Herrera Environmental Consultants Inc. 8/27/2022

Table 3. Building O&M Requirements. O&M Component O&M Activity Frequency Observe condition of interior concrete slabs and exterior sidewalks around perimeter of building Cement Concrete Maintenance noting newly formed cracks or the expansion of Yearly existing cracks. Venting Pipe Valves Exercise each valve. Quarterly Methane Monitoring Sensors Inspect Sensors and exercise alarms. Quarterly and Alarms Methane Monitoring Sensors Response Check for Recalibration 6 months Methane Monitoring Sensors Response Check for Recalibration and response located in ground floor spaces of check for ground floor space exhaust fan 6 months Work/Live Units activation With a handheld sensor, identify any locations Surface Monitoring around with methane concentrations exceeding Every 2 weeks for first 3 Exterior 500 parts per million. Investigate and eliminate months,then Quarterly source. With a handheld sensor, identify any locations Surface Monitoring of Ground with methane concentrations exceeding Every 2 weeks for first 3 Level Interior 100 parts per million. Investigate and eliminate months,then Quarterly source. Boots and Sealants around Visually inspect for any cracks or damage. Repair Every 6 Months Penetrations per manufacturer's instructions. Herrera may also design modifications to the Building LFG System that are needed to ensure proper operation of the system components. Herrera will provide site visits, as requested, for related system observation, sampling, and monitoring. Herrera will provide technical oversight as needed and requested by Riverfront. Assumptions • Building O&M activities detailed in Table 3 will be performed by Herrera and will begin when Buildings A and B are online which is anticipated for third quarter of 2023. • Surface air monitoring in the interior and around the exterior will be sampled by Herrera. • A SEM 5000 unit, provided by Riverfront, will be used for all surface monitoring events, logging methane concentration readings in 5-second increments. Data will be saved in EXCEL format. • Calibration gases for the SEM 5000 and the buildings methane monitoring sensors will be provided by Herrera. • Buildings A and B are assumed to come online at close enough dates in 2023 that surface monitoring for the 2 week intervals during the first 3 months will occur at the same time for both Buildings. • The surface monitoring data from the Buildings will be saved with the data from Task 2.0. Quarterly and Annual Summary Reports of all Task 2.0, 3.0, 4.0, and 4.2 data will be prepared as part of Task 2.0. 8