Water quality discharges from paving operations, grinding and maintenance are sometimes a concern. In pavement preservation projects with little soil disturbance, project managers may still require BMPs to be installed in spot locations where wetlands or waterways are immediately adjacent to the roadway. Pick up brooms may be used to clean surfaces of excess aggregate after a chip seal project instead of a rotary type broom, which can push aggregate toward nearby waters or streams.[N]

Some state environmental agencies have identified issues with runoff from diamond grinding. Diamond grinding consists of removing surface irregularities from concrete pavements that are often caused by faulting, curling, and warping of the slabs. The main benefits of properly using this technique include smoother ride, reduced road noise, and improved friction. Diamond grinding can be used as a stand-alone rehabilitation technique.

Other water quality control measures are described elsewhere in this report, particularly in sections:

• Section 3.7: Design Guidance for Stormwater and Erosion & Sedimentation Control
• Section 4.5: Construction in Streams, Wetlands, and Other Environmentally Sensitive Areas
• Section 4.6: Erosion and Sedimentation Control in Construction
• Section 7.2: Avoiding and Minimizing Impacts to Fish and Wildlife And Enhancing Habitat during Bridge Construction and Maintenance
• Section 10.4: General Maintenance Near Waterbodies

Missouri DOT (MoDOT) developed the following guidelines for preventing discharge of the slurry from entering waters of the state from diamond grinding operations.

• No discharge of water/lime slurry will be allowed to enter "waters of the state".
  • "Waters of the state", all rivers, streams, lakes and other bodies of surface and subsurface water lying within the boundaries of the state which are not entirely confined and located completely upon lands owned, leased or otherwise controlled by a single person or entity.
• The Slurry should not be discharged to drainage ways, non-vegetated areas or anywhere storm water runoff is likely to occur.
• Discharge of the slurry should be stopped at least 25 feet from creeks and rivers on slopes less than 12 percent and 50 feet on slopes 12 percent to 25 percent in areas with healthy vegetation on the road right of way and at least 12 feet from the bottom of the ditch.
• On sites where there is sparse or no vegetation to control the movement of the slurry, alternatives that may be used include:
  • Pump the slurry into tankers and hauled to an area where it can be spread as a lime supplement. This method will require additional tankers and land close to the project site.
  • Incorporate the slurry into the soil on the right of way next to the road where it will not impact waters of the state, highway or shoulders.
• The Area Engineer must approve any other method of application or use of the slurry. An Environmental Compliance Coordinator should be contacted for guidance on the use of alternative methods.
• Precautions must be taken at all times to prevent the slurry from entering the waters of the state. Should improper application occur which may result in a discharge of lime slurry to the waters of the state, the contractor shall immediately remove the slurry and notify the Area Engineer.