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MOUNTAIN HOUSE NEIGHBORHOODS K AND L INITIAL STUDY 5.ENVIRONMENTAL CHECKLIST S.HYDROLOGY AND WATER QUALITY h I excavation,stockpiling,and reconstruction of existing facilities involving grubbing, g 9 removal or replacement of facilities. The construction general permit requires that the landowner and/or contractor file ~-� permit registration documents prior to commencing construction, and then pay an annual fee. These documents include a notice of intent, risk assessment, site I map, storm water pollution prevention plan (SWPPP), and signed certification statement.The permit specifies a risk-based permitting approach that includes requirements specific to three overall levels of risk,which are determined based t on the potential for the project to cause sedimentation as well as the sensitivity of the receiving water to sedimentation. The three risk levels are used to determine i i specific numeric action levels and effluent limitations for pH and turbidity, and the requirements for a rain event action plan, best management practice(BMP) implementation, monitoring, and reporting. The SWPPP must include measures to ensure that all pollutants and their " sources are controlled; non-storm water discharges are identified and eliminated, controlled, or treated;site BMPs are effective and result in the reduction or elimination of pollutants in storm water discharges and authorized non-storm water discharges; and BMPs that are installed to reduce or eliminate pollutants after construction are completed and maintained.The SWPPP must demonstrate that calculations and design details as well as BMP controls for site runoff are complete and correct. Non-storm water discharges include those from improper dumping, accidental spills, and leakage from storage tanks or transfer areas.The general construction permit specifies minimum BMP requirements for storm water control based on the risk level of the site. The general construction permit stipulates that effluent and receiving water monitoring must demonstrate compliance with permit requirements, and that project proponents must take corrective action if these limitations are exceeded. The results of the monitoring and corrective actions must be reported annually to the State Water Resources Control Board (SWRCB).The construction general permit specifies minimum qualifications for a qualified SWPPP developer and qualified SWPPP practitioner(SWRCB,2010). Post-Construction Degradation of Water Quality. Pollutants from roofs, streets, FH parking areas,and landscape areas are carried by runoff into the storm water drainage network. Pollutant concentrations in site runoff are dependent on a number of factors, including land use, site drainage, intensity and duration of d rainfall, and the climatic conditions preceding the rainfall event. Due to the variability'of urban runoff characteristics, it is difficult to estimate pollutant loads in post-construction runoff; however, increases in urban contaminants such as oil and grease, petroleum hydrocarbons, and metals are likely in post-construction runoff from Neighborhoods K and L. In addition,storm water runoff volumes and rates generated from undeveloped, `— unpaved areas can increase significantly when a site is paved,the impervious 4 surface area is increased,and theability of surface water to infiltrate the ground I (91711 i) 5-111 l