Introduction Permit Requirements and Concepts Overview and Source Control and Storm Water Hydromodification changes from 2007 Site Design Pollutant Control Management to 2013 MS4 Permit Practices Requirements Requirements Structure of the Model BMP Design Manual Project Development Approaches PDP Integrating PDP with Only Pollutant Standard Project Hydromodification Management Control Requirement with Pollutant Control 4 5
Pollutant Control BMPs for PDPs Permit Requirements Permit Hierarchy for Onsite BMPs Technical Feasibility BMP Selection Flow Chart Storm Water Pollutant Control BMPs 4 6
Onsite Pollutant Control BMPs Retention Implement technically BMPs feasible retention BMPs Implement technically feasible Biofiltration Biofiltration BMPs for remaining BMPs volume. Flow -thru Treat remaining volume Treatm ent AND participate in Control alternative compliance BMPs program 4 7
Pollutant Control Requirem ent Evapotranspiration Infiltration The “New ” Standard 4 8
Technical Feasibility Physical Lim itations Risk of Site I m pacts Constraints 4 9
Technical Feasibility Physical Lim itations • Soil infiltration rate • Limiting soil horizons • High, mounded groundwater 5 0
Technical Feasibility Risk of I m pacts • Groundwater and/ or soil contamination • Groundwater source protection • Groundwater mounding • Geotechnical, setbacks • Sanitary sewer onflow & infiltration • Ephemeral streams 5 1
Technical Feasibility Site Constraints • Elevation • Utility conflicts • Physical Constrains 5 2
Technical Feasibility Retention Feasibility ◦ Feasibility Screening for Harvest and Use BMPs Is there a demand onsite? ◦ Feasibility Screening for Infiltration BMPs Is infiltration potentially feasible and desirable? If so, what quantity? Biofiltration Feasibility ◦ Can it be designed for remaining DCV onsite? 5 3
Project Planning and Design Assess the site for opportunities and constraints Document site planning and opportunity assessment activities Select Source Develop the Controls and site layout Site Design BMPs 5 4
BMP Selection Priority Development Projects Evaluate at Drainage Management Area (DMA) Scale Adjust runoff factor to account for site Estimate Design Capture design BMPs and Volume (DCV) update DCV NO Is DMA Self-retaining? A YES Com pliant w ith Pollutant Control BMP Sizing Requirem ents 5 5
BMP Selection NO A Is Harvest and Use Feasible? YES Implement Harvest and Use BMPs* Is B remaining NO DCV retained? YES Com pliant w ith Pollutant Control BMP Sizing Requirem ents * Project applicant has an option to choose between 5 6 infiltration and harvest and use BMPs if both feasible
BMP Selection B Is Infiltration Feasible? Full Infiltration Partial Infiltration No Infiltration Implement Implement Implement Infiltration BMPs Bioinfiltration BMPs Biofiltration BMPs Compute Sizing Compute Sizing Compute Sizing Requirements Requirements Requirements More on this later C Com pliant w ith Pollutant Control BMP Sizing Requirem ents 5 7
BMP Selection C Implement BMP using maximum feasible Can the BMP YES footprint and NO be designed for document why the the remaining remaining BMP size DCV? could not fit on site* Design BMP for the Participate in required size, per alternative compliance Implement Flow-thru design criteria and program to mitigate for Treatment Control considerations listed in the pollutant load not BMPs the fact sheets retained onsite Com pliant w ith Pollutant Control BMP Sizing Requirem ents * Project approval at the discretion of agency/ jurisdiction 5 8
