Sediment Sampling. Only the top 2cm to 5cm of each sediment replicate shall be sampled for analysis of contaminants. A grab sampler which collects sufficient sediment from the surface 5cm with minimal disruption of the surficial layer shall be used.
Sediment Sampling. Prior to dredging the pond and sediment disposal and/or on-site reuse, the CONSULTANT will evaluate the potential presence of chemicals of concern (COC) in the sediment to assess if on-site reuse is a viable option. The objective of the proposed limited sediment sampling is to evaluate the presence of total petroleum hydrocarbons (TPH), volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), Priority Pollutant Metals (PPM), polychlorinated biphenyls (PCBs), Organochlorine Pesticides, Organophosphorus Pesticides, Herbicides, pH and ignitability at concentrations above relevant laboratory reporting limits. Three (3) sediment samples will be obtained and analyzed for the purpose of initial evaluation of whether on-site re-use is an option. The results of this sampling should not be considered representative of the total quantity of waste materials generated during dredging activities. Additional characterization may be necessary prior to transporting the material for off-site disposal at an approved treatment or disposal facility and/or on-site reuse of the material, as applicable.
Sediment Sampling. Sediment sampling is currently carried out by DINAMA, because the involved Municipalities do not have the appropriate instruments. The set of instruments is scheduled to be provided at the beginning of 2007, in the frame of a strengthening program of the Water Quality Department of DINAMA to the Municipalities, so that Municipalities are enabled to include this activity from then on. The training for the handling and conditioning of samples was already carried out during the pilot sampling. However, DINAMA could provide additional training if necessary.
Sediment Sampling. Two capping areas were proposed in the Reach J Capping Pilot Study Work Plan. Five surface samples (0 to 6 inches) will be collected from each capping area. One composite sample for each capping area will be created from the five cores and submitted for TEQ analysis. Sample locations will be spaced evenly throughout each area (e.g. oriented similar to five points of a die) to provide representative spatial coverage of each area to be capped. Sampling locations for each of these cap areas are depicted in Figures 2 through 3. The number of locations within each of the Reach J pilot cap areas is summarized below.
Sediment Sampling. VHB will conduct a due diligence review of existing sediment chemistry and physical characteristics compiled from previous sampling to assess any concerns and potential data gaps in the sediment quality and physical characteristic data with respect to sediment migration and ecological risk. VHB will rely on guidance contained in the NHDES Guidance Manual for Assessing and Managing Sediment Behind Dams/Barriers (WD‐16‐04) and will consult with NHDES water quality and dam bureau personnel to discuss any data needs and concerns. Given past sampling results and the 10‐year time span since the previous sampling, some additional sediment sampling is anticipated to be needed to confirm or update the status of previously observed chemistry, particularly the elevated levels of Polycyclic Aromatic Hydrocarbons (PAHs) and several metals that were above NOAA ecological screening thresholds in certain locations. VHB will prepare a brief sampling technical memo to outline the sampling goals and protocols and will consult with NHDES personnel to discuss and confirm exact locations and proposed analyses prior to collecting the sediment samples within the impoundment. The analytical results will be compared to applicable ecological risk thresholds for each contaminant using the most recent NOAA SQuiRT Tables or other relevant reference ecological risk values. Based on the selected ecological risk thresholds, the potential risk of adverse effects on benthic dwelling or higher trophic level organisms will be assessed. For budgeting purposes, VHB has assumed that nine (9) sediment samples will be collected at the following locations where all nine will be analyzed for grain size distribution to help refine the sediment transport analysis and five will be submitted for chemical analysis consistent NHDES guidelines. General Location Description No of Samples Chemical Analyses Grain Size Analyses Xxxxx Xxxxx confluence with impoundment 1 1 Xxxxx Xxxxx upstream near impoundment limits 1 1 Oyster River channel mid‐impoundment 1 1 Oyster River channel immediately upstream of dam 1 1 1 Notes: The eastern depositional area previously had elevated levels of PAHs and metals; thus two verification samples are included These general locations are consistent with the suggested guidance contained in NHDES’ Policy on Evaluation of Sediment Quality (NHDES‐R‐WD‐02‐9). Findings of the due diligence review will also be taken into considerations in selecting the final sampling locations. Each sa...
Sediment Sampling. Prepare Sampling and Analysis Plan (SAP): Prepare a SAP designed to evaluate compatibly of potential source material. The plan will include sample locations, physical (grain size) and chemical testing protocols, and quality assurance/quality control procedures. The results of the receiver site characterization conducted in Phase 1 will be included in the plan. A draft plan will be submitted to the U.S. Army Corps of Engineers (USACE), U.S. Environmental Protection Agency (USEPA), the Regional Water Quality Control Board (RWQCB) and the Southern California Dredge Materials Management Team for concurrence before finalizing.
