HomeMy Public PortalAbout05-10-2011MEDINA
PLANNING COMMISSION AGENDA
TUESDAY, MAY 10, 2011
7:00 P.M.
CITY HALL (2052 County Road 24)
Call to Order
2. Public Comments on items not on the agenda
3. Update from City Council proceedings
4. Planning Department Report
5. Approval of April 12, 2011 draft Planning Commission
minutes.
6. Public Hearing - Ordinance Amendment - Chapter 8 of the
Medina Zoning Code to codify the City's stormwater
management regulations.
7. City Council Meeting Schedule
8. Adjourn
POSTED IN CITY HALL MAY 6, 2011
MEMORANDUM
TO: Mayor Crosby and Members of the City Council
FROM: Dusty Finke, City Planner; through City Administrator Chad Adams
DATE: April 28, 2011
SUBJ: Planning Department Updates May 3, 2011 City Council Meeting
Ordinance Updates
A) Stormwater/LID Ordinance and Parking Regulations — Planning staff have been working
with Engineering on this project. Staff believes these ordinances should be the next priority
with regards to ordinance updates, and plans to present the stormwater regulations to the
Planning Commission in May.
Land Use Application Reviews
A) Pemtom Stage I Plan — N of Highway 55 and W of CR 116 — Pemtom Land Company has
applied for a Stage I Mixed Use Plan on the Jubert and the western portion of Rolling Green
Business Center. The application was heard by the Planning Commission on April 12 and
the Park Commission on April 20. The City Council will review the recommendations of
both Commissions at the May 3 meeting.
B) Puptown Text Amendment and CUP — 810 Tower Drive — Jill and Tom Kingstedt have
requested a CUP in order to operate a dog boarding and animal day care facility. A Public
Hearing was heard by the Planning Commission at the April 12 meeting. The Commission
recommended approval of the application and recommended additional conditions related to
medical waste disposal and potential soil testing for impacts of animal waste.
C) White Variance — 4642 Brook Street — Janet White has requested approval of variances in
order to tear down and rebuild her house. The existing house is nonconforming, and the
applicant wishes to rebuild in a new location on the lot. The Public Hearing went to the
Planning Commission on April 12and the Commission recommended approval of the
variance requests and requested additional information on the proposed drainage
improvements.
D) Ringer Lot Combination, Comp Plan Amendment and Rezoning — 1700 Deerhill Road —
The City Council approved a Comprehensive Plan amendment at the December 21 meeting
with the condition that the two lots be combined, and the Met Council has approved the
amendment. The applicant has submitted an application for a lot combination, and staff has
requested a few additional pieces of information. The item is tentatively scheduled for the
May 17 City Council meeting.
E) J. Cavanaugh Plat — 805 Hamel Road — Joe Cavanaugh has requested subdivision of his
property into three single-family lots at the southwest corner of Hamel Road and Pinto
Drive. Staff has conducted a preliminary review and determined the application is
incomplete, and the applicant recently submitted additional information. The Planning
Commission tabled the Public Hearing at their January 11, requesting more information
related to drainage and stormwater management.
F) Marx Conservation Design Subdivision — 2700 and 2900 Parkview Drive — Wally Marx
has requested review of a CD-PUD Concept Plan for a subdivision which would allow a
Planning Department Update Page 1 of 2 May 3, 2011
City Council Meeting
density bonus and flexibility to lot size and setback requirements and place a portion of their
property into Conservation Easements. Staff has conducted a preliminary review and
determined the application is incomplete. Staff will schedule the request for a Public
Hearing with the Planning Commission when it is complete for review.
G) Enclave of Medina Subdivision - 3212 Hunter Drive — The City Council approved the
preliminary plat resolution and rezoning ordinance on April 5, staff has been working with
the applicant on finalizing the development agreement, and awaits application for final plat
and construction plans for Phase 1.
H) Hunter Ridge Farm Plat — 1382 Hunter Drive — the Council approved the final plat at the
April 5 meeting, and staff will assist the property owner with finalizing the project.
I) Fortuna Farms Plat — 1425 Tamarack Drive — the Council approved the preliminary plat
resolution on November 22, 2010, and staff awaits an application for final plat approval.
J) Holy Name Cemetery — The City Council approved the Site Plan Review and CUP at the
April 19 meeting, and staff is working with the applicant on the conditions of approval.
K) Holasek/Nolan Lot Split — Hunter Drive (north) — The City Council adopted a resolution
and ordinance at the February 1 meeting. Staff is working with the Applicant to complete
all of the documents which were required as conditions of approval in order to finalize the
lot split.
L) Wrangler's Restaurant — 32 Hamel Road — the Council approved resolutions on July 21,
2009. The City Council granted until August 10, 2011 for the applicant to final the plat.
Additional Projects
A) Private Dog Kennels — staff has been assisting the City Clerk and Police with the
coordination of two requests for private dog kennel licenses. One is a request for 7 dogs in
a home at 1822 Morgan Road and the other is a request for 12 small dogs in a home at 25
Hamel Road.
B) Animal Regulation Research — Planning staff has conducted research requested by the
Administration and Police departments related to potential amendments to the City's animal
regulations (dogs/cats). The City Council will review this research at the May 3 meeting.
C) Housing Policy — The City Council held a preliminary discussion on the matter at the
February 1 meeting, and staff is researching the additional items requested by the Council
and has been discussing opportunities with various housing agencies and non -profits. The
City Council will hold a workshop with Interfaith Outreach to discuss opportunities prior to
the May 3 meeting.
D) Zoning Enforcement (Hamel Station tree removal) — The applicant reported that plantings
have been installed to remediate the ordinance violations but the plantings on -site differed
significantly from the remediation plan. The applicant has provided a list of plants, and
staff will review and potentially schedule an inspection.
E) Zoning Enforcement (manure management inspections) — Staff has been inspecting both
commercial horse facilities and private horse facilities currently under a CUP requiring
manure management.
Planning Department Update
Page 2 of 2 May 3, 2011
City Council Meeting
1 CITY OF MEDINA PLANNING COMMISSION
2 Draft Meeting Minutes
3 Tuesday, April 12, 2011
4
5 1. Call to Order: Commissioner Charles Nolan called the meeting to order at 7:00 p.m.
6
7 Present: Planning Commissioners, Robin Reid, Kent Williams, Beth Nielsen,
8 Victoria Reid, Charles Nolan, and John Anderson.
9
10 Absent: Kathleen Martin
11
12 Also Present: Planning Assistant Debra Peterson -Dufresne, City Administrator Chad
13 Adams, City Administrative/Planning Intern Dale Cooney, and Nate Sparks of NAC.
14
15 2. Public Comments on items not on the agenda
16
17 No public comments.
18
19 3. Update from City Council proceedings
20
21 Council member Jeff Pederson presented a report of recent activities and decisions by
22 the City Council.
23
24 4. Planning Department Report
25
26 Chad Adams provided an update of upcoming Planning projects.
27
28 5. Approval of the March 8, 2011 Draft Planning Commission meeting minutes.
29
30 Motion by Anderson, seconded by Nielsen, to approve the March 8, 2011 minutes
31 with minor modification to page five. Motion carried unanimously. (Absent: Martin)
32
33 6. Public Hearing — Pemtom Land Company — A Stage I Plan for a phased Mixed
34 Use Development which will include detached Single Family Homes,
35 Townhomes, and Commercial — located north of State Hwy 55, west of County
36 Road 116 and south of Foxberry Farms (PIDs 02-118-23-43-0002; 02-118-23-44-
37 0052; 02-118-23-44-0054).
38
39 Nate Sparks presented application explaining the three stage review process. He
40 explained the proposed project includes the Jubert site, as well as two Rolling Green
41 Outlots having a total site area of about 54 net acres, with the overall site being over
42 90 gross acres.
43
44 Sparks provided overview of current zoning for each property, explaining the
45 properties would need to be rezoned to Mixed Use with Stage II. He explained the
1
1 Commission and Council would need to provide findings that the rezoning was
2 consistent with the Comprehensive Plan.
3
4 Sparks explained the mixed use district would require a depth of 300 feet of
5 commercial adjacent to Highway 55 and a minimum of 50% residential on the site.
6 The densities are allowed for 3.4 to 6.00 units per acre. He said 193 units were being
7 proposed over an approximate 36 acres, which is slightly over 5 units per acre. He
8 said transitions from uses are also part of the plan requirement.
9
10 Sparks explained the need for a traffic study under the Stage II process to help
11 determine what improvements would need to occur. He explained Meander Road
12 runs east and west, which divides the single family homes from the townhomes and
13 commercial uses.
14
15 Sparks explained that the applicant intends to only develop the single family portion
16 of the proposal. He explained the application is conceptual in nature and a lot of
17 specific standards within the mixed use district would be required in Stage II. The
18 standards would assure properties to be cohesive with one another.
19
20 Sparks explained the application would be reviewed by the Park Commission at the
21 next meeting. He explained the City's park plan called for a 10 acre park in this area.
22
23 Sparks reviewed staffs recommended changes to the project and the applicant agreed
24 to staffs recommended revisions.
25
26 Sparks explained if the Planning Commission found the plan was generally consistent
27 with the Comprehensive Plan goals of the MU district, it would be forwarded to the
28 City Council.
29
30 R. Reid said Tamarack Road doesn't go through to Highway 55. She said there is no
31 intersection at Tamarack and Hwy 55. Nolan asked what the intention was for the
32 intersection of North Tamarack/Hwy 55 area.
33
34 Anderson asked if Meander would be the only road serving the development. Nolan
35 clarified Meander would ultimately continue west to Arrowhead. Nolan asked if the
36 traffic study would look at all the roadways impacted. V. Reid asked if County Road
37 116 would be part of that study and Sparks said it would be included.
38
39 Nolan said too many stoplights may not always be positive. He asked if the stoplight
40 by Target needed to have been installed. He asked that stoplights be looked at more
41 regionally.
42
43 Nolan asked for clarification of the net and gross acreage of the project as it related to
44 each use. Sparks clarified.
45
2
1 V. Reid asked for clarification on the location of Outlot C and Sparks showed the
2 Commission on the map.
3
4 Dan Herbst of 7697 Anagram, Eden Prairie MN, representing Pemtom Company,
5 explained who was involved in the application and provided the Commission with the
6 history of the Pemtom Land Company. He said the goal had always been to provide
7 well planned neighborhoods that would be an asset to the community and their
8 integrity. He said they are currently working on a project called Gray's Bay on Lake
9 Minnetonka. He explained Mattamy Homes had partnered in on the project and
10 David Nash had also partnered in on the project. Lastly, he explained the history of
11 the Jubert family and that they have been around since the turn of the century and
12 their grandfather purchased the land in the 1940's.
13
14 David Nash, 4610 Bluebell Trail North in Medina, explained that the Pemtom project
15 was the first project he'd worked on near his neighborhood. He explained he had a
16 lot of experience with the Medina staff and further provided background of the
17 company he worked for and how they had been in business for 25 years.
18
19 Nash explained he received the City staff report the Friday prior to the meeting (April
20 8th) and staff had suggested revisions. He reviewed each of the staff
21 recommendations with the Commission and informed them he had made all changes
22 over the weekend and didn't have any issues with the recommendations.
23
24 V. Reid asked if the proposed area for a park would be a City Park and if so, would
25 the City take care of it. She said as a Foxberry Farms resident she felt it would be
26 great to create a trail to access the Park from her neighborhood.
27
28 Nolan said he presumed the park location was discussed with City staff. Sparks said
29 the Park location was suggested by City staff and the idea was to take park land
30 dedication from multiple property owners rather than one land owner.
31
32 Nash explained the City Park Plan called for 10 acres and said their Park Dedication
33 requirement was only 6.1 acres. Anderson asked if the applicant was required to
34 come up with the difference of 10 acres and Nash explained it would be from other
35 land owners when they developed in the future. Nolan asked if the vision was for it
36 to be a community park. He said he would anticipate if it was a community park
37 people would be driving to it, and asked if staff had discussed a need for a parking
38 lot. Sparks explained it would be an active recreation area, but not a major ball field
39 area. Conceptually, staff had discussed off-street parking as a means of accessing the
40 park.
41
42 V. Reid said she would be concerned if there wasn't a trail to access the Park. People
43 would be walking through one or more Foxberry Farm lots; in other words, cutting
44 through yards.
45
3
1 Nash said they had a 35 foot wide easement along the back property line and
2 explained a 15 foot wide berm existed along the property line to the north of the
3 proposed development. Nolan suggested the applicant work with Foxberry Farms
4 Homeowners Association to develop a trail to connect to the future park.
5
6 Williams asked which partner would be involved with the townhome portion of the
7 project. Herbst explained they didn't have the property under their control. He
8 explained it was part of the Jubert land, which didn't have a contractor to develop that
9 portion. He explained Stage II would only be for the single family portion of the
10 project.
