Ecological Evaluation Technical Guidance - State of New Jersey

e present at intervals greater than six inches, sampling at depth alsoshould be considered to evaluate potential future risks from the sediments,particularly if future dredging or scouring is likely to occur. To enhancecomparability of the resulting data, the same sediment sampling methodshould be used to collect samples from all of the sampling locations withinthe assessment area, whenever practicable. However, the need to collectboth surficial and deeper sediments may preclude this possibility in certaincircumstances.2. Sample VolumesA key factor of a given sediment study is the types of analyses requiredbecause the analyses will determine the sample mass required and howsamples are processed. The sediment samples that are collected in thefield are likely to be subjected to physical, chemical, and/or biologicaltesting to support the overall sediment assessment program. Therefore,the collection of sufficient volumes of sediment at each sample location tofacilitate the preparation of subsamples for toxicity testing and subsamplesfor chemical analysis from a single, homogenized sediment sample needsto be given consideration prior to field implementation when dealing witha study design that includes multiple indicators of sediment quality.3. Other Typical ParametersIt is important that conventional parameters receive as much carefulattention, in terms of sampling and sample processing procedures, as dothe COPECs or parameters of direct interest. Other parameters to considerfor analysis as a means to help interpret chemical, biological, andtoxicological data collected in an ERA at a sediment site include TOC,acid volatile sulfide (AVS), sediment grain size, total solids, ammonia,and total sulfides.4. Sample SizeThe number of samples collected directly affects the representativenessand completeness of the data for purposes of addressing project goals. Ageneral rule of thumb is that a greater number of samples will yield betterdefinition of the areal extent of the contamination or toxicity. Theappropriate number of samples is generally determined by the size of thestudy site, type, and distribution of the COPECs being measured,characteristics and homogeneity of the sediment, concentrations ofCOPECs likely to be found in the sediments, sample volume requirementsand desired level of statistical resolution or precision.B. Reference Area SamplingBasic guidance for background area sampling is provided in Section 5.3.4.This section describes the suggested reference area sampling to be used inmore comprehensive sediment sampling programs. Given that sedimentinvestigations typically include community surveys, toxicity tests, tissueresidue sampling, and bioaccumulation studies, the identification and selectionEcological Evaluation Technical Guidance Document 56Version 1.2 8/29/12