Part 4: CRS Stormwater Management Activity (450) and Urban Flooding Best Practices

Transcription

1 Coastal Resilience through Community Engagement Webinar Series Part 4: CRS Stormwater Management Activity (450) and Urban Flooding Best Practices 1:00 2:30pm CT 8 Today s Moderator Chad Berginnis, CFM Executive Director, ASFPM 9 1

2 Thanks to our funders! Funding for this project is provided by the Department of the Interior through a grant from the National Fish and Wildlife Foundation s Hurricane Sandy Coastal Resiliency Competitive Grant Program. Coastal Resilience through Community Engagement Webinar Series CRS Stormwater Management (Activity 450) and Urban Flooding Best Practices Dave Carlton, P.E., CFM Principal dkcarlton & associates Lori Rafferty, P.E., CFM Floodplain & CRS Administrator Louisville/Jefferson County Metro Sewer District, KY 2

3 Unit 9. Watershed Management Visual 9.12 In this Unit Activity 450 (Stormwater Management) Unit Objectives Understand why the CRS provides credit for stormwater management activities and be familiar with the techniques that are creditable. Understand the credit criteria and points available. Be familiar with the documentation requirements and know which community departments should be involved in this activity. Visual

4 Why credit stormwater management? Watershed development typically increased impervious area and generates more runoff More runoff means more frequent floods and higher flood heights Watershed development increases erosion and sedimentation, and more impervious areas impact water quality Visual 9.14 Visual

5 Visual 9.16 Visual

6 Visual 9.18 Objective Prevent future development from increasing flood hazards, maintain and improve water quality, and preserve natural functions See Coordinator s Manual, page Visual

7 Detention Detain runoff and release it slowly. Retention Retain runoff and allow it to infiltrate into the ground. Detention and Retention provide water quantity and water quality management. Visual 9.20 Dry Detention Visual

8 Wet Detention Visual 9.22 Wet Detention with Water Quality Visual

9 452.a Stormwater management regulations (SMR) SMR = SZ + DS + LID + PUB SZ = size of the developments required to manage on site DS = design storm(s) used to set detention/retention capacity LID = low impact development techniques required for DS PUB = public right of entry and maintenance See Coordinator s Manual, page Visual a Stormwater management regulations (SMR) Credit Criteria (1) Peak runoff from new development must be no greater than the pre-development runoff from the site. See Coordinator s Manual, page Visual

10 452.a Stormwater management regulations (SMR) Credit Criteria (1) Peak runoff from new development will be no greater than the pre-development runoff from the site. (2) If SZ = 0 or DS = 0, SMR = 0 See Coordinator s Manual, page Visual a Stormwater management regulations (SMR) Credit Criteria (1) Peak runoff from new development can be no greater than the pre-development peak runoff from the site. (2) If SZ = 0 or DS = 0, SMR = 0 (3) SZ = size of developments required to comply: points Maximum development size: 5 acres or 20,000 sf of impervious surface See Coordinator s Manual, page Visual

11 452.a Stormwater management regulations (SMR) Credit Criteria (1) Peak runoff from new development can be no greater than the predevelopment runoff from the site. (2) If SZ = 0 or DS = 0, SMR = 0 (3) SZ = size of developments required to comply: points Maximum development size: 5 acres or 20,000 sf of impervious (4) DS = designs storms: points Minimum design storm: 10-year storm Add 50% if volume is controlled See Coordinator s Manual, page Visual a Stormwater management regulations (SMR) Credit Criteria (1) Peak runoff from new development can be no greater than the predevelopment runoff from the site. (2) If SZ = 0 or DS = 0, SMR = 0 (3) SZ = size of developments required to comply: points Maximum development size: 5 acres or 20,000 sf of impervious (4) DS = designs storms: points Minimum design storm: 10-year storm Add 50% if volume is controlled (5) Required} pre- and post-development flow comparison See Coordinator s Manual, page Visual

12 Visual 9.30 Visual

13 Bioretention See Coordinator s Manual, pages Visual 9.32 Low Impact Development Techniques Required Up to 25 points See Coordinator s Manual, pages Visual

14 LID = 25 points, if all development (SZ = 110) is required to use lowimpact development techniques (instead of pipes, channels, or detention) to control the impacts of development on runoff to the maximum extent feasible; OR LID = 20 points if SZ = 90; OR LID = 15 points if SZ = 60; OR LID = 10 points if SZ = 15. See Coordinator s Manual, pages Visual ) Public right of entry and enforcement (PUB) (a) Community has the right to inspect and force required maintenance, or (b) All new facilities become community property See Coordinator s Manual, pages Visual

15 See Coordinator s Manual, pages Visual 9.36 See Coordinator s Manual, pages Visual

16 452.a Stormwater management regulations (SMR) SMR = SZ + DS + LID + PUB SZ = size of the developments DS = design storm(s) used LID = low impact development techniques PUB = public right of entry Up to 380 points, Puget Sound normal is 270 See Coordinator s Manual, page Visual 9.38 Impact Adjustment for SMR See Coordinator s Manual, pages Visual

17 Impact Adjustment for SMR Think watershed See Coordinator s Manual, pages Visual 9.40 See Coordinator s Manual, pages Visual

18 Impact Adjustment for SMR THINK WATERSHED! rsmr = asmr aw Don t include watersheds > 50 square miles outside your community. Count all areas subject to qualifying regulations in upstream communities. See Coordinator s Manual, pages Visual 9.42 Documentation (1) Technical reviewer s documentation checklist (2) The regulations including all exemptions (3) Five drainage reports for new development (4) [If applicable] regulations for others in watershed (5) Impact adjustment map and area calculations See Coordinator s Manual, page Visual