11
12 Nolan said on the colored site plan it appeared that one of the townhome buildings
13 was in a wetland. Nash explained the building was out of the wetland and met
14 required setbacks. He said he noticed quite a bit of green area between the
15 townhomes and commercial portion. Nielsen asked if the applicant was interested in
16 developing the townhomes and Herbst said they would be if the single family portion
17 was successful.
18
19 Public Hearing opened at 8:17 p.m.
20
21 Bill Ciova of 915 Sunset Court in Medina said he lives in Foxberry Farms and been a
22 resident since 1997 and was President of the Association until just last year. He said
23 when he got the notice he was floored with the density. He said most households
24 would have two people working and vehicular traffic out onto Meander to County
25 Road 116 would be a concern. He asked what would be done with traffic. He said he
26 would be supportive of four lanes being constructed on County Road 116. Secondly,
27 he had concern with the density and recommended reduced density to something
28 more manageable. He asked about the wetlands to the south of Foxberry Farms.
29
30 Nolan asked Adams if the traffic study would cover the County Road 116 intersection
31 with Meander. Adams said the upgrade on County Road 116 would go from
32 Highway 55 to the Clydesdale backage road.
33
34 Nolan explained to the Commission that the application was conceptual in nature and
35 at this point it's just colors on a plan. A lot of due diligence would be necessary to
36 get to the next Stage for review. He explained to the public that the Commission had
37 to look at the overall Concept and that the City guided the property for this type of
38 density. He further explained that the final outcome of density for that area would be
39 determined in Stage II.
40
41 Joe Cavanaugh of 3220 Niagara Lane North asked about how Meander Road could
42 dead end (west), and asked for an explanation. Nash explained the road would be
43 designed as a temporary cul-de-sac until the Cavanaugh property developed.
44
45 Nolan said the Juberts were co -applicants with the Concept application and more
46 emphasis was on the single family portion of the plan. He suggested an alternate
4
1 route be created going north/south. He asked if Tamarack could be extended up to
2 provide an alternate. Nolan said as part of Stage II the applicant should be looking at
3 accessibility.
4
5 Public Hearing closed at 8:34 p.m.
6
7 Nolan asked if any of the Commissioners had any overall issues conceptually. The
8 Commission concurred with traffic concerns, the Park accessibility from Foxberry
9 Farms development and parking, and what would be done with the pie shaped flag
10 (dark green) of land on the colored map. Nash explained to the Commission the dark
11 green area on the site plan was undevelopable. He said they weren't doing anything
12 with it since it wasn't large enough. Nolan suggested that during Stage II additional
13 landscaping be done on the berm adjacent to Foxberry Farms to be a good neighbor
14 and improve transition of housing. Herbst said the documents that were recorded for
15 Foxberry Farms doesn't require maintaining the berm. Ciova said Foxberry Farms
16 hadn't maintained a portion of the berm. Ciova asked if the applicant could be asked
17 to work with Foxberry Farms Homeowners Association.
18
19 Motion by Anderson, seconded by R. Reid, to recommend approval of the Stage I
20 Plan for a phased Mixed Use Development with recommended changes to broaden a
21 traffic study (specific to County Road 116, State Highway 55, and extending
22 Tamarack at State Highway 55), and figure out trail access (possibly through existing
23 berm) from Foxberry Farms development to a future community park. Motion
24 carried unanimously. (Absent: Martin)
25
26 7. Public Hearing — Thomas and Jillene Kingstedt — A Conditional Use Permit
27 (CUP) to operate a dog daycare, grooming and indoor boarding to be known as
28 PupTown in the Commercial General (CG) district — 810 Tower Drive (PID 11-
29 118-23-14-0012).
30
31 Cooney presented the application to the Commission. He showed the location of the
32 property described as 2.32 acres, with a railroad to the north and nearest residential
33 district 425 feet away. The applicant proposed a 13,000 square foot outdoor area for
34 the dogs to play in and to do their business.
35
36 Cooney further explained the majority of the plantings already existed, though they
37 were willing to install additional trees along the proposed fence. He reviewed with
38 the Commission parking, landscaping, trash, interior space, impervious surface,
39 indoor noise mitigation, waste storage/disposal, and distance to residential areas,
40 fencing, and hours of operation. He further explained staff was recommending a
41 condition requiring the applicant meet the MPCA noise pollution standards.
42
43 Cooney reviewed the CUP Review Criteria and staff recommendations with the
44 Commission. Nolan asked if the City had regulations related to disposal of medical
45 waste. He raised a concern that if medical waste was given to private dog owners, it
5
1 wouldn't be disposed of properly. V. Reid raised concern with what dog owners
2 would do if sent home with a syringe and whether it would be disposed of properly.
3
4 Tom Kingstedt, applicant and co-owner with wife, both residing at 12425 43rd
5 Avenue North in Plymouth, explained he didn't want to be a hazardous waste
6 generator and didn't want to be going through the expense of disposing of it.
7
8 Kingstedt explained that one of the huge advantages of being at the Tower location
9 was the access along State Hwy 55. They are trying to make a product that no one
10 else had with the appropriate space dogs need. He said the dogs would bark a lot less
11 with a larger space. He said the people handling the dogs would be playing with
12 them indoor and outdoor. He said they would be one of the largest doggie daycare
13 facilities in the metro area and the building they are proposed to operate in will need
14 minimal modifications, except for the flooring.
15
16 Nielsen asked if the applicant was alright with staff recommendations. Kingstedt said
17 the plan was acceptable and he felt comfortable with a maximum of 60 dogs.
18
19 Anderson asked what he thought the ratio would be of overnight boarding and
20 daytime care. Kingstedt said the four legged economy has increased and said the
21 number is difficult to anticipate, but acknowledged holidays generate higher volumes
22 and was comfortable with 60 dogs.
23
24 Anderson asked about waste receptacles and tightly sealed containers. Kingstedt
25 explained the waste would be sealed in small plastic bags then deposited into another
26 sealed container, and then into Randy's Sanitation container.
27
28 Williams asked about the containers and if they would get additional garbage
29 containers. Kingstedt said he didn't anticipate needing more than two residential type
30 (90 gallon) containers which would seal better than a dumpster.
31
32 Ms. Kingstedt, applicant reviewed the fence location and potty break area identified
33 on the site plan. Nolan asked with an eight foot fence what material would be inside
34 the fenced in area on the ground. Kingstedt said the play area would be grass and they
35 wouldn't let the dogs out on rainy days. He explained the potty area would have a
36 turf grass put on the ground for easy clean up. Nolan expressed his concern as it
37 related to a lack of sunshine getting into the play area with such a tall fence. T.
38 Kingstedt said they would snow blow the potty area during the winter months.
39
40 Public Hearing opened at 9:19 p.m.
41
42 Jeff Pederson said he had concerns that the Council would have issues with the noise
43 that would be generated from the dogs barking. He suggested a condition be placed
44 on the application relating to noise. He said he also has some hesitation with waste
45 filtering into the water bodies and hours of operation of the business. Cooney said the
46 City would respond to complaints. Nolan asked if staff had heard from surrounding
6
1 businesses and Cooney said Finke has spoken to a number of owners and no one
2 voiced concern.
3
4 Kingstedt said everyone gets a free day and if the dog was a barker they may not
5 allow dog to come back. Anderson said the railroad would generate more noise.
6 Nolan said it's a unique location.
7
8 Public Hearing closed at 9:24 p.m.
9
10 Nolan said he had concerns with noise, water quality and medical waste disposal. He
11 asked staff to investigate the cost of annually testing the soil in the potty area and if it
12 was reasonably cost effective the Council could weigh it out. Nolan asked about
13 handling of medical waste and said he didn't think it was real difficult.
14
15 The Commission said they were fine with the fence color being white.
16
17 Motion by R. Reid, seconded by Anderson, to recommend approval of the CUP
18 with the recommended changes to remove the condition to change fence color,
19 research medical waste disposal, and research cost of soil testing. Motion carried
20 unanimously. (Absent: Martin)
21
22 8. Public Hearing — Janet White — Variances from front and rear yard setbacks to
23 reconstruct a new home in the Urban Residential (UR) zoning district — 4642
24 Brook Street (PID 18-118-23-23-0017).
25
26 Sparks presented application. He explained the property was a lot of record and the
27 applicant was proposing to demolish the existing home and replace it with a new
28 home with a slightly larger footprint. The new home would be constructed further to
29 the east, which is the wider portion of the lot. The home would be a one story slab -
30 on -grade and would be slightly shorter than the existing home. Sparks reviewed the
31 Criteria for Variances and explained the recent Supreme Court standing and how the
32 Commission is required to follow its Variance criteria.
33
34 Nolan asked if there was an advantage to having the new home shorter than the
35 existing home height. Sparks said in the shoreland district people tend to like the
36 shorter in height homes for site line purposes. Nolan asked how involved staff had
37 been in shifting the home to the east, the wider portion of the lot. Sparks said the
38 home location was largely established to increase the driveway area, and as a result
39 the applicant had to reduce the depth of the garage.
40
41 V. Reid said the proposed home location blocked the neighboring home to the north
42 more than what it does now.
43
44 Janet White thanked the Commission for their consideration.
45
46 Nolan asked the size of the existing home and White replied 744 square feet.
7
1 Public Hearing opened at 9:53 p.m.
2
3 Monserud, neighbor to the north at 2964 Lakeshore Drive, said he was hoping the
4 home would be at least ten feet from his property line. He would have a better view
5 from the front and could live with the shift to the east. He said he would like the new
6 home to be 10 feet from his property line. Nolan said from a design point of view the
7 position is different than what he would have recommended. White said she had
8 water drainage problems with the existing home and felt if the home was moved to
9 the east, the water issues would be taken care of and it would provide an area for
10 water to drain. She also said they would be installing draintile. Monserud further
11 explained one of the reasons he wanted 10 feet between the homes was to be able to
12 provide appropriate drainage.
13
14 David Raskob, the contractor assisting Janet White with the design and construction
15 of her new home, said with all the issues the current home has today, the best they
16 could do to resolve the issues was to construct a new home. Williams asked if White
17 initially intended to remodel. White concurred. Nolan asked if her engineer had
18 provided some solutions to improve the drainage issues. White said not yet. Nolan
19 asked where the water drained and Raskob said it flows to Brook Street and then
20 floods out the applicant's home. Nolan asked if the construction of the home was the
21 ultimate solution in figuring out all the drainage problems. He would like to see an
22 engineer figure out the drainage issues prior to construction. Nolan asked the
23 applicant to review the drainage and provide a letter or attend the Council meeting.
24 Nolan said he just wants to make sure there is a solution to the problems. He said he
25 is satisfied with the location as long a solution is figured out for the water problem.
26
27 Public Hearing closed at 10:05 p.m.
28
29 V. Reid was alright with the application.
30 R. Reid said she lives in the neighborhood and sees the application as an
31 improvement and solution. She said the dead-end street helps allow the home closer
32 to the property lines and asked that it be a finding of fact. Williams said he was in
33 favor of granting the application and felt like they were doing the applicant a favor by
34 requiring the Engineer to provide letter.
35
36 Findings of Fact by the Commission: The lot is unique in shape, size, and is on a
37 corner which is along a dead-end street on one side. Shifting of the home further to
38 the east places the home away from Lakeshore Avenue which is busier than the side
39 street. The side street which is a dead-end road has much less traffic than Lakeshore
40 Avenue. The shifting of the home to the east allows improved drainage for the lot
41 and adjacent properties.
42
43 Motion by Williams, seconded by Anderson, to recommend approval of the
44 Variance with recommended changes. Motion carried unanimously. (Absent: Martin)
45
46
8
1 9. City Council Meeting Schedule
2
3 May 3, 2011 - Nielsen
4
5 10. Adjourn
6
7 Motion by Anderson, seconded by R. Reid, to adjourn the meeting at 10:10 p.m.
8 Motion carried unanimously. (Absent: Martin)
9
MEMORANDUM
TO: Planning Commission
FROM: Dusty Finke, City Planner
DATE: May 6, 2011
MEETING: May 10, 2011 Planning Commission
SUBJ: Stormwater Management Ordinance —Public Hearing
Background
Attached, for the Commission's review is a DRAFT ordinance related to Stormwater
Management regulations. The purpose of this ordinance is to implement the City's Surface
Water Management Plan which was part of the 2010-2030 Comprehensive Plan. The ordinance,
along with the Medina Stormwater Design Manual (a draft of which is also attached) describe
the improvements which will be required upon construction in order to meet the City's water
quality and other stormwater objectives.
The primary objectives that will likely be discussed include:
1) Runoff Rate Control — the objective here is to control the speed at which water flows off
of a site so that it matches pre -development rates. This prevents a property from
"flooding" their neighbor following a storm.