Site Design / Watershed Site Characteristics Project Type Characteristics I nfiltration Feasibility Site planning principles incorporated, as applicable, and potential BMP locations identified; conduct feasibility screening for each DMA Infiltration Basin Would infiltration of the full design volume be feasible from a physical Yes Bioretention with No Full Infiltration perspective without any undesirable Underdrain (or plugged Category consequences that cannot be underdrain) reasonably mitigated? Permeable Pavement Partial No Bioinfiltration (i.e., Yes Infiltration bioretention with elevated underdrains) Category Would infiltration of water in any appreciable amount be physically Harvest and Use if feasible without any negative feasible, then consequences that cannot be No Infiltration Biofiltration if feasible, then reasonably mitigated? Category No Flow-thru Treatment Control BMPs 5 9
Harvest and Use BMP Roof Downspout First Flush System Irrigation valve for Building “Roof washer” landscape use Access Hatches Filter Optional Storage discharged to discharge to infiltration infiltration Cistern Storage reserved for irrigation Pump system for reuse Sizing BMP manual will have BMPs shall be sized to retain the Design a Fact Sheet for: Capture Volume (DCV; runoff from 85 th • Cistern percentile 24-hr rainfall depth) 6 0
Biofiltration Standards MS4 Permit requires the Copermittee's to provide guidance for hydraulic loading rates and other biofiltration design criteria necessary to maximize storm water retention and pollutant removal ◦ Standards and Checklist to be included in an Appendix of Manual ◦ Facilitates consistent review and approval of Biofiltration BMPs 6 3
Influent Flowrates/ Concentrations Speciation Volumes Bypass Volum e Rem oval Reduction • Sizing Mechanism s/ Conversions • Infiltration rates • Media filtration • Underdrain rate placement • Clogging • Evapotranspiration Sources/ Conversions Effluent Flowrates/ Concentrations Speciation Volumes 6 4
Biofiltration Standard 1) BMP selection process based on documented feasibility analysis 2) Sized using acceptable sizing methods described in the Model BMP Design Manual 3) Sited and designed to achieve maximum feasible infiltration and evapotranspiration 6 5
Biofiltration Standard 4) Designed with a hydraulic loading rate to maximize pollutant retention, preserve pollutant control/ sequestration processes, and minimize potential for pollutant washout 5) Designed to promote appropriate biological activity to support and maintain treatment processes 6 6
Biofiltration Standard 5) Designed to prevent erosion, scour, and channeling within the BMP 6) Include O&M design features to provide for continued effectiveness of pollutant and flow control functions Design features and criteria to meet these goals will be described in BMP Fact Sheets 6 7
6 8
Flow -thru Treatm ent Control BMPs Energy Dissipater Inlet Side Slope: 3H:1V or milder Outlet Bottom Slope: 1.5- 6% Check dam if bottom slope exceeds 2.5% Flow Spreader BMP manual will have Fact Sheets for • Vegetated Swales • Media Filters Proprietary BMPs can be used as • Sand Filters Flow-thru treatment control BMPs • Dry Extended Detention Basin 6 9
Perm it Requirem ents and Concepts Hydrom odification Managem ent Requirem ents Laura Henry, P .E. Rick Engineering Company 7 0
Introduction Permit Requirements and Concepts Overview and Source Control and Storm Water Hydromodification changes from 2007 Site Design Pollutant Control Management to 2013 MS4 Permit Practices Requirements Requirements Structure of the Model BMP Design Manual Project Development Approaches PDP Integrating PDP with Only Pollutant Standard Project Hydromodification Management Control Requirement with Pollutant Control 7 1
Hydrom odification Background I nform ation What is hydromodification? ◦ Hydromodification means changes in a watershed’s runoff characteristics resulting from development, together with associated morphological changes to channels receiving the runoff Hydromodification Management Plan (HMP) for San Diego County ◦ Final HMP dated March 2011 72
Hydrom odification Background I nform ation Strategies for hydromodification flow control ◦ LID Devices ◦ Flow control ponds ◦ Sizing based on continuous simulation modeling Methods ◦ San Diego BMP Sizing Calculator ◦ Project-specific continuous simulation modeling 73
