Puget Sound Marine and Sediment Monitoring Sampling Programs
2006 Routine Marine Beach Water Quality Monitoring Program
2006 Routine Shellfish Monitoring Program
Denny Way/Lake Union CSO Control Project Sediment Monitoring Program
Brightwater Outfall Studies
Duwamish/Diagonal Sediment Remediation
West Point Outfall Sediment Monitoring
Lower Duwamish Waterway Superfund Project
EBDRP Project
2006 Offshore Water Column Monitoring Program
Sixteen stations are sampled monthly as part of the 2006 Offshore Water Column Monitoring Program. Seven outfall monitoring stations are located at outfalls for the West Point, Renton, and Vashon treatment plants. Five ambient monitoring stations are located at Point Wells, Point Jefferson, Elliott Bay, Fauntleroy/Vashon, and East Passage. Two new ambient stations are located in inner and outer Quartermaster Harbor. Two additional ambient stations are located in the Duwamish River for the purpose of collecting water quality data essential to King County’s modeling efforts for the Lower Duwamish Waterway Superfund Project, Sediment Management Plan, and CSO Control Programs. The water column is profiled in situ from surface to depth for salinity, temperature, depth, photosynthetically active radiation (PAR), chlorophyll (fluorescence), dissolved oxygen, and transmissivity. Additionally, discrete water samples are collected from up to seven depths (depending on the station depth) at each station for the determination of fecal coliform and enterococcus bacteria, chlorophyll-a and pheophytin pigments, solids, and nutrients (ammonia, nitrite/nitrate nitrogen, total phosphorus, and silica) by laboratory analysis.
2006 Marine Beach Water Quality Monitoring Program
Water samples are collected monthly from 16 beach stations and one stream station as part of the 2006 Marine Beach Water Quality Monitoring Program. Six outfall-vicinity beach monitoring stations are located onshore of the Alki (two stations), West Point (two stations), Carkeek, and Vashon outfalls. The 10 ambient beach stations are located along the coast from south Snohomish County down to Normandy Park and Tramp Harbor. All of the beach monitoring stations are sampled monthly for analysis of fecal coliform and enterococcus bacteria, temperature, salinity, and nutrients (ammonia, nitrite/nitrate nitrogen, and total phosphorus).
2006 Shellfish Monitoring Program
Butter clams (Saxidomus giganteus) are collected from nine intertidal monitoring stations twice a year. Outfall-vicinity monitoring stations are located inshore of the West Point and Vashon treatment plant outfalls and the Alki and Carkeek CSO treatment plant outfalls. Ambient shellfish monitoring stations are located at Edwards Point, Point Wells, Golden Gardens Park, Fauntleroy Cove, and Normandy Park. Shellfish tissue samples are analyzed for metals and lipid content.
Denny Way/Lake Union CSO Control Project Sediment Monitoring Program
On-going sediment monitoring at this project site is being performed in accordance with the Biological Opinion issued for the project under the Endangered Species Act Section 7 consultation. The new Denny Way CSO outfall came on-line in May 2005. Post-operational sediment sampling will begin in 2006. Surface sediment samples from 16 stations will be collected and analyzed for sediment chemistry and benthic infauna. Some sediment toxicity testing may also be performed on a subset of the samples. Other program activities in 2006 include the collection and analysis of two surface sediment samples from the vicinity of the Denny Way Cleanup Area E. These samples will be collected and analyzed for sediment chemistry after completion of construction activities for the Seattle Art Museum (SAM) Sculpture Park intertidal excavation to evaluate whether the SAM intertidal excavation has impacted Cleanup Area E. Surface sediment samples may also be collected on the Denny Way sediment cap and from potential remediation Areas C, D, and E for chemical analysis and possible toxicity testing.
Brightwater Outfall Studies
There are several monitoring projects currently underway or planned prior to construction of the Brightwater Treatment System marine outfall (currently scheduled for 2008). For more information, please visit the Wastewater Treatment Division's Brightwater page.
