Item 3.2 Hansen Heights Review No. 1
ENGINEERING REVIEW
Residential Subdivision
for the City of Otsego
by
Hakanson Anderson
Submitted to: Honorable Mayor and City Council
cc: Adam Flaherty, City Administrator
Audra Etzel, City Clerk
Dan Licht, City Planner
Dave Kendall, City Attorney
Scott Dahlke, P.E., Civil Engineering Site Design
Henry Hansen, VHF Investments, LLC
Reviewed by: Ronald J. Wagner, P.E.
Brent M. Larson, P.E.
Date: August 11, 2021
Proposed
Development: Hansen Heights (1st Addition)
Street Location A portion of the SE ¼ of Section 28, T121, R23 and a portion of
of Property: the SW ¼ of Section 27, T121, R23. East of Odean Avenue NE
and North of 70th Street NE.
Applicant: Henry Hansen
Developer: VHF Investments, LLC
6750 Stillwater Blvd N #4
Stillwater, MN 55082
Owners of Record: VHF Investments, LLC
Purpose: Hansen Heights is a proposed preliminary plat of 131 lot (includes
2 existing lots) and final plat of 65 single-family residential
development on approximately 92.4 acres in the City of Otsego,
Wright County, Minnesota. The proposed development will be
served with municipal water, sanitary sewer, storm sewer, and
public streets typical of an urban setting.
Jurisdictional Agencies: City of Otsego, Wright County, Minnesota Department of
(but not limited to) Health, Minnesota Department of Natural Resources, Minnesota
Pollution Control Agency, Wright Soil and Water Conservation
District.
Permits Required: NPDES, Minnesota Department of Health (water),
(but not limited to) Minnesota Pollution Control Agency (sanitary sewer), and Wright
County
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TABLE OF CONTENTS
INFORMATION AVAILABLE
PRELIMINARY PLANS
FINAL PLAT
GRADING AND DRAINAGE PLANS (PHASE 1)
COVER SHEET
GRADING AND DRAINAGE PLAN
EXISTING CONDITIONS AND REMOVALS
SWPPP
CONSTRUCTION PLANS (PHASE 1)
COVER SHEET
OVERALL LAYOUT/NOTES
SANITARY AND WATER UTILITY PLANS
STORM SEWER AND STREET PLANS
DETAILS
SURFACE WATER MANAGEMENT
WETLANDS
OTHER CONSIDERATIONS
SUMMARY AND/OR RECOMMENDATION
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INFORMATION AVAILABLE
Preliminary Plans for Hansen Heights, dated 7/27/2021, by Civil Engineering Site Design.
Final Plat for Hansen Heights, dated 7/26/2021, by Civil Engineering Site Design
Construction Plans for Hansen Heights, dated 7/27/2021, by Civil Engineering Site Design
Grading Plans for Hansen Heights, dated 7/27/2021, by Civil Engineering Site Design
Landscaping Plan for Hansen Heights, dated 7/27/2021, by Civil Engineering Site Design
Storm Water Management Plan for Hansen Heights, dated 3/26/19, by Civil Engineering Site
Design.
Storm Sewer Design Calculations for Hansen Heights, dated 3/26/19, by Civil Engineering Site
Design.
Wetland Delineation Report for Henry Hansen, dated 10/30/18, by AG Wetland Services, Inc.
Additional Information
Minnesota Rules, Chapter 4410 – EAW Requirement
City of Otsego Engineering Manual
City of Otsego Zoning and Subdivision Ordinances
National Wetland Inventory Map
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PRELIMINARY PLANS
1. Lot 6, Block 5 (Phase 1) is an existing home and will remain until a future phase where it
is proposed to be divided into four single family lots. The two west lots would require
direct access to Odean Avenue. We recommend that a single driveway be used for these
two lots to access Odean Avenue.
2. The future trail from Ohland Avenue to the east has proposed contours only about ½ way
down the hill. This trail shall be designed to the end point and shown that the alignment
and slopes will meet all ADA and City requirements.
FINAL PLAT
3. The east-west street just south of 75th Street is mislabeled Ohland Avenue, this shall be
75th Lane NE.
4. Verify the 20’ wetland buffer around the wetlands in Outlot A are contained within
Outlot A.
5. A drainage and utility easement shall be placed over all of Outlots A and B.
6. Minimum 10’ easements shall be provided along all rear lot lines (i.e. lots along Outlot B
and rear yards of Block 6, and rear yard of L1, Block 7).
7. The easement between Lot 13 and 14, Block 2 shall be a minimum of 50 feet wide
centered on the sanitary sewer along this lot line. Or a drop manhole will be needed near
the rear of the adjacent house pads with a shallower sewer pipe between the street and
this manhole.
8. All cross drainage shall be covered by drainage easement or the grading plans shall be
revised to show all drainage directed to the easement along the lot lines.
9. A utility easement will be needed to cover the sanitary and watermain stubs to the
property south of Lot 6, Block 5.
10. A 100’ tangent between the reverse curves is required along 74th Street just west of Odell
Avenue.
GRADING AND DRAINAGE PLANS
Cover Sheet
11. No comments.
Grading And Drainage Plan
12. The ponds shall be labeled with a name/number on all sheets. This shall correlate with
the naming in the storm water report.
