FY26 Willapa Sediment Characterization Service

 2.  BACKGROUND

As authorized by Congress, the Seattle District, U.S. Army Corps of Engineers (USACE) is responsible for maintenance dredging of the Willapa Bay project components including the entrance channel at Tokeland Marina, the entrance channel and mooring basin access lane at Bay Center, and the entrance channel and mooring basin access lane at Nahcotta, in Pacific County, Washington.

USACE last dredged portions of the Willapa Bay navigation project in 2002. Since then, the Port of Willapa has used a small private cutterhead dredge to maintain portions of the project every two to six years. USACE has continued to evaluate the project, with sediment testing completed in 2007 at Tokeland, 2011 at Bay Center, 2014 at Tokeland, Bay Center, and Nahcotta, and 2020 at Tokeland, Bay Center, and Nahcotta. In the most recent characterization, all dredged material was found to be suitable for open-water disposal (DMMP 2021). Table 1 summarizes details regarding the dimensions of project features and estimated volume above authorized depth. The USACE is responsible for dredging portions of the authorized project as needed to maintain navigation.

3.  Previous Sediment Characterizations

The navigation channel is ranked “low” by the Dredged Material Management Program (DMMP) agencies for concern for potential contamination. Descriptions of the historical characterization efforts follow.

• Tokeland
• 1991. A single composited dredged material management unit (DMMU) sample representing the marina (including marina area P1) was collected in 1991 and analyzed for DMMP chemicals of concern (COCs). Three COCs (4-methylphenol, phenol, and pyrene) had detected exceedances; non-detect exceedances occurred for an additional number of chemicals. Bioassay testing was conducted, and the DMMP agencies determined that the dredged material was suitable for unconfined open-water disposal (DMMP 1991).
• 1998. Twelve individual grab samples were collected in March 1998 and composited into three DMMUs to represent 76,000 cubic yards (CY) from the entrance channel, marina, and marina area P1. There were no COC detections or non-detect concentrations that exceeded the DMMP screening levels. All material was found suitable for open-water disposal (DMMP 1998a).
• 2006. A total of eleven grab samples were collected from the entrance channel, marina, and marina area P1 in August 2006; the grab samples were composited into three composites to represent the entrance channel, marina, and marina area P1. Based on the two previous sequential testing rounds conducted in 1991 and 1998, the marina and marina area P1 were re-ranked from moderate to low-moderate for testing purposes. No COCs were detected above the DMMP screening levels. Five non-detected chemicals (hexachlorobenzene, dimethylphenol, benzoic acid, N-nitrosodiphenylamine, and alpha-chlordane) had detection limits that exceeded DMMP screening levels in one or all three DMMUs; bioassay testing was thus required for all three DMMUs. The results from the bioassay testing indicated that all of the material was suitable for unconfined open-water disposal (DMMP 2007).
• 2014. Eight cores were collected from the entrance channel, marina, and marina area P1 in September 2014 and composited into four DMMUs (2 surface and 2 subsurface DMMUs). No COCs were detected above DMMP screening levels; three COCs (total chlordane, dieldrin, and heptachlor) were not detected with elevated reporting limits above their respective DMMP screening levels in all four DMMUs. All DMMUs samples were subsequently analyzed for the standard DMMP pesticide COCs using a high resolution method with lower reporting limits; using this method, all pesticides were non-detect with detection limits below the DMMP screening levels. Total dioxin Toxic Equivalencies (TEQs) were below the 15 pptr TEQ and 5 pptr 2,3,7,8-TCDD threshold concentrations for dispersive disposal in Willapa Bay. Total TEQs (U=1/2 reporting limit [RL]) ranged from 1.2 to 2.7 pptr. All material was found suitable for unconfined open-water disposal (DMMP 2015).
• 2020.  Nine cores were collected in August 2020. Material from the cores were composited into three DMMUs to represent the entrance channel, marina, and marina area P1. All material was found suitable for unconfined open-water/flow-lane disposal (DMMP 2021).
  1.  Bay Center
