The purpose of this chapter is to control or eliminate stormwater pollution along with soil erosion and sedimentation within the township. It establishes standards and specifications for conservation practices and planning services, which minimize stormwater pollution, soil erosion, and sedimentation.

(Ord. No. 204, 11-22-2022)

Except where a variance is granted, any person, firm, sole proprietorship, partnership, corporation, state agency, or political subdivision proposing a land disturbance activity within the township shall submit to the township, for approval, a stormwater pollution prevention plan, as required by this article. No land shall be disturbed until the plan is approved by the township and conforms to the standards set forth herein.

(Ord. No. 204, 11-22-2022)

Every applicant for a building permit, subdivision approval, or a permit to allow for excavation, filling, grading, or other such activity shall submit a stormwater pollution prevention plan to the town engineer for review and approval if more than 20,000 square feet of new impervious surface is created or if there will be more than one acre of land disturbance. Sites that create less than 20,000 square feet of a new impervious surface or disturb less than one acre of land but are part of a larger development or connected action creating a cumulative of more than 20,000 square feet of new impervious surface or land disturbance of a cumulative one or more acres shall meet all the requirements of this section.

(a)

Control runoff. Sites shall be designed to control runoff rate so as to not cause downstream flooding or erosion.

(b)

Minimize erosion. Site stormwater pollution prevention plans shall be designed to minimize erosion and to contain sediment from exiting the site.

(c)

Approval. No building permit, subdivision approval, or permit to allow land disturbing activities shall be issued until the township approves this plan.

(d)

Sites that result in land disturbance of equal to or greater than one acre shall be designed and implemented to meet or exceed the requirements of the Minnesota NPDES/SDS Construction Stormwater General Permit MN R100001 (construction stormwater permit).

(e)

General policy on stormwater runoff rates and water quality.

(1)

Stormwater runoff rates, volume, total suspended solids, and total phosphorus from the project site shall not increase over the predevelopment values, based on the last ten-years of how that land was used. Also accelerated channel erosion must not occur as a result of the proposed activity.

a.

Stormwater peak discharge rates shall not increase for the 24 hour, 2-year, ten-year, and 100-year storm events. Storm event analysis shall use Atlas 14 precipitation data.

b.

When stormwater is discharged to downstream wetlands and other waterbodies that are not completely under the ownership of the applicant a storm analysis for the 24 hour, 2-year, ten-year, and 100-year storm events, shall be provided to confirm the proposed development changes will not increase the downstream wetland or waterbody elevations above existing conditions. Existing wetlands that are completely under the ownership of the applicant can be used for rate control. The allowable water level bounce in the wetland must follow the Minnesota Pollution Control Agencies guidance document — "Stormwater and Wetlands: Planning and Evaluation Guidelines for Addressing Potential Impacts of Urban Stormwater and Snowmelt Runoff on Wetlands," Minnesota Pollution Control Agency 1997, or subsequent updates.

c.

Volume, total suspended solids, and total phosphorous may not increase on an average annual basis.

d.

Infiltration. An instantaneous stormwater volume calculated as one inch of runoff from the new impervious surface shall be retained on-site. This volume of water shall be considered the water quality volume.

(2)

Infiltration prohibited. Infiltration shall be prohibited if one or more of the following circumstances are present:

a.

The site is required to obtain a NPDES/SDS Industrial Stormwater Permit and the permit prohibits infiltration;

b.

Where vehicle fueling and maintenance occur;

c.

Less than three feet of separation is present from the bottom of the infiltration practice to the elevation of the seasonally saturated soils or top of bedrock;

d.

Where high levels of contaminants in the soil or groundwater will be mobilized by infiltrating stormwater.

(3)

Infiltration restricted. Higher engineering review shall be required when the infiltration device will be constructed in areas:

a.

Within a drinking water supply management area (DWSMA) as defined in Minn R. 4720.5100, subp. 13;

b.

Where soil infiltration rates are more than 8.3 inches per hour;

c.

Other areas as determined by the town engineer.

(4)

For projects where site constraints limit the ability to infiltrate the water quality volume, other storm water practices shall be constructed such as filtration or wet sedimentation in accordance with the Minnesota Pollution Control Agency's publication, "The Minnesota Stormwater Manual."

(5)

Applicants shall provide documentation showing compliance with the rate and quality requirements of this article. Acceptable documentation shall be:

a.

For rate and volume: Calculations shall be by a methodology listed in the Minnesota Pollution Control Agency's publication, "The Minnesota Stormwater Manual" or other method approved by the township.

b.

For total suspended solids and total phosphorus: Calculations shall be done using the minimal impact design standards (MIDS) calculator available on the MPCA website, P8 or other method approved by the township.

c.

