§ 19-145. Erosion and sediment control.

(a)

Erosion and sediment control plans.

(1)

An erosion and sediment control plan shall be required for any land-disturbing activity that meets any of the following conditions:

a.

Disturbs 5,000 square feet or more of land area; or

b.

Requires the excavation, placement or stockpiling of 50 cubic yards or more of material; or

c.

Any disturbance that is upgradient of and tributary to a water of the state as defined in M.S. § 115.01, subd. 22; or

d.

Any disturbance of land that is considered "highly erodible" as identified by the U.S. Department of Agriculture Natural Resources Conservation Service's Web Soil Survey application or equivalent; or

e.

Any land disturbance within the Bluff Creek Overlay District; or

f.

Any time an earthwork permit is issued; or

g.

An erosion and sediment control plan may be required after the fact if it is determined that sediment has migrated off of a construction site.

(2)

This shall be a stand-alone document that shall include the following:

a.

Site plans for existing and proposed conditions drawn to an appropriate scale. The plans shall include the following:

1.

Site location in relation to surrounding roads, steep slopes and/or bluff areas, other significant geographic features, buildings and other significant structures.

2.

Site property lines.

3.

Area of disturbance.

4.

Drainage boundaries and direction of drainage pre- and post-development.

5.

Location of surface water features as defined in M.S. § 115.01, subd. 22, including but not limited to, storm sewer inlet structures, wetlands, ponds, streams, lakes, on or immediately adjacent to the site, and all appropriate setbacks from these features.

6.

Identification of all receiving waterbodies and/or stormwater conveyance systems to which the site discharges. Notation of an impaired or special management waters status of waterbodies.

7.

Location of all trees and vegetation on the site with identification of what is to be saved. Installation of protective fencing, or other adequate measure, so as to exclude all fill and equipment from the drip line or critical root zone of the vegetation to be protected.

8.

Existing easements and utilities.

9.

Ingress and egress for equipment and materials.

10.

Location of stockpiled materials.

11.

Locations of proposed runoff control, erosion prevention, sediment control and temporary and permanent soil stabilization measures, including, but not limited to: Inlet protection, perimeter control, temporary and permanent soil stabilization, concrete wash areas, slope breaks, energy dissipation, rock construction entrance, silt curtains.

b.

Dewatering plan, if necessary, shall be provided to the city for review. The city must be noticed 24 hours prior to the commencement of any dewatering activities.

c.

As site and/or climatic conditions change additional best management practices may be needed. These changes must be implemented on the site and incorporated into the erosion and sediment control plan.

d.

Where inadequate natural vegetation exists or where it becomes necessary to remove existing natural vegetation, both temporary vegetative and permanent vegetative cover shall be addressed in the plans and specifications.

e.

Six inches of topsoil shall be incorporated into the final grading or four inches of 60 percent sand and 40 percent compost mix must be ripped into existing soil materials to a depth of ten inches on the site.

(3)

Stream bank stabilization and stream bed control structures shall be designed based on the unique site conditions present including soil conditions, flow rate, slope and flow velocity and shall be consistent with Part 654 of the National Engineering Handbook: Stream Restoration Design [H_210_NEH_654 - May 2008 or most recent revision].

(4)

If the disturbance exceeds the minimum threshold for the NPDES permit, erosion and sediment control plans shall be compliant with NPDES General Stormwater Permit for Construction Activity (MN R100001). The applicant shall prepare or cause to be prepared a stormwater pollution prevention plan (SWPPP) and provide this plan to the city.

(5)

Every effort shall be made to minimize disturbance of existing groundcover.

(6)

All erosion control noted on the approved plan shall be installed prior to the initiation of any site grading. Noncompliance with the grading and erosion control plan shall constitute grounds for an order from the city engineer to halt all earthwork and related construction on the site.

(b)

Maintenance. The land owner, or permittee shall be responsible at all times for the maintenance and proper operation of all erosion and sediment control management practices. Specific maintenance requirements are as follows:

(1)

All exposed soil areas must be stabilized as soon as possible to eliminate soil erosion but in no case later than 14 days after construction activity in that portion of the site had temporarily or permanently ceased.

(2)

The normal wetted perimeter of any temporary or permanent drainage ditch or swale that drains water from the site, or diverts water around a site must be stabilized. Stabilization must be completed within 24 hours of connecting to a surface water. Portions of the ditch that are under construction must be stabilized within 24 hours after the construction activity in that portion has ceased.

(3)

Sediment control practices must minimize sediment from entering surface waters, including curb and gutter systems and storm sewer inlets.

