Optimization of Interim Offshore Monitoring Program at Portsmouth Naval Shipyard, Kittery, Maine

摘要

Background/Objectives. Portsmouth Naval Shipyard (PNS), Kittery, Maine, is located on anisland in the Piscataqua River, referred to as Seavey Island. The Piscataqua River is a tidalestuary that forms the southern boundary between Maine and New Hampshire. An InterimRecord of Decision for OU4 was signed in May 1999 that required the Navy to conduct interimoffshore monitoring for OU4. Therefore, the Navy prepared and implemented a monitoring planto provide data on the offshore areas to determine whether onshore remedial actions, naturalprocess, and/or other sources have affected the chemical concentrations in OU4. The data qualityobjective (DQO) process was used to identify data needs, decision rules, and data evaluationmethodology.Approach/Activities. Sampling was conducted at 14 monitoring stations located around PNSand at four reference stations in the Great Bay Estuary. The sampling program initially consistedof collecting sediment, mussel, and juvenile lobsters at the monitoring and reference stations,which were analyzed for a variety of parameters. Data evaluations were conducted throughoutthe monitoring program such as determining whether chemical concentrations were: (1)changing over time, (2) similar to background concentrations, and (3) greater than interimremediation goals, to name a few. To date, eleven rounds of samples have been collected. Basedon the results of the data evaluations, several modifications were made to optimize themonitoring program.Results/Lessons Learned. These modifications occurred at various points in the monitoringprogram and included the following: discontinuation of juvenile lobster and mussel sampling(after Round 5 and 7, respectively), reduction of analyte list (after Round 5, 7, and 10), andelimination of sampling stations (after Round 8). These modifications resulted in significant costsavings for the Navy, and allowed the project team to focus on those chemicals that wereconsidered the risk drivers and on those stations that continue to potentially impact ecologicalreceptors. Having several rounds of monitoring data allowed the Navy to better support therecommendation of remedial actions at four monitoring stations and no further action at tenmonitoring stations.