• 1998. Tier 1 no-test for 15,000 CY from Bay Center Entrance Channel, based on a 1993 grain size characterization that showed 99.7% sand from two samples (DMMP 1998b).
• 2001. Vibracore samples characterized 38,000 CY of proposed dredged material. Cores were composited into three DMMUs: two surface and one subsurface DMMUs. Analyses included all routine DMMP COCs (including tributyltin [TBT], but no dioxin) and included special analyses for pesticides carbaryl and glyphosate. All chemicals were either detected or not detected below DMMP screening levels (SLs), and TBT was quantitated at levels well below the screening limit in the porewater of the three DMMUs characterized. All sediments were found suitable for open-water disposal (DMMP 2001).
• 2011. Port of Willapa proposed 18,000 CY of dredging in shoals leading to the Bay Center Marina. Five individual grab samples were composited into one DMMU. Laboratory analysis was conducted for the standard DMMP COCs plus glyphosate and dioxins. There were no SL exceedances; dioxin TEQ (U=1/2 RL) was 1.36 pptr. All material was found suitable for open-water disposal (DMMP 2011).
• 2015. Eight cores were composited into two surface DMMUs. Porewater TBT was not detected at 0.005 mg/L. Diethyl phthalate initially exceeded the SL in DMMU 2, but further replicated extractions and reanalysis did not replicate this finding. Because diethyl phthalate is a common laboratory contaminant, the DMMP concluded that the original finding was anomalous. Dioxin TEQs (U=1/2 RL) were 1.33 and 0.62 pptr, well below the 15 pptr TEQ threshold for Willapa Bay. All material was found suitable for open-water disposal (DMMP 2015).
• 2020. To characterize approximately 72,000 CY, six cores were collected in the Inner Channel and composited into two DMMUs for laboratory analysis of the DMMP COC list. In the Palix River access lane, three grabs were composited for one DMMU analyzing total solids, total organic carbon, and grain size under the Tier 1 no-test exclusionary status. and all material was found suitable for open-water/flow-lane disposal (DMMP 2021).
  1. Nahcotta
• 2004. In September 2003, cores were collected from a total of 17 locations and composited into four composite DMMUs to represent 145,000 CY of proposed dredging. Only standard DMMP COCs were analyzed for, and there were no detected or undetected results above screening levels. All material was found suitable for unconfined open-water disposal (DMMP 2004).
• 2015. In September 2014, forty cores were collected and subsequently composited to represent eleven DMMUs, of which one was a subsurface DMMU. No COCs were detected above DMMP screening levels. Two COCs (total chlordane and heptachlor) were undetected with elevated reporting limits above their respective DMMP screening levels in two DMMUs. All DMMU samples were subsequently analyzed for the standard DMMP pesticide COCs using a high-resolution method with lower reporting limits; using this method, no pesticides were detected or not detected above the DMMP screening levels. TBT (porewater) was undetected at 0.005 mg/L. Total dioxin TEQs were below the 15 pptr TEQ and 5 pptr 2,3,7,8-TCDD threshold concentrations for dispersive disposal in Willapa Bay. Total TEQs (U=1/2 RL) ranged from 1.2 to 3.7 pptr. All material was found to be suitable for unconfined open-water disposal (DMMP 2015).
• 2020. Sixteen cores were collected in the entrance channel and boat basin to characterize three surface and two subsurface DMMUs. Sampling was conducted in August 2020. The standard DMMP COC list was analyzed and no COCs were detected above DMMP screening levels. All material was found suitable for open-water/flow-lane disposal (DMMP 2021)
• OBJECTIVES

The objectives for this contract are as follows:

• to prepare a sampling and analysis plan (SAP) that shall be suitable for submission to the DMMP agencies for approval;
• to sample and characterize the sediments in the proposed dredging area as described in the SAP; and
• to prepare a report to document characterization results that can then be used by DMMP to make a suitability determination. This PWS includes preparation of the SAP; sampling and testing of dredged material; data collection and analysis; and report preparation
• SCOPE

Perform a sediment characterization in Willapa Bay. The services provided under this contract are detailed in Part 5 – Specific Tasks.

PLEASE SEE ATTACHED PWS, EVALUATION CRITERIA, & BID SCHEDULE for specific information and criteria for this acquisition.