City of Fargo STORMWATER MANAGEMENT PROGRAM July 1, 2009 –March 31, 2013

TABLE OF CONTENTS Purpose Introduction MCM 1 MCM 2 MCM 3 MCM 4 MCM 5 MCM 6 Appendix 2011 Annual Report IDDE Mutual Agreement

PURPOSE The purpose of the City of Fargo Stormwater Management Program (SWMP) is to meet requirements of the North Dakota Department of Health NDR04-0000 and Chapter 37 of the Fargo Municipal Code. Its rationale closely follows the National Pollutant Discharge Elimination System (NPDES) program of the United States Environmental Protection Agency. The NDR-04 requires Fargo’s plan to address six Minimum Control Measures (MCM).

1) Public Education and Outreach on Stormwater Impacts 2) Public Participation/Involvement 3) Illicit Discharge and Detection and Elimination 4) Construction Site Stormwater Runoff Control 5) Post-construction Stormwater Management for New Developments and Redevelopment 6) Pollution Prevention for Municipal Operations

This SWMP is designed to reduce the discharge of Municipal Separate Storm Sewer System (MS4) pollutants to the maximum extent possible (MEP) to protect water quality. The program is operated concurrently in concert with other city departments.

INTRODUCTION The City of Fargo (100,000 population) is located on the flat, fertile plains of the Red River of the North. The City is a transportation hub located at the junction of two Interstate Highways (I29, I94) and is serviced by BNSF Railway and an international airport. Primarily an agricultural community Fargo has a strong educational/government base with a growing medical and information base. The area’s flat, sediment-laden lake bed environment provides for not only exceptionally fertile cropland but also presents special challenges during the spring melt. This is due to the northerly flow of the Red River which results in frequent flooding, occasionally extreme.

Storm Water Drainage System Fargo’s corporate limit is some 50 square miles positioned in an elongated north/south orientation, approximately 12 (long) x 5 (wide) miles. Within Fargo, stormwater runoff from buildings, roadways and other impervious surfaces is collected and conveyed through public drainage facilities, collectively, the Fargo Storm Sewer System. This utility designs, plans, inspects and maintains the storm sewer system.

Red River Basin The Red River is a feature of the Red River Basin, a vast (45,000 square miles), northerly flowing and international drainage system. Red River of the North Uniquely, the Red River of the North indeed does flow north, terminating at Lake Winnipeg, Manitoba, Canada. Topography/soils Flat, glacial lake bottom best describes the Fargo area landscape. Formed by the retreat of a vast glacial lake called Agassiz, the underlying soils are mostly comprised of heavy clays. These clays have expansive properties and are weak.

Fargo Storm Sewer System Area = 50 square miles Miles of Pipe = 400 Inlets = 10,000 Legal drains = 6

Red River Basin

Features of the system include lined, open ditch (legal) drains, nearly 400 miles of pipe, approximately 10,000 inlets, regional/private detention/retention ponds and 74 lift stations to drain storm water. System surface waters can and are often routed long distances before entering the Red River.

PROGRAM COMPONENTS The six Minimum Control Measures (MCM) comprising the City of Fargo Storm Water Management Plan are explained in detail below. These control measure are specifically required in the North Dakota Department of Health NDR04-0000, Municipal Separate Storm Sewer System discharge permit.

MCM 1 - Public Education and Outreach on Stormwater Impacts Permit Requirements

• Implement a public education program or conduct outreach activities that address stormwater discharge on water quality.

• The program must address Illicit Discharge, Construction runoff, Post-construction Management in new areas and Pollution Prevention/good housekeeping for municipal operations.

• Program should identify the audience, educational goals and defined activities and have performance measures.

Current Fargo Activities Fargo utilizes a multi-faceted educational and outreach program. Target audiences include elementary children and the public at large.

River Keepers provides and conducts the main education curriculum with assistance (staff labor and financial assistance from the City. The two main educational activities are the Red River Water Festival conducted each fall and the Storm Drain Marking Program. In addition River Keepers promotes water quality concepts with a permanent demonstration site in south Fargo called the Living Lab. Additionally this non-profit entity utilizes door hangers, factsheets, factual email and civic events to deliver their message. Storm sewer staff participates in the River Keeper activities, conducts public/classroom speaking, purchases billboard time, distributes factsheets writes articles in the City’s newsletter Snapshots and maintains a website. Staff also provides training on construction/illicit discharges to contractors via the FM Homebuilders Association. Training is also conducted with other city departments and the Fargo Park District. Additionally the City partners with Red River Basin Commission, International Water Institute and other departments/agencies to promote water quality awareness. The partner agencies use a variety of media to convey their message including printed brochures, radio spots and event participation booths. Reportable performance measures are observed in target group attitudes and reported violations.