Eelgrass Monitoring
A comprehensive marine outfall siting process began in 1998 to identify environmental constraints and to locate the outfall in an area with as little disturbance as possible to biological resources. Eelgrass results from a 1999 mapping effort indicated the presence of eelgrass along most of the shoreline where the outfall could be located given other constraints, such as slope stability. As it was not possible to site the outfall in a location totally devoid of eelgrass, the final outfall alignment were chosen in an area with as little eelgrass as possible to minimize impacts. Since the outfall construction will disturb intertidal and subtidal habitat, including eelgrass habitat, an eelgrass restoration and implementation workplan was developed by King County, Washington Dept. of Natural Resources, and Washington Dept. of Fish & Wildlife to determine the extent of existing eelgrass, the extent of construction impacts, and to assess recovery following construction.
Pre-construction and post-construction monitoring in the project area incorporates the use of side scan sonar and underwater video imagery for spatial information and SCUBA diver-collected density information. Pre-construction monitoring will be conducted three times: in 2004, 2006, and 2008.
King County will cultivate eelgrass for transplanting by harvesting and propagating shoots from the project area that is slated for displacement. This eliminates the need to disturb other eelgrass beds to obtain transplant stock. Salvaged eelgrass will be grown off-site for propagation and reproduction over five years to develop a larger population that can be used to replace eelgrass damaged from construction. Eelgrass transplanting into the project area will occur in the spring following construction. Transplanted eelgrass will be monitored for transplant success and habitat recovery over a 6-year period from 2009 to 2014, and potentially over an 11-year period (2019) dependent upon recovery success. Post-construction monitoring will use methods similar to the pre-construction monitoring methods. Post-construction monitoring design includes performance standards, or benchmarks, that can be used to verify site success or guide contingency actions if the transplant fails.
Intertidal Epifauna and Infauna Monitoring Project
The purpose of this project is to monitor and document recovery of intertidal biota following construction of the Brightwater marine outfall. During construction, all intertidal biota will be lost. It will be necessary to monitor the intertidal biota community prior to construction to establish a baseline which to assess recovery following construction. Epibiota and infauna will be surveyed twice at the project site prior to construction of the outfall and at least twice following construction. Two reference sites will also be monitored for comparison to the impacted site. This project is being done in partnership with the University of Washington and Washington Dept. of Natural Resources (WDNR).
A series of four intertidal transects will be established at each of the three beaches (the outfall corridor and two reference sites). To make data as consistent as possible with other WDNR Nearshore Habitat Program monitoring data, the SCALE sampling protocol for intertidal organisms will be followed. To more fully characterize the intertidal biota, transects will be run at 4 intertidal levels rather than just at MLLW. At each beach the biota at: -2’, MLLW (0’), Mean Low Water (+2.8 ft), and Mean Sea Level (+6.6 ft) will be sampled. This design concentrates sampling at the lower levels where the biota are much more diverse but provides a sufficient overview of impacts to higher–shore organisms as well.
At each site and each level, a 50 m transect tape running parallel to the water’s edge will be placed, along which 10 locations will be intensively sampled following the SCALE sampling protocol for intertidal organisms. Each sample consists of a 0.25 m2 quadrat in which all macroscopic surface flora and fauna (and percent cover of cobbles and sand) are enumerated, and a 10 cm diam x 15 cm deep core in which infauna are enumerated. Infaunal cores will be sieved on 4 and 2 mm sieves (to be consistent with the SCALE sampling protocol for this mixed substrate type), and organisms retained for identification later in the lab. The exception to this sampling plan is that following construction, the 10 samples will be taken along shorter transects at the impact site. This will enable most samples to actually be contained within the impacted section of the beach, which is anticipated to be considerably less than 50m wide. In addition, at each level and at each sampling date, 3 sediment samples will be taken for analyses of grain sizes (following standard grain size protocols).
This sampling protocol will be followed in summer of 2007, summer of 2008, and for at least 2 years after construction to follow the process of community recovery.
Baseline Sediment Characterization at the Outfall Diffuser
King County is undertaking a baseline sediment characterization in Autumn 2006 at the planned terminus of the Brightwater Treatment System marine outfall. This characterization will assess sediment quality in the vicinity of the outfall alignment prior to construction activities and operation of the outfall.
The work conducted during the 2006 sampling event will represent the first year of a planned three-year sediment characterization study. Similar sampling events will occur in both 2007 and 2008, prior to commencement of outfall construction activities. The sediment quality baseline established during this study will be used as a reference point, against which to compare future monitoring data.
