Outline. Environmental Setting. Background 6/25/2012

Transcription

1 City of Fort Worth Floatables & Sediment Control Pilot Study EPA Region 6 MS4 Operators Conference June 2012 Aiza Jose, PhD, PE, LEED AP Outline Background Regulatory Framework Water Quality Issues and Initiatives Pilot Study Conclusions Next Steps Background Environmental Setting Fort Worth Population 2011: 740, : 1,200,000 Low taxes Limited regulations All American City Main water body- Trinity River Average annual precipitation 35 Intense local storms between long periods without rain Large areas drained by undersized pipes Aging infrastructure 3 4 1

2 Stormwater Program Funding Stormwater Utility established in 2006 after severe flooding Budget $7.6 M $31 M CIP - $40M/yr currently Water Quality not major driver Regulatory Framework Lake Worth 7 Current Regulations 2006 Design Manual (iswm) - voluntary water quality design guidance 2011 MS4 Permit -monitor/reduce floatables TRWD policy trash controls at every outfall Trinity River Water Quality Concerns and Initiatives 9 Chemicals of Concern Nutrient Concerns PCBs, DDE, dioxins, dieldrin, and more recently bacteria. TMDLs Implementation Plans: PCBs and bacteria for West Fork (downtown area) Nutrients Eutrophic Lakes Excess algae growth Increased mortality wildlife 11 California Courtesy of WCS 12 2

3 Floatable Concerns Sediment Concerns SW network Blockage flooding Maintenance Aesthetics Loss of use (lake closings) Health hazard (sharps or infectious items) Increase mortality of wildlife Boating and swimming hazards Economic impact on recreation and business Accumulation on culverts, streams and ditches Shortened life of lakes, ponds and reservoirs Decreased quality of habitat & sunlight Decreased quality of drinking water Decreased recreational use of water bodies Sediment absorbs/carries toxic pollutants JPS Hospital 13 Wildcat Branch 14 Water Quality Initiatives Water Quality Initiatives Trinity River Vision Central City Project TRWD End of Pipe Controls Lake Worth Quality Improvements Dredging and Green Printing Trash Collection Fort Worth Capital Improvements Program Trash Collector Sump # 19 Outlet 16 Lake Worth CIP Rehabilitation project End of Pipe trash collector Snout at Eastern Hills ES COFW Storm Water Credit Program: Financial Incentives for Reducing Pollution Baxter MS Wet Pond Brewer HS-Grass Pavers Floatables and Sediment Control Pilot Study 17 McLung MS-Bioswales John Tidwell- Dry Basin/Bioswale 3

4 Pilot Study Objectives Pilot Study Methodology and Procedures General To identify the most practical methods for minimizing floatables and sediment to respond to the regulatory requirements and current initiatives in the City (Central City Project) Specific Efficiency AND Feasibility (O&M) testing BMPs at small scale Reduction of Lateral Blockages Reactive vs. Proactive maintenance Public Education * 2-year pilot study (1.5 years complete) Site and BMP selection Inspection Maintenance Trash Characterization Sediment Analysis Documentation Pilot Study Best Management Practices (BMPs) Beginning-of-Pipe BMPs BMPs Selection Criteria Effective for removing debris and floatables Inexpensive and easy to install Easy to maintain using existing equipment and procedures Not subject to frequent repair Flood protection Automatic Retractable Screen (ARS) at Downtown Inlet 21 Beginning-of-Pipe BMPs Connector Pipe Screen (CPS) inside catch basin/vault- Lake Worth 4

5 In-Stream BMPs Boom Systems Proposed boom System Wildcat Branch Proposed boom System Willow Lake Channel Two End-Of-Pipe BMPs - Lake Worth and Eastern Hills 25 Pilot Study Areas Downtown (City Hall area) - Sweeping program - CPS/ARS Lake Worth Sediment issues CPS with silt plate small watershed and visible ibl outfall - CPS only John Peter Smith Hospital - CPS only Paschal High School Student availability - CPS/ARS 27 *Willow Lake, Wildcat Branch, Eastern Hills in line and end of pipe Lake Worth CPS Inspection Inspection O&M Sweeping Impacts Trash Characterization i Inspections were completed biweekly or after every 1/2 rain Total of 38 inspection events (average twice per month) Sediment Analysis Rainfall Monitoring Monitoring of debris level in catch basin Visual performance or issues for both CPS and ARS Stenciling in catch basin Provided cleaning frequency requirements 5