Prepared and certified by a professional engineer licensed in the State of Minnesota.

(Ord. No. 204, 11-22-2022)

These minimum control measures are required where bare soil is exposed for all sites.

(a)

Easements. If a stormwater management plan involves directing some or all of the site's runoff onto adjacent properties, the applicant or their designated representative shall obtain from adjacent property owners any necessary easements or other property interests concerning the flowing of such water. It shall be the responsibility of the applicant to obtain any necessary easements or other property interests to allow permanent access to the stormwater management facilities for inspection and maintenance purpose.

(b)

Mining operations. Shall be in accordance with division 8 of this Code.

(c)

Sweeping. Traveled surfaces including but not limited to streets, parking lots, sidewalks and trails must be cleaned and swept whenever tracking of sediments occurs but no later than the end of each business day. Establishment of a regular sweeping schedule is encouraged.

(d)

Catch basins. All newly installed and rehabilitated catch basins immediately prior to rivers, lakes, streams, or wetlands must be provided with a minimum four-foot sump area for collecting coarse-grained material or a permanent sedimentation pond between the outlet and such water bodies.

(e)

Township inspections. The applicant shall be responsible for all required erosion and sediment inspections required in the approved stormwater pollution prevention plan. The township may perform inspections to ensure conformance with this section. The applicant and/or builder shall provide access to the site and address any deficiencies noted by the township to maintain proper erosion and sediment control at all sites within the timeframes noted in this article and the construction stormwater permit. In cases where cooperation is withheld, construction stop orders may be issued by the township, until erosion and sediment control measures are compliant with the construction stormwater permit and this article. Follow up erosion and sediment control/grading inspections must then be scheduled and passed before the construction stop order is lifted or any other inspections will be done.

(f)

Inspection and maintenance. All stormwater pollution control management facilities must be designed to minimize the need of maintenance, to provide easy vehicle and personnel access for maintenance purposes, and be structurally sound. The township or its designated representative shall inspect all stormwater management facilities during construction and during the first year of operation.

(g)

Maintain access roads. Access roads shall be provided to all storm water pollution control management facilities. Access roads shall be a minimum of ten feet wide and shall have a cross slope and profile slope of six percent or less. Vehicle maintenance access roads shall be constructed around the entire perimeter of all stormwater ponds and infiltration basins. Vehicle maintenance access roads shall be fully contained within a drainage and utility easement. The easement, at a minimum, shall be 20 feet wide and the vehicle maintenance access road shall be centered in the easement.

(h)

Private facilities. Where private facilities are allowed by the town board the applicant must provide as part of the design a plan of operation and maintenance. The plan must indicate the responsible party or parties charged with the long-term maintenance, repair, or replacement of the facilities. The plan shall also include information on the intended final ownership of the properties containing such facilities and the means by which inspection, maintenance, repair, or replacement, when necessary, shall be funded and accomplished and the party that will be responsible for the operation and maintenance. The details shall be included in an agreement that shall be recorded against the property being developed. In addition, the agreement shall provide for:

(1)

Access in perpetuity for inspection of the facilities by the township.

(2)

Access in perpetuity for maintenance of the facilities should the township find that storm water facility maintenance is required and upon written notice the property owners fail to take corrective action with the cost of such maintenance to be paid by the property owner.

(3)

If upon inspection, the township finds that any private stormwater management facilities require maintenance, repair, or replacement, but such deficiencies do not create a critical or imminent threat to adjacent properties, the environment, or other stormwater facilities; the party or parties responsible for the continued operation of the facilities shall be given written notice of the findings.

(4)

If upon inspection, the township finds that any private stormwater water management facilities require maintenance, repair, or replacement and such deficiencies create a critical or imminent threat to adjacent properties, the environment, or other stormwater facilities, the township may take immediate corrective action and charge the costs to the properties identified in the agreement as benefiting from the private stormwater facilities. The town board shall, by appropriate resolution, assess the costs including appropriate administrative fees against said properties, and certify the same to the county assessor of Anoka County, Minnesota.

(Ord. No. 204, 11-22-2022)

(a)

Stormwater fees. The applicant shall install or construct, and pay all appropriate township stormwater fees for all stormwater management facilities necessary to manage increased runoff, so that the proposed stormwater runoff rates and water quality meet the criteria in this article.

(b)

Maintenance of existing facilities. Maintenance of existing permanent pollution controls that do not have adequate capacity to meet the runoff and water quality criteria of this article shall not be accepted in lieu of new or retrofit permanent stormwater pollution controls.