MCM 2 - Public Participation and Involvement Permit Requirements

• Provide opportunity for public involvement and input on the Stormwater Management Plan. Current Fargo Activities Significant floodplain issues exist in the city which promulgates significant public input. Floods, FEMA remapping, flood sales tax issues and permanent flood protection concerns are debated publically. With respect to stormwater public input is garnered though partnership entities and feedback on specific projects or incidents. The public is openly recruited to participate in River Keeper activities like the Storm Drain Marking Program, etc. Partner agencies provide public volunteer opportunities and input. The City maintains feedback forms on the website along with a host of information on stormwater and environmental health issues. Participation is also solicited by other city departments concerning water, sewers and vacant lots. Measurable feedback can be determined from the level of public input during flood meetings, flood fighting or related projects.

MCM 3 – Illicit Discharge Detection and Elimination Permit Requirements

• Develop and maintain MS4 map (pond, streams, lakes and wetlands, pipes and outfalls • Enact laws to prohibit illicit discharges • Develop plan to address non-stormwater discharges • Develop municipal staff training program for detection recognition • Address non-stormwater discharges or flows (sumps, flushing, irrigation and potable)

Current Fargo Activities Most stormwater features are mapped and maintained annually with photos and LiDAR are flown every 3 years system wide. This data set is available staff citywide. Private development site plan reviews are required for stormwater discharge. Plumbing and building permits are required and inspections are made by the building Inspections Department. Illegal dumping is controlled via ordinance, other city departments, and core partners. Illegal discharges are investigated immediately and administered by the appropriate department. For example those reports involving a restaurant grease dumping would be referred to Fargo Cass Public Health – food inspection division and hazardous waste via the Fargo Fire Department’ Hazardous Materials Unit. These departments would take the lead and Fargo Storm Sewer Utilities would act as support. (see 2008 policy) Education and outreach is conducted in concert with MCM 1 and 2 along with staff site visits to incident areas. Factsheets or violations are also used to educate the public and business on illegal dumping. Chapter 37 of the Fargo City Ordinance strictly governs stormwater quality concerns.

CM 4 – Construction Site Stormwater Runoff Control Permit Requirements

• Develop and enforce a program to reduce construction sediment runoff • Adopt ordinance with non-compliance penalty requiring sediment control • Ordinance must address construction site waste controls, concrete washout and non-

stormwater discharges • Procedures for site plan review • Procedures for inspection and enforcement of control measures

Current Fargo Activities Chapter 37 of the City Code requires all construction sites of 5,000 or more square feet to apply for an Erosion and Sediment Control Permit (ESC Permit), see figure below. The ESC Permit requires contractors to address temporary entrances, BMPs, stock piles and dewatering for erosion and sediment conditions. Commercial sites are reviewed by a qualified technician. Construction sites are patrolled daily by fulltime staff. Compliance issues are recorded on the Notice of Violation / Order to Correct form (see next page) and delivered to the permitee or site owner. All infraction have a 48 hour correction period with the exception of a live discharge which requires immediate response. The City of Fargo Stormwater Program partners with NDSU (another MS4) for construction Erosion and Sediment Control permitting operations.

MCM 5 – Construction Post-construction Stormwater Management

Permit Requirements • Develop a post-construction BMPs with a water quality component • Plan must include municipal operations (enclose salt storage, snow dump BMPs, etc.) • Use regulatory mechanism/penalty to address post construction runoff

Current Fargo Activities Chapter 37 requires new construction/development meet current policy for post construction stormwater requirements. Construction/development applicants must submit plans for review/approval with stormwater features: locations, volume and runoff calculations, BMP and maintenance issues. The City of Fargo has developed a storm water master plan. A major part of that plan will address the need to control storm water runoff from developed and developing areas. Storm water retention will be required for all new development and should be included as part of the developer's master plan. Storm water retention will also be required for new sites in existing developments. Local retention is classified as a retention pond or facilities that provide storm water retention on an individual property or site. Local retention facilities are constructed and maintained by the individual property owner. Regional retention is generally larger facilities, easily maintained and generally, more cost effective to build. The City of Fargo believes that regional retention provides the most effective method to control localized runoff. The City of Fargo encourages developers to provide regional, rather than local, retention. Regional or area wide retention are classified as publicly constructed retention ponds installed to serve multiple properties or ponds privately built to City Standards within an individual development not exceeding a quarter-section of land and meeting the requirements listed below. The City of Fargo’s storm water retention policy (see next page) is a supplement to the North Dakota Department of Health requirements. All proposed development and redevelopment will be required to, at a minimum, meet the North Dakota Department of Health permit NDR04-0000, effective date July 1, 2009. In scenarios where the City of Fargo’s storm water retention policy exceeds permit NDR04-0000 requirements, the City’s policy shall apply.

