Utilization of the DQO Process in the Application of Sediment Data to the Sediment Quality Triad and its Outcome

Barbara Albrecht, EnSafe Inc., 201 North Palafox Street, Suite 200, Pensacola, Florida 32501 , Tel:  850-434-2230, Fax:  850-434-2288
William Hill, Southern Division Naval Facilities Engineering Command, 2155 Eagle Drive, North Charleston, SC 29419-9010, Tel: 843-820-7324, Fax: 843-820-7465
Tom Johnston, Tetra Tech NUS, Inc., 661 Andersen Drive, Pittsburgh, PA 15220-2745, Tel:  412-921-8615, Fax:  412-921-4040
Allison Harris, EnSafe Inc., 5724 Summer Trees Drive, Memphis, TN 38134, Tel:  901-372-7962, Fax:  901-372-2454

Nearshore sediments near a former waterfront paint stripping, metal refinishing, metal plating shop, and associated hazardous waste storage, were impacted from activities associated with the operations of this military facility from 1935 to 1980's.  Sediment analyses in 1993 indicated PCBs, PAHs, pesticides, and metals above screening benchmark values throughout the area.  Survival effects were noted in sediment toxicity tests performed with the opossum shrimp, Mysidopsis bahia, but not observed in tests with the sheepshead minnow, Cyprinodon variegatus.  However, sublethal effects were observed in the sheesphead minnow test. 

In 1995, two hurricanes, Erin and Opal, were experienced in the Pensacola Bay area.  In 1998, a third hurricane, Georges, was experienced.  The effect of the hurricanes on the site sediments is uncertain.  In addition, past data collection efforts focused on the top six inches of sediment only, and now there is concern about chemical concentrations at greater depth.  Dredging could possibly uncover contaminated sediments.  Therefore, decision-makers (i.e., EPA, FDEP and Navy) agreed to investigate the area to establish current site conditions. 

Using the Data Quality Objective (DQO) process, the investigation was designed to assess whether the sediments create a condition adverse to benthic communities.  If adverse conditions do exist, do they warrant remedial action?  Before collecting any samples onsite, the inputs, boundaries, and decision-making rules were established.  Sampling techniques, chemical analysis, toxicity analysis, detection limits, and order of sample collection were discussed and consensus was reached.  A decision-making triad was also developed to direct how the data were to be used.  Investigators weighed possible options for the site and explored all potential outcomes prior to entering the field and collecting the first sample.  This technique saved valuable time at the end of the study, where decisions were made.  In addition, decision-makers were able to fully support the final decision for the site. 

Clean-up Goals for a Coal Tar Deposit in a River Located in the Vicinity of a Former MGP

William Ayling, O’Brien & Gere Engineers, Inc., 5000 Brittonfield Parkway, Syracuse, NY 13221, Tel: 315-437-6100 Email: aylingwa@obg.com
Tracy Blazicek, New York State Electric & Gas Corporation, Corporate Drive, Kirkwood Industrial Park, P.O. Box 5224, Binghamton, New York 13902-5224, Tel: 607-762-8839, Email: tlblazicek@nyseg.com

Establishing sediment cleanup goals in river systems can be controversial largely because guidance for developing site-specific goals is limited and understanding of environmental risks is often incomplete.  Screening criteria provide a basis for preliminary evaluation of site risks, but clean-up goals require consideration of site-specific risks.  Natural attenuation is a component of all sediment sites, as complete removal of contaminants is often not technically possible or practical.

To establish site clean-up goals at a former MGP site, risks associated with PAHs were evaluated using several approaches.  A total PAH concentration of 4 mg/kg based on sediment sampling and analysis delineated an area around a pipe where a coal tar deposit was identified.  Environmental forensics were used to evaluate the composition of the PAHs in sediment where coal tar was not observed, but elevated total PAH concentrations occurred compared to local background.  Evaluating the fate of PAHs included comparing the environmental risks associated with “aged” and “fresh” materials. Urban background concentrations reported for sediment were compared to site levels.  Statistical evaluation of sediment concentrations identified median concentrations and statistical outliers.  Physical features of the site such as the size of the affected area, public accessibility to the site, sediment type, river bottom substrate, and the potential for downstream contamination were also considered.