6 Inspection - CPS Performance Large debris were successfully removed Sediment removed was surprisingly high Inspection - ARS Performance Debris retained during dry events and minor rains Ease of cleaning during dry periods Improved overall performance of CPS 31 CPS JPS Hospital CPS 32 Inspection - Device Issues CPS silting 5 individual flushing events over 18 months Inlet flushing >2 in rain within 48 h period Flushing event areas with old/undersized inlets Flushing more frequent at sites not protected with ARS Design modification proposed at specific inlets (undersized) JPS Hospital CPS Operations and Maintenance Inlet Cleanings (quarterly or at >60% capacity) Sweeping (downtown and Paschal) Six scheduled inlet cleaning events (quarterly) Street Sweeper Three non quarterly cleaning events over the 18 month period JPS Hospital and having the most frequent inlet cleaning occurrences (no ARS) Vactor Truck - Downtown 35 O&M - Inlet Cleaning frequency Cost cleaning $50/inlet Generally once to twice in the 18 month period would be acceptable Downtown and Paschal HS once during the 18 months Lake Worth twice JPS once, two CPSs will be modified to improve performance twice, with three CPSs modified to improve performance Vactor Truck - JPS 36 O&M Sweeping program impacts Areas with sweeping programs generated 26% of the total trash collected Sweeping Program Consistent low levels of trash within the inlets and low flushing Downtown and Paschal HS. Trash levels in Paschal reduced by 66% once the students started the sweeping and outreach program Combined sweeping and ARS decrease the frequency of inlet cleaning requirements and flushing occurrence 6

7 Pile of Material recovered from CPS Scale Paschal HS students characterizing recovered materials Trash Characterization Results 34 inlets 128-acre 6.7 lbs/acre-month and 0.2 ft 3 /acre-month are being removed Major constituent removed is sediment 37 Trash Characterization 38 Downtown Trash Characterization 39 JPS Hospital Trash Characterization Lake Worth 40 Higher trash generation areas: Lake Worth and JPS Lowest: Paschal HS good sweeping and outreach program and Downtown recovered comparable volumes. However, Lake Como was the area with most flushing events. Lake Worth area generated the most sediment Sediment Analysis Added benefit of removing sediment Conducted every other quarter COCs measured TPHs PAHs Metals Nutrients VOCs and SVOCs PCBs Sediment Analysis TPH levels 30 to 240 mg/kg. An order of magnitude smaller than the Protective Concentration Levels (PCLs) under TRRP PAHs below two orders of magnitude for all EXCEPT Benzo(a)pyrenes, which h concentrations ti higher h than action levels METALS - Lead levels at JPS (512 mg/kg) above PCL of 500 mg/kg. Lead, Arsenic, Barium, Cadmium, Chromium, and Mercury are being trapped in the sediment with levels generally orders of magnitude below PCL 41 Sediment recovered CPS 42 7

8 43 Sediment Analysis PCBs - (Aroclor 1254) downtown (2.29 mg/kg) and JPS (4.17 mg/kg) above PCL of 1.14 mg/kg High PCB levels in aged urban areas, below detection in all other areas Segments of the West Fork of Trinity historically impaired with PCBs Levels are three orders of magnitude higher than concentration reported in the West Fork of Trinity* Active sources of PCB contamination *CPS capturing sediment containing PCBs that would otherwise get in the impaired segments 44 Nutrients Total Phosphorous and Total Nitrogen TN 380 to 1400 mg/kg 3 orders of magnitude higher than West Fork of Trinity same order of magnitude predicted levels at Lake Arlington (euthropic) TP consistent levels 100 mg/kg two times higher than the critical phosphorous levels in soil higher than the average levels predicted on sediment samples at Lake Arlington of 68 mg/kg *CPS is capturing sediment containing high nutrient levels Conclusions Conclusions and Next Steps Inlet controls are effective floatables, debris and sediment ARS operate well during rain events, trapping material at low flows Silting issues/blockage of CPS was observed. Hydraulic capacity not compromised and sediment retained Combined ARS/CPS sweeping train outperforms the CPS only system 46 Conclusions Next Steps 47 Outreach efforts at Paschal HS improved efficiency of the BMPs Flushing - not a major issue No significant BMP maintenance Frequency of cleaning reasonable once per year on average Sediment removed was significant Chemical of Concern and nutrients removed at levels that produce a positive impact 48 Expansion - Central City Project Support Lake Worth WQ Initiative Two new boom systems and the two end-of-pipe Other floatables and silt control BMPs (CIP) Use knowledge from pilot study as basis to refine Credit Program Implementation in built out ISD sites Lake Worth 8

9 QUESTIONS Aiza Jose, PhD, PE, LEED AP Brown & Gay Engineers, Inc. 9