2) Runoff Volume Control — the objective is to infiltrate as much water into the ground after
development as infiltrates pre -development. This objective can be hard to achieve in
many areas of tight clay soils in Medina where water infiltrates very slowly.
3) Water Quality — the objective is to remove nutrients from the stormwater, and specifically
reduce the amount of phosphorus leaving the site by 20% of what leaves pre -
development.
A memo from Dan Edgerton, the City's water resources engineer, is attached. The memo
summarizes a few of the big picture items in the ordinance and Design Manual. Mr. Edgerton
present to the Commission at the May 10 meeting and will describe the various types of
improvements which may be constructed to protect water quality.
At the end of this memo, I have included an excerpt from the City's Surface Water Management
Plan related to "Land Development and Redevelopment." Similar to other zoning ordinances the
City has completed over the past few years, the goal of this ordinance is to be consistent with and
to implement the goals and policies of the Plan.
Primary Discussion Points
The ordinance, and especially the Design Manual, are very technical in nature. There are,
however, a few very important policy questions which the Planning Commission and City
Council will need to make decisions on.
Stormwater Management Page 1 of 5 May 10, 2011
Ordinance Planning Commission Meeting
Applicability for Water Quality and Volume Control
The City needs to determine what scale of project will trigger the need to provide Water Quality
and Volume Control improvements. As drafted, this would be required for the following size of
projects:
A. Any new development disturbing one (1) acre or more of land.
B. Redevelopment or expansion on commercial, institutional and multi -family property
which disturbs one (1) acre or more of land, OR that increases impervious area more than
1000 square feet.
C. Improvements from existing single family residential property disturbing one (1) acre or
more of land AND increasing impervious area more than 1000 square feet.
Staff believes that new development should clearly meet all of the City's stormwater objectives
when constructed. The City will need to determine if all expansions of hardcover should also
meet all requirements, or if very small additions/expansions could be exempt. The current draft
exempts any project which adds less than 1,000 square feet of hardcover.
Mr. Edgerton will help guide this discussion by summarizing some of the costs of providing
Water Quality and Volume Control improvements at the Planning Commission meeting.
Redevelopment/Expansion: 20% Phosphorus of whole site, or just expansion area
The City's objective is to reduce Phosphorus loading by 20%. In the case of an addition or
expansion, the current draft requires the property owner to treat the stormwater created by the
new hardcover, PLUS 20% of the existing hardcover. In the case of a large site, this could lead
to the need to build a large improvement (and also a large reduction in Phosphorus) in
comparison to a relatively small addition.
Attachments
1. Memo from Dan Edgerton
2. DRAFT Ordinance
3. DRAFT Medina Stormwater Design Manual
Excerpt from City's Surface Water Management Plan
6.2 LAND DEVELOPMENT, REDEVELOPMENT, AND CITY PROJECTS
Overall Goal: Manage land disturbance and increased impervious surfaces to prevent flooding and
adverse impacts to water resources.
Overall Policy: Medina will pursue a nondegradation policy in regard to runoff volume, runoff rate, and
nutrient loading from development projects. Low Impact Development, or LID, techniques are Medina's
preferred method of controlling runoff volume and nutrient loading. Medina considers LID techniques as
complementary to pipes, ponds, and wetlands for its flood control system.
Overall Policy: Medina will consider redevelopment and linear projects as an opportunity to retrofit
nondegradation to previously developed areas and infrastructure.
Overall Policy: Medina will amend or modify its subdivision ordinance to facilitate stormwater quantity and
quality performance measures identified in its Local Surface Water Management Plan.
Stormwater Management
Page 2 of 5 May 10, 2011
Ordinance Planning Commission Meeting
Overall Policy: Medina will consider water quality retrofits on existing City properties as a means of
providing treatment to currently developed areas without treatment.
Overall Policy: Medina will reference the following documents as guidance for Best Management Practices
in the City: The Minnesota Pollution Control Agency's Protecting Water Quality in Urban Areas and its
Minnesota Stormwater Manual, and the Metropolitan Council's Minnesota Urban Small Sites BMP Manual.
6.2.1 RUNOFF VOLUME MANAGEMENT
Goal: Maintain existing runoff volumes so that runoff from development does not increase volume
loading to wetlands, lakes and streams.
Policy: Any site that requires an NPDES construction site permit will be required to implement permanent
volume management such that existing runoff volumes are maintained. Sites that do not require an
NPDES construction site permit shall maintain existing runoff volumes to the extent practical.
Policy: Redevelopment and linear projects will implement runoff volume management practices for new
impervious surfaces such that these surfaces cause no increase in runoff volume. Redevelopment and
linear projects will consider whether additional runoff volume management practices might feasibly be
incorporated for existing impervious surfaces, as well.
Policy: Any development site that requires an NPDES construction site permit and lies within the tributary
drainage to Lake Independence and Lake Sarah shall provide on -site infiltration capacity as required by
the construction site permit.
6.2.2 RUNOFF RATE
Goal: Control the rate of stormwater runoff from development to reduce downstream flooding and
erosion and protect water resources.
Policy: Future peak rates of discharge from new development and redevelopment will not exceed pre -
development peak rates of discharge for the 1-yr or 2-yr, 10-yr and 100-yr, 24 -hr storm events.
Policy: New storm sewer systems shall be designed using the following guidelines:
• New storm sewer systems shall be designed to accommodate discharge rates for the 5-yr critical
storm event.
• New storm sewer systems shall be designed to match the inside top elevation of adjacent pipes.
• Outflow velocities from storm sewer discharge points shall not exceed 5 feet per second.
Policy: The City will base all drainage system analyses and designs on proposed full development land
use patterns.
Policy: Where development occurs upstream of a known flood -prone area, the City may seek additional
rate control as a means to mitigate this flooding.
Policy: When off -site regional ponding is available and this off -site ponding accomplishes the rate control
requirement, then the rate control requirement can be waived for a particular site.
Policy: In areas tributary to Elm Creek stream protection volumes must be calculated and implemented
according to the methods outlined in ECWMC's design standards.
Stormwater Management Page 3 of 5 May 10, 2011
Ordinance Planning Commission Meeting
6.2.3 FLOOD PREVENTION
Goal: Provide adequate storage and conveyance of runoff to protect the public safety and minimize
property damage.
Policy: The volume of runoff may not increase due to a project when the receiving area of this runoff is
landlocked and not capable of handling the increased volume of runoff. Anyone proposing increased
runoff volume to landlocked areas shall have proper rights over the landlocked property to handle water
from the development. Outletting will not be permitted unless there is a demonstrated threat to public
structures or public safety.
Policy: Building low floor elevations within the City of Medina shall be required to be at least 2 feet above
the 100-yr HWL of hydraulically connected water and wetlands.
Policy: Flood storage for those landlocked depressions with no outlet present must accommodate the
volume generated by back-to-back 100-yr, 24 -hr storm events or the 100-yr, 10 -day snowmelt event,
whichever generates the higher calculated HWL.
Policy: The City will encourage, to the extent practicable, implementation of Low Impact Development
techniques and mitigation of stormwater runoff volume within development and redevelopment areas
draining to landlocked depressions.
Policy: The City shall require that rate control structures and stormwater drainageways are included in a
drainage or utility easement.
Policy: The City will require compensatory storage for any filling in the floodplain at a 1:1 ratio.
Policy: Medina will amend or modify its Floodplain Management Ordinance to incorporate the policies
identified in its Local Surface Water Management Plan.
6.2.4 NUTRIENT AND SEDIMENT LOADING
Goal: Reduce the nutrient and sediment loads over current conditions.
Policy: Medina's minimum standard is water quality treatment that meets the requirements of the NPDES
construction site permit. Under no circumstances shall overall treatment fall below the requirements of
this permit.
Policy: Any site that requires a NPDES construction site permit will be required to reduce phosphorus
loadings over current conditions. In cases where existing land cover is natural, the maintenance of
existing loading rates is acceptable if the minimum requirements identified in the policy above are met. In
all other cases a 20% reduction in phosphorus loading over current rates over current conditions will be
required. For redevelopment projects only disturbed areas fall under this requirement.
Policy: Medina will institute a standard practice of evaluating all development, redevelopment, and linear
projects for opportunities to retrofit water quality treatment to areas without significant existing
treatment.
Policy: Guidelines for the design of water quality ponds are as follows:
1. A permanent pool volume below the normal outlet which shall be greater than or equal to the
runoff from a 2.5 -inch storm over the entire contributing drainage area assuming full
development.
2. A permanent pool average depth (basin volume/basin area) which shall be greater than or equal
to 4 feet with a maximum depth of 10 feet.
3. Pond side slopes above the normal water level should be no greater than 4:1.
Stormwater Management Page 4 of 5 May 10, 2011
Ordinance Planning Commission Meeting
4. A safety bench with a minimum width of 10 feet and 1 foot deep below the normal water level is
required (see Appendix D for the City's standard bench detail).
5. The pond shall contain a maintenance bench with a minimum width of 10 feet at a 10:1 slope
beginning at the normal water level and extending 1 foot above the normal water level.
6. The distance between inlets and the normal outlet shall be maximized to prevent short circuiting.
7. An armored emergency overflow (EOF) shall be located at or above the 100-yr HWL.
8. A minimum of 1 foot of freeboard shall be required between the EOF elevation and top-ofberm
elevation.
Policy: The City will require outlet skimming in all water quality ponds. Skimming shall occur for up to the
10 -year, 24 -hour event. The City shall not allow the use of submerged pipes to provide skimming.
Policy: The City will require the use of its standard outlet structure (Appendix D) for new water quality
ponds.
Goal: Facilitate watershed organization review of development projects to manage nutrient and
sediment loading.
Policy: Medina will coordinate development review activities with the watershed organizations with
jurisdictions overlapping that of the City.
6.2.5 EROSION AND SEDIMENT CONTROL
Goal: Prevent sediment from construction sites from entering the City's surface water resources.
Policy: The City will enforce the Construction Site Storm Water Runoff Control Ordinance as outlined in
Chapter 8 of the City Code; Section 828 Performance Standards and Enforcement. The ordinance was
revised and adopted in 2008 and was written to be consistent with the standards identified in the NPDES
construction permit, the City's MS4 permit,.Metropolitan Council's guidance, and the policies of the
watershed organizations with jurisdiction over the City.
Policy: The City will periodically review its Construction Site Storm Water Runoff Control Ordinance to
maintain conformance with the NPDES construction permit, the City's MS4 permit, guidance from
Metropolitan Council and the requirements of the watershed management organizations.
Stormwater Management
Page 5 of 5 May 10, 2011
Ordinance Planning Commission Meeting
Memorandum Bonestroo
To: Dusty Finke
Project: Stormwater
Management Ordinance
Date: 5/5/11
From: Dan Edgerton Client: City of Medina
Re: Ordinance and Design Manual File No: 000190-10031-1
Attached are the draft Stormwater Management Ordinance and Stormwater Design
Manual for the City of Medina. The ordinance focuses on applicability, procedural
requirements, and enforcement. The design manual focuses on sustainable
stormwater management (sometimes referred to as Low Impact Development, or LID)
and contains the detailed stormwater requirements for development and
redevelopment in the City.
Placing the detailed requirements in the design manual will allow for flexibility in
revising and updating these requirements over time. This is especially important in
light of the continuously -evolving LID approaches and technology. Some background
on LID and remarks regarding the ordinance and design manual are presented below.
Conservation Development
LID is really a subset of a larger planning approach or philosophy known as
conservation development. Conservation development is based on the principle of
allowing limited sustainable development while protecting an area's natural
environmental features in perpetuity, including preserving open space landscapes and
vistas, protecting farmland and natural habitats for wildlife, and maintaining the
character of rural communities.
A full description of the conservation design approach is beyond the scope and need
of this memo. Many books and manuals have been written on the subject. A
summary of the conservation development process is:
1. Develop an assessment of a community's natural resources, historic and
cultural sites, and scenic vistas.
2. Identify areas to preserve and maintain, including buffers and
interconnections.
3. Define land use ,and zoning requirements around these conservation areas.
Buffers, setbacks, impervious coverage, and housing density are all addressed
here.
4. Promote site design that protects and preserves natural resources.
LID, in our context, focuses on Item #4, better site design. For the purposes of this
ordinance and design manual, we have prescribed design methods for maintaining the
natural hydrology of the site and improving water quality. Specifically, the design
manual addresses:
2335 Highway 36 W
St. Paul, MN 55113
Tel 651-636-4600
Fax 651-636-1311
www.bonestroo.com
" V o l u m e c o n t r o l : R e q u i r i n g f e a t u r e s t h a t r e t a i n s t o r m w a t e r o n s i t e a n d a l l o w
i t t o s e e p i n t o t h e g r o u n d , t h e r e b y p r o m o t i n g i n f i l t r a t i o n o r f i l t r a t i o n o f t h e
s t o r m w a t e r . P o t e n t i a l f e a t u r e s c o u l d i n c l u d e r a i n g a r d e n s , b i o r e t e n t i o n
f e a t u r e s , t r e e t r e n c h e s , a n d p e r v i o u s p a v e m e n t , a m o n g o t h e r s .