King County conducted its first sediment characterization for the Brightwater marine outfall during 2001. Sediments from the outfall diffuser location were mainly a sandy-silt with a relatively large clay fraction, indicating areas of deposition. The organic carbon content was consistent, ranging from 1.4 to 1.6%. Concentrations of trace metals and organic compounds were similar between all initial stations sampled and all well below their respective regulatory and guidance criteria. Based on the similarity of these results, ten sediment chemistry stations were selected for the Brightwater marine outfall baseline sediment characterization. The number of stations, as well as their positioning, was also based on guidance for sampling multi-port diffusers. Samples will be comprised of sediment composited from a minimum of three deployments of a 0.1m2 modified van Veen grab sampler, which will be collected concurrently with benthic taxonomy samples.
The benthic community assemblages found at all stations sampled in 2001 were virtually identical, almost completely dominated by a single species of small clam, Macoma carlottensis. Sampling stations in the outfall diffuser area were all located at depths within a range of -570 to -700 feet MLLW and physical sediment properties such as particle size distribution and organic carbon content were consistent. Previous benthic studies performed in Puget Sound have documented the domination by M. carlottensis in deep, muddy, clayey sediments such as those found at the Brightwater outfall diffuser location As a result of the previous, consistent benthic results, samples for benthic taxonomy analysis will be collected from only three stations proximal to the outfall alignment and from one nearby reference station. Benthic taxonomy samples will be collected in triplicate at each station to evaluate environmental variability. Sediment chemistry analysis will also be performed on a sample collected from the benthic taxonomy reference station.
Ten of the sediment chemistry stations will form two transects, perpendicular to the planned outfall alignment and parallel to the mean current flow and bathymetric contours. Each transect will consist of five stations with the center station positioned at the diffuser location, two stations positioned at the northern and southern edges of the calculated mixing zone (approximately 805 feet), and two stations positioned midway between the edges of the mixing zone and the diffuser location (approximately 402 feet). A single station, located approximately 3,200 feet north of the diffuser location will also be sampled for sediment chemistry to evaluate chemical concentrations at the benthic reference station.
The benthic taxonomy samples will be collected from the western-most transect; at the end-of-pipe station and at the two stations located at the northern and southern edges of the planned mixing zone. Benthic taxonomy samples will also be collected from the nearby reference station. Benthic taxonomy samples will be collected in triplicate at each of the four stations for a total of 12 samples.
Sediment chemistry samples will be collected from the top two cm of sediment to characterize the most recently deposited material, and will be composited from sediment recovered from a minimum of three deployments of the grab samplers. Samples will be composited, homogenized, and split into laboratory containers in the field. Parameters of interest will include trace metals and organic compounds, as well as conventional sediment chemistry and physical properties.
Sediment chemistry analytical parameters were selected primarily based on Washington State Department of Ecology guidance for conducting sediment studies and will allow comparison of analytical results with published sediment quality criteria. Other analytical parameters were selected based on previous sediment studies in the vicinity, as well as a desire to begin monitoring emerging chemicals of concern such as nonylphenols and polybrominated diphenyl ethers (PBDEs). Analytical parameters will include:
- conventionals – ammonia, particle size distribution, total organic carbon, total solids, and total sulfide;
- metals – aluminum, antimony, arsenic, beryllium, cadmium, chromium, copper, iron, lead, mercury, nickel, selenium, silver, thallium, and zinc; and
- organics - base/neutral/acid semivolatile organic compounds (BNAs), butyltins, chlorinated herbicides, chlorinated pesticides, organophosphorus pesticides, PBDEs, polychlorinated biphenyls (PCBs), and total nonylphenols.
Benthic taxonomy samples will be collected concurrently with chemistry samples from three outfall stations and the nearby reference station. Each of these sediment samples will consist of the entire contents of a single van Veen grab sampler. The deployment of tandem van Veen grab samplers will allow the concurrent collection of the chemistry and benthic taxonomy samples.
Nearshore Benthic Community Characterization
King County is undertaking a baseline benthic community characterization in Autumn 2006 at the planned location of the construction trench for the Brightwater Treatment System marine outfall. This study will characterize the benthic community assemblages at the planned location of the outfall construction trench prior to construction activities.
