Part III. Conducting the Sanitary Survey
Once potential pollution sources have been compiled through background research, the initial risk assessment, and special monitoring studies, the next step is to con- duct on-site investigations. Several areas may need to be re-surveyed, especially seasonal properties. It may be im- possible to prove that every factor is an “actual” pollution source; therefore, document all potential and confirmed sources. Every property within the watershed area of con- cern should be considered. This does not mean that there must be a thorough search of every property within a drainage area. Those properties that are far enough from any surface water drainage may not warrant an on-site investigation.
State agency partners, such as the DEP and DMR, may be able to provide sanitary survey technical support and expertise to the local code enforcement officer or plumb- ing inspector. It is especially important to coordinate with DMR if the area(s) surveyed affects a shellfish growing area. Municipalities may want to consider a regional approach to identifying illicit discharges within shared watersheds.
What to look for: 1. Environmental characteristics of the shoreline area
The dynamic nature of the coastal zone makes assessment of bacteria levels in the water column difficult. Bacteria concentrations vary depending on sunlight, rainfall, tidal stage, currents/waves/wind direction, temperature, and other features such as beach sand, seaweed wrack, and wild- life. While assessing the shoreline, consider all the potential bacteria sources during dry and wet weather conditions.
Where are the freshwater inputs to the beach or shoreline?
Freshwater inputs can carry contaminants from various sources in the watershed, especially during and following rainfall. Rain and resulting stormwater runoff transport non-point source pollutants (pet waste, manure, waste from malfunctioning septic systems, etc.) to rivers and storm drains, which eventually drain into coastal waters. Rainfall is associated with increased bacteria concentrations on
Conducting the Sanitary Survey
both seasonal and daily time scales. Concentrations higher than regulatory standards are generally greater within 24 hours after rainfall and decline over time.8 Excess rainfall can exceed the capacity of sewage treatment plants, lead- ing to combined sewer/sanitary sewer overflows delivering untreated waste into receiving waters.7, 30 Freshwater inputs to the shoreline can be a pathway of bacterial contamination. Studies of coastal watersheds have demonstrated a nega- tive correlation between salinity and fecal bacteria; in other