Eating the Elephant: Stormwater Management for Boone County Georganne Bowman, Stormwater Coordinator – Boone County, MO Christina Luebbert, P.E., CFM, Project Manager – Shafer, Kline and Warren, Inc.

One Bite at a Time… 1.Build a comprehensive stormwater program for the County 2.Fix the internal processes 3.Develop regulations that encourage stormwater management flexibility and growth

Community Direction  Obstacles – Political Climate  Buffer Regulations  City of Columbia ordinance/manual  Hinkson Creek TMDL – Internal Changes  Legal staff, management, new staff  Minimal standards/codes buried in Road & Zoning Regulations

Community Direction  The good news… –Hinkson Creek project  TMDL development –Additional monitoring – UMC –Partnering efforts with the City and UMC –Stormwater Task Force suggestions  Protection for homeowners from flooding  Stream Buffer protection

Comprehensive Program Common sense approach to compliance Common sense approach to compliance –Fix what needs to be fixed –Do not implement programs just to satisfy the permit

Comprehensive Program  Develop a long-range plan & set priorities  Develop a comprehensive program for each MCM

Comprehensive Program  5-year plans –IDDE  Select the small handful of politically “HOT” chemicals.  Collect some data.  Tell a story about the hot topics.  Bring attention to the IDDE program.  Get more $ next year to do more good stuff, and broaden scope.

Comprehensive Program MCM 3 – Illicit Discharge Detection and Elimination Goal: Develop a program to reduce illegal connections and discharges to the County system   Develop an ordinance   Conduct a Storm Sewer Assessment (priority)   Develop/conduct monitoring   Enforcement   Program review and modification

Comprehensive Program  5-year plans –Construction  Early plan review and issues meetings  Develop guidance  Train inspectors  Track recommendations and changes  Incremental enforcement

Comprehensive Program MCM 4 – Construction Site Stormwater Runoff Control Goal: Develop a meaningful program that meets the intent and requirements of the permit by reducing erosion and sediment from construction sites.   Development ordinance, and guidance manual   Provide construction site oversight, and plan review   Develop a training program   Enforcement   Program review and modification

One Bite at a Time… 1.Build a comprehensive stormwater program for the County 2.Fix the internal processes 3.Develop regulations that encourage stormwater management flexibility and growth

Broken Processes Plan Review Process Improvements Problems identified Problems identified  Cohesion with PZ and PW  Consistent message to design community  Standardize –Getting everyone on the same page

Concept Review More information up front  Work with developers/engineers earlier in process  Identify environmental issues prior to design dollars being spent –Buffer regulations –Karst/sinkhole areas

One Bite at a Time… 1.Build a comprehensive stormwater program for the County 2.Fix the internal processes 3.Develop regulations that encourage stormwater management flexibility and growth

Ordinances Legal Authority  Started with a basic framework –IDDE, Construction, some Post-Construction  Worked with the new County attorney –Reviewed the County authority –Class 1 counties are different from cities

Ordinances Borrowed Resources  CWP post-construction model ordinance  Karst protection from Springfield  Other programs –Tree preservation – King County –Background – Iowa, Wisconsin, Georgia, etc

Design Guidance  Opposing objectives – –Consistent with City of Columbia’s manual –But customized for County style development –Feedback from Development community  issues with City manual –Value rating system –Redevelopment

Design Guidance Stakeholder process  Engineering community  Previous Stormwater Task Force members  Developers  Staff at Planning and Zoning and Public Works

Design Guidance Stakeholder process… Positives:  Early involvement from engineering firms  Open discussion to work out bugs  Expose commission to language Negatives:  Tangents/agendas from stakeholders  Minimal direction/guidance from commission

Design Guidance External Review… Two local engineering firms have agreed to review the ordinance and design guidance for cost differences. Two local engineering firms have agreed to review the ordinance and design guidance for cost differences.Objectives: The current Boone County design standards, The proposed Boone County Stormwater Manual, and The current City of Columbia Stormwater manual.

Stormwater Management Nested Stormwater Approach –Runoff Reduction –Water Quality Volume Treatment –Channel Protection –Flood Control Safety Net

Stormwater Management

Runoff Reduction To replicate pre-development hydrologic conditions, and to promote baseflow, 10% of the water quality volume shall be permanently reduced. –by disconnecting impervious areas, –maintaining sheet flow –infiltration practices where soils conditions allow and/or –collection and reuse of runoff.

Water Quality Volume To protect the receiving waters from NPS, the remainder of the water quality volume that was not removed through runoff reduction, shall be treated through filtration BMPs.

Channel Protection The stormwater system shall be designed so that post-development discharges will not erode natural channels or steep slopes. The stormwater system shall be designed so that post-development discharges will not erode natural channels or steep slopes. Tier 1 less than 5 acres of land disturbance OR less than 20% imperviousness Tier 2 Sites greater than 5 acres of land disturbance OR greater than 20% imperviousness

Channel Protection Tier 1  maintain sheet flow  Use energy dissipaters and level spreaders  Conveyances designed to reduce velocity  Concentrated flows discharged at an elevation that will not cause erosion or require discharge across any constructed slope or natural steep slopes.  Outfall velocities must be non-erosive from the point of discharge to the receiving channel or waterbody where the discharge point is calculated

Channel Protection Tier 2  Site design techniques that decrease runoff volumes and peak flows. This shall be accomplished by controlling the post- development peak discharge rate to the pre- development rate. This criterion shall be met for the 5-year, 24-hour storm event, (or equivalent storm runoff volume using other methodologies).

Flood Control  This criterion shall be met for the 10- year, 24-hour storm event on residentially zoned properties and the 25-year, 24 hour storm event on non- residentially zoned properties.  Stormwater BMPs shall safely pass the 100-year storm without creating damaging conditions downstream.

Redevelopment Land development that qualifies as redevelopment shall meet one of the following criteria:  Reduce Impervious Cover (20%)  Provide Treatment (20% & 100%)  Apply Innovative Approaches  Provide Off-Site Treatment  Address Downstream Issues  Combination of Measures

Conclusion Boone County is currently developing a comprehensive ordinance and guidance  Consider the political and community values  Trying untested approaches, and  Encourage flexibility

For more information: and follow the links to Stormwater Georganne Bowman, Boone County Public Works Christina Luebbert, P.E., CFM – SKW