Sump manhole with SAFL baffle

The SAFL Baffle is a postconstruction storm-water pretreatment system. It fits into a sump manhole (new or existing) and keeps sediment out of downstream conveyance systems, water bodies, and other BMPs. It works by capturing sediment through settling; a vacuum truck removes the captured pollutants once or twice per year.

The SAFL Baffle can be a cost-effective option for capturing sands and large silt sediments in runoff and may be implemented as part of a treatment train to meet goals for total suspended solids.  The baffle can also be used to reduce maintenance required for downstream water-quality treatment BMPs, such as bioretention installations and underground vaults.

Retrofit Applicability

Some projects may incorporate the SAFL Baffle as a retrofit to upgrade the sedimentation removal performance of existing sump manholes. The SAFL Baffle fits through most standard castings, making a retrofit easy and inexpensive.

Cold Climate Suitability

Tested for nearly four years at the University of Minnesota’s St. Anthony Falls Laboratory, the SAFL Baffle is documented to remove sediment from storm water at a wide variety of flow rates and temperatures.

Water Quality Benefits

SAFL Baffle is a pretreatment BMP and maintenance tool that can be used in a treatment train in which a primary treatment BMP provides the water quality benefits. The main water-quality benefit of the SAFL Baffle installation is up to a 55% reduction in deposition of total suspended solids in downstream water bodies.

Design Considerations

Critical components for an effective SAFL Baffle design:

  • The sump depth below the outlet pipe must be a minimum of 3 feet.

  • The bottom of the SAFL Baffle needs to be at an elevation 1 foot below the invert of the outlet pipe.

  • The top of the SAFL Baffle should be roughly 2 to 6 inches above the top of the inlet pipe.

  • Use a 27 inch casting for the manhole.

  • SAFL Baffles can be installed in sump structures with diameters of 3 feet, 4 feet, 5 feet, 6 feet, and 8 feet, and with depths of 3 feet or greater. Custom SAFL Baffles can be manufactured for other diameter dimensions.

  • Make sure that the vacuum truck’s hose can enter the casting and not run into the SAFL Baffle.

Maintenance

Like all storm water BMPs, the SAFL Baffle must be maintained. It is recommended that new installations be maintained three times within the first year. These site visits will allow engineers and maintenance crews to assess how frequently the system must be maintained at specific sites. 

Cleaning procedures

  • Remove large debris that may be clogging the SAFL Baffle.

  • Ensure that the structure is accessible with a vacuum truck hose.

  • Ensure that the vacuum truck hose can reach the bottom of the sump.

  • Blow sediment to the upstream or downstream end of the sump, where the vacuum truck can remove the material.

Standard Designs

Square sump manhole, one inlet and one outlet, 180 degrees apart.Round sump manhole, one inlet and one outlet, 180 degrees apart.Round sump manhole, one inlet and one outlet, 90 degrees apart.

Square sump manhole, one inlet and one outlet, 180 degrees apart

Illustration: Upstream Technologies

 

Round sump manhole, one inlet and one outlet, 180 degrees apart

Illustration: Upstream Technologies

Round sump manhole, one inlet and one outlet, 90 degrees apart

Illustration: Upstream Technologies