Green street maintenance and innovative design
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An estimated 50+% of stormwater pollution comes from municipal streets. Viewers will learn how different communities are infiltrating stormwater in municipal rights-of-way, why that is cost-effective, and how to maintain green infrastructure and infiltration areas.
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Green street maintenance and innovative design
- 1. Green Streets and Porous Pavement: Lessons for Sustainability, Savings, and Success EVAN N. PRATT, P.E. WASHTENAW COUNTY, MI Water Resources Commissioner
- 2. TODAY’S LEARNING OBJECTIVES: • SUSTAINABILITY: (AT LEAST) FIVE TECHNIQUES FOR STREET RUNOFF INFILTRATION • SAVINGS: WHAT TO COMPARE & COSTS • SUCCESS: POST-CONSTRUCTION PERFORMANCE
- 3. EVAN’S FOCUS AREAS: • WHY SHOULD ROW INFILTRATION BE 1ST CHOICE? • TECHNIQUES: – Porous Pavements – Infiltration Beds/Planters in the ROW – 3 New ways to infiltrate road drainage • SAVINGS: WHAT YOU’VE NEVER HEARD ABOUT POROUS O/M • SUCCESS = FEEDBACK LOOP AND ADAPTATION.
- 5. EVOLUTION OF WATER QUALITY • 1972 – CLEAN WATER ACT • 1970s-80s -- INDUSTRIAL POLLUTION TARGETED • Late 1980’s – present – SEWER OVERFLOWS • Late 1990’s – PHASE I TARGETS MS4 POINT/NON • 2000’s – present PHASE II – KEY QUESTIONS: – What is Non-Point Source (NPS) Pollution? – Will Public Education Take care of NPS? – Who can have the biggest impact on NPS?
- 6. WALT KELLY DEBUNKS “NON-POINT SOURCE” • ANN ARBOR, MI: POP. ~115,000: 27.7+ SQ. MI. • ROW = 2.9 SQUARE MILES IMPERVIOUS AREA • =10.5% of total City area • = 25.9% of total impervious area in the City but generates 54% of runoff* • LARGELY UNTREATED!! • =54% OF NPS POLLUTION – IT IS US!! *Roger Bannerman, Wisconsin DNR
- 7. (Drapper et al [Source: Kobringer, N.P. 1984. Volume I. Sources and Migration of Highway Runoff Pollutants- Executive Summary. FHWA/RD-84/057. Federal Highway Administration, Rexnord, EnviroEnergy Technology Center, Milwaukee, WI]) Constituent Primary Sources Particulates Pavement wear, vehicles, atmosphere, maintenance, snow/ice abrasives, sediment disturbance Nitrogen, Phosphorus Atmosphere, roadside fertiliser use, sediments Lead Leaded gasoline, tire wear, lubricating oil and grease, bearing wear, atmospheric fallout Zinc Tire wear, motor oil, grease Iron Auto body rust, steel highway structures, engine parts Copper Metal plating, bearing wear, engine parts, brake lining wear, fungicides and insecticides use Cadmium Tire wear, insecticide application Chromium Metal plating, engine parts, brake lining wear Nickel Diesel fuel and gasoline, lubricating oil, metal plating, brake lining wear, asphalt paving Manganese Engine parts Bromide Exhaust Cyanide Anticake compound used to keep deicing salt granular Sodium, Calcium De-icing slats, grease Chloride De-icing salts Sulphate Roadway beds, fuel, de-icing salts Petroleum Spills, leaks, blow-by motor lubricants, antifreeze, hydraulic fluids, asphalt surface leachate PCBs, pesticides Spraying of highway right of ways, atmospheric deposition, PCB catalyst in synthetic tires Pathogenic bacteria Soil litter, bird droppings, trucks hauling livestock/stockyard waste Rubber Tire wear Asbestos * Clutch and brake lining wear * No mineral asbestos has been identified in runoff, however some breakdown products of asbestos have been measured
- 8. CITY =54% OF NPS POLLUTION • HOW TO HANDLE THIS?? • OPPORTUNISTIC INFILTRATION – CURB NOTCHES/RAINGARDENS, BUMP-OUTS, ETC – FIND SAND -- PERFORATED PIPE, CISTERN SHAFTS – BASE UNDER POROUS/IMPERVIOUS PVMT • MINIMIZE SWIRL CHAMBERS!!