Policy on Storm Water Retention City of Fargo

The City of Fargo is in the process of developing a storm water master plan. A major part of that plan will address the need to control storm water runoff from developed and developing areas. This proposed policy addresses that issue. Storm water retention will be required for all new development and should be included as part of the developers master plan. Storm water retention will also be required for new sites in existing developments. Local retention is classified as a retention pond or facilities that provide storm water retention on an individual property or site. Local retention facilities are constructed and maintained by the individual property owner. Regional retention is generally larger facilities, easily maintained and generally, more cost effective to build. The City of Fargo believes that regional retention provides the most effective method to control localized runoff. The City of Fargo encourages developers to provide regional, rather than local, retention. Regional or area wide retention are classified as publicly constructed retention ponds installed to serve multiple properties or ponds privately built to City Standards within an individual development not exceeding a quarter-section of land and meeting the requirements listed below. Listed below are the retention requirements for development: 1. For sites under 1 acre-

It is not practical to require retention on very small sites. On-site or individual retention will not be required, however retention is required on a regional basis. Regional retention is based on the acreage being developed and shall meet the requirements shown below.

2. For all sites between 1 acre and less than 2 ½ acres On-site retention is not required for sites with less than or equal to 65% imperviousness, however retention is required on a regional basis On-site retention is required for sites with greater than 65% imperviousness

Retention based on equation method- 10 year and 100 year requirements Discharge is two stage; 10 year allowable and 100 year allowable Note: On-site retention requirements will be waived if regional retention is provided.

3. For developments or sites greater than 2 ½ acres and less than 25 acres On-site retention is required for all lots.

Retention based on equation method- 10 year and 100 year requirements Discharge is two stage- 10 year allowable and 100 year allowable

Note: On-site retention requirements can be waived if regional retention is provided and storm water discharge can be delivered to the regional retention facility without impacting existing drainage conditions.

1. This can be accomplished if the site is in close proximity to the regional facility 2. This can be accomplished by providing increased capacity of mainline storm sewers

between the site and the regional facility. 3. If the runoff coefficient is greater than the design coefficient of the regional

retention, on-site storage providing the volume difference between the two methods will be required, with the discharge pipe size limited to the 100-year pre-developed standard

4. For sites and developments greater than 25 acres Retention is generally required for all developments or sites in this category unless regional retention is provided

Retention based on modified equation method (Retention requirements are increased by requiring 0.2% additional capacity for every acre in the drainage area)

Discharge calculated by the large basin equation method; two-stage, 10-year and 100-year allowable

If regional retention is provided, and if the runoff coefficient is greater than the design coefficient of the regional retention, on-site storage providing the volume difference between the two methods will be required with the discharge pipe size limited to the 100-year pre-developed standard

Attached are sheets showing the required retention and allowable discharge equations and various typical development requirements.

Retention Requirement Formulas

3/19/2001

Retention is required to limit the 10 year and 100 year allowable site discharge to pre-developed conditions. The site is required to hold or retain the difference between their allowable pre-developed condition and their actual fully developed condition. This is required for both the 10-year and the 100-year condition. Once the 10-year retention capacity conditions have been met, discharge is allowed to increase up to the 100-year pre-developed condition. During this time, in major storm events, the retention ponds will continue to fill until they reach the 100-year retention requirements. The retention formulas are intended to approximate the results that are obtained using the TR-55 method. The formula method is easier to use and check and provides for consistent application of the retention policy. The equation method for retention and discharge are used for sites less than 25 acres. Above 25 acres, the retention formula is still used, however adjustments are made to reflect historical rainfalls and the reduced allowable discharge. This adjustment provides for a 0.2% increase in storage per acre once the drainage basin exceeds the 25-acre size. Allowable discharge is calculated by the large basin method, which is a modification of the MNDOT method commonly used in Minnesota counties. These allowable discharges are also two stage discharge conditions. The actual formulas are as follows: Areas 25 acres or less Detention volume required V=KA (Volume = Runoff coefficient * Area) V is in acre-feet of storage required K is the runoff coefficient (calculated below) A is area is in acres Runoff coefficient calculations K10=(0.95 I – 1.90)/1000 K100=((1.78 I – 0.002 Iª)– 3.56)/1000 Where I= % of imperviousness Allowable release rates Q10 = 0.5 * A Q100 = 1.0 * A Q is in cubic feet per second (cfs) A is in acres Areas greater than 25 acres Detention volume required V=KA * (1+(A*.002)) (Volume = Runoff coefficient * Area * 0.2% per acre) V is in acre-feet of storage required K is the runoff coefficient (calculated below) A is area is in acres Runoff coefficient calculations K10=(0.95 I – 1.90)/1000 K100=((1.78 I – 0.002 Iª)– 3.56)/1000 Where I= % of imperviousness Allowable release rates Q10 = (120*(A/640)¼ © ° ° * 0.71 Q100 = (120*(A/640) ¼ © ° ° * 1.21 Q is in cubic feet per second (cfs) A is in acres

Retention Requirements for Sites under 25 acresStormwater retention and allowable release rates for various size lots

"K" "V"-10 yr V-10 yr "K" "V"-100 yr V-100 yr Allowable approx. approx approx Allowable approx.Total Per cent 10 year Acre-feet Cubic ft 100 year Acre-feet Cubic ft Release pipe size orifice sq orifice Release pipe size @Acres Impervious Coeff. Retention Retention Coeff. Retention Retention Rate(10) min. grade area(sq ft) size-inches Rate(100) min. grade

