06-12-2002 Council Agenda - Laserfiche WebLink

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4.11) Models /Methodologies /Computations. Hydrologic models and design methodologies used for the determining runoff characteristics and analyzing storm water management structures must be approved by the city engineer. Plans, specifications and computations for storm water management facilities submitted for review must be sealed and signed by a registered professional engineer. All computations must appear in the plans submitted for review, unless otherwise approved by the city engineer. * * * * * * * * ** Special information item on vegetated buffers. Do not include this information item in an actual ordinance. A 16.5 foot value shows up in several Minnesota statutes and rules. Because of the mariner that it is used, it is usually inferred to be a water quality protection value. This is a common misconception. The 16.5 foot value originates from the state's state ditch law. The relevant part of the state's ditch law is presented below. Minnesota Statute § 103E.021 103E.021 Ditches must be planted with permanent grass. Subdivision 1. Spoil banks must be spread and grass planted. In any proceeding to establish, construct, improve, or do any work affecting a public drainage system under any law that appoints viewers to assess benefits and damages, the authority having jurisdiction over the proceeding shall order spoil banks to be spread consistent with the plan and function of the drainage system. The authority shall order that permanent grass, other than a noxious weed, be planted on the banks and on a strip 16 -1/2 feet in width or to the crown of the leveled spoil bank, whichever is the greater, on each side of the top edge of the channel of the ditch. The acreage and additional property required for the planting must be acquired by the authority having jurisdiction. The 16.5 foot vegetated buffer strip for ditches is intended to reduce the cost of ditch maintenance by keeping the ditch's banks from eroding. It does not protect the receiving water from sheet runoff pollution. It is unfortunate that this maintenance prevention value is so often misapplied as a water quality protection value. * * * * * * * * **