Amendment No 2 to PSA - Arcadis US Inc - WWTP Stress Testing Evaluation

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STANDARD AGREEMENT FOR PROFESSIONAL SERVICES Page 2 of 3 Between City of South Bend and ARCADIS U.S., Inc. Project Number: 03029041.0000 _. __......__. ...._..._ ...._ _ AMENDMENT No. 2 Schedule A-2 Scope of Amended Services and Related Matters ENGINEERING SERVICES BY ARCADIS Disinfection Pilot Testing: Arcadis will continue to perform a disinfection pilot test to determine the effectiveness of using 10 to 15 minutes of chlorine contact time in the existing chlorine contact tanks to achieve current microorganism kill permit limits. Three additional full scale and three additional bench scale pilot tests will be performed during typical peak wet weather flows. The intent is to perform the tests during a sustained 77 mgd peak flow event or close to it. Arcadis will work closely with the City to coordinate the time and date of the pilot tests. Arcadis will use the previously developed pilot testing protocol. Arcadis will provide the colorimeter, jar testing apparatus, sodium hypochlorite, and other equipment necessary to perform the bench scale pilot tests. The goals of the additional disinfection pilot testing are: • Perform three full scale pilot tests in the existing chlorine contact tanks using wet weather secondary effluent. • Perform three bench scale desktop pilot tests in the lab using wet weather secondary effluent. • Evaluate the effectiveness of less than 15 minutes of contact time in terms of (i) microorganism kill and (ii) chlorine concentration. Document the results for potential future use in IDEM discussions. In addition, Arcadis will analyze the most recent 5-years of MRO data and summarize the available influent ammonia into the chlorine contact tanks, and final effluent ammonia and TSS concentrations during wet weather and dry weather events. This is important because ammonia and TSS concentrations can impact disinfection. To date, the ammonia and TSS levels into the tanks during the pilot tests performed have been low, and it is important to understand a worse case situation. Arcadis will summarize the results of the pilot testing in a brief memorandum. Meetings and Site Visits: Arcadis will attend one additional meeting via conference call to discuss the pilot test results with City staff. Pilot tests will be performed on site and will require three site visits. The pilot tests are scheduled to be performed during May to July 2019. Should the pilot test schedule extend beyond the anticipated date or additional tests be desired, additional visits may be necessary through a future amendment. INFORMATION PROVIDED BY CLIENT Client will provide the following information and assistance during the assignment: 1. Assistance to obtain the secondary treatment effluent sample for the bench scale pilot test. 2. Coordinate wet weather events and timing of pilot testing. 3. Maximize the chlorine dose to the fullest extent during pilot events. 4. Analyze E. coli samples (estimated total number of samples: 28 per test). 5. Analyze ammonia samples (estimated total number of samples: 4 per test). 6. Analyze TSS samples (estimated total number of samples: 4 per test). 7. Provide Monthly Report of Operations (MRO) and other operational data for 5-year period with available influent ammonia into chlorine contact tanks, and final effluent ammonia and TSS concentration data for analysis. SB W WTP Peak Flow Stress Testing and Optimization_Amendment No. 2