Los Angeles Basin Contaminated Sediments Task Force

Summary of Sediment Screening Thresholds Committee Meeting
May 12, 1999

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Attendees

Lauma Jurkevics (CCC)
Steve Bay (SCCWRP)
Tom Johnson (POLB)
Michael Lyons (RWQCB)
David Moore (MEC Analytical)
Mitzy Taggart (Heal the Bay)
Guangyu Wang (SMBRP)
Hayley Lovan (Corps – Env.)
Ellen Johnck (SFBPC – conf. phone)
Brian Ross (EPA – conf. phone)
Steven John (EPA)

EPA will prepare a literature list addressing sediment screening values, approaches to setting such values, etc. Additionally, the list will include the PSDDA numbers and how they have been modified, as well as the Canadian, Great Lakes, and sediment inventory values. Information on the soon to be released EPA/Corps Equilibrium Partitioning Screening Guidance will also be included in this compilation. RWQCB Lyons provided copies of a portion of the SWRCB June 1990 document Evaluation of AET Approach for Assessing Contamination of Marine Sediments in California. Much of this information is currently available on the Internet. The Subcommittee members agreed to compile a list of documents, web addresses, etc., relevant to the issue of sediment screening values and will forward it to EPA to be compile into one master list.

The subcommittee continued the discussion initiated at the previous meeting on problems, if any, with the current process of evaluating sediment quality. Heal the Bay and POLB mentioned perceptions that the process was subjective and inconsistent in how testing is conducted and results interpreted. Without specific sediment quality values, Heal the Bay pointed out that it is difficult to set target values for watershed management measures.

POLB stated that, while it would be helpful to have sediment quality values, the Port does not do multiple sampling of sediments (e.g., collect samples, conduct bulk chemistry analysis, evaluate chemistry data, determine which sites may be suitable for ocean disposal by demonstrating the dredged materials pass biological testing, resample those sites and conduct biological testing). Typically, a best professional judgment is made up-front about which materials may pass biological testing and only those are tested. MEC Analytical pointed out that data from the vicinity of the proposed dredging would be helpful in making these judgments.

While CCC pointed out that a single value for a particular contaminant may not be sufficiently environmentally protective, MEC and RWQCB pointed out that AETs look at synergistic effects for co-occurring chemicals and that multiple AETs tend to screen out the possibility of missing problematic levels of contaminants.

EPA pointed out that what might appear to be inconsistency is actually a reflection of the flexibility that the regulations afford the agencies in determining suitability. While chemistry and biological testing data are a primary consideration in the suitability determination, other factors, such as the volume of the material, are also considered. The Greenbook and the Inland Testing Manual are effects-based measurements as there aren’t simple values for sediments regarding what is and what isn’t acceptable for ocean or aquatic disposal. Screening values are useful in eliminating from additional testing dredged materials that are clean enough for aquatic disposal; dredged materials with chemistry values greater than the screening levels would still need additional testing. Screening values provide only limited "predictability."

RWQCB and POLB stated that having sediment quality values that identified dredged materials that are too contaminated for aquatic disposal would be useful. EPA discussed that the Puget Sound program has this structure with the Maximum Level, which is a presumptive suitability failure (Tier IV testing can still be conducted on these materials to reverse or verify their disposal suitability). A greater degree of predictability is a benefit, although there is still a large gray area between the screening level and the maximum level where testing is required. Under the Puget Sound system some dredging operations will save testing money, while others will still need to spend additional dollars for extra testing. This is less of a "black box" mystery for the public as there is a level of comfort over what is defined as clean or as dirty – dredged materials that fall between the two values remain the problematic areas.

SFBPC indicated that in the Bay Area the goal is to save having to expend funds for testing while still being environmentally protective. Tier 1 determinations are common with approximately 90% of dredged materials requiring additional testing ultimately proving to be suitable for aquatic disposal. One concern of SFBPC was that the Inland Testing Manual does not have an "end of testing" trigger.

EPA stated that screening values would likely be a benefit to some projects by providing predictability while being environmentally protective.

SMBRP listed benefits of screening levels as cost savings from reduced testing requirements, time savings from reduced data review for individual projects and enhanced public confidence by having a consistent review process. Heal the Bay stated that their concern with the current process did not stem from lack of understanding about the process and the various testing requirements, but rather from the degree of subjectivity they felt was inherent in this process.

EPA discussed that national groups would likely scrutinize any local effort to set screening values. National ESGs, which set screening levels for various programs, are imminent. These values may provide a starting point, modifying the values for local conditions. Likely we could only ignore these ESGs if we eliminate screening of sediments completely (requiring full testing). A public draft document addressing ESGs will likely be available some time soon, with a user guide to be published in the Federal Register in the fall.

A possible starting place would be to determine what types of local data exist now, and then comparing these data with various approaches (AETs, ERL/ERMs, etc.). It would be possible to have a mix of numbers for different contaminants, for example, ESGs for pesticides, AETs for metals, etc. MEC pointed out that there is the precedent for effects-based testing (AETs) to be used in place of ESGs. This would be consistent with the regulatory requirement that decisions on suitability of sediments must be based on test data from the sediments.

Returning to the original question of whether there are problems with the current process, CCC staff voiced their support for the current procedures, and a preference for biological testing.

SCCWRP promoted an integrated approach which links northern and southern reaches of the coast from sediment quality values with ecological impacts and wide applicability (with identified reference sites, areas of concern, and areas of maximum concern). Formulating values that are applicable to many different programs (NPDES, clean-up programs?) through consensus approach would expand the usefulness of such values. MEC pointed out that ESGs were originally devised for TMDLs and are now being considered for dredging.

EPA stated that the Scientific Advisory Board has the position that ESGs are broader based than AETs (for example – PSDDA AETs don’t seem to be predictive in San Francisco Bay, but are more predictive for other marine waters). EPA proposed that it might be worthwhile to evaluate the current local data relative to other AETs, including potentially incorporating local data in to another AET database and recalculating local AET values. MEC concurred that AETs may be the most efficient approach.

The subcommittee generally agreed that the first step would be to summarize existing data, including the types of test conducted, chemistry, number of years of available data, types and results of biological testing, etc. POLB thought that while the Ports and the Corps would be the primary sources of these data, typically the most problematic materials have not been evaluated, as the Ports and Corps have simply considered these materials not suitable for aquatic disposal and saved on the testing costs by not including them in the sediment evaluations. RWQCB indicated that the Bay Protection and Toxic Cleanup Program would be able to provide that type of data.

The subcommittee agreed that it would be valuable to conduct a quick survey of the type and amount of data available currently. EPA opined that with approximately 10 years of Greenbook testing, and the inclusion of data from SCCWRP and SMBRP, we might already have a good start on AETs. EPA agreed to provide a "worksheet" of the type of information to be gathered in this initial data inventory. SMBRP, SCCWRP, EPA (EMAP), the Ports, Corps and RWQCB (Bay Protection) were identified as likely sources of sediment quality data.

The next subcommittee meeting was set for June 23 at 1pm to 3 pm at the Corps of Engineers office.


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