(4)

Sediment control practices must be established on all down-gradient perimeters before any up-gradient land-disturbing activities begin. These practices shall remain in place until the city has determined that the site soils have been permanently stabilized.

(5)

All storm drain inlets must be protected by best management practices as shown in the most current edition of "City of Chanhassen Standard Specifications and Detail Plates", during construction until all sources with potential for discharging to the inlet have been stabilized.

(6)

Pipe outlets must be provided with temporary or permanent energy dissipation within 24 hours of connection to a surface water.

(7)

In order to maintain sheet flow and minimize rills and gullies, there shall be no unbroken slope length of greater than 30 feet for slopes with a grade of 3:1 or steeper.

(8)

Temporary stockpiles must have effective sediment controls in place to prevent discharge to surface waters including stormwater conveyances such as curb and gutter.

(9)

Site access roads (entrances to construction sites) shall be graded or otherwise protected with silt fences, diversion channels or dikes and pipes to prevent sediment from exiting the site via the access road. Primary site access roads shall be surfaced with crushed rock or wood chips. The rock entrance shall extend for a minimum distance of 75 feet (150 for wood chips) beginning at existing paved surface; length may be reduced or lengthened at the discretion of the city engineer based upon site considerations. All construction traffic shall utilize the entire length of the rock entrance.

(10)

Soil tracked from the site by motor vehicles shall be cleaned from paved roadway surfaces at least daily or as needed throughout the duration of construction. Roadway cleaning shall be the responsibility of the party or parties having a permit with the city. If the tracked soil is not cleaned in a timely manner, the city may elect to clean the surface and invoice the responsible party.

(11)

During construction of an infiltration or biofiltration system, rigorous prevention and sediment controls must be used to prevent the discharge of sediment into the infiltration/biofiltration area. Infiltration/biofiltration areas must not be excavated to final grade until the contributing drainage area(s) has been constructed and finally stabilized. Infiltration/biofiltration areas shall be protected from heavy equipment operation.

(12)

Dewatering or basin draining (e.g., pumped discharges, trench/ditch cuts for drainage) related to the construction activity that may have turbid or sediment laden discharge water must be discharged to a temporary or permanent sedimentation basin on the site whenever possible. If water cannot be discharged to a sedimentation basin prior to entering the surface water, it must be treated with the appropriate BMPs, such that the discharge does not adversely affect the receiving water or downstream landowners.

(13)

Inlet protection devices and all perimeter control shall be maintained once sediment accumulates to a depth one-third of the designed capacity.

(14)

Detention basins may be used as temporary sediment retention during the construction phase. Upon final stabilization and before final approval, accumulated sediment must be removed to restore the required permanent pool volume in the detention area and an as-built survey showing this must be provided to the city.

(c)

Inspections and notifications.

(1)

Work sites must be inspected once every seven days and within 24 hours of a 1.0 inch rainfall event to assure that all sediment and erosion control elements are working effectively.

(2)

Inspection and maintenance records must be maintained and retained with the erosion control plan. Upon request, the inspection records must be made available to the city within 24 hours.

(3)

The city may contract inspections out to the Carver County Soil and Water Conservation District or other entities. The city may pass the costs on to the applicant.

(4)

The applicant or its authorized agent shall notify the city in writing at the following points:

a.

On completing installation of perimeter erosion and sedimentation controls.

b.

On completing land-disturbing activities and putting into place measures for final soil stabilization and revegetation.

c.

Whenever any site dewatering is proposed to take place.

d.

When the site has been permanently stabilized and revegetated.

e.

When all temporary erosion and sedimentation controls have been removed from the site.

(d)

Financial assurance. To guarantee compliance with the plan, and related remedial work, a cash escrow or letter of credit, satisfactory to the city, shall be furnished to the city before a building permit is issued. The escrow amount shall be not less than $250.00, but may be greater than $250.00 if, after review of the site, the city deems it necessary to require a greater amount to guarantee compliance. The maximum escrow allowable per parcel is $7,500.00 per acre. The city may use the escrow or draw upon the letter of credit to reimburse the city for any labor or material costs it incurs in securing compliance with the plan or in implementing the plan. If the city draws on the escrowed funds, no additional building permits shall be issued until the pre-draw escrow balance has been restored. The city shall endeavor to give notice to the owner or developer before proceeding, but such notice shall not be required in an emergency as determined by the city. The assurance shall be maintained until final stabilization and removal of erosion and sediment controls.

(Ord. No. 444, § 3, 2-12-07; Ord. No. 524, § 3, 6-27-11)