19 Poll Question 1: Which of the following stormwater management activities is credited under CRS Element 452.a (SMR)? a. Design standards for road drainage b. Requiring new structures to be elevated above runoff in the road c. Controlling peak flows onsite d. Design standards for new channels See Coordinator s Manual, pages Visual 9.44 Poll Question 2: Under Element 452.a. (SMR), Design Storm refers to a. The storms used to size culverts b. The storms used to size detention c. The frequency of flooding allowed d. When the levee will fail See Coordinator s Manual, pages Visual

20 See Coordinator s Manual, pages Visual b. Watershed master plan (WMP) Credit is provided if the community implements a plan to control the impacts of development through an adopted watershed master plan (WMP1). See Coordinator s Manual, page Visual

21 452.b. Watershed master plan (WMP) Credit is provided for watershed master plans that examine Long-duration storms, Evaluate the impact of sea level rise and climate change Identify wetlands and natural areas, Address the protection of natural channels, and Provide a dedicated funding source for implementing the plan. See Coordinator s Manual, page Visual b. Watershed master plan (WMP) Credit Criteria (1) Adopted watershed master plan (2) Evaluates runoff from full development for the 100- year event and at least one smaller event. See Coordinator s Manual, page Visual

22 452.b. Watershed master plan (WMP) Credit Criteria (1) Adopted watershed master plan (2) Evaluates runoff from full development for the 100-year event and at least one smaller event (3) Manages future peak flows so they will not increase over present values (4) Manage at least the 10-year and the 25-year events onsite for credit. 100-year is a Class 4 requirement See Coordinator s Manual, page Visual b. Watershed master plan (WMP) Credit Criteria Change (1) No longer required to analyze your onsite requirements (2) No longer required to recommend in your plan the onsite management requirements in your ordinance or design standards See Coordinator s Manual, page Visual

23 452.b. Watershed master plan (WMP) Credit Criteria (1) Adopted watershed master plan (2) Evaluates runoff from full development for the 100-year event (3) Future peak flows will not increase over present values (4) Controls at least the 10-year and the 25-year events (5) Evaluate a plan that is more than five years old (6) Must receive WMP1 credit (all the above criteria) See Coordinator s Manual, page Visual b. Watershed master plan (WMP) Technical review Courtesy review See Coordinator s Manual, page Visual

24 Verification Review of permit records SMR: Drainage calculations WMP: Plan, regulations ESC: Erosion/sediment control plans WQ: Subdivision plans Visual 9.54 Verification Who should be involved? SMR: Drainage Engineer WMP: Public Works and Planning or Community Development ESC: WQ: Development permit reviewer Development permit reviewer Visual

25 Questions? Visual 9.56 November 27, 2017 Managing Stormwater and its Impacts on the CRS 25

26 Louisville-Jefferson County, KY Population 616,261 Merged City and County governments in 2003 Largest community in Kentucky Class 3 CRS community Floodplain Statistics for Jefferson County Approximately 15% of Jefferson County is located in a regulated floodplain Approximately 8,000 buildings are in the FEMA Special Flood Hazard Area 26

27 CRS 450 Stormwater Management Stormwater Management Regulations Watershed Master Planning Erosion and Sediment Control Water Quality Poll Question: Does your community currently receive CRS credit for Activity 450 Stormwater Management? a. Yes b. No c. I don t know d. My community does not currently participate in the CRS program 27

28 Stormwater Management Regulations Size of Development Credit is calculated based on the types of developments regulated by your stormwater requirements Louisville requires reviews all projects that have more than 2,000 sq ft of disturbance Stormwater Management Regulations Design Storms Credit given for design storms required for detention analyses Additional credit for volume control Louisville s Requirements: Design storms are 2, 10, 25, and 100 yr storms Volume control is not required due to poor soil conditions in many areas 28

29 Stormwater Management Regulations Low-Impact Development Credit provided if the community requires the implementation of LID techniques to the maximum extent feasible to control peak runoff Not creditable for Louisville s program because LID is encouraged, but not required Incentive program to encourage property owners to construct green infrastructure projects Stormwater Management Regulations Public Maintenance Credit for requiring inspection and maintenance of stormwater management facilities Louisville requires that new detention basins be located in drainage easements or open space Detention Credit available on stormwater bill for property owners maintaining detention basins (up to 50% off drainage service charge) 29

30 Watershed Master Plan MSD took over stormwater drainage from the City in st Comprehensive Stormwater Master Plan completed in 1987 included: Evaluated the existing stormwater regulations Made recommendations for improvements Watershed plans for 11 individual watersheds within Jefferson County Master Plan met many of the future CRS requirements Watershed Plan was updated in 2011 and 2017 Erosion and Sedimentation Control (EPSC) Regulations Credit for requiring EPSC regulations Louisville regulates projects that are disturb land greater than 2000 sq ft EPSC ordinance passed in

31 Water Quality Regulations CRS credit available for regulations that require new developments of one acre or more to include best management practices to improve water quality Louisville s MS4 permit requires the first 0.6 of rain be treated for all projects 1 acre or larger Lessons Learned Community outreach MSD attends monthly meeting with Building Industry Association Annual Field Day conference with engineers, contractors, developers Create stakeholder groups for new rule changes Outreach to general public about green infrastructure, water quality, flooding Partnership with other local permitting agencies Monthly meetings with the city s permitting office Shared permitting software Visit other similar communities to share experiences Credit and incentive programs New green infrastructure projects Detention basin sizing, infiltration, and maintenance 31

32 Questions? Lori Rafferty, PE, CFM Floodplain & CRS Administrator Louisville Metropolitan Sewer District Coastal Resilience Webinars Coastal Resilience through Community Engagement Webinars -ORhttp://bit.ly/2ys