1.0 70 0.06 0.06 2,814 0.11 0.11 4,846 0.5 6" 0.048 2.6 1.0 8"1.0 80 0.07 0.07 3,228 0.13 0.13 5,490 0.5 6" 0.048 2.6 1.0 8"1.0 90 0.08 0.08 3,642 0.14 0.14 6,118 0.5 6" 0.048 2.6 1.0 8"2.0 70 0.06 0.13 5,628 0.11 0.22 9,691 1 8" 0.096 3.7 2.0 10"2.0 80 0.07 0.15 6,456 0.13 0.25 10,981 1 8" 0.096 3.7 2.0 10"2.0 90 0.08 0.17 7,283 0.14 0.28 12,235 1 8" 0.096 3.7 2.0 10"2.5 70 0.06 0.16 7,035 0.11 0.28 12,114 1.25 8" 0.120 4.2 2.5 12"2.5 80 0.07 0.19 8,069 0.13 0.32 13,726 1.25 8" 0.120 4.2 2.5 12"2.5 90 0.08 0.21 9,104 0.14 0.35 15,294 1.25 8" 0.120 4.2 2.5 12"3.0 50 0.05 0.14 5,959 0.08 0.24 10,512 1.5 10" 0.144 4.6 3.0 12"3.0 60 0.06 0.17 7,200 0.10 0.29 12,551 1.5 10" 0.144 4.6 3.0 12"3.0 70 0.06 0.19 8,442 0.11 0.33 14,537 1.5 10" 0.144 4.6 3.0 12"3.0 80 0.07 0.22 9,683 0.13 0.38 16,471 1.5 10" 0.144 4.6 3.0 12"3.0 90 0.08 0.25 10,925 0.14 0.42 18,353 1.5 10" 0.144 4.6 3.0 12"4.0 50 0.05 0.18 7,945 0.08 0.32 14,016 2 10" 0.192 5.3 4.0 15"4.0 60 0.06 0.22 9,601 0.10 0.38 16,734 2 10" 0.192 5.3 4.0 15"4.0 70 0.06 0.26 11,256 0.11 0.44 19,382 2 10" 0.192 5.3 4.0 15"4.0 80 0.07 0.30 12,911 0.13 0.50 21,961 2 10" 0.192 5.3 4.0 15"4.0 90 0.08 0.33 14,566 0.14 0.56 24,470 2 10" 0.192 5.3 4.0 15"5.0 50 0.05 0.23 9,932 0.08 0.40 17,520 2.5 12" 0.240 5.9 5.0 15"5.0 60 0.06 0.28 12,001 0.10 0.48 20,918 2.5 12" 0.240 5.9 5.0 15"5.0 70 0.06 0.32 14,070 0.11 0.56 24,228 2.5 12" 0.240 5.9 5.0 15"5.0 80 0.07 0.37 16,139 0.13 0.63 27,452 2.5 12" 0.240 5.9 5.0 15"5.0 90 0.08 0.42 18,208 0.14 0.70 30,588 2.5 12" 0.240 5.9 5.0 15"6.0 50 0.05 0.27 11,918 0.08 0.48 21,024 3 12" 0.288 6.4 6.0 18"6.0 60 0.06 0.33 14,401 0.10 0.58 25,101 3 12" 0.288 6.4 6.0 18"6.0 70 0.06 0.39 16,884 0.11 0.67 29,074 3 12" 0.288 6.4 6.0 18"6.0 80 0.07 0.44 19,367 0.13 0.76 32,942 3 12" 0.288 6.4 6.0 18"6.0 90 0.08 0.50 21,850 0.14 0.84 36,705 3 12" 0.288 6.4 6.0 18"7.0 50 0.05 0.32 13,904 0.08 0.56 24,528 3.5 12" 0.335 7.0 7.0 18"7.0 60 0.06 0.39 16,801 0.10 0.67 29,285 3.5 12" 0.335 7.0 7.0 18"7.0 70 0.06 0.45 19,698 0.11 0.78 33,919 3.5 12" 0.335 7.0 7.0 18"7.0 80 0.07 0.52 22,595 0.13 0.88 38,432 3.5 12" 0.335 7.0 7.0 18"7.0 90 0.08 0.59 25,491 0.14 0.98 42,823 3.5 12" 0.335 7.0 7.0 18"8.0 50 0.05 0.36 15,891 0.08 0.64 28,032 4 15" 0.383 7.4 8.0 21"8.0 60 0.06 0.44 19,201 0.10 0.77 33,468 4 15" 0.383 7.4 8.0 21"8.0 70 0.06 0.52 22,512 0.11 0.89 38,765 4 15" 0.383 7.4 8.0 21"8.0 80 0.07 0.59 25,822 0.13 1.01 43,922 4 15" 0.383 7.4 8.0 21"8.0 90 0.08 0.67 29,133 0.14 1.12 48,941 4 15" 0.383 7.4 8.0 21"9.0 50 0.05 0.41 17,877 0.08 0.72 31,536 4.5 15" 0.431 7.9 9.0 21"9.0 60 0.06 0.50 21,601 0.10 0.86 37,652 4.5 15" 0.431 7.9 9.0 21"9.0 70 0.06 0.58 25,326 0.11 1.00 43,611 4.5 15" 0.431 7.9 9.0 21"9.0 80 0.07 0.67 29,050 0.13 1.13 49,413 4.5 15" 0.431 7.9 9.0 21"9.0 90 0.08 0.75 32,775 0.14 1.26 55,058 4.5 15" 0.431 7.9 9.0 21"10.0 50 0.05 0.46 19,863 0.08 0.80 35,040 5 15" 0.479 8.3 10.0 24"10.0 60 0.06 0.55 24,002 0.10 0.96 41,835 5 15" 0.479 8.3 10.0 24"10.0 70 0.06 0.65 28,140 0.11 1.11 48,456 5 15" 0.479 8.3 10.0 24"10.0 80 0.07 0.74 32,278 0.13 1.26 54,903 5 15" 0.479 8.3 10.0 24"10.0 90 0.08 0.84 36,416 