Results supported the recommendation to use visual observations for guiding coal tar removal at the site.  Sediment concentrations of PAHs surrounding the coal tar impacted area were comparable to urban background levels.  The PAH composition of the sediment was “aged” suggesting reduced bioavailability to aquatic organisms compared to “fresh” sources.  The affected area was relatively small and the riverbed was comprised of primarily rocks, cobbles, and sand.  Silt was limited by the flow patterns in the river.  Public accessibility was also limited. These physical features supported the proposed clean-up plan.

Use of In-situ Dializers for Determination of Sediment Porewater Contaminant Concentrations

A. Lee Gustafson, Harding ESE, Inc., 32 Daniel Webster Highway, Suite 25, Merrimack, NH  03054, Tel: 603-889-3737, Fax: 603-880-6111

As part of many site investigations for risk characterization, an understanding of impact to biota which inhabit sediment is usually required. In many cases, contaminant concentrations in sediment are used to estimate the potential impact of constituents on benthic organisms. Estimation of porewater concentrations from sediment data using Henry’s law may result in erroneous data being used to calculate the potential risk to biota. In-situ dializers, which operate through osmotic processes, can be placed in sediment to allow collection of samples that are representative of porewater concentrations. Use of in-situ dializers allows laboratory analysis of contaminant concentrations in porewater, which can then be used to accurately estimate potential risk associated with porewater.

This approach has been used at a number of sites, including where specific data were needed to determine constituent concentrations within the upper six inches of sediment, as well as at twelve discreet intervals within the upper 18 inches of sediment. Site-specific in-situ dializer designs have been developed to allow collection of precise depth interval data.

Post-Remediation Biomonitoring at The United Heckathorn Superfund Site  

Nancy Kohn, Battelle Marine Sciences Laboratory, 1529 West Sequim Bay Road, Sequim, WA  98382, Tel: 360-681-3687, Fax: 360-681-3681
Carmen White, U.S. Environmental Protection Agency, Region IX, 75 Hawthorne Street, San Francisco, CA  94105,  Tel: 415-972-3010, Fax: 415-972-3520
Andrew Lincoff, U.S. Environmental Protection Agency, Region IX Laboratory, 1337 S. 46th St., Bldg. 201, Richmond, California  94804, Tel: 510-412-2330, Fax: 510-412-2304  

The United Heckathorn Site in Richmond, California, was listed as a federal superfund site in 1990, after California State Mussel Watch monitoring data from the mid-1980s showed that mussels in Richmond Harbor had the highest DDT concentrations in the state.  Pesticides had been formulated at Heckathorn between 1947 and 1966.  A marine sediment RI/FS was completed in 1994.  Between September 1996 and March 1997, 112,660 tons of pesticide-contaminated sediment was dredged from the waterway adjacent to the site.  EPA’s Record of Decision required post-remediation monitoring for at least five years to assess the effectiveness of sediment cleanup.  State Mussel Watch sampling and analysis methods and four State Mussel Watch stations in Richmond Harbor were adopted for the post-remediation biomonitoring program to allow comparison of pre- and post-remediation DDT bioavailability.  Mussel tissue and water samples were collected annually, starting six months after sediment remediation.  All samples were analyzed for chlorinated pesticides, and lipid concentrations determined in all tissue samples.  For the first three years, total pesticides in water were analyzed, but in 2001 and 2002, dissolved pesticides and total suspended solids were added to address pesticides associated with suspended particles.  In fall/winter 1997, mussel tissue concentrations were slightly higher than pre-remediation levels.  The next two years of monitoring showed a decrease in tissue concentrations to below pre-remediation levels, but not a dramatic decrease that would indicate significantly reduced bioavailability.  This triggered a sediment investigation that showed that surface sediment DDT concentrations exceeded the cleanup goal, and some concentrations were higher than those originally found during the RI/FS.  The sediment investigation and the most recent years of tissue and water concentrations suggest continued bioavailability of pesticides near the Heckathorn Site.

