1995). The current TGM includes valuable guidance on defining the removal of LNAPL to the Maximum Extent Practicable (MEP). The LNAPL guidance in the TGM is based in large part on the Interstate Technology & Regulatory Council’s (ITRC) LNAPL Team publications and trainings ( ASTM’s LNAPL Transmissivity Guidance (E2856), and ASTM LCSM Guide (E2531).  BSTI’s Vice President and Principal Hydrogeologist Tripp Fischer, P.G. served as co-chair on this ITRC committee, is a trainer for the ASTM LNAPL Transmissivity Standard, and continues to provide training to regulatory bodies on the topic.

When Guidance Becomes Rule

Guidance Becomes Rule

I outlined before what makes a great guidance document, but that doesn’t automatically make the guidance a rule.


Guidance documents which standardize a set of procedures are typically not only relevant, but may even be required by policy or law. Federal law and policies, such as the Office of Management and Budget Circular A-119 (revised January 2016), even require federal agencies to refer to standards by “incorporation by reference” rather than recreating the material in federal code. In such cases, these “Voluntary Consensus Standards (VCS)” become law. A-119 expands not only on the federal government’s reliance on VCSs, but also encourages participation in the development process.  A-119 also requires that VCS’s which are incorporated by reference be developed in an open and balanced system and be considered for the costs associated with accessing the documents. Some standard development organizations, such as ASTM, have made available such referenced standards free to the public.


State and local regulatory agencies may also rely on industry guidance documents in their corresponding regulations. Most do not have policies or procedures regarding incorporation by reference, so it is imperative that these documents be reviewed during promulgation or when the public has an opportunity to review and comment. Regardless of the referring agency, complications may rise when these documents are not updated or where references included in those documents are out of date.


Finally, industry guidance may be written to support federal, state or local regulation but not necessarily referenced in the regulation. These may be state guidance documents, industry documents, or even peer-reviewed journals. Although not rule by reference, these documents sometimes become the “common law” simply by widespread industry acceptance. Users of these documents should be aware of their limitations, the process in which they were created and the frequency in which they are updated. Although useful for potentially predictive outcomes, these documents may be flexible and or open to challenge.


Guidance becomes the rule when either regulatory agencies refer to them in such a way or when widespread acceptance makes them the norm.


Return to Blogs >

What Makes a Guidance Great


The environmental science and remediation industry is chock-full of guidance documents. Some are wonderful resources, while others are a colossal waste of time. Some pass rigorous peer review processes prior to publication, while others are written in a vacuum. Whether you are reviewing one, learning from one or getting ready to participate in the creation of one, there are important fundamental concepts to consider in what makes one great. Every great guidance document shares the following qualities:

  1. The audience and purpose are clear
  2. The significance is clear and concise
  3. There is a current “go to” resource
  4. There is wide range acceptance or concurrence

Team - Guidance document

Clear Intentions to Audience

A user of any guidance should know within the first couple pages, if not by title, if the guidance is intended for him/her and what the purpose is. Generally, there are three primary purposes of guidance:

  1. To Inform a general audience by compiling multiple ideas, publications and research work into one concise document
  2. To Standardize a set of practices to reduce inconsistent behavior between practitioners
  3. To Regulate the user by either providing clarity or expanding regulatory language or by being incorporated into law

As you can imagine, the three categories listed above are not listed by importance. Informational documents are somewhat flexible in their usage while those that are referenced by law are not.



The resources which go into developing guidance documents are sometimes astounding. I have estimated the costs of human time, travel, and resources on a key industry document for which I had a leadership role and my estimate was very near $900,000. I was probably low. With this amount of resources, the whole project should start with the conversation of significance. Then, make sure the concept stays throughout the document in a very concise manner. The significance is simply why the document is important and what problem it is trying to solve.


Current “Go To” Resource

Many of the great guidance documents have that one set of tables, charts, figures, appendices, or matrices that make it a great resource. You pick them back up knowing exactly where you are going to go in it. The bad ones you look at as 100 pages of words and just go “ugh”. The resource also must be current or the user must know if the material has the potential to be out of date.

Graph - Guidance Document
Relevant and useful figures make a big difference in the quality of a resource.



Acceptance of a guidance document comes in many forms. Many industry leaders use Standard Development Organizations (SDOs), such as ASTM or ANSI, as an avenue for publishing guidance due to their rigorous concurrence procedures, such as balanced voting. Concurrence may also come in far less formal and less timely methods. For example, a guidance may be written by a state agency or small work group and become accepted industry wide simply based on use and word of mouth. This form of concurrence may take months or years following publication. An example may be a new, innovative but controversial guidance that takes years to “catch on.”


Take Home Message

Understanding the criteria listed above will help any user understand the applicability of an industry guidance document. More importantly, if starting one, this list provides a good starting point from which to base future discussions.


Return to Blogs >