0.14 1.40 61,176 5 15" 0.479 8.3 10.0 24"11.0 50 0.05 0.50 21,850 0.08 0.88 38,544 5.5 18" 0.527 8.7 11.0 24"11.0 70 0.06 0.71 30,954 0.11 1.22 53,302 5.5 18" 0.527 8.7 11.0 24"11.0 90 0.08 0.92 40,058 0.14 1.54 67,293 5.5 18" 0.527 8.7 11.0 24"12.0 50 0.05 0.55 23,836 0.08 0.97 42,048 6 18" 0.575 9.1 12.0 24"12.0 70 0.06 0.78 33,768 0.11 1.33 58,147 6 18" 0.575 9.1 12.0 24"12.0 90 0.08 1.00 43,699 0.14 1.69 73,411 6 18" 0.575 9.1 12.0 24"13.0 50 0.05 0.59 25,822 0.08 1.05 45,552 6.5 18" 0.623 9.5 13.0 27"13.0 70 0.06 0.84 36,582 0.11 1.45 62,993 6.5 18" 0.623 9.5 13.0 27"13.0 90 0.08 1.09 47,341 0.14 1.83 79,528 6.5 18" 0.623 9.5 13.0 27"14.0 50 0.05 0.64 27,809 0.08 1.13 49,056 7 18" 0.671 9.8 14.0 27"14.0 70 0.06 0.90 39,396 0.11 1.56 67,839 7 18" 0.671 9.8 14.0 27"14.0 90 0.08 1.17 50,983 0.14 1.97 85,646 7 18" 0.671 9.8 14.0 27"15.0 50 0.05 0.68 29,795 0.08 1.21 52,559 7.5 21" 0.719 10.2 15.0 30"15.0 70 0.06 0.97 42,210 0.11 1.67 72,684 7.5 21" 0.719 10.2 15.0 30"15.0 90 0.08 1.25 54,624 0.14 2.11 91,763 7.5 21" 0.719 10.2 15.0 30"16.0 50 0.05 0.73 31,781 0.08 1.29 56,063 8 21" 0.767 10.5 16.0 30"16.0 70 0.06 1.03 45,024 0.11 1.78 77,530 8 21" 0.767 10.5 16.0 30"16.0 90 0.08 1.34 58,266 0.14 2.25 97,881 8 21" 0.767 10.5 16.0 30"17.0 50 0.05 0.78 33,768 0.08 1.37 59,567 8.5 21" 0.815 10.8 17.0 30"17.0 70 0.06 1.10 47,838 0.11 1.89 82,375 8.5 21" 0.815 10.8 17.0 30"17.0 90 0.08 1.42 61,907 0.14 2.39 103,999 8.5 21" 0.815 10.8 17.0 30"18.0 50 0.05 0.82 35,754 0.08 1.45 63,071 9 21" 0.863 11.1 18.0 33"18.0 70 0.06 1.16 50,652 0.11 2.00 87,221 9 21" 0.863 11.1 18.0 33"18.0 90 0.08 1.50 65,549 0.14 2.53 110,116 9 21" 0.863 11.1 18.0 33"19.0 50 0.05 0.87 37,740 0.08 1.53 66,575 9.5 24" 0.911 11.5 19.0 33"19.0 70 0.06 1.23 53,466 0.11 2.11 92,067 9.5 24" 0.911 11.5 19.0 33"19.0 90 0.08 1.59 69,191 0.14 2.67 116,234 9.5 24" 0.911 11.5 19.0 33"20.0 50 0.05 0.91 39,727 0.08 1.61 70,079 10 24" 0.959 11.7 20.0 33"20.0 70 0.06 1.29 56,280 0.11 2.22 96,912 10 24" 0.959 11.7 20.0 33"20.0 90 0.08 1.67 72,832 0.14 2.81 122,351 10 24" 0.959 11.7 20.0 33"21.0 50 0.05 0.96 41,713 0.08 1.69 73,583 10.5 24" 1.006 12.0 21.0 36"21.0 70 0.06 1.36 59,093 0.11 2.34 101,758 10.5 24" 1.006 12.0 21.0 36"21.0 90 0.08 1.76 76,474 0.14 2.95 128,469 10.5 24" 1.006 12.0 21.0 36"22.0 50 0.05 1.00 43,699 0.08 1.77 77,087 11 24" 1.054 12.3 22.0 36"22.0 70 0.06 1.42 61,907 0.11 2.45 106,604 11 24" 1.054 12.3 22.0 36"22.0 90 0.08 1.84 80,116 0.14 3.09 134,586 11 24" 1.054 12.3 22.0 36"23.0 50 0.05 1.05 45,686 0.08 1.85 80,591 11.5 24" 1.102 12.6 23.0 36"23.0 70 0.06 1.49 64,721 0.11 2.56 111,449 11.5 24" 1.102 12.6 23.0 36"23.0 90 0.08 1.92 83,757 0.14 3.23 140,704 11.5 24" 1.102 12.6 23.0 36"24.0 50 0.05 1.09 47,672 0.08 1.93 84,095 12 24" 1.150 12.9 24.0 36"24.0 70 0.06 1.55 67,535 0.11 2.67 116,295 12 24" 1.150 12.9 24.0 36"24.0 90 0.08 2.01 87,399 0.14 3.37 146,822 12 24" 1.150 12.9 24.0 36"25.0 50 0.05 1.14 49,658 0.08 2.01 87,599 12.5 27" 1.198 13.1 25.0 36"25.0 70 0.06 1.62 70,349 0.11 2.78 121,140 12.5 27" 1.198 13.1 25.0 36"25.0 90 0.08 2.09 91,040 0.14 3.51 152,939 12.5 27" 1.198 13.1 25.0 36"

