Low Impact Development and Bioretention Maintenance

1. Low Impact Development and Bioretention Maintenance Module 7: Maintenance Practices II Dennis Chestnut

2. Contributors The Low Impact Development Center, Inc. John Shorb Landscaping, Inc. Logo Groundwork Anacostia River, D.C. Logo

3. Overview • Routine bioretention maintenance • Maintaining tree spaces • Maintaining small permeable pavement installations • Maintaining rain barrels and cisterns

4. Expected Outcomes • Know how to perform routine maintenance of bioretention cells, as well as minor repairs • Be able to perform basic maintenance of rain barrels and permeable pavers

5. Basic Activities

6. Watering

7. Pruning

8. Mulching

9. Maintaining structures

10. Plant replacement

11. Major rehabilitation

12. Materials and equipment

13. Plant restoration and removal

14. Structure and inlet repair

15. Clean-up

16. Maintaining Tree Spaces • Contact DDOT arborists for tree identification and maintenance recommendations

17. Maintenance – Street Tree-Box Filter • The maintenance requirements for street tree-box filters are similar to those of other bioretention devices, although less complicated

18. Maintenance – Street Tree-Box Filter Inspections • Bimonthly • If possible, conduct during or immediately after a rain event • Debris removal: • Inspect system and clear drainage path of accumulated leaves, debris, and trash • Remove accumulated materials on the top layer of the soil media, test, and dispose • Inspect discharge pipe for clogging and clean if necessary

19. Soils Maintenance Same maintenance as bioretention cells Runoff bypassing the tree-box = clogged inflow area, or reduced infiltration properties of soil mixture Soils analysis, disposal requirements, and corrective measures are the same as bioretention cells For remediation assistance, contact Americast at (800) 999-2278 or (804) 798-6068 Maintenance – Street Tree-Box Filter Planting Maintenance • Same maintenance as bioretention cells

20. Maintenance – Street Tree-Box Filter • First two years of maintenance typically included with the purchase of single and multiple-unit tree box filters • These would include removal of trash, debris and sediment, replenishment of the mulch, and care or replacement of plants • Annual maintenance = $500 per unit (performed by the manufacturer) or $100 per unit (performed by the owner) (sample cost estimate based on the Filterra™ Stormwater Bioretention Filtration System.)

21. Maintenance – Street Tree-Box Filter Corrective Actions • Plants may have to be replaced because: • they have overgrown the filter • environmental stress • they are mistaken as weeds growing through the grate, and are removed

22. Maintenance Schedule – Street Tree-Box Filter

23. Maintaining rain barrels and cisterns • Virtually maintenance free • Periodic inspections of system components • Most important - ensure spigot is set to slowly release the barrel’s water

24. Inspections • Bimonthly inspection: • rain barrel is free of debris • filtration screen and downspout not clogged • overflow system properly directing the water away from siding and foundations and not causing erosion problems • mosquito screen properly installed • Once a year, wash the barrel with mild (preferably biodegradable) soap and water

25. Corrective Action There are few mechanical parts on cisterns or rain barrels Spigot, valve, and screen replacements can be ordered from the manufacturer Cracked rain barrel = replace rain barrel Large cisterns constructed out of materials such as metal or concrete may need repairs to walls by parging (for concrete) or welding (for metal) Corrective Actions

26. Maintenance Schedule – Rain Barrels & Cisterns

27. Primary maintenance requirement - clean the surface drainage voids Can be incorporated into regular street sweeping program Annual inspections  Maintaining small permeable pavement installations

28. Maintenance schedule • Inspections • Routine maintenance is key: • Conventional street sweepers equipped with vacuum sweepers and high-pressure water can used to restore permeability • Street sweeping frequency varies depending on drainage area inputs (leaf debris, erosion, etc.). An active street sweeping program in the site’s drainage area will also help to prolong the functional life of the pavement • If necessary, add additional gravel chips to fill pore spaces after vacuum sweeping • In case of localized settling, individual paver blocks can be removed, new gravel added, and the blocks replaced

29. Preventive maintenance • Restrict use by heavy vehicles • Limit use of de-icing chemicals and sand • Implement stringent sediment control plan • Failure of systems: • poor design • inadequate construction techniques • low permeability soils • heavy vehicular traffic • resurfacing with nonporous materials

30. Maintenance Schedule Permeable Pavers

31. Maintenance – Permeable Pavement Routine Maintenance • Similar to permeable pavers • Recommended: Vacuum sweep twice per year

32. Maintenance – Permeable Pavement Corrective Action • Fill potholes and cracks with permeable patching mixes • Fix spot clogging by drilling ~0.5-inch holes through the porous pavement layer every few feet

33. Review

34. Resources