" W a t e r q u a l i t y t r e a t m e n t : I n f i l t r a t i o n / f i l t r a t i o n p r o v i d e s e x c e l l e n t t r e a t m e n t
o f s t o r m w a t e r . A s n e e d e d , a d d i t i o n a l f e a t u r e s a r e r e q u i r e d t o m e e t s t r i n g e n t
w a t e r q u a l i t y r e q u i r e m e n t s .
" R a t e c o n t r o l : T r a d i t i o n a l a p p r o a c h e s w i l l s t i l l b e r e q u i r e d t o a d d r e s s
f l o o d i n g , d r a i n a g e , a n d c o n t r o l o f p e a k r a t e s o f s t o r m w a t e r r u n o f f .
C o m m e n t s o n t h e O r d i n a n c e a n d D e s i g n M a n u a l
T w o k e y p o i n t s a b o u t t h e o r d i n a n c e a n d d e s i g n m a n u a l t h a t r e q u i r e p o l i c y r e v i e w a n d
d i s c u s s i o n a r e a s f o l l o w s :
" A p p l i c a b i l i t y i s d e f i n e d i n t h e o r d i n a n c e . E s s e n t i a l l y , n e w d e v e l o p m e n t t h a t
d i s t u r b s m o r e t h a n o n e a c r e o f l a n d , r e d e v e l o p m e n t t h a t d i s t u r b s m o r e t h a n
o n e a c r e o f l a n d o r i n c r e a s e s i m p e r v i o u s a r e a , a n d s i n g l e - f a m i l y r e s i d e n t i a l
i m p r o v e m e n t s t h a t d i s t u r b m o r e t h a n o n e a c r e o f l a n d a n d i n c r e a s e
i m p e r v i o u s a r e a a l l n e e d t o m e e t t h e s t o r m w a t e r r e q u i r e m e n t s .
" V o l u m e C o n t r o l a n d W a t e r Q u a l i t y C o n t r o l b o t h a d d r e s s t r e a t i n g n e w
i m p e r v i o u s a r e a p l u s 2 0 % o f e x i s t i n g i m p e r v i o u s a r e a . T h i s i s c o n s i s t e n t w i t h
t h e C i t y ' s 2 0 0 9 L o c a l S u r f a c e W a t e r M a n a g e m e n t P l a n , w h i c h c a l l s f o r a
p h o s p h o r u s r e d u c t i o n o f 2 0 % o v e r c u r r e n t c o n d i t i o n s .
P a g e 2 o f 2
CITY OF MEDINA
ORDINANCE NO. XXX
An Ordinance Pertaining to the Management of Stormwater
Adding Section 828.33 to the Medina Zoning Ordinance
The City Council of the City of Medina, Minnesota Ordains as Follows:
Section 828.33. Stormwater Management
Subd. 1. Findings of Fact
It is hereby determined that:
Land development projects, and associated increases in impervious cover, alter the hydrologic
response of local watersheds and increase stormwater runoff rates and volumes, flooding, stream
channel erosion, and sediment transport and deposition. Increasing stormwater runoff
contributes to increased quantities of water -borne pollutants, and increases of stormwater runoff,
soil erosion, and nonpoint source pollution can be controlled and minimized through the
regulation of stormwater runoff from development sites.
The City Council of the City of Medina establishes this set of water quality and quantity policies
applicable to all surface waters to provide reasonable guidance for the regulation of stormwater
runoff for protecting local water resources from degradation. It is determined that the regulation
of stormwater runoff discharges from land development projects and other construction activities
in order to control and minimize increases in stormwater runoff rates and volumes, soil erosion,
stream channel erosion, and nonpoint source pollution associated with stormwater runoff is in the
public interest and will prevent threats to public health and safety.
Subd. 2. Purpose and Authority
The purpose of this Ordinance is to establish minimum stormwater management requirements
and controls to protect and safeguard the general health, safety, and welfare of the public
residing in the City of Medina. This Ordinance seeks to meet that purpose through the following
objectives:
a) minimize increases in stormwater runoff from any development in order to reduce
flooding, siltation and streambank erosion and maintain the integrity of stream channels,
b) minimize increases in nonpoint source pollution caused by stormwater runoff from
development which would otherwise degrade local water quality,
Ordinance No. XXX
May 05, 2011
c) minimize the total annual volume of surface water runoff that flows from any specific site
during and following development so as not to exceed the predevelopment hydrologic
regime to the maximum extent practicable,
d) reduce stormwater runoff rates and volumes, soil erosion and nonpoint source pollution,
wherever possible, through stormwater management controls,
e) ensure that these management controls are properly maintained and pose no threat to
public safety, and
f) implement stormwater management controls to help meet current and future TMDL
goals, to address the need to improve water quality, and meet objectives in the Local
Surface Water Management Plan.
The provisions of this Ordinance are adopted under the authority of the City of Medina Code.
These provisions apply to all developments within the areas of the City of Medina. The
application of this Ordinance and provisions expressed herein shall be the minimum stormwater
management requirements and shall not be deemed a limitation or repeal of any other powers
granted by State statute. The City of Medina shall be responsible for the coordination and
enforcement of the provisions of this Ordinance.
Subd. 3. Incorporation by Reference
The Medina Stormwater Design Manual is incorporated by reference by the City of Medina.
The Manual shall serve as the official guide for stormwater principles, methods, and practices for
proposed development activities.
Subd. 4. Definitions
For the purpose of this Ordinance, the following definitions describe the meaning of the terms
used in this Ordinance:
a) "Applicant" means a property owner or agent of a property owner who has filed an
application for a stormwater management permit.
b) "Channel" means a natural or artificial watercourse with a definite bed and banks that
conducts continuously or periodically flowing water.
c) "Impervious Area" means those surfaces that cannot effectively infiltrate rainfall (e.g.,
building rooftops, pavement, sidewalks, gravel, driveways, etc).
d) "Land Disturbance Activity" means any activity that changes the volume or peakflow
discharge rate of rainfall runoff from the land surface. This may include the grading,
digging, cutting, scraping, or excavating of soil, placement of fill materials, paving,
construction, substantial removal of vegetation, or any activity that bares soil or rock or
involves the diversion or piping of any natural or fabricated watercourse.
e) "Maintenance Agreement" means a legally recorded document that acts as a property
deed restriction, and which provides for long-term maintenance of stormwater
management practices.
Ordinance No. XXX 2
Month XX, 2011
f) "Nonpoint Source Pollution" means pollution from any source other than from any
discernible, confined, and discrete conveyances, and shall include, but not be limited to,
pollutants from agricultural, silvicultural, mining, construction, subsurface disposal and
urban runoff sources.
g) "Off -Site Facility" means a stormwater management measure located outside the
subject property boundary described in the permit application for land development
activity.
h) "Redevelopment" means any construction, alteration or improvement exceeding 1,000
square feet in areas where existing land use is commercial, industrial, institutional or
multi -family residential.
i) "Site" means:
a. For "new development" any tract, lot of parcel of land or combination of tracts, lots,
or parcels of land, which are in one ownership, or are contiguous and in diverse
ownership where development is to be performed as part of a unit, subdivision, or
project.
b. For "redevelopment" the area of new construction, as shown on an approved site
plan, or the original parcel. Final determination of the applicable area for
stormwater management shall be made by The City of Medina.
j) "Stop Work Order" means an order issued which requires that all construction activity
on a site be stopped.
k) "Stormwater Management" means the use of structural or non-structural practices that
are designed to reduce storm water runoff pollutant loads, discharge volumes, and/or
peakflow discharge rates.
1) "Stormwater Management Plan" means a set of drawings or other documents submitted
by a person as a prerequisite to obtaining a stormwater management approval, which
contain all of the information and specifications pertaining to stormwater management.
m) "Stormwater Runoff' means flow on the surface of the ground, resulting from
precipitation.
n) "Stormwater Treatment Practices (STPs)" means measures, either structural or
nonstructural, that are determined to be the most effective, practical means of
preventing or reducing point source or nonpoint-source pollution inputs to stormwater
runoff and waterbodies.
o) "Water Quality Volume (WQ,,)" means the runoff storage volume needed to treat the
specified phosphorous loading as determined in the Medina Stormwater Manual
p) "Watercourse" means a permanent or intermittent stream or other body of water, either
natural or fabricated, which gathers or carries surface water.
q) "Watershed" means the total drainage area contributing runoff to a single point.
Subd. 5. Applicability
This Ordinance shall be applicable to all applications for subdivision, site plan review, and other
Land Disturbance Activity, unless eligible for an exemption or granted a waiver by the City of
Medina. The Ordinance also applies to land development activities that are smaller than the
minimum applicability criteria if such activities are part of a larger common plan of development
that meets the following applicability criteria, even though multiple separate and distinct land
development activities may take place at different times on different schedules. In addition, all
Ordinance No. XXX
Month XX, 2011
3
plans must also be reviewed by local environmental protection officials to ensure that post
construction runoff levels are consistent with any local and regional watershed plans.
The standards of the Medina Stormwater Design Manual shall be met by all activities to which
this ordinance is applicable, except that standards related to Runoff Volume Control and Water
Quality Control shall apply only to the following conditions:
A. New development disturbing one (1) acre or more of land.
B. Redevelopment disturbing one (1) acre or more of land, OR that increases impervious
area.
C. Improvements from existing single family residential property disturbing one (1) acre or
more of land AND increasing impervious area.
The following activities may be exempt from these stormwater performance criteria:
A. Land Disturbance Activity which does not increase impervious surfaces more than 1,000
square feet.
B. Agricultural activity that is consistent with an approved soil conservation plan or a timber
management plan prepared or approved by the City of Medina, as applicable.
C. Repairs to any stormwater treatment practice deemed necessary by the City of Medina.
D. Emergency actions as declared by the City of Medina.
Subd. 6. Permit or Plat Approval Required
No landowner or land operator shall receive a building permit or plat approval from the City of
Medina until first meeting the requirements of this Ordinance prior to commencing the proposed
activity.
Subd. 7. Application Requirements
Unless otherwise exempted by this Ordinance, a stormwater management submittal must include
the following as a condition for its consideration:
a) a stormwater management plan;
b) a maintenance agreement;
The stormwater management plan shall be prepared to meet the requirements of Section 4 of this
Ordinance; the maintenance agreement shall be prepared to meet the requirements of Section 5
of this Ordinance.
Subd. 8. Application Procedure
• Applications for land disturbance activity permits or plat approvals must be filed with the
City of Medina on any regular business day.
• A copy of this application shall be forwarded to City of Medina for review
Ordinance No. XXX 4
Month XX, 2011
" A p p l i c a t i o n s s h a l l i n c l u d e t h e f o l l o w i n g : t h r e e c o p i e s o f t h e s t o r m w a t e r m a n a g e m e n t
p l a n , t h r e e c o p i e s o f t h e m a i n t e n a n c e a g r e e m e n t , a n d r e q u i r e d r e v i e w f e e s .
" U p o n s u b m i s s i o n o f a c o m p l e t e a p p l i c a t i o n , t h e C i t y E n g i n e e r s h a l l r e v i e w t h e
a p p l i c a t i o n a n d s h a l l i n f o r m t h e a p p l i c a n t w h e t h e r t h e a p p l i c a t i o n , p l a n , a n d m a i n t e n a n c e
a g r e e m e n t a r e a p p r o v e d o r d i s a p p r o v e d .
S u b d . 9 P e r m i t o r P l a t A p p r o v a l D u r a t i o n
A p p r o v e d p l a n s i s s u e d u n d e r t h i s s e c t i o n s h a l l b e v a l i d f r o m t h e d a t e o f a p p r o v a l t h r o u g h t h e
d a t e t h e C i t y o f M e d i n a n o t i f i e s t h e o w n e r t h a t a l l s t o r m w a t e r m a n a g e m e n t p r a c t i c e s h a v e p a s s e d
t h e f i n a l i n s p e c t i o n r e q u i r e d u n d e r a p p r o v e d c o n d i t i o n s , o r t h e a p p r o v a l i s r e v o k e d .
S u b d . 1 0 . W a i v e r s f o r P r o v i d i n g S t o r m w a t e r M a n a g e m e n t
E v e r y a p p l i c a n t s h a l l p r o v i d e f o r s t o r m w a t e r m a n a g e m e n t , u n l e s s a w a i v e r i s g r a n t e d . R e q u e s t s
t o w a i v e t h e s t o r m w a t e r m a n a g e m e n t p l a n r e q u i r e m e n t s s h a l l b e s u b m i t t e d t o t h e C i t y o f M e d i n a
f o r a p p r o v a l .