Retention Requirements for Sites over 25 acresMinnesota Drainage outflow with modified 100 year retention requirements of + 0.2% per acre of drainage basin Q=120*A.55*1.2

"K" "V"-10 yr V-10 yr "K" "V"-100 yr V-100 yr Allowable approx. approx approx Allowable approx.Total Per cent 10 year Acre-feet Cubic ft 100 year Acre-feet Cubic ft Release pipe size orifice sq orifice Release pipe size @Acres Impervious Coeff. Retention Retention Coeff. Retention Retention Rate(10) min. grade area(sq ft) size-inches Rate(100) min. grade

0.525.0 50 0.05 1.14 49,658 0.08 2.11 91,979 14.3 27" 1.373 14.1 24.2 36"25.0 70 0.06 1.62 70,349 0.12 2.92 127,197 14.3 27" 1.373 14.1 24.2 36"25.0 90 0.08 2.09 91,040 0.15 3.69 160,586 14.3 27" 1.373 14.1 24.2 36"30.0 50 0.05 1.37 59,590 0.09 2.56 111,426 15.8 30" 1.517 14.8 26.8 36"30.0 70 0.06 1.94 84,419 0.12 3.54 154,091 15.8 30" 1.517 14.8 26.8 36"30.0 90 0.08 2.51 109,248 0.15 4.47 194,539 15.8 30" 1.517 14.8 26.8 36"35.0 50 0.05 1.60 69,522 0.09 3.01 131,224 17.2 30" 1.652 15.4 29.1 42"35.0 70 0.06 2.26 98,489 0.12 4.17 181,468 17.2 30" 1.652 15.4 29.1 42"35.0 90 0.08 2.93 127,457 0.15 5.26 229,103 17.2 30" 1.652 15.4 29.1 42"40.0 50 0.05 1.82 79,453 0.09 3.48 151,371 18.5 33' 1.777 16.0 31.3 42"40.0 70 0.06 2.58 112,559 0.12 4.81 209,331 18.5 33' 1.777 16.0 31.3 42"40.0 90 0.08 3.34 145,665 0.15 6.07 264,279 18.5 33' 1.777 16.0 31.3 42"45.0 50 0.05 2.05 89,385 0.09 3.95 171,870 19.8 33' 1.896 16.5 33.4 42"45.0 70 0.06 2.91 126,629 0.12 5.46 237,677 19.8 33' 1.896 16.5 33.4 42"45.0 90 0.08 3.76 163,873 0.15 6.89 300,067 19.8 33' 1.896 16.5 33.4 42"50.0 50 0.05 2.28 99,317 0.09 4.42 192,718 21.0 36" 2.009 17.0 35.4 42"50.0 70 0.06 3.23 140,699 0.12 6.12 266,509 21.0 36" 2.009 17.0 35.4 42"50.0 90 0.08 4.18 182,081 0.15 7.72 336,466 21.0 36" 2.009 17.0 35.4 42"55.0 50 0.05 2.51 109,248 0.09 4.91 213,917 22.1 36" 2.118 17.5 37.3 42"55.0 70 0.06 3.55 154,769 0.12 6.79 295,825 22.1 36" 2.118 17.5 37.3 42"55.0 90 0.08 4.60 200,289 0.16 8.57 373,477 22.1 36" 2.118 17.5 37.3 42"60.0 50 0.05 2.74 119,180 0.09 5.41 235,467 23.2 36" 2.221 17.9 39.2 48"60.0 70 0.06 3.88 168,839 0.12 7.48 325,625 23.2 36" 2.221 17.9 39.2 48"60.0 90 0.08 5.02 218,497 0.16 9.44 411,100 23.2 36" 2.221 17.9 39.2 48"65.0 50 0.05 2.96 129,112 0.09 5.91 257,366 24.2 36" 2.321 18.3 40.9 48"65.0 70 0.06 4.20 182,908 0.13 8.17 355,910 24.2 36" 2.321 18.3 40.9 48"65.0 90 0.08 5.43 236,705 0.16 10.32 449,335 24.2 36" 2.321 18.3 40.9 48"70.0 50 0.05 3.19 139,044 0.09 6.42 279,617 25.2 36" 2.418 18.7 42.6 48"70.0 70 0.06 4.52 196,978 0.13 8.88 386,680 25.2 36" 2.418 18.7 42.6 48"70.0 90 0.08 5.85 254,913 0.16 11.21 488,182 25.2 36" 2.418 18.7 42.6 48"75.0 50 0.05 3.42 148,975 0.09 6.94 302,217 26.2 36" 2.512 19.0 44.3 48"75.0 70 0.06 4.85 211,048 0.13 9.59 417,934 26.2 36" 2.512 19.0 44.3 48"75.0 90 0.08 6.27 273,121 0.16 12.11 527,640 26.2 36" 2.512 19.0 44.3 48"80.0 50 0.05 3.65 158,907 0.09 7.46 325,168 27.1 36" 2.602 19.4 45.9 48"80.0 70 0.06 5.17 225,118 0.13 10.32 449,673 27.1 36" 2.602 19.4 45.9 48"80.0 90 0.08 6.69 291,329 0.16 13.03 567,710 27.1 36" 2.602 19.4 45.9 48"85.0 50 0.05 3.88 168,839 0.09 8.00 348,469 28.1 36" 2.691 19.7 47.4 54"85.0 70 0.06 5.49 239,188 0.13 11.06 481,896 28.1 36" 2.691 19.7 47.4 54"85.0 90 0.08 7.11 309,537 0.16 13.97 608,392 28.1 36" 2.691 19.7 47.4 54"90.0 50 0.05 4.10 178,770 0.09 8.54 372,121 29.0 42" 2.776 20.0 49.0 54"90.0 70 0.06 5.81 253,258 0.13 11.81 514,604 29.0 42" 2.776 20.0 49.0 54"90.0 90 0.08 7.52 327,745 0.17 14.91 649,686 29.0 42" 2.776 20.0 49.0 54"95.0 50 0.05 4.33 188,702 0.10 9.09 396,123 29.8 42" 2.860 20.3 50.4 54"95.0 70 0.06 6.14 267,328 0.13 12.58 547,797 29.8 42" 2.860 20.3 50.4 54"95.0 90 0.08 7.94 345,954 0.17 15.88 691,591 29.8 42" 2.860 20.3 50.4 54"

