HDR Engineering, Inc. 4/8/2025 Amendment 1

EXHIBIT A ADDITION TO SCOPE OF WORK Task 5.2 – PBDE Reduction Program and New NPDES permit support (NEW TASK UNDER EXISTING TASK 5.0 ON-CALL BUDGET ALLOWANCE) The City was issued a new NPDES permit on November 21, 2024 with effective date of January 1, 2025. The permit requires substantial new activities and submittals under a newly-established PBDE Reduction Program. Additionally, new monitoring is required for PFAS and other compounds. HDR will support the City in NPDES permit compliance activities and deliverables as directed by the City. Establishing this task under the existing on-call budget allows a means to track expenses for related support services. Specific deliverables and known support needs include the following: • PBDE Quality Assurance Project Plan (QAPP) – This submittal is required to memorialize the PBDE sampling plan and quality assurance/quality control protocols. HDR will assist in preparing the QAPP based on experience from other Ecology-approved QAPPs and standing City protocols for PBDE sampling. • PBDE BMP identification and implementation – PBDE reduction best management practice (BMP) identification and implementation is required and to be documented as part of the City’s annual pretreatment report. HDR will assist the City with evaluating industrial user sampling data, BMP identification, and implementation strategies. • Seasonal Flow Management – The NPDES permit requires the City to formalize operational protocols aimed at minimizing discharge to Outfall 015 during the March – June Chinook salmon migration window. HDR will assist the City with developing, evaluating, and documenting such strategies. • Technical Assessment of Lagoon process PBDE management – The NPDES permit requires the City to evaluate lagoon process management to identify viable strategies to minimize BPDE discharge from Outfall 015. HDR will assist the City with developing, evaluating, and documenting such strategies to the extent that viable strategies exist. • Overall PBDE reduction program evaluation and modification – The NPDES permit requires evaluation of PBDE reduction program efficacy and opportunities for adaptive management. HDR will assist the City with ongoing overall PBDE reduction program evaluation, adaptive management, documentation, coordination with Ecology, and related needs as directed by the City.