The Chollas Creek Watershed Master Plan

Transcription

1 The Chollas Creek Watershed Master Plan FMA Luncheon March 13, 2017 City of San Diego Rick Engineering Company Tetra Tech HELIX Environmental Planning

2 Key Drivers and Considerations Drivers Considerations Drainage Management Trash Water Quality CIPs O&M Rehabilitation/ Restoration Hydromod Asset Mgmt. 2

3 Role of a Watershed Master Plan Inform data-driven decision making using High-Resolution Data Prioritization Logic Specific Project Visualization Balance water quality, stormwater conveyance, and wildlife habitat Program Synergies Enable Wise Spending Specific Street-by-Street and Parcel-by-Parcel Project Recommendations

4 Project Location-Chollas Creek Upper Chollas Creek Watershed Master Plan 4

5 Components of the Watershed Master Plan Common Data High-Resolution Data Generation Surface cover DEM/Contours Impervious surfaces Rooftop extraction BMP identification Stormdrain system Field Investigations Water Quality LSPC Model H&H Existing PC SWMM Model Three Tier SUSTAIN Model Proposed PC SWMM Model Non-modeled Prioritization Criteria Prioritization Matrix WQ BMP verification Canyon BMP opps. Stormdrain inventory and surveying Env. Assessment Environmental Assessment Dynamic Watershed Master Plan Upper Chollas Creek Watershed Master Plan 5

6 High Resolution Data Generation BMP Identification Feature Digitization 6

7 High Resolution Data Generation Storm Drain Verification Drainage Area Delineation Upper Chollas Creek Watershed Master Plan 7

8 Drainage Assessment Summary Rick Engineering Company 1

9 Data Collection and Compilation 9

10 Hydrologic Methodology 10

11 Creating a the Hydraulic Model 11

12 1D Dual Drainage Hydraulic Model Conceptualization of surface and sub-surface conveyance 12

13 Existing Condition 2D H&H Model Identify Existing Undersized Facilities and Locations of Flooding Visually Display limits of Existing Flooding 13

14 Proposed Drainage Improvements Upsize Deficient Pipes Extend Conveyance Systems: Upstream for Improved Street Conveyance Downstream to Reduce Erosion and Habitat Degradation at Outfalls Realign Existing Systems to City ROW/Easements Channel Improvements: Concrete Removal Channel Widening Bed and Bank Stabilization Implement Storage to Attenuate Increased Peak Flows 14

15 Realignment of Storm Drain into Right of Way Existing Deficient pipes under private parcels Proposed Deficient pipes upsized and realigned to City ROW 15

16 Proposed Condition 2D H&H Model Model the results of implementing the proposed flood control improvements Visually Display reduced flood inundation limits 16

17 Existing vs. Proposed Inundation Existing Proposed 17

18 Stream Restoration Opportunities Existing Erosion within Channels Ex. Constraints due to Development Degraded Infrastructure in Need of Repair / More Environmentally Friendly Restoration 18

19 Environmental Assessment Summary HELIX Environmental Planning, Inc. 1

20 HELIX Environmental Role Assist with site selection Inventory and map baseline conditions Evaluate environmental constraints and opportunities Assess opportunities for functional lift and spatial gain Develop standardized restoration opportunity screening tool Identify top restoration candidates in watershed Watershed-wide and focused work in Upper Chollas 20

21 Environmental Evaluation Comprehensive review of existing data Site-specific assessments Identification of constraints and opportunities Conceptual stream re-establishment and rehabilitation planning 21

22 Environmental Evaluation Water Quality Basin Assessments 22

23 Environmental Evaluation Flood Control Improvement Assessments 23

24 Restoration Opportunity Screening Standardized and repeatable screening tool Screen based on key factors and assign weighted scores Jurisdictional Area (Spatial Gain) Riparian and Wetland Habitat Expansion (Functional Lift) Habitat Connectivity and Regional Preserve Design Land Acquisition and LongTerm Preservation Immediate Mitigation Needs Identify priority areas 24