100.0 50 0.05 4.56 198,634 0.10 9.65 420,476 30.7 42" 2.942 20.6 51.9 54"100.0 70 0.06 6.46 281,398 0.13 13.35 581,474 30.7 42" 2.942 20.6 51.9 54"100.0 90 0.08 8.36 364,162 0.17 16.85 734,108 30.7 42" 2.942 20.6 51.9 54"105.0 50 0.05 4.79 208,565 0.10 10.22 445,179 31.5 42" 3.022 20.9 53.3 54"105.0 70 0.06 6.78 295,467 0.13 14.13 615,635 31.5 42" 3.022 20.9 53.3 54"105.0 90 0.08 8.78 382,370 0.17 17.84 777,237 31.5 42" 3.022 20.9 53.3 54"110.0 50 0.05 5.02 218,497 0.10 10.80 470,232 32.3 42" 3.100 21.1 54.7 54"110.0 70 0.06 7.11 309,537 0.14 14.93 650,281 32.3 42" 3.100 21.1 54.7 54"110.0 90 0.08 9.20 400,578 0.17 18.85 820,977 32.3 42" 3.100 21.1 54.7 54"115.0 50 0.05 5.24 228,429 0.10 11.38 495,636 33.1 42" 3.177 21.4 56.0 54"115.0 70 0.06 7.43 323,607 0.14 15.73 685,412 33.1 42" 3.177 21.4 56.0 54"115.0 90 0.08 9.61 418,786 0.17 19.87 865,330 33.1 42" 3.177 21.4 56.0 54"120.0 50 0.05 5.47 238,360 0.10 11.97 521,390 33.9 42" 3.252 21.6 57.3 54"120.0 70 0.06 7.75 337,677 0.14 16.55 721,027 33.9 42" 3.252 21.6 57.3 54"120.0 90 0.08 10.03 436,994 0.17 20.90 910,294 33.9 42" 3.252 21.6 57.3 54"125.0 50 0.05 5.70 248,292 0.10 12.57 547,495 34.7 42" 3.326 21.9 58.6 54"125.0 70 0.06 8.08 351,747 0.14 17.38 757,127 34.7 42" 3.326 21.9 58.6 54"125.0 90 0.08 10.45 455,202 0.18 21.94 955,870 34.7 42" 3.326 21.9 58.6 54"130.0 50 0.05 5.93 258,224 0.10 13.18 573,950 35.5 42" 3.399 22.1 59.9 54"130.0 70 0.06 8.40 365,817 0.14 18.22 793,712 35.5 42" 3.399 22.1 59.9 54"130.0 90 0.08 10.87 473,410 0.18 23.00 1,002,057 35.5 42" 3.399 22.1 59.9 54"135.0 50 0.05 6.16 268,155 0.10 13.79 600,755 36.2 42" 3.470 22.4 61.2 60"135.0 70 0.06 8.72 379,887 0.14 19.07 830,781 36.2 42" 3.470 22.4 61.2 60"135.0 90 0.08 11.29 491,618 0.18 24.08 1,048,857 36.2 42" 3.470 22.4 61.2 60"140.0 50 0.05 6.38 278,087 0.10 14.41 627,911 36.9 42" 3.540 22.6 62.4 60"140.0 70 0.06 9.04 393,957 0.14 19.93 868,334 36.9 42" 3.540 22.6 62.4 60"140.0 90 0.08 11.70 509,826 0.18 25.17 1,096,268 36.9 42" 3.540 22.6 62.4 60"145.0 50 0.05 6.61 288,019 0.10 15.05 655,417 37.7 42" 3.609 22.8 63.6 60"145.0 70 0.06 9.37 408,027 0.14 20.81 906,372 37.7 42" 3.609 22.8 63.6 60"145.0 90 0.08 12.12 528,034 0.18 26.27 1,144,291 37.7 42" 3.609 22.8 63.6 60"150.0 50 0.05 6.84 297,950 0.10 15.69 683,273 38.4 48" 3.677 23.0 64.8 60"150.0 70 0.06 9.69 422,096 0.14 21.69 944,895 38.4 48" 3.677 23.0 64.8 60"150.0 90 0.08 12.54 546,242 0.18 27.39 1,192,925 38.4 48" 3.677 23.0 64.8 60"155.0 50 0.05 7.07 307,882 0.11 16.33 711,480 39.1 