The work will occur during three separate sampling events, conducted in 2006, 2007, and 2008, prior to commencement of outfall construction activities. Conducting three sampling events will allow King County to establish a benthic baseline and fully characterize the benthic community assemblage by evaluating inter-annual variability. The benthic baseline established during this study will be used as a reference point, against which to compare future benthic community data collected during post-construction monitoring events. The post-construction monitoring events will be conducted to evaluate the recovery of the benthic communities at the outfall construction trench site.
King County’s new Brightwater Treatment System will include a marine outfall that will discharge secondary treated effluent to Puget Sound. The outfall will consist of a 60-inch diameter pipeline starting on land at the Point Wells portal and continuing underwater approximately one mile offshore to a depth of about -605 feet referenced to mean lower low water (MLLW). A 500-foot diffuser at the end of the pipeline will disperse the effluent into Puget Sound through small ports placed along its length. The outfall was sited and designed to provide efficient mixing and dilution of the effluent, to be protective of water quality standards and the health of Puget Sound, and to maintain proper hydraulic performance over the design life of the outfall.
Open-trench excavation and pipeline installation will be utilized for 725 feet of the onshore segment of the outfall; from the portal to the tip of Point Wells just south of the existing Paramount Petroleum dock. Open-trench construction will continue for 525 feet; from the shoreline to a water depth of -80 feet MLLW. Trench sheeting is anticipated for both onshore and nearshore construction (up to -30 feet MLLW) to minimize trench width, thereby minimizing surface impacts. The remaining pipeline length and diffuser will be placed directly on the seafloor. Unsheeted trench construction will occur from a depth of approximately -30 feet MLLW to a depth of approximately -80 feet MLLW. The maximum width of potential construction impacts along the unsheeted trench corridor is estimated at approximately 40 feet.
The goal of the nearshore benthic community characterization study is to evaluate the benthic community assemblages and fully characterize these communities prior to construction of the Brightwater Treatment System marine outfall. The study will occur over a three-year period to measure inter-annual variability in benthic communities within the nearshore area that will be trenched during outfall construction activities.
Sediment samples will be collected from seven stations within the proposed trench corridor, which will provide sufficient spatial coverage of the trench corridor as currently designed. The seven stations range in depth from -35 feet MLLW to -85 feet MLLW and cover an area roughly 40 feet wide by 175 feet long. The shallowest sampling station was established to be protective of nearby eelgrass, which has been surveyed at a maximum depth of -25 feet MLLW in the trench corridor. The deepest sampling station was established at -85 ft MLLW to encompass the full length of the trench corridor, which has been designed to a maximum depth of -80 feet MLLW.
Sediment samples will be collected for taxonomic identification of benthic organisms as well as measurement of biomass. Benthic taxonomy samples will be collected in triplicate at each station, which is the minimum number of replicates recommended in the Puget Sound Estuary Program’s Puget Sound Protocols. Sediment samples will also be collected for analysis of conventional parameters to characterize the physical structure of the sediment from which the benthic organisms were collected.
Benthic taxonomy and sediment conventionals samples will be collected concurrently from the top 10 centimeters of sediment, representing the most biologically-active zone. Tandem van Veen grab samplers will be deployed with benthic taxonomy samples collected from one of the grabs and sediment conventionals samples collected from the other grab. A minimum of three successful grab deployments will be done at each station to collect the triplicate benthic taxonomy samples. The sediment conventionals samples will be composited from sediment collected from the same three grab deployments as the benthic taxonomy samples.. The sediment conventionals samples will be thoroughly homogenized prior to subsampling to minimize environmental variability.
Duwamish/Diagonal Sediment Remediation
The objective of this project was to remediate sediment identified with legacy phthalate and PCB contamination stemming from four pipes that discharge into the Duwamish/Diagonal area of the Duwamish River. The project site is on the east side of the Duwamish River, upstream of Harbor Island and immediately downstream of Kellogg Island in the lower portion of the Duwamish River. The site is within the south industrial section of Seattle. The project isolated contaminated sediment near the following four outfall pipes on the Duwamish River in Seattle:
- Diagonal Way storm drain
- Duwamish combined sewer overflow
- Former Diagonal Avenue Treatment Plant outfall
- Diagonal Avenue South storm drain.