T h e m i n i m u m r e q u i r e m e n t s f o r s t o r m w a t e r m a n a g e m e n t m a y b e w a i v e d i n w h o l e o r i n p a r t u p o n
w r i t t e n r e q u e s t o f t h e a p p l i c a n t , i f a t l e a s t o n e o f t h e f o l l o w i n g c o n d i t i o n s a p p l i e s :
a ) I t c a n b e d e m o n s t r a t e d t h a t t h e p r o p o s e d d e v e l o p m e n t i s n o t l i k e l y t o i m p a i r a t t a i n m e n t
o f t h e o b j e c t i v e s o f t h i s O r d i n a n c e .
b ) A l t e r n a t i v e m i n i m u m r e q u i r e m e n t s f o r o n - s i t e m a n a g e m e n t o f s t o r m w a t e r d i s c h a r g e s
h a v e b e e n e s t a b l i s h e d i n a s t o r m w a t e r m a n a g e m e n t p l a n t h a t h a s b e e n a p p r o v e d b y t h e
C i t y o f M e d i n a .
c ) P r o v i s i o n s a r e m a d e t o m a n a g e s t o r m w a t e r b y a n o f f - s i t e f a c i l i t y . T h e o f f - s i t e f a c i l i t y i s
r e q u i r e d t o b e i n p l a c e , t o b e d e s i g n e d a n d a d e q u a t e l y s i z e d t o p r o v i d e a l e v e l o f
s t o r m w a t e r c o n t r o l t h a t i s e q u a l t o o r g r e a t e r t h a n t h a t w h i c h w o u l d b e a f f o r d e d b y o n -
s i t e p r a c t i c e s a n d h a s a l e g a l l y o b l i g a t e d e n t i t y r e s p o n s i b l e f o r l o n g - t e r m o p e r a t i o n a n d
m a i n t e n a n c e o f t h e s t o r m w a t e r p r a c t i c e .
I n i n s t a n c e s w h e r e o n e o f t h e c o n d i t i o n s a b o v e a p p l i e s , t h e C i t y o f M e d i n a m a y g r a n t a w a i v e r
f r o m s t r i c t c o m p l i a n c e w i t h s t o r m w a t e r m a n a g e m e n t p r o v i s i o n s t h a t a r e n o t a c h i e v a b l e , i f
a c c e p t a b l e m i t i g a t i o n m e a s u r e s a r e p r o v i d e d .
S u b d . 1 1 . G e n e r a l P e r f o r m a n c e C r i t e r i a f o r S t o r m w a t e r M a n a g e m e n t
U n l e s s j u d g e d b y t h e C i t y o f M e d i n a t o b e e x e m p t o r g r a n t e d a w a i v e r , a l l s i t e d e s i g n s s h a l l
e s t a b l i s h s t o r m w a t e r m a n a g e m e n t p r a c t i c e s t o c o n t r o l t h e p e a k f l o w r a t e s a n d p o l l u t a n t s o f
s t o r m w a t e r d i s c h a r g e a s s o c i a t e d w i t h s p e c i f i e d d e s i g n s t o r m s a n d r u n o f f v o l u m e s , a s d e t a i l e d i n
t h e M e d i n a S t o r m w a t e r D e s i g n M a n u a l . T h e s e p r a c t i c e s s h o u l d s e e k t o u s e p e r v i o u s a r e a s f o r
s t o r m w a t e r t r e a t m e n t a n d t o i n f i l t r a t e s t o r m w a t e r r u n o f f f r o m d r i v e w a y s , s i d e w a l k s , r o o f t o p s ,
p a r k i n g l o t s , a n d l a n d s c a p e d a r e a s t o t h e m a x i m u m e x t e n t p r a c t i c a l t o p r o v i d e t r e a t m e n t f o r b o t h
w a t e r q u a l i t y a n d q u a n t i t y .
O r d i n a n c e N o . X X X 5
M o n t h X X , 2 0 1 1
Subd.12. Stormwater Treatment Maintenance Plan and Agreement
During the application process, the City of Medina shall determine which party will be
responsible for stormwater facility ownership and long-term maintenance responsibilities.
If the applicant is determined to have ownership and maintenance responsibilities, the applicant
and city shall enter into an agreement that documents all responsibilities for operation and
maintenance of all stormwater practices. Such responsibility shall be documented in a
maintenance plan and executed through an agreement. The agreement shall be executed and
recorded with the parcel.
a) Maintenance Agreement
The stormwater maintenance agreement shall be in a form approved by the city, and
shall, at a minimum:
1. Designate the owner or other responsible party, which shall be permanently
responsible for maintenance of the structural or nonstructural measures.
2. Pass responsibility for such maintenance to successors in title.
3. Grant the city and its representatives the right of entry for the purposes of inspecting
all stormwater measures at reasonable times and in a reasonable manner. This
includes the right to enter a property when the city has a reasonable basis to believe
that a violation of this division or maintenance agreement is occurring or has occurred
and to enter when necessary for abatement of a public nuisance or correction and
enforcement of a violation of this division or agreement.
4. Allow the city to repair and maintain the facility, if after proper and reasonable notice
by the city to the owner of the facility. The agreement shall permit the city to certify
the costs of the maintenance/correction to the taxes for the subject property.
5. Include a maintenance plan that contains, but is not limited to the following:
a. Identification of all structural stormwater practices.
b. A schedule for regular inspection, monitoring, and maintenance for each
practice. Monitoring shall verify whether the practice is functioning as
designed and may include, but is not limited to quality, temperature, and
quantity of runoff.
c. Identification of the responsible party for conducting the inspection,
monitoring, and maintenance for each practice.
6. Identify a schedule and format for reporting compliance with the maintenance plan to
the city.
b) Inspection of Stormwater Facilities
Inspection programs may be established on any reasonable basis, including but not limited to:
routine inspections; random inspections; inspections based upon complaints or other notice
of possible violations; inspection of drainage basins or areas identified as higher than typical
sources of sediment or other contaminants or pollutants; inspections of businesses or
industries of a type associated with higher than usual discharges of contaminants or
Ordinance No. XXX 6
Month XX, 2011
pollutants or with discharges of a type which are more likely than the typical discharge to
cause violations of state or federal water or sediment quality standards or the NPDES
stormwater permit; and joint inspections with other agencies inspecting under environmental
or safety laws. Inspections may include, but are not limited to, reviewing maintenance and
repair records; sampling discharges, surface water, groundwater, and material or water in
drainage control facilities; and evaluating the condition of drainage control facilities and
other stormwater treatment practices.
c) Right -of -Entry for Inspection
When any new drainage control facility is installed on private property, or when any new
connection is made between private property and a public drainage control system, sanitary
sewer, or combined sewer; the property owner shall grant to the City of Medina the right to
enter the property at reasonable times and in a reasonable manner for the purpose of
inspection. This includes the right to enter a property when it has a reasonable basis to
believe that a violation of this Ordinance is occurring or has occurred, and to enter when
necessary for abatement of a public nuisance or correction of a violation of this Ordinance.
d) Records of Installation and Maintenance Activities.
Parties responsible for the operation and maintenance of a stormwater management facility
shall make records of the installation and of all maintenance and repairs, and shall retain the
records for at least three (3) years. These records shall be made available to the City of
Medina during inspection of the facility and at other reasonable times upon request.
e) Failure to Maintain Practices
If a responsible party fails or refuses to meet the requirements of the maintenance covenant,
the City of Medina, after reasonable notice, may correct a violation of the design standards or
maintenance needs by performing all necessary work to place the facility in proper working
condition. In the event that the stormwater management facility becomes a danger to public
safety or public health, the City of Medina shall notify the party responsible for maintenance
of the stormwater management facility in writing. Upon receipt of that notice, the
responsible person shall have thirty (30) days to apply maintenance and repair of the facility
in an approved manner. After proper notice, the City of Medina may assess the owner(s) of
the facility for the cost of repair work and any penalties; and the cost of the work shall be a
lien on the property, or prorated against the beneficial users of the property, and may be
placed on the tax bill and collected as ordinary taxes by the county.
Subd.13. Performance Bond/Security.
The City of Medina requires the submittal of a performance security or bond prior to issuance of
a permit in order to insure that the stormwater practices are installed by the permit holder as
required by the approved stormwater management plan. The amount of the installation
performance security shall be the total estimated construction cost of the stormwater
management practices approved, plus 50%, or 150% of estimated construction cost. The
performance security shall contain forfeiture provisions for failure to complete work specified in
the stormwater management plan.
Ordinance No. XXX 7
Month XX, 2011
The installation performance security shall be released in full only upon submission of "as built
plans" and written certification by a registered professional engineer that the stormwater practice
has been installed in accordance with the approved plan and other applicable provisions of this
Ordinance. The City of Medina will make a final inspection of the stormwater practice to ensure
that it complies with the approved plan and the provisions of this Ordinance. Provisions for a
partial pro -rata release of the performance security based on the completion of various
development stages can be done at the discretion of the City of Medina.
Subd.14. Notice of Construction Commencement
The applicant must notify the City of Medina in advance before the commencement of
construction. Regular inspections of the stormwater treatment practice construction shall be
conducted by the staff of the City of Medina or certified by a professional engineer or their
designee. All inspections shall be documented and written reports prepared that contain the
following information:
• the date and location of the inspection,
• whether construction is in compliance with the approved stormwater management plan,
• variations from the approved construction specifications,
• any violations that exist.
If any violations are found, the property owner shall be notified in writing of the nature of the
violation and the required corrective actions. No added work shall proceed until any violations
are corrected and all work previously completed has received approval by the City of Medina.
Subd.15. As Built Plans
All applicants are required to submit actual "as built" plans for any stormwater management
practices located on -site after final construction is completed. As -built plans must show the final
design specifications for all stormwater management facilities, and the plans must be certified by
a professional engineer. A final inspection by the City of Medina is required before the release
of any performance securities can occur.
Subd.16. Violations
Any development activity that is commenced or is conducted contrary to this Ordinance may be
restrained by injunction or otherwise abated in a manner provided by law.
a) Notice of Violation.
When the City of Medina determines that an activity is not being carried out in
accordance with the requirements of this Ordinance, it shall issue a written notice of
violation to the owner of the property. The notice of violation shall contain:
1) the name and address of the owner or applicant,
2) the address when available or a description of the building, structure, or land upon
which the violation is occurring,
3) a statement specifying the nature of the violation,
Ordinance No. XXX 8
Month XX, 2011
4) a description of the remedial measures necessary to bring the development activity
into compliance with this Ordinance and a time schedule for the completion of such
remedial action,
5) a statement of the penalty or penalties that shall or may be assessed against the person
to whom the notice of violation is directed, and
6) a statement that the determination of violation may be appealed to the City of Medina
by filing a written notice of appeal within fifteen (15) days of service of notice of
violation.
b) Stop Work Orders
Persons receiving a notice of violation will be required to halt all construction activities.
This "stop work order" will be in effect until the City of Medina confirms that the
development activity is in compliance and the violation has been satisfactorily addressed.
Failure to address a notice of violation in a timely manner can result in civil, criminal, or
monetary penalties in accordance with the enforcement measures authorized in this
Ordinance.
c) Civil and Criminal Penalties
In addition to or as an alternative to any penalty provided herein or by law, any person
who violates the provisions of this Ordinance is guilty of a misdemeanor and subject to
prosecution. Such person shall be guilty of a separate offense for each day during which
the violation occurs or continues.
d) Restoration of lands
Any violator may be required to restore land to its undisturbed condition. In the event
that restoration is not undertaken within a reasonable time after notice, the City of
Medina may take necessary corrective action, the cost of which shall become a lien upon
the property until paid.
Subd.17. Appeals
Any person aggrieved by the action of any official charged with the enforcement of this
Ordinance, as the result of the disapproval of a properly filed application for a permit or plat
approval, issuance of a written notice of violation, or an alleged failure to properly enforce the
Ordinance in regard to a specific application, shall have the right to appeal the action to the City
Council. The appeal shall be filed in writing within 60 days of the date of official transmittal of
the final decision or determination to the applicant, shall state clearly the grounds on which the
appeal is based, and shall include relevant fees.
Subd.18. Holds on Occupation Permits
Occupation permits will not be granted until all stormwater practices have been made and
accepted by the City of Medina, unless a financial guarantee, in a form acceptable to the City, is
provided to ensure completion.
Ordinance No. XXX 9
Month XX, 201' 1
Subd.19. Revocation of Approval
Revocation of the stormwater approval may be made by the City of Medina if requirements
within this ordinance are not fulfilled, or the owner/applicant is unable to fulfill the ordinance
requirements. If an approval is revoked, the applicant must re -submit a stormwater management
plan.