Hydrom odification Managem ent Requirem ents Background information What is new under the 2013 MS4 Permit What is not changing at this time Logistics of implementing new/ updated standards Future of San Diego BMP Sizing Calculator 7 4
Hydrom odification Managem ent Applicability Hydromodification management applies to PDPs when runoff from the project site will drain to systems susceptible to erosion Does not apply to projects discharging runoff to exempt water bodies Detailed applicability requirements will be addressed later in this workshop 7 5
W hat is new in the 2 0 1 3 MS4 Perm it? Changes to applicability / exemption criteria Requirement to control to “pre-developm ent” condition instead of “pre-project” condition New requirement to protect coarse sediment yield areas 7 6
Lane’s Diagram From Rosgen (1996), from Lane, Proceedings, 1955. Published with the permission of American Society of Civil Engineers 7 7
W hat is NOT Changing Flow control performance standard (range of flow rates to be controlled) ◦ 0.1, 0.3, or 0.5Q 2 to Q 10 Methods to determine lower flow threshold ◦ SCCWRP Channel Screening Tools ◦ Critical Flow Calculation 7 8
W hat is NOT Changing San Diego 2011 Final HMP is not being updated ◦ 2011 HMP components are being incorporated into the Model BMP Design Manual with modifications as necessary 7 9
I m plem entation of Updated Standards Where criteria has changed, the Model BMP Design Manual will supersede the Final HMP ◦ Applicability / exemption criteria ◦ “Pre-development” condition New requirements will be addressed in the Model BMP Design Manual ◦ Management of critical coarse sediment yield areas 8 0
I m plem entation of Updated Standards Model BMP Design Manual will compile guidance and parameters for continuous simulation modeling 8 1
BMP Sizing Calculator Accessing the tool Use of BMP Sizing Calculator and sizing factors under the 2013 MS4 Permit 8 2
BMP Sizing Calculator June 30, 2014 end of support for web-based application LID Sizer Tool replaced with spreadsheet tool ◦ available now on www.projectcleanwater.org ◦ Sizing factors are still valid for sizing LID facilities under the 2007 MS4 Permit Pond Sizer Tool will not be replaced Critical Flow Calculator 8 3
BMP Sizing Calculator Under the 2013 Permit: ◦ Do not use “impervious” surface coefficients when determining “pre-development” Q 2 for outlet orifice sizing ◦ Sizing Factors for some facilities will be removed due to inconsistency with new retention requirements ◦ “Treatment-Only” sizing will not be available – use procedures presented in the Model BMP Design Manual 8 4
BREAK 1 0 Minutes 8 5
Structure of the Model BMP Design Manual Trevor Alsop, P .E. Geosyntec Consultants 8 6
Introduction Permit Requirements and Concepts Overview and Source Control and Storm Water Hydromodification changes from 2007 Site Design Pollutant Control Management to 2013 MS4 Permit Practices Requirements Requirements Structure of the Model BMP Design Manual Project Development Approaches PDP Integrating PDP with Only Pollutant Standard Project Hydromodification Management Control Requirement with Pollutant Control 8 7
Organization Chapter 1 Policies and Procedural Requirements Chapter 3 Chapter 2 Planning and Design Performance Standards of a Project and Concepts Chapter 7 Chapter 8 BMP Long Term Requirem ents Submittal Operation & Requirements Maintenance Chapter 4 Chapter 5 Chapter 6 Source Control Storm Water Hydromodification and Site Design Pollutant Management BMPs Practices for all Control BMPs for PDPs Projects for PDPs 8 8
Model SUSMP Model BMP Design Manual Chapter 1. Policies and Procedural Chapter 1. Policies and Procedures Requirements Chapter 2. Performance Standards and Chapter 2. Concepts and Criteria Concepts Chapter 3. Preparing your Project Chapter 3. Planning and Design of a Project Submittal Chapter 4. Source Control and Site Design Practices for all Projects Chapter 5. Storm Water Pollutant Control BMPs Chapter 4. Low Impact Development for PDPs Design Guide Chapter 6. Hydromodification Management BMPs for PDPs. Chapter 5. Operation & Maintenance of Chapter 7. Long term Operation & Maintenance Stormwater Facilities Chapter 8. Submittal Requirements 8 9