- 9. TSS Removal Efficiencies SOURCE: 2005 DATA REPORT, UNH STORMWATER CENTER
- 10. Top 5 TSS Removal Efficiencies • POROUS PAVEMENT– 100% • GRAVEL WETLAND – 100% • STORAGE BASIN INFILTRATION– 100% • TREE FILTER – 93% • BIORETENTION – 92%
- 11. Case Study: Boulder Hills Pelham, NH • 2009 -- 900’ OF PRIVATE RESIDENTIAL PAVING IN NE • SITE GOAL OF ZERO DISCHARGE • 55+ ACTIVE ADULT COMMUNITY • SANDY SOILS (NOT A MUST)
- 12. The Design
- 13. COST AVOIDANCE • 1616’ CONCRETE CURB • 785’ PIPE • 8 CATCHBASINS • 2 DETENTION BASINS & 2 OUTLET STRUCTURES • SAVED 1.3 ACRES IN LAND CLEARING/CONSUMPTION • CONVENTIONAL = $789,500 vs. LID SWM= $740,300 • INFILTRATION COST SAVINGS = $49,000 = (6.2%) • O/M DISCUSSION LATER – ALSO LESS
- 14. Comparison of Unit Costs
- 15. Performance of Porous Asphalt Willard Beach Park: Porous vs. Regular Asphalt Battle Creek, MI Entrance to Pringle Creek Community: Porous vs. Regular Asphalt Salem, OR
- 16. Other Project Benefits • GLARE REDUCTION SUBSTANTIAL • BETTER TRACTION THAN HMA • SOUND REDUCTION USE BY CALTRANS, OTHERS • ELIMINATED ICING & CRASHES IN ANDERSON CO, OH • LESS SALTING NEEDED - $$ AND ENVIRONMENTAL • LESS MOSQUITO BREEDING AREA • REDUCES THERMAL IMPACT TO STREAMS
- 17. POROUS vs. REGULAR ASPHALT POROUS REGULAR vs. PAVER & TRANSVERSE JOINTS
- 18. PREVENTING PITFALLS OF POROUS KNOW YOUR MIX DESIGN -- MULTIPLE OPTIONS IF LOADING OR RAVELING ARE CONCERNS SUB-BASE COMPACTION IS IMPORTANT TOO CHOKER LAYER IS KEY TO A WORKING PLATFORM NO SANDING FOR WINTER MAINTENANCE!! THE MYTH OF “MORE EXPENSIVE MAINTENANCE”
- 19. HOW POROUS O/M IS MUCH LESS • WHAT IF YOU HAD PAVEMENT THAT NEVER CRACKED?
- 20. HOW POROUS O/M IS MUCH LESS …AND IS SUPPOSED TO HAVE WATER IN THE BASE
- 21. HOW POROUS O/M IS MUCH LESS • WHAT IF YOU HAD PAVEMENT THAT NEVER CRACKED? • AND PAVEMENT THAT DIDN’T FAIL DUE TO WET BASE? • WHO IS UNDER AN NPDES PERMIT? • SWEEPING COSTS ARE ACTUALLY SIMILAR • A MILE OF POROUS CAN COST $57,750 LESS IN O/M
- 22. HOW POROUS O/M IS MUCH LESS $- $10,000 $20,000 $30,000 $40,000 $50,000 $60,000 $70,000 $80,000 $90,000 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 HMA Maintenance With Sweeping Cumulative Porous Sweeping Costs
- 23. HOW POROUS O/M IS MUCH LESS • *$57,750/MILE HMA PAVEMENT MAINTENANCE COSTS – YEAR 0-4 – NO COSTS – YEAR 5: FIRST CRACK SEALING; $750 – YEAR 6-10: LIMITED PATCHING; $6,000 ($2,000/LANE MILE) – YEAR 6-10: 2ND CRACK SEAL; $3,000, CHIPSEAL; $15,000 – YEAR 10-15: 3RD/4TH CRACK SEAL; $12,000 – YEAR 16-20: MAJOR PATCHING, POSSIBLE SEALCOAT; $21,000 – 4x ANNUAL STREET SWEEPING, $1,000/YR--IF PERMIT REQ’S. *YOU MAY WISH TO REVISE COSTS BASED ON YOUR AGENCY PRACTICES BASED ON 20 YEAR CYCLE FOR 1 MILE RESIDENTIAL STREET WITH 36’ PAVEMENT WIDTH