48" 3.744 23.2 66.0 60"155.0 70 0.06 10.01 436,166 0.15 22.59 983,902 39.1 48" 3.744 23.2 66.0 60"155.0 90 0.08 12.96 564,450 0.18 28.52 1,242,172 39.1 48" 3.744 23.2 66.0 60"160.0 50 0.05 7.30 317,814 0.11 16.99 740,038 39.7 48" 3.810 23.4 67.2 60"160.0 60 0.06 8.82 384,025 0.13 20.28 883,556 39.7 48" 3.810 23.4 67.2 60"160.0 70 0.06 10.34 450,236 0.15 23.49 1,023,394 39.7 48" 3.810 23.4 67.2 60"160.0 90 0.08 13.38 582,659 0.19 29.66 1,292,030 39.7 48" 3.810 23.4 67.2 60"

Notes:At 25 acres the methods are roughly equivalent, both in retention requirements and the allowable dischargesAt 160 acres (with a C-factor of 0.6), this method provides for approximately 20 Acre-feet of storageIf sites exceed a C-factor of 0.6, they would be required to provide on-site retention on all sites whether regional retention facilities are provided or not

MCM 6 – Pollution Prevention for Municipal Operations

Permit Requirements • Develop and implement a stormwater training program to reduce stormwater pollution

from municipal operations. • Annually inspect structural pollution control devices and 20% of outfalls, snow disposal

areas and determine maintenance/repair based on these inspections and keep records of the inspections.

• Ensure potential for stormwater pollution is minimized by enclosing salt storage pile and locate snow disposal site using BMPs to minimize litter/sediment from leaving site.

• A Stormwater Pollution Prevention Plan (SWPPP) must be developed and implemented for maintenance garages, public works facilities, transfer stations or waste handling facilities.

Current Fargo Activities Stormwater training is provided on a rotating basis for city departments and the Fargo Park District. All public stormwater features are inspected at least annually for function, maintenance or repair. Those inspections requiring repair are forwarded to the engineering department for evaluation. Ponds and basins are inspected during maintenance activities, lined channels are cleaned and inspected annually, and outfalls (and lift stations) are inspected both fall and spring. Salt storage operations are covered and not exposed to precipitation. Snow disposal sites use grass buffers or other BMPs and are inspected spring and fall. Maintenance is typically conducted after the spring inspection. The City of Fargo Solid Waste Division (transfer station and appurtenant operations) operates under another state NPDES permit (SW260).

Appendix Current Annual Report IDDE Mutual Agreement