Asphalt - Clean Fill

The presence of asphalt materials at a site either in the form of "base material" (recycled asphalt), division berms,  or as "clean fill material"  (asphalt fragments/chunks) etc is an evolving topic in the state that needs to be clarified by the CTDEEP in the new regulation. 

The existing definition of "clean fill" contained at 22a-209-1 includes asphalt fragments.  The definition contains the following qualifier "The material must be virtually inert and pose neither a pollution threat to either ground or surface water".  However, virtually inert is not defined and the current working definition is so restrictive that little to no asphalt materials meet the definition of virtually inert. 

Based on verbal conversations with the department, the working definition of virtually inert means that PAH's and other constituent concentrations in water samples must be below groundwater protection criteria concentrations (GWPC), and direct exposure concentrations (DEC) in soil samples (even those containing observed asphalt fragments) must be below the Residential Direct Exposure Criteria (RDEC) for all constituents. 

The GWPC for PAH's is measured and reported in the low ppb concentration range.   The smallest asphalt fragment (unobservable to the negated eye) contained in a water sample from a monitoring well installed in asphalt containing fill material, and preserved to a pH of 2 will likely result in the exceedance of  the PAH criteria thus triggering remediation.  

This despite the fact that numerous 3rd party and independent studies have demonstrated that asphalt cement products are acceptable as a clean fill alternative in most instances and have very low leaching characteristics.

The CTDEEP should address the following topics relative to asphalt reuse in the proposed regulation:

1)  "Virtually inert" should be defined by a clear test or evaluation method with a scientific basis. Does the CTDEEP intend to define virtually inert" as asphalt that contains no constituents above the any RSR criteria regardless of the analytical test method used (i.e. total,  TCLP, SPLP etc)?  This seems to be an overly broad definition of inert that the majority of asphalt materials will not meet. 

Asphalt is a commercial chemical product suitable for use in both commercial and residential establishments.  There are millions of miles of roads and walkways in the US.  Pets and wildlife alike walk on asphalt pathways routinely.  In the case of pets, they lick there paws afterwards.     When a person falls and scratches their skin on an asphalt surface, PAH toxicity via the direct exposure route is generally not a concern.  The low toxicity of asphalt cement products is well established in technical literature and does not correlate well with published toxicity values for PAH's as standalone constituents. 

2) If the RSR criteria are used to define "virtually inert",  the regulation should clarify which criteria should be used to demonstrate compliance with the requirements of this regulation (presumably leachate (SPLP)) .  Asphalt sampling and analysis should then be exempted from the test methods used for evaluating the other criteria (i.e. direct exposure criteria as all asphalt materials would likely fail this test).   Exposure to asphalt concrete products is so widespread that some level of discretionary evaluation by the department is appropriate despite what the individual PAH concentrations would appear to suggest. 

3) The regulatory status regarding the historical placement of asphalt materials used as "clean fill" at a site should be clarified. If these materials are considered a concern moving forward, it would seem appropriate to set a date before which the practice was considered "acceptable".  Reuse of this material has historically been considered an acceptable management practice both inside and outside the State of Connecticut.  The historical use of this material should be recognized and established as an acceptable historical practice whether or not it is acceptable moving forward.  

4) Does the CTDEEP intend that the presence of surfacial asphalt materials (including base materials) that are not part of an active road surface become a recognized environmental condition requiring reporting and remediation?   The presence of surfacial asphalt materials at a site under the proposed regulation appears to represent a recognized condition that would likely require reporting and remediation (i.e. test results from asphalt of any kind would most likely identify PAH's and TPH above proposed direct exposure criteria regulatory thresholds),  These regulation, if enacted,  would impact a large number of sites in the state, and would generate significant unintended consequences for Connecticut businesses moving forward.  

Businesses that were encouraged to reuse asphalt materials in the form of aggregate base products etc would be impacted, and find themselves having to spend perhaps ten of thousand of dollars to return their property to pre-asphalt placement conditions.  Based on the available science, the proposed regulatory cure seems far worse that the condition.  

Sample problem
During a site investigation, acceptable industry practice is to install sampling points in locations that are most representative of the concern being evaluated.  In the case of fill material, this equates to installing sampling locations within the boundaries of the fill.  If the fill contains asphalt, this results in a condition where the sample will likely contains asphalt fragments and the sample will test above the RSR criteria for TPH and/or PAH's triggering a remediation requirement.  

  The available remediation options appear to be:
  1. Cap the area with an asphalt cap to make the area inaccessible and file an ELUR for the property.  It's hard to understand how this solution resolves any environmental long term concerns associated with the presence of asphalt.  Sites electing this alternative would then have exposed asphalt (in addition to the historically placed asphalt) which if tested for total PAH and TPH would likely test above the RDEC and or the IDEC for TPH and PAH's.   In addition to the presence of additional asphalt, the pollution generated during the placement of the cap is known and quantifiable.  It includes pollution related to the manufacture, transportation and placement of the material.   
  2. Excavate the material for offsite disposal at a permitted solid waste management site.  While this solution removes the asphalt material from the subject site, the pollution profile from the excavation, transportation, and placement of the asphalt material at the permitted facility is also quantifiable; as is the pollution generated from the transportation and placement of additional clean fill at the subject site.   
In conclusion, asphalt tends not to be used as fill material in the same nature as soil, which most of the direct exposure limits or guidelines are developed for. It is not a material with soil-like 
characteristics amenable to a human child digging or playing in. Most Asphalt fragment particle sizes
are much larger than soil and not suitable for ingestion. 

In construction, Asphalt fragments are typically used as structural or non structural fill below a layer of topsoil or other dirt. The scenario where Asphalt fragments would be most likely be in contact with humans is where the material was used as a surface material for a road, driveway or parking lot (See remedial option #1). It should be noted that the practice of using asphalt in areas with direct human contact is already common in the State of Connecticut.

In conclusion, it is seems well documented in technical literature that human exposure to asphalt concrete/pavement does not pose an increased risk to the humans or the environment in the absence of unique considerations.  It is widely accepted that the hazardous constituents know to be present in asphalt are permanently tied up in the asphalt concrete matrix and that exposure routes are limited. 

Based on the above, the department should consider asphalt cement products to have a separate and distinct toxicity value from non bound PAH's and should regulate them accordingly.