- 24. HOW POROUS O/M IS MUCH LESS • POROUS PAVEMENT MAINTENANCE COSTS: – 2x ANNUAL STREET SWEEPING, $1,000/YR REGEN VACUUM – NO CRACK SEALING – NO PATCHING DUE TO FROST HEAVE OR BASE FAILURE – NO RESURFACING DUE TO CRACKING, ETC • TOTAL LIFE CYCLE COST SAVINGS: – $57,750 IF STREET SWEEPING IS DONE ON HMA ANYWAY – $37,750 IF NO HMA STREET SWEEPING BASED ON 1 MILE RESIDENTIAL STREET WITH 36’ PAVEMENT WIDTH
- 25. REPAIRS AND REPLACEMENT • UTILITY CUTS, OTHER PATCHING NEEDS • BASE FAILURES TYPICALLY RARE – BETTER BASE • CAN REPAIR WITH REGULAR HMA • CAN REPAIR BY HEATING AND RE-ROLLING • TO REPLACE – MILL TO CHOKER COURSE
- 26. INFILTRATION TOOLKIT: 1. POROUS MIX DESIGNS ARE NOT ALL THE SAME 2. HMA WITH PAVERS OR POROUS IS AN OPTION 3. INFILTRATION UNDER TRADITIONAL HMA Easy Street, Ann Arbor, MI
- 27. INFILTRATION TOOLKIT #1: • MIX DESIGN IS IMPORTANT (STRENGTH & DURABILITY GOALS) – AZ-87 30,000vpd • KEY VARIABLES: –AGG SIZE –FIBER/ADDITIVE –ASPHALT CONTENT • SEE RESOURCES FOR MIX DESIGN INFO – WASHINGTON DOT, UNH
- 28. TOOLKIT #2: SYLVAN AVE, ANN ARBOR, MI • Reconstructed in 2010 • Approx. 825’ long; and 20’ wide. • Scope: Full reconstruction; full replacement of sidewalks, curb & gutter; construction of permeable HMA section; some infiltration at east 200’ of project, but remainder had an impervious line to prevent flooding of adjacent basements; installation of underdrains below sidewalks with tees to allow connection of sump pumps from individual properties. • Construction Cost: $385,000
- 29. TOOLKIT #2: SYLVAN AVE, ANN ARBOR, MI
- 31. INFILTRATION TOOLKIT #2: Permeable HMA 4” or as designed Permeable Asphalt Typical Cross Section
- 32. INFILTRATION TOOLKIT #2: POST CONSTRUCTION INFILTRATION WORST INTENSITY* RAIN IN SE MI: 0.23 in/hr for the 5 minute, 1,000-year storm 5 MIN, 10-Yr storm = 0.11 in/min = .55 in/hr 2 ASPHALT STREETS: 0.25 to 9 in/min = 15 to 540 1 CONCRETE ALLEY: 0.8 to 14 in/min = 48 to 840 3 POROUS LOTS: 11 to 60 in/min = 660+ in/hour *June 2013 NOAA Atlas 14
- 33. INFILTRATION TOOLKIT #3: NO POROUS PAVEMENT • CITY OF ANN ARBOR, MI 2013 INFILTRATION PAVING • TRADITIONAL HMA WITH SITE-SPECIFIC BASE INFILTRATION –FOREST STREET –FOURTH AVENUE –MADISON STREET
- 34. West Madison Street Cross Section
- 36. FOREST STREET X-SECTION 1
- 37. FOREST STREET X-SECTION 2
- 38. FOREST STREET LEACHING BASIN
- 39. FOURTH AVE. PLAN AND PROFILE
- 40. FOURTH AVE. X-SECTION 1
- 41. FOURTH AVE. LEACHING BASIN
- 42. INFILTRATION TOOLKIT #3: NO POROUS PAVEMENT • HMA PAVEMENT WITH POROUS BASE • STRATEGIC INFILTRATION AREAS IN ROW
- 43. Curb & Gutter vs. Swales
- 44. Street Trees and Planter Design • Tree planting areas often too small • Tree planting areas typically raised • Can be lowered to accommodate stormwater • Many design alternatives
- 45. IN CONCLUSION… • UP TO 54% OF POLLUTANTS FROM STREETS • INFILTRATION IS BEST, MOST SUSTAINABLE • MANY OPTIONS FOR INFILTRATION
- 46. Acknowledgements Thank you to the City of Ann Arbor and the University of New Hampshire Stormwater Center for their support.
