Appendix J Hydrology and Water Quality Analysis DRAFT Hydrology and Water Quality for North Communications Hill Development San José, California October 28, 2013 Schaaf & Wheeler Consulting Civil Engineers Hydrology and Water Quality North Communications Hill Table of Contents 1. Introduction ..................................................................................................................................1 2. Environmental Setting ...................................................................................................................2 2.1 Regional Setting ................................................................................................................................................. 2 2.1.1 Topography ........................................................................................................................................... 2 2.1.2 Climate................................................................................................................................................... 3 2.1.3 Precipitation .......................................................................................................................................... 3 2.1.4 Evapotranspiration ............................................................................................................................... 3 2.1.5 Regional Runoff and Infiltration ......................................................................................................... 4 2.2 Geology and Soils .............................................................................................................................................. 5 2.3 Surface Water Hydrology ................................................................................................................................. 6 2.3.1 Guadalupe River Watershed ............................................................................................................. 6 2.3.2 Coyote Creek Watershed................................................................................................................. 13 2.3.3 Project Surface Water Drainage ..................................................................................................... 15 2.3.4 Flooding................................................................................................................................................ 18 2.3.5 Other Surface Water Hazards........................................................................................................... 18 2.4 Surface Water Quality..................................................................................................................................... 19 2.4.1 Mercury ................................................................................................................................................ 19 2.4.2 Pharmaceuticals and Personal Care Products (PPCPs).............................................................. 19 2.4.3 303(d) List of Water Quality Impaired Limited Segments ............................................................ 21 2.4.4 Other Surface Water Quality Issues................................................................................................. 22 2.5 Groundwater .................................................................................................................................................... 24 2.5.1Groundwater Discharge Components ........................................................................................... 26 2.5.2 Groundwater Recharge Components........................................................................................... 26 2.5.3 Groundwater Levels........................................................................................................................... 28 2.5.4 Groundwater Quality......................................................................................................................... 29 3. Regulatory Framework................................................................................................................32 3.1 Federal Regulations ......................................................................................................................................... 32 3.1.1 National Flood Insurance Program ................................................................................................. 32 3.1.2 Clean Water Act................................................................................................................................. 32 3.1.3 National Pollutant Discharge Elimination System Permit ............................................................. 33 3.1.4 Section 404 of the Federal Clean Water Act ................................................................................ 33 3.2 State Regulations ............................................................................................................................................. 33 3.2.1 Porter-Cologne Water Quality Control Act ................................................................................... 33 3.2.2 NPDES Municipal Stormwater Permit .............................................................................................. 33 3.2.3 NPDES General Permit for Construction Activity........................................................................... 33 3.2.4 NPDES Industrial Discharge Permit(s)............................................................................................... 34 3.2.5 California Fish and Game Code - Lake and Streambed Alteration ......................................... 34 3.2.6 California Department of Public Health Drinking Water Program............................................. 34 3.2.7 Dam Safety.......................................................................................................................................... 35 3.3 Local Regulations............................................................................................................................................. 35 3.3.1 City of San José .................................................................................................................................. 35 3.3.2 Santa Clara Valley Water District .................................................................................................... 41 3.3.3 San Francisco Bay Conservation and Development Commission............................................ 41 4. Project Analysis ..........................................................................................................................42 4.1 Introduction....................................................................................................................................................... 42 4.2 Project Location ............................................................................................................................................... 42 4.3 Description of Project ...................................................................................................................................... 43 4.4 Surface Water Drainage................................................................................................................................. 45 Schaaf & Wheeler i October 28, 2013 Hydrology and Water Quality North Communications Hill 4.5 Drainage Design .............................................................................................................................................. 48 4.5.1 Tuscany Hills Drainage System.......................................................................................................... 48 4.5.2 No Detention Basin Areas ................................................................................................................ 53 4.5.3 North Development Area ................................................................................................................. 53 4.5.4 North Residential/Commercial Area .............................................................................................. 53 4.5.5 Industrial Area ..................................................................................................................................... 57 4.6 Umbarger Road Drainage System................................................................................................................ 60 4.6.1 Drainage Area .................................................................................................................................... 60 4.6.2 System Performance.......................................................................................................................... 62 4.6.3. 72-hour Storm Results ........................................................................................................................ 69 4.7 Conclusion......................................................................................................................................................... 72 5. Environmental Impacts ...............................................................................................................73 5.1 Thresholds of Significance .............................................................................................................................. 73 5.2 Proposed Project.............................................................................................................................................