Contaminated sediment was isolated from the environment by building an isolating sediment cap. A layer of contaminated sediment was mechanically dredged from the site in order to provide the space necessary for the sediment cap. Following dredging, a thin layer of sand was place around the dredged area to reduce the level of contaminants from previous dredging activity.
Remediation was completed in 2004 and a 10-year monitoring plan is currently in progress. The Duwamish/Diagonal CSO/SD Sediment Remediation Project Closure Report was issued July 2005.
This project is part of the Elliott Bay/Duwamish Restoration Program, or EBDRP.
West Point Outfall Sediment Monitoring
NPDES-required sediment sampling and analysis at the West Point outfall will be completed in 2006. Sediment samples will be collected from between 12 and 18 stations for analysis of Sediment Management Standards (SMS) chemicals of concern as well as conventional parameters. Bioassay testing will be performed on two of the samples and may be performed on additional samples if they exceed one of more SMS chemical criteria. Benthic community analysis will be performed on a subset of the samples collected for chemical analysis.
Lower Duwamish Waterway Superfund Project
King County is a participant in the Lower Duwamish Waterway Group (LDWG), which also includes the City of Seattle, the Port of Seattle, and The Boeing Company. For more than three decades, the individual partners of the LDWG have been involved in environmental cleanup and habitat restoration efforts along the Duwamish. Their work complements federal Superfund requirements, assesses targeted human and ecological risks, and carries out cost-effective cleanup actions as quickly as possible.
EBDRP Project
Elliott Bay Nearshore Substrate Enhancement Project
A nearshore subtidal enhancement project was initiated in March 1998 near Duwamish Head in Elliott Bay, Washington to increase habitat diversity for marine organisms by introducing approximately 60 cubic yards of material. The project was undertaken jointly by the Elliott Bay/Duwamish Restoration Panel (comprising federal, tribal, state, and local agencies) and the U.S. Army Corps of Engineers to address natural resource damages in Elliott Bay. The Elliott Bay Nearshore Substrate Enhancement Monitoring Report was published in December 2000.
Substrate material, placed at –4 to –12 ft. and at –35 ft. MLLW, consisted of pea gravel and oyster shell (one plot each), quarry spall and cobble (3 plots each). The materials were chosen to enhance productivity of benthic infauna, increase the distribution and density of macroalgae and other primary producers, and improve the attributes that support resident and migratory marine and estuarine fish species. The materials were placed in 8 plots at 2 sites (off Duwamish Head and near Seacrest Park) with a maximum height of 18 inches. A five-year monitoring program was established to assess macroalgae and invertebrate colonization includes physical observation, biological sampling and video documentation.
Monitoring through September 2002 demonstrated that the cobble and spall substrates were effective for increasing macroalgae and providing cover for fish and invertebrates. Epibenthic invertebrate surveys conducted at the pea gravel plot were inconclusive due to the limited sampling size. The oyster shell plot showed red rock crab and shore crab recruitment but not juvenile Dungeness crab recruitment.
This project is part of the Elliott Bay/Duwamish Restoration Program, or EBDRP.
Norfolk Combined Sewer Overflow (CSO) Sediment Remediation Project
Contaminated sediments from the Duwamish River were removed in order to enhance and restore the river habitat in the area around the Norfolk Combined Sewer Overflow (CSO). The Norfolk CSO is located near the south end of Boeing Field on the Duwamish River and is part of the King County wastewater system. Precipitation run-off and, at times of heavy rainfall, untreated sewage can discharge into the Duwamish River at the CSO. Submerged sediments around the CSO were found to contain high levels of certain contaminants including mercury, bis (2-ethylhexyl) phthalate, and PCBs. Site remediation activities took place in February and March 1999 and consisted of dredging contaminated sediment and backfilling the dredged area to original grade with clean sediment.
Currently, the project is monitored for possible recontamination of the backfill sediment as a result of continuing CSO discharges. After the monitoring period is completed, the site will be evaluated as part of the early action sites in the Superfund area.
This project is part of the Elliott Bay/Duwamish Restoration Program, or EBDRP.
To download data from the water quality monitoring projects, please visit the CTD data download page. To request data from any of the other projects, please contact Scott Mickelson.
