Amendment to Sediment Sampling by the City of San Diego at the Laurel Hawthorn Embayment

The proposed project involves an amendment to the previously approved sediment sampling project (previous project) by the City of San Diego at the Laurel Hawthorn Embayment in the city of San Diego, California. The previous project (Document No. 72368) involved sediment sampling in response to Investigative Order R9-2019-0040 (IO) issued by the San Diego Regional Water Quality Control Board (Regional Board) for the 84-inch stormwater conveyance system outfall in Laurel Hawthorn Embayment. Sediment samples were collected at twenty-three (23) specified locations to characterize sediment quality for benthic community protection. A marine sampling vessel was utilized to deploy the equipment to collect samples at each sampling location. Two collection techniques were utilized at each sediment sampling location including (1) grab samples and (2) core samples, consistent with the requirements of the IO. Following completion of the previous project, the Regional Board has requested recollection and analysis of sediment samples within the Laurel Hawthorn Embayment to fill data gaps identified during the initial investigation. The proposed project is a supplemental investigation that would include recollection of sediment surface grab and core samples using the same equipment and methods at a subset of the same locations identified in the previous project. The proposed project would include collection of sediment samples from twelve (12) of the twenty-three (23) previously specified locations within the Laurel Hawthorn Embayment. No sampling locations outside of the previously identified locations are proposed as part of this recollection effort. Bay sampling is anticipated to occur approximately between May and September 2026 and would take approximately four (4) days to complete. Due to its nature and limited scope, construction of the proposed project would generate a minor amount of vehicle trips and would require limited use of equipment. Therefore, impacts related to air quality, greenhouse gas emissions, and transportation and traffic are not anticipated to occur. Furthermore, the Applicant would be responsible for complying with all applicable federal, state, and local laws regarding construction demolition debris, hazards and hazardous materials, and stormwater.