Town Of Rockport Goodies Beach Stormwater Treatment Feasibility Study

Goodies Beach is a small (approximately 100’ wide) protected pocket beach frequented by residents and visitors to the Town of Rockport’s Marine Park. It has been the subject of past Public Health Advisories due to bacterial contamination. Through the extensive efforts of town staff and the Rockport Conservation Commission, the adjacent stormwater outfall pipe was identified as a contributor of contamination. Gartley & Dorsky Engineering & Surveying, Inc. was retained to “provide an estimate of the volume of surface runoff for the area draining to a culvert adjacent to Goodies Beach, to include peak flows and seasonal total runoff,” as well as to “identify and assess the feasibility of stormwater management options for eliminating or greatly reducing negative impacts on water quality observed at Goodies Beach.” Two watersheds associated with the outfall adjacent to Goodies Beach were delineated, characterized, and modeled for seasonal base flows, 1, 2, 5, 10,and 25-year return interval storm events, provided in Table 4 through 6.Maine Healthy Beaches performs water quality testing weekly at Goodies Beach during the summer season. Currently, Public Health Advisories are posted by Maine Healthy Beaches(MHB) when a single sample exceeds 104 MPN/100mL (MPN = Most Probably Number) of Enterococci or when five results within a 30 day period exceed 35 MPN/100mL. The objective of implementing water quality treatment is to beneficially reduce or decrease the number of Public Health Advisory Days by reducing Enterococci exceedances. To summarize this study we:  Determined the base and storm event related flows incident to the beach from the single input.  Concluded that treatment of bacterial contamination of stormwater, while atypical, is technically viable. Treatment costs, upon estimation, are high.  Identified, in confirmation with prior data, that additional surface waters and contamination sources remain as a potential risk. This risk brings into question the effectiveness of treating the outfall.  Short duration testing of rerouting the discharge pipe should be implemented upon acquiring the necessary permitting.  Further housekeeping, public education, and rulemaking is recommended.  After completing education measures, determine if bypass piping contributed substantially to reducing exceedances, decide if bypass should be permanent or to implement treatment.