- 47. References/Resources • http://tinyurl.com/streetrunoff • Porous Pavement Presentation, City of Puyallup, WA– Extra focus on mix design and aggregate selection for asphalt, choker, and base courses. • Roseen Robert, Thomas Ballestro, et al. Sustainable Stormwater Management in Road Environments: Porous Asphalt for Local Roads (2010). Accessed 1 Apr. 2013. (University of New Hampshire Stormwater Center) • City of Ann Arbor. Willard Street Permeable Pavement Project (2012), Madison, Fourth, and Forest Paving Projects (2013). (734) 794-6430 • Resource 3 is a detailed listing of contacts at agencies that have porous pavement installations, and other helpful resources accessed for this presentation.
Editor's Notes
- To make sure we are all on the same page, the first thing I need to cover is that this is a presentation about Green Streets - infiltrating street runoff. About 3/4 of our presentation will be case studies on post-construction porous pavement maintenance and performance, but what you hear today is intended to make clear that porous is just a tool. Our primary goal is to understand the extent of pollution from municipal ROWs and demonstrate how infiltration is both the most effective and best life cycle cost-effective approach. Along the way, my presentation offers two powerful observations you have never heard before that will help you succeed. Listen for me to say AHA!!.
- Because we found some new ideas for design that may be of interest, my section of the presentation will focus First on why it may make sense to consider infiltrating street runoff as your “first choice”. Second I will cover some pros and cons of porous asphalt w/r/t maintenance, including an AHA! Moment. Then I will conclude with telling you about a failed porous installation in the context of a feedback loop – A feedback loop is an aerospace systems design concept that ensures results are observed, analyzed, and system improvements made. This ensures continuous improvement regardless of initial success or failure. In other words, Don’t quit and don’t rest on your laurels. You will have the opportunity to decide if you agree that new infiltration techniques fit better with your current maintenance programs, address concerns about loading on porous pavement, all while putting you on the path for MS4 compliance, much cleaner street effluent, and the possibility of solving flooding issues. I know many of you are most interested in hearing cost comparisons of porous installations, and the next two presenters will cover that topic, both for asphalt and concrete pavements.
- So first of all, what is a Green Street?
- Phase I was large municipalities, phase II for all other urbanized areas.
- For those who have not heard of Walt Kelly, he was a satirist on the human condition, through his cartoon Pogo Possum, one famous malaprop is “We have met the enemy and it is us!”. Look at your GIS If you are not the top decision maker in your agency, and you are an MS4, the #1 takeaway I have for you is to let the top decision maker know that more than half of the pollutant loading your community is responsible for addressing comes from City-owned ROW and property. The biggest game changer for clean water is road agencies providing treatment of ROW runoff.
- It is important to understand that ROW runoff is some of the worst. To steal from a comedian hero of mine Tom Lehrer:
- Why focus on infiltration?? Because it works best.
- Your swirl chambers are often advertised in the 80-85% range, no doubt from lab tests. I spent several hours researching field test results over the past 2-3 years. I have not found one subsequent to 2005, and in summary, the conclusion of just about every field test was that results varied considerably based on field conditions, but it was very rare to see lab results in the field. Somewhere in the 60s seems to be the high end of reality – assuming you clean them often enough, which is another variable that has to be established in the field for each location through trial and error. I will say that road BMPs clog more quickly so swirl chambers are good for concentrated load pre-treatment.
