photo of a pretreatment device for a bioretention practice in St. Cloud, MN
Pre-treatment concept developed by the City of Eagan, modified and implemented by the City of St. Cloud. Two 5 inch by 40 inch channel drains bolted to the back of the curb. Construction adhesive used where concrete and drains meet; weep holes drilled in bottom of drains. Maintenance completed by removing screws with cordless drill, then the grates and scooping out sediment/debris. Hex head screws required. this is a cost-effective BMP for small surface infiltration practices and can be easily used for retrofits. Photo courtesy of the City of St. Cloud.

The Manual user will notice that many of the stormwater practices discussed in this Manual recommend pretreatment as an integral part of the BMP application. In fact, in many applications (ex. infiltration, stormwater ponds), the BMP would not be properly used if pre-treatment is ignored. The simple reason for the use of pretreatment techniques is the necessity to keep a BMP from being overloaded, primarily by sediment. Pretreatment can also be used to dampen the effects of high or rapid inflow, dissipate energy, and provide additional storage. All of these ancillary benefits help BMP performance.

Pretreatment is a required part of infiltration and filtration practices covered under the Minnesota Construction Stormwater General Permit. This manual describes three general types of pretreatment practices - settling devices, screens, and vegetated filter strips. These are described on the pages below.

Warning: The Construction Stormwater general permit states: To prevent clogging of the infiltration or filtration system, the Permittee(s) must use a pretreatment device such as a vegetated filter strip, small sedimentation basin, or water quality inlet (e.g., grit chamber) to settle particulates before the stormwater discharges into the infiltration or filtration system.

Acknowledgements


The following page was previously included in this pretreatment section of the manual. Much of this information has been updated and the reader is encouraged to use the information in the updated sections, shown in the above Table of Contents. However, there may be some useful information on this page. We hope to eventually update the information on this page. Flow-through structures for pre-treatment



This page was last modified on 23 January 2017, at 14:46.

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