CSA HDR Inc Nutrient Analysis 11-20-2024

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Consulting Services Agreement between City of San Leandro and Last revised 10/28/2024 HDR, Inc. for Nutrient Alternatives Evaluation Exhibit A – Page 1 of 7 EXHIBIT A SCOPE OF SERVICES Background Nutrients in the San Francisco Bay (SF Bay) are a growing concern for the Bay Area water quality community. Historically, the SF Bay has not been adversely impacted by nutrient loading. However, there are signs that its historic resilience to the effects of nutrient enrichment may be weakening. While the definition of impairment has not been reached, there is concern that SF Bay has reached a tipping point that might lead to impairment, especially following two harmful algae bloom episodes in the last several years. Numerous scientific studies have been conducted to understand the impact of nutrients on SF Bay. As a result, it may be necessary to limit the availability of essential nutrients by implementing nutrient removal to address three potential challenges: Ammonia toxicity and/or inhibition of phytoplankton growth. Full or partial nitrification may be required. Eutrophication. Denitrification may be required where total inorganic nitrogen is the limiting nutrient. Undesirable conditions of low dissolved oxygen (DO) concentration. This can result in aquatic life impairment. On July 11, 2024, the Regional Water Quality Control Board (RWQCB) adopted the third Nutrient Watershed Permit (watershed permit) and it includes nutrient load limits (both Baywide and for each outfall). In this third watershed permit, the final limits for major dischargers are based on a nitrogen concentration of approximately 20.5 mg/L and 2022 flows. This equates to an overall 40 percent load reduction Baywide for agencies discharging into the SF Bay. The third watershed permit will also include Interim Limits (May 1 through September 30) based on current treatment performance from May through September (95th percentile). For East Bay Dischargers Authority (EBDA), of which San Leandro is a Joint Power Authority (JPA) member, these interim limits will be 9,000 kg total inorganic nitrogen (TIN)/day. San Leandro, like other member agencies of EBDA and Bay Area Clean Water Agencies (BACWA), will need to document efforts to minimize nutrient discharges to the SF Bay and demonstrate progress on achieving compliance with final limits. There are also Final Limits (May 1 through September 30) that will demonstrate the attainment of the narrative biostimulatory substances objective by the dry season 2035. For EBDA, these limits will be 4,500 kg TIN/day. It is up to EBDA and its member agencies to decide the distribution of TIN discharge levels amongst themselves. Scope of Services The following scope is the expected services to be provided by HDR for the City of San Leandro Water Pollution Control Plant (WPCP). Docusign Envelope ID: F4C31A54-5BDC-41AE-BF85-10613D6DCA60