Subd. 20. Compatibility with Other Permit and Ordinance Requirements
This Ordinance is not intended to interfere with, abrogate, or annul any other Ordinance, rule or
regulation, statute, or other provision of law. The requirements of this Ordinance should be
considered minimum requirements, and where any provision of this Ordinance imposes
restrictions different from those imposed by any other Ordinance, rule or regulation, or other
provision of law, whichever provisions are more restrictive or impose higher protective standards
for human health or the environment shall be considered to take precedence.
Subd. 21. Severability
If the provisions of any article, section, subsection, paragraph, subdivision or clause of this
Ordinance shall be judged invalid by a court of competent jurisdiction, such order of judgment
shall not affect or invalidate the remainder of any article, section, subsection, paragraph,
subdivision or clause of this Ordinance.
This Ordinance shall become effective upon its adoption and publication.
Adopted by the city council of the city of Medina this XX day of May, 2011.
T.M. Crosby, Jr., Mayor
ATTEST:
Chad M. Adams, City Administrator -Clerk
Published in the South Crow River News this XX day o
Ordinance No. XXX 10
Month XX, 2011
MEDINA
Stormwater Design Manual
City of Medina
May 2011
Project No. 000190-10031-0
Bonestroo
MEDINA — STORMWATER DESIGN GUIDE
Table of Contents
Table of Contents 1
1.0 DESIGN OVERVIEW 2
2.0 Procedure for Reviewing Stormwater Management Plans 2
4.0 List of Acceptable Practices 5
5.0 Guidance on STP Selection 6
6.0 Basic Sizing Criteria 7
7.0 Design Examples 14
8.0 BMP Detail Drawings 14
9.0 Construction Specifications 14
10.0 Checklists 16
Checklists for Construction Inspection 18
Checklists for Operation & Maintenance 19
City of Medina
Stormwater Design Guide
Bonestroo
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000190-10031-0
MEDINA — STORMWATER DESIGN GUIDE
1.0 DESIGN OVERVIEW
The City of Medina's Local Surface Water Management Plan (LSWMP) identifies the goals and
policies that define the City's stormwater management program. Medina's stormwater
requirements were written meet the City's goals to preserve, protect, and manage its water
resources as well as to meet federal, state, and watershed stormwater regulations. Additionally,
the City of Medina will need to meet the pollutant reduction requirements of current and future
TMDLs specified for waterbodies in whose watershed it resides.
2.0 Procedure for Reviewing Stormwater Management
Plans
All new development and redevelopment will require the submittal of a stormwater management
plan. It is highly recommended that a concept plan be submitted prior to the preparation of a
final stormwater management plan. The concept plan identifies basic site information, locations
of proposed development features, and preliminary locations and sizing of stormwater treatment
practices. The concept plan allows the review to be conducted in conjunction with a preliminary
development plan or site plan. The review of a concept plan helps to identify major issues
related to regulatory oversight of the planned development. It is less time consuming and more
efficient to evaluate proposed development plans with this step of the review process. The final
plan provides more detailed design information for the proposed stormwater practices, and
includes much more detail in terms of hydrologic conditions and site features. The general
review process, from the submittal of the concept and final plans to the issuance of the
Stormwater Management Plan approval, is summarized in the following five steps.
1) What permits, or approvals, are required for the project site, and what waivers and/or
exemptions are applicable?
2) Are the selected practices appropriate for this site?
3) Are the practices designed to meet the minimum performance criteria?
4) Does the Plan meet other resource protection requirements as specified in the City of
Medina Code?
5) Are provisions for long-term maintenance adequate?
3.0 Submittal Requirements
Requirements for Stormwater Management Plan Approval
Stormwater Management Plan Required for All Developments.
No application for development, or redevelopment, will be approved unless it includes a
stormwater management plan detailing how runoff and associated water quality impacts resulting
from the development will be controlled or managed. This plan must indicate whether
stormwater will be managed on -site or off -site and, if on -site, the general location and type of
practices.
The stormwater management plan must be signed by a licensed professional engineer in the
State of Minnesota, who will verify that the design of all stormwater management practices meet
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000190-10031-0
the submittal requirements outlined in the Submittal Checklist found in the stormwater design
manual. No building permit, grading permit, sediment control permit, or plat approval shall be
issued until a satisfactory final stormwater management plan, or a waiver thereof, shall have
undergone a review and been approved by the City of Medina after determining that the plan or
waiver is consistent with the requirements of this manual.
Stormwater Management Conceptual Plan Requirements (Optional)
A stormwater management concept plan submittal is optional, but highly encouraged. A concept
plan submittal has a greater chance of identifying major obstacles and can facilitate alternative
stormwater management arrangements in a timely fashion. If a concept plan is submitted for
review, it should include sufficient information (e.g., maps, hydrologic calculations, etc) to
evaluate the environmental characteristics of the project site. This information should show the
potential impacts of all proposed development of the site, both present and future, on the water
resources, and show the effectiveness and acceptability of the measures proposed for managing
stormwater generated at the project site. The intent of this conceptual planning process is to
determine the type of stormwater management measures necessary for the proposed project,
and ensure adequate planning for management of stormwater runoff from future development.
To accomplish this goal the following information shall be included in the concept plan:
1. A map (or maps) indicating the location of existing and proposed buildings, roads,
parking areas, utilities, structural stormwater management and sediment control
facilities. The map(s) will also clearly show proposed land use with tabulation of the
percentage of surface area to be adapted to various uses; drainage patterns; locations of
utilities, roads and easements; the limits of clearing and grading; a written description of
the site plan and justification of proposed changes in natural conditions may be required.
2. Sufficient engineering analysis to show that the proposed stormwater management
measures are capable of controlling runoff from the site in compliance with the
Stormwater Design Manual.
3. A written or graphic inventory of the natural resources at the site and surrounding area
as it exists prior to the commencement of the project and a description of the watershed
and its relation to the project site. This description should include a discussion of soil
conditions, forest cover, topography, wetlands, and other native vegetative areas on the
site. Particular attention should be paid to environmentally sensitive features that
provide particular opportunities or constraints for development.
4. A brief written description of the required maintenance burden for the proposed
stormwater management facility.
5. The concept plan may also consider the maximum development potential of a site under
existing zoning, regardless of whether the applicant presently intends to develop the site
to its maximum potential.
For development or redevelopment occurring on a previously developed site, an applicant should
include within the concept plan measures for controlling existing stormwater runoff discharges
from the site in accordance with the standards of this Manual to the maximum extent practicable.
After review of the concept plan and modifications are made to that plan as deemed necessary
by the City of Medina, a final stormwater management plan may be submitted for approval.
Stormwater Management Plan Requirements (Required)
The final stormwater management plan shall include all of the information required in the Final
Stormwater Management Plan checklist found at the end of the Medina Stormwater Design
Manual. This includes:
City of Medina
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000190-10031-0
1. Contact Information
The name, address, and telephone number of all persons having a legal interest in the property
and the tax reference number and parcel number of the property or properties affected.
2. Topographic Base Map
A 1" = 200' topographic base map of the site which extends a minimum of fifty (50) feet beyond
the limits of the proposed development and indicates existing surface water drainage including
streams, ponds, culverts, ditches, and wetlands; current land use including all existing structures;
locations of utilities, roads, and easements; and significant natural and manmade features not
otherwise shown.
3. Calculations
Hydrologic and hydraulic design calculations for the predevelopment and postdevelopment
conditions for the design storms specified in this manual. Such calculations shall include:
1. design storm frequency, amount, and duration,
2. time of concentration,
3. Runoff Curve Numbers or runoff coefficients,
4. peak runoff rates and total runoff volumes for each watershed area,
5. pond and wetland high-water levels and storage volumes,
6. infiltration rates, where applicable,
7. culvert capacities,
8. flow velocities,
9. data on the change in rate and volume of runoff for the design storms referenced in the
Medina Stormwater Design Manual, and
10. documentation of sources for all computation methods and field test results.
4. Soils Information
If a stormwater management control measure depends on the hydrologic properties of soils
(e.g., infiltration basins), then soils information (e.g., Hennepin County Soil Survey, soil boring
data, or soils report) shall be submitted. The soils report shall be based on on -site boring logs or
soil pit profiles. The number and location of required soil borings or soil pits shall be determined
based on what is needed to determine the suitability and distribution of soil types present at the
location of the control measure.
5. Maintenance and Repair Plan
The design and planning of all stormwater management facilities shall include detailed
maintenance and repair procedures to ensure their continued function. These plans will identify
the parts or components of a stormwater management facility that need to be maintained and
the equipment and skills or training necessary. Provisions for the periodic review and evaluation
of the effectiveness of the maintenance program and the need for revisions or additional
maintenance procedures shall be included in the plan.
• Landscaping plan
The applicant must present a detailed plan for management of vegetation associated
with stormwater features after construction is finished, including who will be responsible
for the maintenance of vegetation at the site and what practices will be employed to
ensure that adequate vegetative cover is preserved.
• Maintenance Easements
The applicant must ensure access to all stormwater treatment practices at the site for the
purpose of inspection and repair by securing all the maintenance easements needed on a
City of Medina
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000190-10031-0
permanent basis. Maintenance easements will be recorded with the plat, and will remain
in effect, even if the title of the property is transferred to a new owner.
• Maintenance Agreement
The applicant must execute an easement and an inspection and maintenance agreement
binding on all subsequent owners of land served by an on -site stormwater management
measure in accordance with the requirements of this manual.
• Other Environmental Permits
The applicant shall assure that all other applicable environmental permits have been or
will be acquired for the site.
4.0 List of Acceptable Practices
In the development of the stormwater management practice appropriate for the development or
redevelopment, infiltration (water quality volume) is foremost in importance to apply in the
design. Filtration is warranted when site conditions do not allow for an effective infiltration
facility. For flooding or rate control, detention systems are typically the preferred practice.
Alternative practices may be approved at the discretion of the City Engineer.
Infiltration Systems:
• Infiltration Trench
• Infiltration Basin
• Raingarden
• Underground Storage
Filtration Systems:
• Surface Sand Filter
• Underground Sand Filter
• Perimeter Sand Filter
• Organic Filter
• Bioretention System
• Raingarden
• Pervious Pavement
• Underground Storage
• Tree Trench
Detention Systems:
• Wet Pond
• Multiple Pond System
• Extended Detention Basin
• Micro -pool Extended Detention Basin
• Dry Detention Ponds
• Underground Storage
• Other, as approved by the City of Medina
Wetlands:
• Shallow Wetland
• Pond/Wetland System
Open Channel Systems:
City of Medina
Stormwater Design Guide
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" D r y S w a l e
" W e t S w a l e
" G r a s s S w a l e
" N a t u r a l c h a n n e l , o r s t r e a m
5 . 0 G u i d a n c e o n S t o r m w a t e r T r e a t m e n t P r a c t i c e
( S T P )
D e s i g n e r s a r e e x p e c t e d t o f o l l o w t h e n i n e ( 9 ) s t e p s c r e e n i n g p r o c e s s f o r ( S T P ) s e l e c t i o n d e t a i l e d
i n C h a p t e r 7 o f t h e M i n n e s o t a S t o r m w a t e r M a n u a l . S t o r m w a t e r T r e a t m e n t P r a c t i c e s w i l l b e
s c r u t i n i z e d u s i n g t h e s a m e m a t r i c e s f o u n d i n C h a p t e r 7 a s p a r t o f t h e r e v i e w p r o c e s s . D e v i a t i o n s
f r o m r e c o m m e n d e d g u i d a n c e i n t h e M i n n e s o t a S t o r m w a t e r M a n u a l w i l l r e q u i r e d e t a i l e d w r i t t e n
e x p l a n a t i o n . A p p r o v a l o f a n y d e v i a t i o n f r o m t h e M i n n e s o t a S t o r m w a t e r M a n u a l g u i d a n c e w i l l b e
a t t h e d i s c r e t i o n o f t h e C i t y o f M e d i n a .
T h e 9 s t e p s c r e e n i n g p r o c e s s t h a t s h o u l d b e u s e d i n t h e B M P s e l e c t i o n p r o c e s s i s a s f o l l o w s :
1 . I n v e s t i g a t e P o l l u t i o n P r e v e n t i o n O p p o r t u n i t i e s :
E v a l u a t e t h e s i t e t o l o o k f o r o p p o r t u n i t i e s t o p r e v e n t p o l l u t i o n s o u r c e s o n t h e l a n d f r o m
b e c o m i n g m o b i l i z e d b y r u n o f f .
