Maine Stormwater Conference Portland Marriott at Sable Oaks South Portland, Maine November 21, 2013

Transcription

1 1 POROUS PAVEMENT IN THE NORTHEAST THE MAINE DOT AND MASS DOT EXPERIENCE Maine Stormwater Conference Portland Marriott at Sable Oaks South Portland, Maine November 21, 2013 Stephen W. Tibbetts, PE Mark Lickus, CG Environmental Office Maine Department of Transportation

2 2 Porous Pavement Primer Source: UNH Stormwater Center

3 3 Where To Use It Typically recommended for: Parking lots Low ADT roadways Higher volume roadways in some areas Developments with large areas of impervious surfaces. Sidewalks, trails, recreational areas. Wet Porous-Nice and dry! Porous Pavement Gravel Wetland GREENLANDS MEADOWS GREENLAND, NH

4 4 Why Use It Water Quality Treatment TSS Reduction: Pollutant Reduction: Petroleum hydrocarbons Metals: Zinc and Copper Reduces salt needed for winter maintenance Temperature Mitigation, maybe Water Quantity Control Peak Flow Reduction Infiltration systems recharge groundwater (where allowable)

5 5 Safety Why Use It Reduced road glare when wet Reduce/eliminate hydroplaning Reduce/eliminate icing Reduced traffic spray during rain events Maine Mall Parking Lot 1/17/2013 Maine Mall Road Same Day

6 Maine DOT Maine Mall Road, South Portland Porous Pavement On A High Volume Roadway: It Can Be Done 6 New ideas pass through three periods: 1) It can't be done. 2) It probably can be done, but it's not worth doing. 3) I knew it was a good idea all along! - Arthur C. Clarke

7 7 Long Creek Watershed Plan 2200 ACRES 28% IMPERVIOUS MAINE MALL ROAD MaineDOT owns 64 acres of impervious surface within the Watershed

8 8 Fall of 2008 Project Concept Rumors of a Federal Stimulus Bill American Recovery and Reinvestment Act 100 % Federal cost-sharing Long Creek Watershed Management Plan Identified possible DOT BMP locations. BMPs had utility conflicts and difficult catchment hydraulics So, MaineDOT chose porous pavement Project would satisfy part of MaineDOT Regulatory Requirements Opportunity to apply porous pavement to a urban highway

9 9 Maine Mall Road Construction Porous Cross Section CLAY SUBSOIL 6-12 OGFC 3 ATPB 6 RESERVOIR STONE 15 SAND FILTER UNDERDRAIN OGFC - Open Graded Friction Course ATPB - Asphalt Treated Permeable Base

10 10 Traffic Considerations: Constructability Philbrook/ME Mall Intersection ~19360 AADT ~16750 AADT within Project Limits Gorham Rd/ME Mall Intersection ~18760 AADT Each pavement layer requires a minimum 24hr cure time Full closure of the roadway or maintain one or two way traffic? The adjacent hotel only had a single entrance. Rest of the mall area had alternatives. Accelerated Schedule limited R/W takes Decision was made to: Shorten the full construction area Maintain two way traffic with a longitudinal closure

11 Porous Pavement Construction Construction Began Summer RESERVOIR STONE SAND FILTER 6 PERF UNDERDRAIN CLAY SUBSOIL

12 12 Sub Base and Drainage EXISTING CATCH BASIN EXISTING 36 SD 6 inch Perforated UD web. Three longitudinal runs, lateral runs every 120ft Cored into existing basins and pipes Everything drains to an existing 36 RCP

13 But Does It Really Work? Contractor did not believe this would work Drove the backhoe loaded with water and dumped it. This is what happened

14 14 Project Complete Project completed on Nov 7, 2009 Project constructed within budget

15 15 Cost Analysis Water Quality Total Low Bid: $1.47M Total Construction Cost: $1.44M Total Cost of PP Items: $622K (43% of Total) LC WMP Recommended: $165K Area Treated 1.21ac Cost per Acre: ~$137K Total Cost of PP Items: $622K Area Treated 2.75ac Cost per Acre: ~$226K

16 16 Perceived Risks MaineDOT Researching pavement performance Surface Pavement Raveling Project in place for Four years Overall the surface is in good shape. Surface Pavement Rutting and Cracking Not an issue to date, even at turn lanes

17 17 Perceived Risks Pavement clogging from off-site sand tracking Regular sweeping with regenerative air sweeper Contracted by Long Creek Management District South Portland uses salt on this section Flash freezing of OGFC Both UNH and MaineDOT have seen no evidence No water in system, so no freezing Subbase freezing No issue

