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Mr.Aragon November 21, 2008 Page 5 of 9 ■ Covering the excavation area at the end of each day if vapors/odors were encountered. To monitor the excavation operations for volatile organic compound (VOC) emissions, a photo- ionization detector (PID) (MiniRae 2000) was used to measure VOCs in air. The PID was calibrated daily to 100 parts per million (ppm) isobutylene during excavation operations. Results from the monitoring showed no elevated levels of VOCs in the air. Table 2 provides the results of VOC monitoring data collected during the excavation operations. Dust Monitoring To comply with the federal, state and local air quality regulations, dust control measures were implemented during remediation activities. Because the planned excavation operations were completed during fall months, which is typically warm and dry, fugitive dust mitigation measures were implemented. Typical dust control measures included water spray to eliminate visible dust and placement of impacted materials into roll-off bins. Dust suppression measures were conducted through the application of water from an on-Site water source. Special considerations were applied during all earth moving operations (excavation and loading of impacted soil and unloading of clean soil). Care was taken to avoid visible emissions from excavation and loading operations. During excavation and loading operations, dust monitoring was conducted on-Site using a portable dust meter (MIE pDR-1000) to measure potential dust emissions. Results from the dust monitoring showed that dust control measures were effective in controlling dust emissions to levels below the federal, state and local standards. Dust monitoring results are provided in Table 2. Noise Control Engineering controls were implemented to reduce noise to acceptable levels. In compliance with the City of Tracy noise ordinance, on-Site work hours were limited to 7:00 AM to 5:00 PM. The purpose of the noise control was to identify noise sources and receptors and to reduce the noise level during the Site operations via engineering mitigation measures. At a minimum, the following were incorporated into the requirements for excavation: ■ Sources of noise during remediation included heavy earth moving equipment and machinery, saw-cutting, and portable generator operation. Manufacturer's literature was reviewed and the manufacturer consulted for anticipated noise levels, and mitigation measures for reduction of noise. ■ Equipment operation was limited to daylight hours, Monday through Friday. ■ Routine and proper maintenance was conducted on equipment used during the excavation effort. In general, the excavation equipment was not exceedingly large and didn't generate elevated decibel levels. Stormwater Pollution Prevention All stormwater management systems complied with the procedures outlined in USEPA guideline manual Processes, Procedures and Methods to Control Pollution Resulting From All Construction Activity (USEPA, 1973). Because this project resulted in a disturbance of less than 1 acre, the project did not require a State Water Resources Control Board National Pollutant Discharge Elimination System General Permit for Storm Water Discharges Associated with Construction Activity (General Permit). As defined by State Water Resources Control Board Order No. 99-08-DWQ, a General Permit is not required for "construction projects that result in disturbance of less than one acre of total land area." However, stormwater pollution control best