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13. A maintenance path is shown for access to the Pond #6 between Lots 17 and 18, Block 2.
This maintenance path shall be extended to provide access to the outlet structure at the
east side of Pond #6 as well. The top of the berm around the pond shall widened to be a
minimum of 10’ wide to accomplish this.
14. The wet pre-treatment basin for Pond #6 requires a 10:1 bench below the NWL.
15. The wetland buffer shall be shown on the grading plans. The buffer shall be 20’ wide.
16. The delineated wetland boundaries shall be labeled in the grading plans.
17. An emergency overflow elevation shall be labeled for the low area in the rare of Lot 1
and 2, Block 4. It appears to be approximately 924.6 over the existing driveway to the
north which is sufficient freeboard from the proposed low opening elevations.
18. An EOF is needed for the low point in Odell Avenue, south of 75th Lane.
19. A minimum of 1.5’ of freeboard is required from all EOF’s to the lowest openings for all
houses. (i.e. L15, B3 should be a minimum of 920.5).
20. Proposed lot corner elevations shall be provided for all lots (lots along 75th Street are
missing rear elevations).
21. Additional spot elevations are required between houses on the side yard lot lines at the
front and rear setback lines. Provide a spot elevation at the property line at the front/rear
of the house if the adjacent house elevations are + 1.5 feet. The elevations shall be a
minimum of 0.3’ below the lower house to provide to the side lot line. A number of lots
may require retaining walls.
22. It s unclear why the dual elevations for the lot opening for Lot 3, Block 6 are required.
The higher elevation do not agree with the contours in the area.
23. Cross drainage shall be contained with drainage and utility easements. The rear yards of
Block 3 appear to have cross drainage that will not be within easements.
24. Draintile shall be installed along the rear lot lines to provide a connection point for all lots
sump pumps if they are more than one lot away from a storm catch basin or storm basin.
Draintile will be required for some Blocks 3, 5, and 6.
Existing Conditions and Removals
25. No comments.
SWPPP
26. Inlet protection shall be installed on all of the nearest catch basins and culverts located
downstream from the construction entrance(s) along Odean Avenue.
27. A concrete washout area shall be called out.
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28. A double layer of erosion control is required around all wetlands if a minimum of 50’ of
undisturbed vegetative buffer cannot be maintained.
CONSTRUCTION PLANS
Cover Sheet
29. No comments.
Overall Layout/Notes
30. A water and sanitary sewer stub shall be provided to the west right-of-way at Sanitary
Sewer MH 6.
31. The ponds shall be labeled with a name/number on all sheets. This shall correlate with
the naming in the storm water report. Provide Pond #5 Normal and High water
elevations.
Sanitary And Water Utility Plans
32. Water services shall be on the upstream side of the sanitary sewer service. Some services
along throughout the plans are switched.
33. The sanitary sewer manholes shall be revised to show 0.1’ of fall across the inverts.
34. The sanitary sewer and watermain crossing shall be directed to the north of the property
line on the west side of Odean Avenue. City staff will work with the developers engineer
to provide an acceptable stub location.
35. See comment #7 regarding sanitary sewer between 13 and 14, Block 2.
Storm Sewer And Street Plans
36. The vertical curve at station 9+00 on Odell Avenue does not meet a 30 mph design speed
and shall be revised.
37. No trash guards are required on pipe sizes less than 24” diameter.
38. The outlet pipe and structure for Pond #5 does not appear to provide any rate control or
skimming. This will required discussion with the developers engineer.
Details
39. Additional detail and spot elevations are required for all pedestrian ramps to depict the
comply with ADA requirements.
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SURFACE WATER MANAGEMENT
40. No new stormwater calculations or storm design calculations have been submitted with
this resubmittal. A new updated stormwater management plan and storm sewer design
calculations shall be submitted to agree with the current revisions. The overall layout of
the site has only changed slightly with the exception of some ponding being infiltration
basins. We would assume that the changes would be minor and the site will function as
originally planned.
41. Submit a geotechnical exploration report. Verify existing ground water elevations are a
minimum 3’ below infiltration basin(s) bottom. Percolation tests will be required at the
proposed infiltration basin locations to verify designed rates.
42. Pre-treatment of the storm water into infiltration basin 5 is required.
43. Previous comment - Please submit inlet spread calculations (only needed for critical CBs
i.e. CB 50 & 51)
WETLANDS
44. A Wetland Delineation has been submitted and approved (Notice of Decision dated
12/20/2018). This is still valid as it is within 5 years of the current project. No wetlands
are proposed to be impacted by this project.
OTHER CONSIDERATIONS
45. A Geotechnical Exploration Report prepared by a professional engineer shall be submitted
with a recommended R-value for the street section design.
46. A statement certifying the environmental condition of the site including the presence of
any hazardous substance as defined in Minnesota Statutes 115B.02, Subd 8 is required.
Developer’s Engineer has indicated that they have confirmed with the property owner that
no hazardous substances are known. This shall be confirmed in writing.
SUMMARY AND/OR RECOMMENDATION
We recommend approval contingent upon the above items being addressed.