Ecological Evaluation Technical Guidance - State of New Jersey

of appropriate reference area samples is a key component to consider in thedevelopment of a sediment study design. Comparison of site sediments tomultiple reference area sediments representative of the physical characteristicsof the site sediment will facilitate interpretation of the resultant data. Furtherguidance on the use of reference area samples for sediment and sediment porewater toxicity tests are provided in Appendices D and E, respectively.To ensure meaningful comparison of sediment chemistry and toxicity testresults, it is important that physical and chemical factors at the reference areaaffecting the site chemistry and bioavailability (e.g., grain size, TOC, Eh, pH,concentrations of salts, nutrients, chemicals, and AVS) are similar to theconditions at the site. In addition, habitat conditions at reference arealocations should be as similar as possible to ensure that receptors identified asappropriate for site conditions also might be exposed to reference areas. Ifsite conditions are heterogeneous, it may be necessary to select more than onereference area for evaluation to ensure that all possible variations areaddressed.If an off-site reference area is selected, it should be located within the samewatershed and should be of a similar habitat type. Any differences inmorphology between the reference area and the site should be documented.Contaminant levels in the reference area should also be characterized anddocumented. In addition, established regional background contaminant levels,reflecting ambient sediment or tissue concentrations based on monitoring datacollected from throughout a specified area over a given period, might beuseful in select cases if reference area locations are not able to be established.6.2.2.2 Sediment Habitat Assessments and Community SurveysBenthic macroinvertebrate surveys have been performed historically byUSEPA and state regulatory agencies to evaluate the ecological integrity ofaquatic systems as mandated by the Clean Water Act. More recently, theyhave been used in conjunction with other analyses such as sediment chemistryand sediment toxicity tests to provide a measure of ecosystem health. Thistype of integrated approach, where sediment chemistry, sediment toxicity, andcommunity assessments are evaluated simultaneously, has been termed theSediment Quality Triad approach (Long and Chapman, 1985).Typically, benthic macroinvertebrate surveys are conducted to determinewhether the sediments at a given location are impaired (benthic communityshift) in comparison to a reference area. The survey consists of benthicmacroinvertebrate collection, organism identification, and data analysis. Dataanalysis often involves generating various metrics associated with community,population, and functional parameters such as species richness and toleranceindices (USEPA, 1990a).The benthic macroinvertebrate community is considered an important bioticcomponent of most aquatic systems and plays a significant role in thestructure and function of ecosystems, including the processing and transfer oforganic material and nutrient cycling. Benthic macroinvertebrates areEcological Evaluation Technical Guidance Document 57Version 1.2 8/29/12