(c)

Calculations. All calculations and information used in the design shall be submitted along with the stormwater pollution prevention plan for the review and approval of the town engineer.

(d)

Minimum design standards for all stormwater facilities.

(1)

At a minimum these facilities must conform to the most current technology as reflected in the current version of the Minnesota Pollution Control Agency's publication, "The Minnesota Stormwater Manual" and the construction stormwater permit, and the Sunrise River Watershed Management Organization's watershed management plan including all amendments.

(2)

Major stormwater facilities (i.e., ponds, pond outlet systems, and major conveyance systems) shall be designed for a return period of 100 years.

(3)

All minor drainage systems (i.e., piped collection systems and minor conveyance systems) shall be designed for a return period of ten years.

(4)

Designs shall use Atlas 14 precipitation data for storm analysis.

(5)

Minimum building (low floor) elevations shall be above in-situ, designed or designated water levels. The lowest building floor elevation shall be three feet above mottled soils or the highest known or anticipated water table, whichever is higher. The town engineer may allow deviation from these separations if the applicant submits evidence certified by a licensed geotechnical engineer that a lesser separation can be achieved. Certification by a licensed geotechnical engineer shall include field monitoring of the groundwater with piezometers to establish the highest anticipated ground water elevation.

(6)

Minimum opening elevations shall be above designed or designated flood levels. The minimum building opening elevation shall be two feet above the 100-year flood level and one foot above the emergency overflow elevation. The 100-year flood level shall be the highest 100-year level resulting from a single event analysis; the 100-year, 10-day snowmelt event; a multiple day runoff event analysis, or the critical event analysis.

(7)

Landlocked runoff basins shall be sized to handle back-to-back 100-year SCS 24 hour rainfall events, the ten inch SCS 24 hour rainfall event or the 100-year, 10-day snowmelt snow melt event, whichever produces the higher peak pond elevation (landlocked high-water level). The lowest building floor elevation around landlocked basins shall be three feet above the landlocked high-water level.

(8)

Emergency overflows or outlets to drainage systems shall be provided to any landlocked area if the available stormwater storage capacity is inadequate to prevent flooding of residences and if the available downstream conveyance system capacity is adequate to accept additional flow.

(9)

The area of a pond's high-water level plus two feet of freeboard shall be contained entirely within a drainage and utility easement.

(Ord. No. 204, 11-22-2022)

The town engineer shall review the stormwater pollution prevention plan.

(a)

Permit issued. If the township determines that the stormwater pollution prevention plan meets the requirements of this article, the township shall issue a permit valid for a specified period of time that authorizes the land disturbance activity contingent on the implementation and completion of the approved plan.

(b)

Denial. If the township determines that the stormwater pollution prevention plan does not meet the requirements of this article, the township shall not issue a permit for the land disturbance activity. All land use and building permits must be suspended until the applicant has an approved stormwater pollution prevention plan.

(Ord. No. 204, 11-22-2022)

An approved stormwater pollution prevention plan may be modified upon submission of a written application for modification to the township, and after written approval by the town engineer. In reviewing such an application, the town engineer may require additional reports and data.

(Ord. No. 204, 11-22-2022)

The applicant shall provide security for the performance of the work described and delineated on the approved grading plan involving the stormwater pollution prevention plan related remedial work in an amount of $2,000.00 per disturbed acre or $750.00 for each single or twin family home, whichever is greater. This security must be available prior to commencing the project. The form of the securities must be:

(a)

Currency. The first $10,000.00 (in U.S. currency) or 15 percent, whichever is greater, of this financial security must be by cash deposit to the township.

(b)

Deposit. Deposit, either with the township, a responsible escrow agent, or trust company, at the option of the township, money, negotiable bonds of the kind approved for securing deposits of public money or other instruments of credit from one or more financial institutions, subject to regulation by the state and federal government wherein said financial institution pledges that the funds are on deposit and guaranteed for payment. The type of security must be of a type acceptable to the township.

(c)

Financial security. The township may request a greater financial security, if the township considers that the development site is especially prone to erosion or the resource to be protected is especially valuable.

(d)

Maintaining the financial security. If at any time during the course of the work the security falls below 50 percent of the required deposit, the applicant shall make another deposit in the amount necessary to restore the cash deposit to the required amount.

(1)

If the applicant does not bring the financial security back up to the required amount within seven days after notification by the township that the amount has fallen below 50 percent of the required amount the township may:

a.

Withhold the scheduling of inspections and/or the issuance of a certificate of occupancy.

b.

Revoke any permit issued by the township to the applicant for the site in question or any other of the applicant's sites within the township's jurisdiction.