18 Maine Mall Road Thermocouple Readings 18

19 19 Water Quality Monitoring Objectives Document WQ performance of Porous Pavement (PP) Determine effect on Peak flows (Qp) Temperature Selected water quality parameters TSS Cu Zn

20 20 Water Quality Monitoring Paired-Watershed Approach Pre/post or before/after BMP not feasible Compare locations with similar conditions and traffic Conventional pavement runoff vs outflow from PP Focus on PP outflow characteristics

21 Paired-Watershed Approach 21

22 Maine Mall Road WQ Sampling Site 22 Weir in Catch Basin Sampling Equipment

23 23 Preliminary Findings 2013 WQ Monitoring Hydrology Temperature WQ Parameters

24 24 Preliminary Findings - Hydrology 0.5 Rainfall Event - Maine Mall Road September 2, Flow Depth (ft) 0.5 Rainfall (in) Sep 6:00 12:00 18:00 6:00 12:00 3-Sep 1

25 25 Preliminary Findings - Temperature Gorham Road (Reference) Baseflow 19 to 20 C (67 F±) 1 to 2 C diurnal change Temp rise during storm varies with event up to 3 C Decline follows air temperature Maine Mall Road (Porous) Baseline 22 to 23 C (73 F±) <1 C diurnal change Temp rise during storm varies with event - 1 to 3 C typical Gradual decline during recession limb of hydrograph

26 26 Preliminary Findings - TSS 150 TSS July - October TSS (mg/l) Gorham Road Maine Mall Road

27 27 Preliminary Findings Metals 0.1 Total Cu July - October 2013 Total Cu (mg/l) Gorham Road Maine Mall Road

28 28 Preliminary Findings Metals 1 Total Zn July - October Total Zn (mg/l) Gorham Road Maine Mall Road

29 29 Conclusions and Observations Porous pavement can work on main roads If well constructed Pavement designed to meet vehicle loading Pavement is holding up well after 3 years Requires regular vacuum sweeping Not limited to parking lots

30 30 Conclusions and Observations Success as a stormwater BMP Requires careful planning Can be cheaper than end of pipe treatment Provides stormwater treatment without additional R.O.W. costs Incorporate underdrains and impervious liners where there is a possibility of ground water contamination, especially from chlorides. Porous Pavement WQ monitoring results to date show: Lower peak flows, longer response times Temperature data may not meet expectations (???) Lower concentrations of TSS, and Total Metals

31 Mass DOT Porous Pavement Installations 31 Open Graded - No Tire Spray Dense Graded - Tire Spray

32 32 Full Depth Porous Construction Used on two Park and Rides Proposed for an I-95 non-travel median Installed to control peak discharges Mass DOT concerns: Not possible to maintain with simple milling and overlay Highway must be closed to construct Greater risk of groundwater contamination from spills.

33 33 Open-Graded Friction Course (Or OGFC If You Prefer) OGFC is a layer of porous asphalt placed as a wearing course over a conventional HMA pavement base Typical Installation:1 to 2 overlay on conventional asphalt OGFC is typically limited in use on travel lanes and shoulders of high volume limited access roadways Observed Life expectancy 15 to 22 years OGFC CONVENTIONAL PAVEMENT

34 34 Open-Graded Friction Course Massachusetts DOT Used on high volume highways: Interstates: I-93, I-95, I-495, I-290, I-190 State Routes 2 and Lane Miles (2008) Not used on: Ramps (higher loading stresses) Reduced Salt Zones MassDOT does not sand on these roads

35 35 Open-Graded Friction Course Benefits Improves Safety Improves Wet Weather Skid Resistance Reduces Spray Reduces Hydroplaning Improves Visibility Noise Reduction 3 to 5 decibels Quieter Like reducing traffic volume by 1/2

36 36 Open-Graded Friction Course Stormwater Benefits Recent research shows: OGFC results in significantly lower amounts of pollutants in runoff than observed for conventional pavement. Reduction in pollutants occurs through: Entrapment of particulates in the pavement voids, Reduction in fines generated by pavement wear, because of the lower volume of fines in the pavement mix; and/or Reduction in splash which in turn minimizes vehicular washoff. OGFC does not reduce runoff volume

37 37 Open-Graded Friction Course Stormwater Benefits MassDOT recently proposed OGFC as a stormwater BMP along I-95 MassDEP would not give any credit until they conduct a study If study is inconclusive then MassDOT must go off-site to provide treatment

38 38 Questions? Green infrastructure is the interconnected natural systems and ecological processes that provide clean water, air quality and wildlife habitat. Green infrastructure sustains a community s social, economic, and environmental health.