SITE INFORMATION AND CORRESPONDENCE

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t Mike Vivas, P.E. City of Lodi's City Hall Annex May 17, 2002 Page 3 of 4 5. dimensions of each outside (fresh) air vents installed on the return air ducts of the East and West roof units (HVAC modifications). This information will allow ESU to perform a mass balance of air to evaluate if additional measures could further reduce indoor air contaminant concentration(s). Additionally, we recommend that indoor air monitoring frequency continue on a monthly basis to confirm the instituted controls are effective. Once this has been established, we recommend that indoor air monitoring frequency be reduced to quarterly. With regard to performance evaluation of the HVAC modification and compliance with Title 24 CCR, the data collected pursuant to ESU's recommendations for continued monitoring above must be reported to allow further assessment of the performance of the HVAC system and other indoor air controls. The operating cycle for each HVAC unit in hours per day should also be reported. To further evaluate whether sufficient ventilation is achieved, additional information is required. Via e-mail ESU has requested information from the City of Lodi regarding the frequency of the City's inspections of the HVAC systems of the City Hall Annex. ESU has requested this information be included in the next report and that confirmation of the air exchange rate(s) be verified if the concentrations of VOCs remain at levels of concern. (Confirmation via pitot tube at the vents, ducts, use of hoods to obtain velocities, etc.). ESU has not received this information. Due to the increased flow of unconditioned air, there will be a higher electrical demand and seasonal cooling/heating loads. Based upon the current HVAC system configuration, the economizer (south unit) will assist reducing the HVAC loading (cooling or heating). When the city provides the requested information a more thorough evaluation can be performed to determine what additional measures, if any, may be required to comply with Title 24 CCR. ADDITION RECOMMENDATIONS AND COMMENTS Previously, I sent you an e-mail with the following four comments which you forwarded to John Bird of Magellan Environmental, Inc. regarding the proposed WORK PLAN addendum for indoor air sampling: 1. Although, 8 hours will be the duration of the sample gathering, the submittal does not include when the approximate start and end of the collection period will be (i.e., sample to be collected from 8 AM - 4 PM or some other time, etc.). 2. There is no mention of the start and shut-off times of the current HVAC system (i.e. system on at 6 AM and off at 5 PM). This information may be critical in providing a solution to indoor air issues.