(e)

Proportional reduction of the financial security. When more than half of the development's exposed soil area achieves final stabilization, the township may reduce the total required amount of the financial security by half, if recommended by the town engineer.

(f)

Action against the financial security. The township may act against the financial security if any of the conditions listed below exist. The township shall use funds from this security to finance remedial work undertaken by the township, a private contractor hired by the township, or to reimburse the township for all direct costs incurred in the process of remedial work including, but not limited to, staff time, consultant time, and attorney's fees.

(1)

The applicant ceases land disturbing activities and/or filling and abandons the work site prior to completion of final stabilization.

(2)

The applicant fails to conform to the grading plan and/or the stormwater pollution prevention plan as approved by the township.

(3)

The permanent stormwater control measures required by this article fail within one year of site final stabilization.

(4)

The applicant fails to reimburse the township for corrective action taken under this article.

(g)

Returning the financial security. Any unspent amount of the financial security deposited with the township for faithful performance of the stormwater pollution prevention plan and any stormwater pollution prevention plan related remedial work may be released one full year after the completion of the installation of all stormwater pollution control measures as shown on the grading and/or stormwater pollution prevention plan and establishment of final stabilization.

(Ord. No. 204, 11-22-2022)

(a)

Powers. The permittee shall allow the township and their authorized representatives, upon presentation of credentials to:

(1)

Enter upon the permitted site for the purpose of obtaining information, examination of records, conducting investigations or surveys.

(2)

Bring such equipment upon the permitted development as is necessary to conduct such surveys and investigations.

(3)

Examine and copy any books, papers, records, or memoranda pertaining to activities or records to be kept under the terms and conditions of this permitted site.

(4)

Inspect the stormwater pollution control measures required as part of the storm water pollution prevention plan.

(5)

Sample and monitor any items or activities pertaining to permits issued by the township.

(Ord. No. 204, 11-22-2022)

(a)

Notification by the township. The initial contact will be to the party or parties listed on the application and/or the stormwater pollution prevention plan. Forty-eight hours after notification by the township or 72 hours after the failure of erosion control measures, whichever is less, the township, at its discretion, may begin corrective work.

(b)

Erosion off-site. If erosion breaches the perimeter of the site, the applicant shall immediately develop a cleanup and restoration plan, obtain the right-of-entry from the adjoining property owner, and implement the cleanup and restoration plan within 48 hours of obtaining the adjoining property owner's permission. In no case, unless written approval is received from the township, shall more than seven calendar days lapse without corrective action being taken. If in the discretion of the township, the applicant does not repair the damage caused by erosion, the township may do the remedial work required and charge the cost to the applicant.

(c)

Erosion into streets, wetlands or water bodies. If eroded soils (including tracked soils from construction activities) enter or appear likely to enter streets, wetlands or other water bodies, prevention strategies, cleanup and repair must be immediate. The applicant shall provide all traffic control and flagging required to protect the traveling public during the cleanup operations.

(d)

Failure to do corrective work. When an applicant fails to conform to any provision of this policy within the time stipulated, the township may take the following actions:

(1)

Withhold the scheduling of inspections and/or the issuance of a certificate of occupancy.

(2)

Revoke any permit issued by the township to the applicant for the site in question or any other of the applicant's sites within the township's jurisdiction.

(3)

Direct the correction of the deficiency by the township or by a separate contract. The issuance of a permit constitutes a right-of entry for the township or its contractor to enter upon the construction site for the purpose of correcting deficiencies in erosion control.

(4)

All costs incurred by the township in correcting stormwater pollution control deficiencies must be reimbursed by the applicant. If payment is not made within 30 days after costs are incurred by the township, payment will be made from the applicant's financial securities as described in this article.

(5)

If there is an insufficient financial amount, in the applicant's financial securities as described in this article to cover the costs incurred by the township, then the township may assess the remaining amount against the property. As a condition of the permit, the owner shall waive notice of any assessment hearing to be conducted by the township, concur that the benefit to the property exceeds the amount of the proposed assessment, and waive all rights by virtue of M.S.A § 429.081 to challenge the amount or validity of assessment.

(Ord. No. 204, 11-22-2022)

No part of this article is intended to repeal, abrogate, or impair any existing easements, covenants, or deed restrictions. However, where this article imposes greater restrictions, the provisions of this article shall prevail. All other ordinances inconsistent with this article are hereby repealed to the extent of the inconsistency only.

(Ord. No. 204, 11-22-2022)

The provisions of this article are severable, and if any provisions of this article, or application of any provision of this article to any circumstance, is held invalid, the application of such provision to other circumstances, and the remainder of this article must not be affected thereby.

(Ord. No. 204, 11-22-2022)