2 . D e s i g n S i t e t o M i n i m i z e R u n o f f :
A s s e s s w h e t h e r a n y b e t t e r s i t e d e s i g n t e c h n i q u e s c a n b e a p p l i e d a t t h e s i t e t o m i n i m i z e
r u n o f f a n d t h e r e f o r e r e d u c e t h e s i z e o f s t r u c t u r a l B M P s . B e t t e r s i t e d e s i g n c o n s i d e r s t h e
f o l l o w i n g p r i n c i p l e s i n t h e d e s i g n o f t h e S T P :
" P r e s e r v e s N a t u r a l A r e a s
" R e d u c t i o n o f I m p e r v i o u s A r e a s a n d D i s t r i b u t i n g S t o r m w a t e r
" R e d u c i n g I m p e r v i o u s C o v e r
3 . S e l e c t T e m p o r a r y C o n s t r u c t i o n S e d i m e n t C o n t r o l T e c h n i q u e s :
C h e c k t o s e e w h a t s e t o f t e m p o r a r y s e d i m e n t c o n t r o l t e c h n i q u e s w i l l p r e v e n t e r o s i o n a n d
m i n i m i z e s i t e d i s t u r b a n c e d u r i n g c o n s t r u c t i o n .
4 . I d e n t i f y R e c e i v i n g W a t e r I s s u e s :
U n d e r s t a n d t h e r e g u l a t o r y s t a t u s o f t h e r e c e i v i n g w a t e r t o w h i c h t h e s i t e d r a i n s .
D e p e n d i n g o n t h e n a t u r e o f t h e r e c e i v i n g w a t e r , c e r t a i n B M P s m a y b e p r o m o t e d ,
r e s t r i c t e d , o r p r o h i b i t e d , o r s p e c i a l d e s i g n o r s i z i n g c r i t e r i a m a y a p p l y .
5 . I d e n t i f y C l i m a t e a n d T e r r a i n F a c t o r s :
C l i m a t e a n d t e r r a i n c o n d i t i o n s v a r y w i d e l y a c r o s s t h e s t a t e , t h u s d e s i g n e r s n e e d t o
e x p l i c i t l y c o n s i d e r h o w e a c h r e g i o n a l f a c t o r w i l l i n f l u e n c e t h e B M P s p r o p o s e d f o r t h e s i t e .
6 . E v a l u a t e S t o r m w a t e r T r e a t m e n t S u i t a b i l i t y :
N o t a l l B M P s w o r k o v e r t h e w i d e r a n g e o f s t o r m e v e n t s t h a t n e e d t o b e m a n a g e d a t t h e
s i t e , s o d e s i g n e r s n e e d t o c h o o s e t h e t y p e o r c o m b i n a t i o n o f B M P s t h a t w i l l p r o v i d e t h e
d e s i r e d l e v e l o f t r e a t m e n t .
7 . A s s e s s P h y s i c a l F e a s i b i l i t y a t t h e S i t e :
C i t y o f M e d i n a
S t o r m w a t e r D e s i g n G u i d e
B o n e s t r o o
P a g e 6
0 0 0 1 9 0 - 1 0 0 3 1 - 0
Each development site has many physical constraints that influence the feasibility of
different kinds of BMPs; designers confirm feasibility by assessing eight physical factors
at the site.
8. Investigate Community and Environmental Factors:
Each group of BMPs provides different economic, community, and environmental benefits
and drawbacks; designers need to carefully weigh these factors when choosing BMPs for
the site.
9. Determine Any Site Restrictions and Setbacks:
Check to see if any environmental resources or infrastructure is present that will
influence where a BMP can be located at the development site.
6.0 Basic Sizing Criteria
Proposed stormwater management plans must incorporate Volume Control, Water Quality
Control, and Rate Control as the basis for stormwater management in the proposed development
plan. All proposed stormwater management practices must fulfill Volume Control, Water Quality,
and Rate Control sizing requirements.
6.1 Volume Control Requirements
Volume control measures are required on projects to meet the water quality criteria of the City of
Medina's Local Surface Water Management Plan. If an applicant can demonstrate that the
volume control standard has been met, then the water quality sizing criteria shall be considered
satisfied.
The following are volume control treatment requirements:
Development and Redevelopment:
1. If there is no increase in impervious area, then treatment should be for 20% of the
volume of runoff produced over the existing impervious area.
2. If the site plan increases impervious area, the treatment includes treating the volume
control for the new impervious area, as well as, 20% of the volume of runoff from
existing impervious area.
Single-family residences:
1. Treatment shall include the volume control requirement for the new impervious area.
6.1.1 Volume Control Calculations
Depending on applicability, a proposed development shall have one of the following Stormwater
Treatment Practices (STP), an infiltration STP, or a filtration STP that collects and treats the
following volume of stormwater runoff:
Volume calculation for Infiltration Practice (VCinf):
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VCvinf (cf) = (1" x (1/12) x (area of proposed impervious area in sq. ft.)) + (1" x (0.20 X (area of
existing impervious area in sq. ft.))
Volume Calculation for Filtration Practice (VCfil):
VCvfil (cf) = VCinf x 1.5
If volume control is infeasible due to site restrictions such as tight soils, contaminated soils, or
lack of separation between facility and ground water (3' of separation), the site may employ a
management practice that demonstrates a reduction in 20% phosphorus loading over existing
conditions. Specifications for this practice are detailed in the Water Quality Control section.
Volume Control with Irrigation
Irrigation as an STP may receive full credit towards satisfying the VCinf requirement in lieu of
using on -site infiltration. However, acceptance of this practice will be determined on a site -by -
site basis subject to the approval of the City of Medina City Engineer.
6.3 Water Quality Control
The water quality control standard shall be considered satisfied, if the volume control
standard has been satisfied. In the event that that it is infeasible to meet the volume control
standard due to contaminated soils, site constraints, etc., the proposed management practice will
need to detain and treat a sufficient volume of stormwater to achieve a phosphorus load
reduction of 20% from existing conditions using an approved Stormwater Treatment Practice
(STP). If existing conditions consist of meadow, forested, or wetland land use, see Table 1, then
proposed phosphorus loading must meet existing conditions loading. If unable to apply an
infiltration or filtration management practice due to site physical constraints, then justification
shall be documented and submitted for approval by the City Engineer. Approval of a waiver from
the Volume Control requirement will be evaluated on a case -by -case basis. Demonstration that
the water quality criteria have been met shall be done using PondNet, or other approved water
quality modeling method. If using PondNet, then the event mean concentrations found in Table
2 shall be used. The volume required using PondNet would be known as the Water Quality
Volume (WQv) required for the proposed development.
Table 1: Event Mean Concentrations for PondNet Modelin
Land Use
Phosphorus (P) Runoff Concentration (PPB)
Row Crop Agriculture
540
Pasture
350
Meadow
200
Rural Residential
255
Urban Residential
450
Forested
200
Commercial, Industrial
350
Open Space
200
Golf Course
550
Right -of -Way
400
Wetland
200
A Microsoft Excel" version of PondNet can be made available upon request to the City of
Medina.
6.4 Rate Control
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Post development discharge rates must be less than or equal to existing conditions discharge
rates for the 1 -year (2.4 -inch), 10 -year (4.1 -inch) and 100 -year (5.9 -inch) NRCS Type II, 24 -hour
storm events. In some cases where there is the potential for adverse downstream impacts, the
rate control requirement is more stringent than the existing conditions standard. Ultimately, the
stormwater system will be managed so that development, redevelopment, and other
infrastructure projects do not overburden the existing downstream system for the design event.
All runoff calculations shall be according to the methodology described in the Natural Resources
Conservation Service's Technical Release 55,"Urban Hydrology for Small Watersheds" (commonly
referred to as TR-55). Example acceptable modeling software includes HydroCAD and XP-
SWMM. Other methodology may be used with prior approval by the City. Composite curve
numbers shall not be used; instead, proposed contributing areas shall be broken into one of the
cover types in Table 2.
Curve numbers for each land use shall be chosen based on Table 2.
Table 2: Curve Numbers for Use in Hydrologic Computations
Hydrologic Soil Group
Cover Type
A
B
C
D
Open Water
100
100
100
100
Pasture
68
79
86
89
Meadow
30
58
71
78
Forested
55
55
70
77
Developed Open Space'
61
61
74
80
Impervious Areas2
98
98
98
98
Agricultural Land3
Peak Growth Formula
Row Crop - Fallow
77
86
91
94
Row Crop — Average
72
81
88
91
Gravel Road
76
85
89
91
Wetlands
98
98
98
98
1 Lawns, parks, golf courses, other grassy areas, etc.
z Streets, parking lots, roofs, driveways, etc.
3 Where existing conditions are characterized by agricultural land use, the "peak growth" curve
number should be utilized. Calculation of the peak growth curve number is based on
the following formula:
CN average = % * (CN normal peak growth + CN fallow), or
CN normal peak growth = 2 * (CN average) - CN fallow
For example, for row crop agriculture and hydrologic soil group B, the peak growth
curve number is 76. This is based on average and fallow curve numbers of 81 and
86, respectively.
A Type II 24 -hour rainfall distribution with, average antecedent moisture conditions, should be
utilized for runoff calculations. The recommended minimum outlet diameter is 6 -inches due to
plugging susceptibility and may supersede the rate control requirement for the 2 -year event.
Infiltration will not be considered when determining rate control or freeboard. Waterbodies
should be modeled with the starting water level at their outlet elevation.
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City standard detail plates should be utilized for pond outlet structures. It is recommended that
outlet structures be designed in three phases with a primary outlet structure and secondary
overflow structure routed to the storm sewer and a defined emergency overflow as the tertiary
outlet structure.
Bounce of water level within the wetlands shall be maintained according to the following table:
Table 3: Bounce Restriction for Runoff Directed Through Wetlands
Protection Classification
Additional Protection Requirements
Bounce - Change in water level due to
runoff event
Preserve
Maintain bounce at or below existing
conditions
Manage 1
Maintain bounce at or below existing
conditions plus 0.5 feet
Manage 2
Maintain bounce at or below existing
conditions plus 1.0 feet
Manage 3
No quantity requirement
The following items shall be considered in the management of landlocked basins:
• The flood levels established for landlocked basins shall take into consideration the effects of
water level fluctuations on trees, erosion, and property values. Steeply sloped shorelines
subject to slope failure and shoreline damage should not be in contact with floodwaters for
extended periods.
• The capacity of proposed outlets to landlocked basins should not be so small as to cause
extended duration of high water levels that would result in damage to upland vegetation.
Exceptions to this policy include basins that are strictly regional stormwater management
basins and not formerly wetlands. Exceptions also include wetlands converted to regional
stormwater management basins through mitigation of the affected wetland areas.
6.5 Freeboard
Elevation separations of buildings with respect to ponds, lakes, streams, and storm water
features shall be designed as follows:
1. At least two feet of vertical separation is required from an area's emergency overflow
elevation to the lowest opening of a home. In areas where this separation is not or
cannot be provided, we require additional analysis showing that the 100 -year back-to-
back storm event does not impact adjacent homes.
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2. Drainage easements and outlots for ponds, lakes, wetlands, streams etc. shall
encompass an area to the calculated one foot above the 100 -year HWL.
6.6 Stormwater Treatment Practice Design Standards
6.6.1 Storm Sewers
1. Manhole spacing shall not exceed 400 feet.
2. Where more than one pipe enters a structure, a catch basin/manhole shall be used.
3. Storm sewer pipe should match top of pipe to top of pipe unless grade constraints
prevent this. In that case, hydraulic calculations will be necessary to verify that
excessive surcharging will not occur.
4. Storm water pipes shall be designed utilizing the Rational Method. Channel design shall
be hydrograph method only. All methods are subject to the City Engineer's approval.
5. Lateral systems shall be designed for the 10 -year rainfall using the Rational Method.
State Aid roadway storm sewer shall be designed per the State Aid requirements.
6. The minimum full flow velocity within the storm sewer should be 3 feet per second (fps).
The maximum velocity shall be 10 fps, except when entering a pond, where the
maximum velocity shall be limited to 6 fps.
7. Trunk storm sewer should be designed at a minimum to carry 100 -year pond discharge
in addition to the 10 -year design flow for directly tributary areas. The following table
may be used for the calculation of peak rates using the Rational Method:
Table 3: Rational Method Runoff Coefficients for Storm Sewer Design
Cover Type
10 -Year Runoff Coefficient
Single-family Residential
0.4
Multi -family Residential
0.5
Commercial
0.7
Industrial
0.7
Parks, Open Space
0.2
Ponds, Wetlands
1.0
8. For storms greater than the 10 -year event, and in the case of plugged inlets, transient
street ponding will occur. For safety reasons, the maximum depth in streets should not
exceed 1.5 feet at the deepest point.
9. To promote efficient hydraulics within manholes, manhole benching shall be provided to
1/2 diameter of the largest pipe entering or leaving the manhole.
10. Vaned grate (3067V) catch basin castings shall be used on all streets.
11. The maximum design flow at a catch basin for the 10 -year storm event shall be 3 cubic
feet per second (cfs), unless high capacity grates are provided. Catch basins at low
points will be evaluated for higher flow with the approval of the City Engineer.