- Note that our policy takes ½ the field infiltration rate (perc test), and we find that soils that would be considered A and B by SCS work in virtually every situation, and C soils are worth checking.
- See link on the last slide for our resources, including design guidance from UNH and WSDOT
- May not be a factor on every site, but make sure to consider
- AHA #1 ---- What if you had a pavement that never cracked and was supposed to have water in the base? Butt joints shown after 5.5 Years. Plus 7 transverse cracks over 140’ vs no cracks over 190’.
- Rutting, raveling, explain mix-design key points, explain porosity
- Find out from the top decision maker in your road agency what they spend on crack and patch repairs – show them the side by side photos and ask them the same question – “What if you had….”
- The costs of pavement management include crack sealing, Microsurfacing (and slurry, cape, chip seal), Patching. Does anyone have the experience that traditional pavement has the same ride after 15 yrs if you don’t spend that money?? It self-heals like a chip seal, b/c it is more flexible. What if you could have pavement that never cracks.
- AHA #2 ---- Note the two example cost savings, the larger number would presume you are an MS4 who does street sweeping. I’m sure your local numbers would be a little different than this, but any way you slice it, eliminating pavement patching, cracking, and potholes is surely a strong point that has a financial benefit for any agency.
- THERE IS A REASON IT’S CALLED A MIX DESIGN AGENCIES WITH THE LEAST PROBLEMS HAVE SPENT TIME GETTING THIS RIGHT Chandler, Arizona, SR – 87 in 1986, studied several times, performed well. 3,500 lft 3-lane
- Oops, Sylvan Ave got sanded, all manner of regenerative sweeping, pressure washing have been tried, and now the City does not want to do porous anymore due to maintenance (and the state DEQ that funded won’t fund anymore until it infiltrates) A nearby street is working, but post-construction infiltration rates could be better.
- Willard Street: How is water getting through pavement and interacting w/ catch basin? No under drain on sand trench, dims are 4.5’ x 3’ plus 1’ stone reservoir (35-40% voids) When water is at capacity it goes to sand seam (1st flush and bank full at minimum) Per city engineer, 6” edge drains T into these structures (catch basins) When there is overflow how does it reach the pipes? Sand trench drains quickly no freeze/ self cleaning Overflow: street still has standard basins maintained water goes through and passes into the storm water system Once system is full, water comes up to the surface when sand trench and porous pavement reaches capacity and water can’t get into the porous system- runs off like regular asphalt.
- Because the parking lots work so well, the infiltration numbers make it look like the streets are bad. The only reason that one of these 5 locations is considered a failure is because the rates are at this level for new pavement. The main question is whether the infiltration rates will meet your design criteria over time, and as you can see, our worst case is close to a storm no one uses for design, and all of these meet a conservative version of the 10 year storm normally used for pipe design. Studies show that all porous pavements (like any filter) will lose permeability over time, with an asymptotic curve – permeability starts to stabilize after a few years. (More text below) Don’t freak out b/c you see decline, stay focus on field performance, design goal, and trends/rates. Multiple readings critical for any infiltration test, pavement, basin, raingarden, other planters. One bad reading does not mean failure if the water can still be infiltrated without causing any more problem than normal HMA street drainage flow. I have seen results from basins where 2 of 6 tests had 0 permeability (hunk of clay), but no back-up, because the water has a plenty of places to infiltrate. Rule of thumb, about ¼ of the surface area can easily handle all infiltration needs.
- AHA #3! We’re talking about infiltrating water into the ground. How can we do that without using porous pavement.
- Trench is like a giant edge drain
- City of Portland is a real leader in this area, as is Seattle, I’m sure a few others. Or when doing a minor repair, C B patch at an intersection, ADA ramp repair – add in a small planted area.
- Maintenance is also an issue here, but I would posit that its easier to get businesses or homeowners to share in maintenance of planted areas than it is to get them to even rake leaves off of a drainage structure.
- Your charge is to make sure the top decision maker in your agency is aware of these facts – and if she or he believes you, offer to help share this information across the department, and take the lead on implementation. Check your GIS for untreated municipal runoff – and include municipal properties