Organization Chapter 4: Chapter 6: Chapter 8: Source Control Chapter 5: Storm Water Hydromodification Submittal and Site Design Pollutant Control BMPs for Management Requirements Practices for All PDPs BMPs for PDPs Projects Appendix I: Appendix B: Hydrologic Appendix B: Appendix A: Forms and Calculations and Sizing Hydrologic Source Checklists Methods Calculations Control BMP and Sizing Requirements Methods Appendix C: Geotechnical and Groundwater Investigation Requirements Appendix G: Guidance for Appendix D: Approved Continuous Infiltration Rate Simulation Assessment Methods for Selection and Design of Storm Water BMPs Appendix H: Regional Appendix E: BMP Design Watershed Fact Sheets Management Area Analysis Appendix F: Biofiltration Standard and Checklist 9 0
Chapter 1 – Model BMP Design Manual Is Project a Priority NO Development Project (PDP)? YES Is Hydromodification YES Management Applicable? NO PDP with Pollutant Control PDP with Only Pollutant Standard Project and Hydromodification Control Requirement Management Requirements Section 2.1 & Chapters 2 & 3 Section 2.1; 2.2 & Chapter 3 Chapter 3 9 1
Chapter 3 – Model BMP Design Manual Step 1 Step 2 Step 3 • Gathering • Site Planning and • Coordinating Between Information About Assessing Disciplines the Site Opportunities & Constraints Chapter 4, 5 & 6 Step 4 Step 5 • Developing Final • Preparing a Project Site Layout and Storm Water Storm Water Design Submittal Chapter 8 Chapter 4, 5, 6 & 7 9 2
Standard Project Chapter 3: Planning and Design of a Project Chapter 4: Source Chapter 8: Control and Site Submittal Design Practices Requirements for all Projects 9 3
PDP W ith Pollutant Control Chapter 3: Planning and Design of a Project Chapter 7: Long Chapter 8: BMP Requirements Term Operation & Submittal Maintenance Requirements Chapter 4: Source Control and Site Design Practices for all Projects Chapter 5: Storm Water Pollutant Control BMPs for PDPs 9 4
PDP W ith Pollutant Control & Hydrom odification Mgt. Chapter 3: Planning and Design of a Project Chapter 7: Long Chapter 8: BMP Requirements Term Operation & Submittal Maintenance Requirements Chapter 4: Source Control and Site Design Practices for all Projects Chapter 5: Storm Water Pollutant Control BMPs for PDPs Chapter 6: Hydromodification Management BMPs 9 5 for PDPs
Project Developm ent Approaches Standard Project Venkat Gummadi, P .E. Geosyntec Consultants 9 6
Introduction Permit Requirements and Concepts Overview and Source Control and Storm Water Hydromodification changes from 2007 Site Design Pollutant Control Management to 2013 MS4 Permit Practices Requirements Requirements Structure of the Model BMP Design Manual Project Development Approaches PDP Integrating PDP with Only Pollutant Standard Project Hydromodification Management Control Requirement with Pollutant Control 9 7
Standard Project Implement most of the same measures as before Source Control Protect Outdoor Storage Areas Prevent Buffer Illicit Zones Discharges Project Site Protect Minimize Trash Impervious storage Areas Areas Impervious Area Dispersion Site Design 9 8
Standard Project Must Now I m plem ent PDPs in 2007 Minimize disturbance to natural drainages Landscaping Conserve with native or natural drought areas, soils tolerant and species vegetation Project Site Minimize soil Small compaction collection and use of strategies permeable material Harvesting and using precipitation New 9 9
Docum enting Design Use Checklists to document design ◦ Priority Development Project determination Checklist ◦ Source Control & Site Design Checklist Prepare and submit a Storm Water Management Plan 1 0 0
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