12. All structures located in the street are to be a minimum of four feet deep (rim to invert)
and a minimum of three feet deep elsewhere. Two -by -three catch basins are to be four
feet deep.
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13. The last structure in the street prior to discharging into a pond is to be a minimum of five
feet deep with a four -foot deep sump, where appropriate.
6.6.2 Outlet and Inlet Pipes
1. Inlet pipes of stormwater ponds should be extended to the pond normal water level
whenever possible.
2. Outfalls with velocities greater than 4 fps into channels, where the angle of the outfall to
the channel flow direction is greater than 30 -degrees, requires energy dissipation or
stilling basins.
3. Outfalls with velocities of less than 4 fps, that project flows downstream into a channel in
a direction 30 -degrees or less from the channel flow direction, generally do not require
energy dissipaters or stilling basins, but will require riprap protection.
4. In the case of discharge to channels, rip rap should be provided on all outlets to an
adequate depth below the channel grade and to a height above the outfall or channel
bottom. Rip rap should be placed over a suitably graded filter material and filter fabric to
ensure that soil particles do not migrate through the riprap and reduce its stability.
Riprap should be placed to a thickness at least 2.5 times the mean rock diameter to
ensure that it will not be undermined or rendered ineffective by displacement. If riprap
is used as protection for overland drainage routes, grouting may be recommended.
5. Discharge velocity into a pond at the outlet elevation shall be 6 fps or less. Riprap
protection is required at all inlet pipes into ponds from the NWL to the pond bottom.
6. Where outlet velocities to ponds exceed 6 fps, the design should be based on the unique
site conditions present. Submergence of the outlet or installation of a stilling basin
approved by the City is required when excessive outlet velocities are experienced.
7. Submerged outlet pipes from ponds are not allowed.
6.6.3 Channels and Overland Drainage
1. Overland drainage routes where velocities exceed 4 fps should be reviewed by the City
Engineer and approved only when suitable stabilization measures are proposed.
2. Open channels and swales are recommended where flows and small grade differences
prohibit the economical construction of an underground conduit. Open channels and
swales can provide infiltration and filtration benefits not provided by pipe.
3. The minimum grade in all unpaved areas shall be 2%.
4. Maximum length for drainage swales shall be 400 feet.
5. Channel side slopes should be a maximum of 4:1 (horizontal to vertical) with gentler
slopes being desirable.
6. Rock riprap should be provided at all points of juncture. Particularly between two open
channels and where storm sewer pipes discharge into a channel.
7. Open channels should be designed to handle the expected velocity from a 10 -year design
storm without erosion. Riprap or concrete liners may need to be provided.
8. Periodic cleaning of an open channel is required to ensure that the design capacity is
maintained. Therefore, all channels should be designed to allow easy access for
equipment.
6.6.4 Ponds
1. Maximum allowable pond slopes above the outlet elevation are 4:1.
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2. All constructed ponds and wetland mitigation areas shall have an aquatic or safety bench
around their entire perimeter. The aquatic bench is defined as follows:
a. Cross -slope no steeper than 10:1.
b. Minimum width 10 feet.
c. Located from pond outlet elevation to one foot below pond outlet elevation.
3. All constructed ponds shall be provided a maintenance access from an adjacent roadway.
The maintenance access shall be provided in the form of an easement no narrower than
20 feet. The maintenance access shall have a longitudinal slope no steeper than 6:1 and
minimal cross slope. Maintenance access routes, due to their extra width, also serve well
as emergency overflow (EOF) routes.
4. All constructed ponds and wetland mitigation areas shall have a maintenance access
bench around sufficient perimeter to provide access to all inlets and outlets. The
maintenance bench should be located within a designated outlot, or within a permanent
easement. The maintenance bench should extend from the outlet elevation to 1 foot
above the outlet elevation and its cross slope should be no steeper than 10:1. The
maintenance bench shall connect to the maintenance access.
5. Maximum pond wet volume depth is 8 feet.
6. Mean depth for wet ponds should be a minimum of 4 feet. If the pond is smaller than 3
acre-feet in volume, mean depths of 3 to 4 feet may be used. Mean depth is defined as
the area at outlet elevation divided by the wet volume.
7. All ponds shall be graded to one -foot below design bottom elevation. This "hold down"
allows sediment storage until site restoration is complete.
8. The top berm elevation of ponds shall be a minimum of one foot above the 100 -year
pond HWL.
9. Grading shall not block or raise emergency overflows from adjoining properties unless
some provision has been made for the runoff that may be blocked behind such an
embankment.
10. All ponds shall have a protected EOF.
6.6.5 Infiltration/Filtration Practices
1. Sizing of filtration/infiltration practices shall be in conformance with the volume control
requirements of this manual.
2. When designing an infiltration practice for volume control and water quality
management, on -site testing and detailed analysis are strongly encouraged in order to
determine the infiltration rates of the proposed infiltration facility. Documented site -
specific infiltration or hydraulic conductivity measurements (double -ring infiltrometer)
completed by a licensed soil scientist or engineer is required. In the absence of a
detailed analysis, the saturated infiltration rates listed in the Table 4: Infiltration
Rates for Infiltration STPs, found in Appendix A of this manual, must be used. A
piezometer shall be installed in order to ascertain the level of the local groundwater table
and demonstrate at least three (3) feet of separation between the bottom of the
proposed facility and the groundwater. The soil boring is required to go to a depth of at
least five feet below the proposed bottom of the facility, or STP. The soils must be
classified using the Unified Soil Classification system. The least permeable soil horizon
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will dictate the infiltration rate. Infiltration practices shall be designed to infiltrate the
required runoff volume within 48 hours.
3. Pretreatment, in the form of ponds, forebays or filter strips or other approved methods
shall be provided for all infiltration areas. Pretreatment upstream of volume
management practices is a key element in the long-term viability of infiltration areas.
The level of pretreatment varies largely depending on the BMP and drainage area. Local
watershed district, City staff, and Minnesota Stormwater Manual recommendations will
be utilized for determining the appropriate level of pretreatment on a case -by -case basis.
4. The infiltration practice cannot be used within fifty (50) feet of a municipal, community
or private well, unless specifically allowed by an approved wellhead protection plan.
5. The infiltration practice cannot be used for runoff from fueling and vehicle maintenance
areas and industrial areas with exposed materials posing contamination risk, only if the
infiltration practice is designed to allow for spill containment.
6. The infiltration practice cannot be used in HSG types C & D soils without soil corrections.
7. Vegetation of infiltration/filtration practices shall be as shown on the BMP details of the
City of Medina Detail Standards. A plan for the management of vegetation shall be
included in the stormwater management plan.
8. If soils are unsuitable for infiltration, then filtration may be used with drain tile, provided
in accordance with the BMP Details of the City of Medina Detail Standards.
9. Subgrade soils for infiltration/filtration practices shall be as presented in the BMP Details
of the City of Medina Detail Standards. Assume a 30% void ratio for the purposes of
volume calculations.
10. For infiltration benches adjacent to ponds, benches shall have slopes no steeper than 5:1
over the proposed infiltration zone. A slope of 10:1 is preferred. The Minnesota
Stormwater Manual cites concerns with locating infiltration features immediately adjacent
to ponds. To address this, benches shall be located to maintain hydraulic separation
from the saturated zone of the pond in order to decrease the infiltration potential over
time.
6.6.6 Emergency Overflow Paths
1. Emergency Overflows (EOF) should be sized with a minimum bottom width of five feet
and 4:1 side slopes.
2. The maximum flow depth in EOFs should be less than or equal to one foot as calculated
for a 100 -year back-to-back storm event.
7.0 Design Examples
Design process for each of the acceptable Stormwater Treatment Practice is detailed in Chapter
12 of the Minnesota Stormwater Manual.
8.0 Stormwater Treatment Practice Detail Drawings
Please refer to the City of Medina Engineering Details.
9.0 Construction Specifications
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Construction specifications and details are found in the Minnesota Stormwater Manual in Chapter
12 for each of the acceptable BMPs, unless otherwise restricted by this ordinance.
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10.0 Checklists
Final Stormwater Management Plan Checklist
Checklist for Final Stormwater Management Plan Preparation and Review
• Applicant information
o Name, legal address, and telephone number
• Common address and legal description of site
• Signature or stamp of registered engineer
• Vicinity map
• Existing and proposed mapping and plans (recommended scale of 1" = 50' or greater
detail) which illustrate at a minimum:
o Existing and proposed topography (minimum of 2 -foot contours recommended)
o Perennial and intermittent streams
o Mapping of predominant soils from USDA soil surveys as well as location of any
site -specific borehole investigations that may have been performed
o Location and boundaries of resource protection areas such as wetlands, lakes,
ponds, and other setbacks (e.g., stream buffers, drinking water well setbacks,
septic setbacks)
o Location of existing and proposed roads, buildings, and other structures
o Location of existing and proposed utilities (e.g., water, sewer)
o Location of existing and proposed conveyance systems such as grass channels,
swales, and storm drains
o Existing and proposed drainage boundaries, including off -site drainage
boundaries
o Flow paths
o Location of floodplain/floodway limits and relationship of site to upstream and
downstream properties and drainages
o Location and dimensions of proposed channel modifications, such as bridge or
culvert crossings
o Location, size, maintenance access, and limits of disturbance of proposed
structural stormwater management practices
• Representative cross-section and profile drawings and details of structural stormwater
management practices and conveyances (i.e., storm drains, open channels, swales, etc.)
which include:
o Existing and proposed structural elevations (e.g., invert of pipes, catchbasins,
etc.)
o Design water surface elevations
o Structural details of outlet structures, embankments, spillways, stilling basins,
grade control structures, conveyance channels, etc.
o Logs of borehole investigations that may have been performed along with
supporting geotechnical report.
• Hydrologic and hydraulic analysis for all structural components of stormwater system
(e.g., storm drains, open channels, swales, management practices, etc.) for applicable
design storms including:
o Existing condition analysis for runoff rates, volumes, velocities, and water surface
elevations showing methodologies used, design parameters, and supporting
calculations
o Proposed condition analysis for runoff rates, volumes, velocities, water surface
elevations, and routing showing the methodologies used, design parameters, and
supporting calculations
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o Final sizing calculations for structural stormwater management practices
including contributing drainage area, storage, high water level, peak inflow and
outflow, and outlet configuration
o Stage -discharge or outlet rating curves and inflow and outflow hydrographs for
storage facilities (e.g., stormwater ponds and wetlands)
o Analysis, computations, and supporting materials indicating that water quality
and quantity design criteria are being met
o Final analysis of potential downstream impact/effects of project, where necessary
o Dam breach analysis, where necessary
• Maintenance plan which will include:
o Name, address, and phone number of responsible parties for maintenance.
o Description of annual maintenance tasks
o Description of applicable easements
o Description of funding source
o Minimum vegetative cover requirements
o Access and safety issues
o Testing and disposal of sediments that will likely be necessary
• Waiver requests
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Checklists for Construction Inspection
Construction Inspection Checklists for each of the approved Stormwater Treatment Practice are
available in Appendix D of the Minnesota Stormwater Manual.
Bioretention — p.685
Media Filter System — p.687
Vegetative Filter System — p.689
Infiltration Trench — p.691
Infiltration Basin — p.693
Stormwater Pond/Wetland — p.695
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Checklists for Operation & Maintenance
Operations & Maintenance Checklist for each of the approved Stormwater Treatment Practice are
available in Appendix D of the Minnesota Stormwater Manual.
Bioretention — p.702
Media Filter System — p.704
Vegetative Filter System — p.706
Infiltration Trench — p.708
Infiltration Basin - p.708
Stormwater Pond/Wetland — p.710
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MEDINA — STORMWATER DESIGN GUIDE
Appendix A:
Table 4: Infiltration Rates for Infiltration STPs
Corresponding Unified Soil Classification
Infiltration Rate
(inches/hour)
GW — Well -graded or well -graded gravel with sand
GP — Poorly graded gravel or poorly graded gravel with
sand
1.63
GM — Silty gravel or silty gravel with sand
SW — Well -graded sand or well -graded sand with gravel
SP — Poorly graded sand or poorly graded sand with
gravel
0.8
SM — Silty sand or silty sand with gravel
0.6
ML — Silt
OL — Organic silt or organic silt with sand or gravel or
gravelly organic silt
0.3
GC — Clay gravel or clayey gravel with sand
SC — Clayey sand or clayey sand with gravel
0.2
CL — Lean clay or lean clay with sand or gravel or
gravelly lean clay
CH — Fat clay or fat clay with sand or gravel or gravelly
fat clay
OH — Organic clay or organic clay with sand or gravel
or gravelly organic clay
MH — Elastic silt or elastic silt with sand or gravel
<0.2
Source: Minnesota Stormwater Manual
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