Module 3: Typical Roadway Drainage

1. Module 3: Typical Roadway Drainage Where it goes in Where it comes out Stormwater System Maintenance: A 4-Part Workshop Series

2. (Chart for illustrative purposes only, based on Best Professional Judgment of Southern RI Conservation District)

3. Where stormwater enters our system: Inspecting and maintaining catch basins Minimizing erosion of shoulders and ditches Where stormwater leaves our system: Addressing scouring and excessive sedimentation at outfalls We will review Good Housekeeping

4. We will • Review the goals as written in the General Permit • Clarify or expand as needed • Review what we are doing now • Review how we report our activities • Look for ways to improve our effectiveness and/or efficiency

5. Inspecting & Maintaining Catch Basins

6. O&M Program • Required Goal • Procedures for implementing regular catch basin inspection & cleaning program • Inspect all annually, document • Clean as necessary • Coordinate with illicit discharge detection • Increase inspections in problem areas • May request lesser frequency after 2 years documentation

7. Inspect, Document

9. Locate system components manhole Catch basin outlet

10. How often to inspect? • All catch basins annually for at least 2 consecutive years • May request approval of lesser frequency based on documentation • RIGL 45-61.1: at least once per year for those designated as prone to flooding or contributing significantly to storm water management problems

11. Remove trash Remove sediment when trap is 1/3 full Make necessary physical repairs Document activities and volumes Maintain as necessary

12. Our Catch Basin Procedures • Maps • Schedule • Forms • What to inspect • Typical maintenance • Database

13. Literature recommends • Bring: • Maps • Camera • Inspection/maintenance forms • Pens • Rod, tape or probe to measure depths • Prybar to lift grates • Cellphone for emergencies

14. Trash & debris Estimate volume Sediment Measure depth Vegetation Note blockages Contamination Petroleum products Biohazards Structural integrity Nothing broken Pipes free-flowing Illicit connection Inspect, Document

15. Estimating Sediment Volume • Volume = area X depth • Area typically = pipe size x 4 x 3.12 • Total sump depth typically = pipe size x 4 • Sediment depth = total sump depth – distance from pipe invert to top of sediment

16. Infiltrating Catch Basins • “Dry wells” • No bottom and/or short lengths of pipe with no outlet • Standing water indicates clogging

17. Safety Tips • Wear appropriate safety equipment • Use proper temporary traffic control • Use care and proper equipment to lift grates & covers • Don’t enter a catch basin without proper training, and another person nearby

18. Minimizing Erosion of Shoulders & Ditches

19. O&M Program • Required Goal • Procedures to minimize erosion of road side shoulders & ditches by requiring stabilization • Reduce velocity

21. Low Impact Development

22. Shoulder Problems

25. Size and velocity are important!

26. Rain Gardens & Biofilters NCSU-BAE

27. Our Procedures for Shoulders & Ditches • Maps, database • Schedule • Forms • Typical maintenance

28. Safety Tips • Wear appropriate safety equipment • Use proper temporary traffic control • Be properly trained and familiar with equipment • Don’t leave edge drop-offs unprotected overnight

29. Locate potential problem areas • Steep slopes • Weak vegetation • Un-foreseen areas of concentrated flow • Un-planned vehicle pull-offs

30. Shoulder Repair • Scoured areas should be filled and compacted • Remove sediment/sand buildup when >3” higher than road

31. Select for salt tolerance, minimum maintenance

32. We don’t want … Phragmites Purple loosestrife

33. Ditch Maintenance • Area of concentrated flow = Freshwater Wetlands Permit • Work only in driest time of year • Short sections at a time • Start at outlet end, wait for it to stabilize

34. Recommended Practices • Remove sediment build-up when 3” deep (about every 5 years) • Restore infiltration in bottom by ripping with disc or roto-tiller

35. Recommended Practices • Seed & mulch at the end of each day • Install temporary check dams as needed • If channel gullies persist • size stone based on velocity, or • Consider grade control structure

36. Any time you’re out … • Note odors, sheen (illicit discharge) • Watch impact of new curb cuts, culverts

37. Scouring, Excessive Sedimentation at Outfalls

38. O&M Program • Required Goal • Procedures to identify and report annually on scouring/excessive sedimentation at outfalls • Procedures to remediate upon notification

40. SECTION III.B Discharges Causing Scouring or Excessive Sedimentation (Part IV.B.6.b.1.v)

42. Note source

43. Note source

44. Our Procedures at Outfalls • Maps, database • Inspection • Forms • Reports • Maintenance • Schedules • Typical outfall maintenance • Reports

45. Outlet Protection

46. Outfall extensions Half-culvert Flexible Downdrain

47. Remove sediments with care

48. Retrofit opportunities

49. Typical Roadway Drainage • Traditional Purpose: • Remove runoff from the driving surface • Good Housekeeping Purpose: • Provide multiple opportunities for pollutants to be separated from runoff

50. Stormwater System Maintenance: Employee Training Brought to you by: This program was developed by the Southern Rhode Island Conservation District in partnership with the URI Cooperative Extension RI NEMO Program and the Rhode Island T2 Center. Funding was provided by the RI Department of Environmental Management and the RI Department of Transportation under the Phase II Stormwater Education and Outreach Project.