Capping Contaminated River Sediments

Joseph Mihm, P.E., Camp Dresser & McKee, 88 Parker Avenue, Massena, NY 13662,Tel: 315-769-7011, Fax: 315-769-6606, Email:  mihmje@cdm.com
Larry McShea, Alcoa Inc., 100 Technology Drive, Alcoa Center, PA 15069, Tel: 724-337-5458, Fax: 724-337-2451 Email: larry.mcshea@alcoa.com
Heather VanDewalker, Blasland, Bouck & Lee, Inc., 6723 Towpath Road, Syracuse, NY 13214, Tel: 315-446-2570, Fax: 315-445-9161, Email: hmv@bbl-inc.com
James Quadrini, Quantitative Environmental Analysis, LLC., 305 West Grand Avenue, Montvale, NJ 07645, Tel: 201-930-9890, Fax: 201-930-9805, Email: jquadrini@qeallc.com  

An in-river capping pilot study was conducted by Alcoa in the Grasse River in 2001.  A subaqueous cap was constructed over PCB-containing sediments in a seven acre portion of the river (750’ long, 400’ wide, 16’ deep) using various combinations of capping materials and placement techniques. The objectives of the study were to evaluate: placement techniques; coverage effectiveness; potential entrainment of underlying sediment into cap material; particle size fractionation; water column impacts; costs; and recolonization by benthic organisms.

The cap placement techniques included surface and subsurface clamshell placement and a tremie pumping method.  The cap materials tested included a 1:1 sand/topsoil mixture, a granular bentonite clay layer and AquaBlok (a manufactured composite aggregate core coated with bentonite clay).  The cap materials were installed in thickness’ ranging from 2-to 24-inches thick. 

The study was conducted with a test cell and a pilot cell phase.  Extensive monitoring was performed.  Cap materials were tested for grain size distribution, total organic carbon (TOC), lift thickness and PCBs.  Water column samples were analyzed for field parameters, suspended solids and PCBs.  Benthic samples were collected prior to and after capping.  The test cell monitoring results were evaluated to select the placement techniques and cap materials for use in the pilot cells.

Results of the pilot study indicate that capping of PCB-containing sediments can be successfully implemented in the Grasse River. Optimal results were achieved with a 12 inch lift of 1:1 sand/topsoil material applied at the water surface or subsurface via a clamshell.  Monitoring data collected during the study demonstrated acceptable cap uniformity and thickness, no significant PCB entrainment from the in-place sediments, and no significant fractionation of the cap material during placement. A WINOPS clamshell positioning system and crane operator experience were important to the success.  Water quality impacts during capping were negligible.

Remediation of a Sediment Contaminated Pond Located on a Sinkhole

Paul Reeser, P.E., Parsons, 2443 Crowne Point Drive, Cincinnati, OH 45241, Tel: 513-326-3040, Fax: 513-326-3044, Email: Paul.Reeser@Parsons.com

Sediment in a mid-western pond was contaminated by sludge from a package sanitary treatment system.  The pond water is considered a Water of the State because it discharges to a sinkhole, and remediation restrictions were made by the state regulators because of this.

Two options to clean the pond were considered.  The first was to dredge the pond.  Costs for dredging a ¼ acre pond, however, were relatively high.  Also, without being able to see the bottom of the pond, verification would be difficult.

The other option was to drain the pond, thicken the sediment in the pond bed, and haul it off-site.  The state, however, had several concerns about this method.  The first was that the water being discharged was considered contaminated.  NPDES concentrations limits would have to be met.  The second concern was that the state did not want thickening agents brought into the pond bed.  Further study of the pond geology demonstrated that most of the pond bed is located within a silty clay layer with a water table higher than the pond bed.  Thus water contacted by the thickening agent could be kept in the pond.  This arrangement allowed the project to proceed in a cost-effective manner, while maintaining the highest protection to the environment. 

Remediation of the pond began with dewatering.  Ammonia was reduced by enhanced aeration, while solids were treated using a particulate filter.  800 tons of sludge, as well as 95 tons of cement kiln dust, was disposed.  A compacted layer of sludge existed underneath a loose layer.  While the amount of sludge was nearly ten times the amount originally estimated, the final cost was only slightly higher than original estimate.  The site has been completely restored without damage to the underlying cave system or adjacent watershed.   

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