25 Upper Chollas Focus Project- and reach-specific studies Wightman/Auburn Creek 25

26 Interactive Environmental Web App HELIX web app for data catalogue, sharing, map creation, etc. 26

27 Immediate and Future Mitigation Needs In addition, the City s work in the watershed is providing: Conceptual planning for real, implementable near-term projects to resolve immediate mitigation needs Identification of longer-term projects available for future mitigation needs 27

28 Green Infrastructure & Water Quality Summary Tetra Tech 1

29 Water Quality Compliance Roadmap Water Quality Impairments 303d Listed Waterbodies Pollutant Specific TMDLs Compliance Plans (WQIPs/EWMP/WMP)??? GI Implementation CA SWRCB 2010 Integrated Report-303d Listed Waters Upper Chollas Creek Watershed Master Plan 29

30 Compliance Plan (WQIPs) LOWER-RESOLUTION DATA SUBWATERSHED-SCALE PROJECT ASSESSMENT???? SUBWATERSHED-SCALE MODEL APPROACH??? GENERALIZED STRUCTURAL SOLUTIONS CSD acres of green streets (12.76 acres of bioretention and acres of permeable pavement) have been identified as potential opportunities for green street projects to treat a total drainage area of 7, acres with a total storage volume of acre-feet) GENERIC BMP REPRESENTATIONS Upper Chollas Creek Watershed Master Plan 30

31 GI Implementation Plan (WMP) DATA-DRIVEN PROJECT ANALYSIS DYNAMIC MASTER PLAN VISUALIZATION HIGH-RESOLUTION DATA CATCH BASIN INLET MODEL SCALE REFINED MODELING APPROACH DETAILED GI REPRESENTATIONS Specific Projects Prioritized Projects Pathway to compliance Upper Chollas Creek Watershed Master Plan 31

32 Components of the GI Master Plan High Resolution Data Watershed/ BMP Model Optimization System Dynamic Watershed Master Plan Upper Chollas Creek Watershed Master Plan 32

33 High-Resolution Data - Land Cover Compliance Plan Implementation Plan 33

34 High-Resolution Data Drainage Scale Compliance Plan Implementation Plan 34

35 High-Resolution Data GI Opportunities Compliance Plan Implementation Plan 35

36 Distributed BMPs (Green Streets) 1. Appropriate BMP Types/Assumptions 2. Length of new SD needed 3. Specific BMP drainage area 36

37 Regional BMPs (MUTAs) 1. Appropriate BMP Types/Assumptions 2. Pumping Needs 3. Diversion Rate/Location 4. Hundreds of nested GI opps. Canyon Regenerative MUTA Sub-surface, off-line MUTA 37

38 High-Resolution Data Impacts Compliance Plan Implementation Plan Parameter Compliance Plan Implementation Plan Available Distributed GI Footprint Area 218 ac. 47 ac. Estimated Potential Distributed GI Drainage Area 1288 ac ac. Available MUTA Footprint Area 6.2 ac. (6 MUTAs) 134 ac. (91 MUTAs) Estimated Potential MUTA Drainage Area 441 ac. 701 ac.

39 Watershed-wide Optimization Final TMDL Target Interim TMDL Target Physics Cost Effluent EMC 39

40 Green Infrastructure Master Plan

41 Data-Driven Smart Optimization Compliance Plan Implementation Plan.... Uniform distributed GI application Coarse MUTA representations Strategic MUTA placement Eliminates redundancy

42 Dynamic Watershed Master Plan (Web-GIS) 42

43 Value of Good Data Total BMP Footprint Requried (ac) WQIP MUTAs WMP GI/GS MUTA 24% decrease GI/GS 82% decrease Total 74% decrease Water Quality Impairments 303d Listed Waterbodies Pollutant Specific TMDLs Compliance Plans (WQIPs/EWMP/WMP) Cost savings Adaptive management Compliance certainty GI Master??? Plan GI Implementation 43

44 Application & Synergies 1

45 Additional Applications & Synergies Flood Control/Conveyance Rehabilitation & Restoration Hydromodification Capitol Improvement Projects Trash Capture Devices Operations & Maintenance 45

46 Additional Applications & Synergies C1-2 C1-2 C1-1 Q = cfs T-0004: H = 17, W = 78 T-0005: H = 17, W = 40 C1-3 Q = cfs

47 Additional Applications & Synergies

48 Completed Stream Restoration 48