Sustainable Stormwater: Optimized Management of Ponds and Other BMPs. Kerry A Reed, P.E., LEED AP MACTEC Engineering and Consulting, Inc.

Transcription

1 Sustainable Stormwater: Optimized Management of Ponds and Other BMPs Kerry A Reed, P.E., LEED AP MACTEC Engineering and Consulting, Inc.

2 Preliminary Conceptual Sustainability Planning for Stormwater Ponds Guided by: Existing Stormwater System Sustainability (improved operation now and in the future) Need for cost reduction Need to meet TMDLs Permitting processes and changing regulatory requirements Overall Goal: Reduce StormwaterPollution to Maximum Extent Possible

3 Most Common BMPs Wet Detention Basins Dry Detention Basins Vegetated Swales Vegetated Buffers Stormwater Wetlands

4 Sustainable Designs and Retrofits Take advantage of natural processes through design changes during maintenance Assimilation (N, P) Transformation and Volatilization (C, N) Annual Growth Renewal Cycle Inflow Water Depth Emergent Macrophytes Sedimentation and Sorption (BOD 5, TSS, N, P) Diffusion (N, P) Outflow Detritus Microbes Soils Roots/Rhizomes

5 Why Use Ranking? Conserve resources while achieving results Target ponds with high value Piggy-back on maintenance needs Pilot projects through grant funding Incorporate sustainable ( green ) elements for resource conservation and monetary savings

6 Stormwater Sustainability Assessment Step 1:Development of Pond Ranking System and Screening Potential for water quality treatment Proximity to impaired waterbodies Land availability for LID modifications, retrofits Current condition and ease of retrofit Additional benefits (flood control, aesthetics, recreation) Cost Step 2: Conceptual Sustainability Planning for Highest Ranked Ponds

7 Develop weighted criteria How To Do Stormwater Sustainability Ranking

8 Verify with field work Use GIS for initial screening and ranking analysis

9 Conceptual Sustainable Concepts Stormwater Harvesting Effluent Treatment (chemical or filter) Reduced Flow to Ponds (volume reduction, LID) StormwaterPond Treatments (shoreline and floating vegetation) Put them all together -Treatment Trains

10 Stormwater Harvesting Use of detained stormwater for non-potable uses: irrigation, car washing, toilet flushing, wetland enhancement, cooling tower make up water

11 Harvesting Benefits Less cost to supply water for all uses. Lengthens the life of existing potable water supplies. Can help meet TMDL standards on water bodies within the County. Can enhance stormwaterpond functioning with respect to nutrient removal. Can be and usually is a revenue source and can be part of a utility. This may be an alternative that will offset all the construction and operating cost.

12 Conceptual example for high ranking stormwater pond

13 Effluent Treatment Benefits Improvement of water quality leaving the ponds Mass load reduction to impaired waterbody Significant reductions in pollutant mass can be obtained Credit for TMDL load reductions mandated in the NPDES permit

14 Alum Injection for Effluent Nutrient Removal Alum or other coagulants can be used in ponds for maximum load reductions to impaired waterbodies.

15 Aeration With Polyacrylamides

16 Sorption Media to Remove Nutrients From StormwaterManagement Systems Black and Gold TM Media

17 Effluent Treatment

18 Disconnect directly connected impervious areas Various LID options: Green roofs Pervious pavements Reduce the Water Volume to the Pond Retention systems, swales, bio filters, rain gardens, cisterns, and other retention systems.

19 Reduced pond cost: Reduced volume of water For new ponds, less area is required and for existing ponds, more area can be treated LID methods can be attractive alternatives Credit for TMDL load reductions for impaired water bodies Can be part of a utility reducing the cost to the owner who is discharging less stormwater LID options provided by local industries, such as local roofing companies and material companies (pervious pavements and plant nurseries) Benefits of Volume Reductions and LID

20 Collection of Runoff for Irrigation

21 Stormwater Pond Treatments Improve Pond Water Quality or Enhancement of Pond Pollutant Removal Efficiency Shoreline Vegetation Floating Mats Mechanical and Physical Harvesting

22 Attractive Low maintenance In the future, will help meet TMDL load reductions on waterbodies A modest increase in removal effectiveness, but not costly Enhancement of habitat Benefits of Shoreline Enhancements

23 Use of Vegetation for Nutrient Removal

24 Configuration Upgrades for Nutrient Removal and Habitat Enhancement Littoral wetlands and islands Micro-pool holds 0.1 per impervious acre

25 Conceptual Configuration and Littoral Vegetation Upgrades

26 Adding another caboose onto the stormwatertreatment train

27 Conceptual Design with Effective Use of Treatment Train

28 Questions?