HomeMy WebLinkAboutLot Certifications - 04/29/2019 (3)Ronald H. Slosson, P.E.
Civil Engineering
2230 Hiawatha Court
Fort Collins, Colorado 80525
Phone: 970-481-0833
Fax: 970-493-4399
Email: rhslosson@gmail.com
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April 16, 2019
Dan Mogen, EI, CFM
Development Review Engineer
Stormwater Engineering & Development Review Division
City of Fort Collins Utilities
Re: Grade Certification 2243 Hiawatha Court
Dear Mr. Mogen:
All work has been completed on the pool, building, and landscaping at 2243 Hiawatha Court in
Fort Collins. King Surveyors, Inc. completed an as-built survey under my direction on April 22,
2019 as part of the grade certification. This was not a typical grade certification survey as the
house has been in place since the mid-1970’s and there was no initial stormwater drainage plan
for the subdivision. As such, I prepared a drainage plan for this lot only, as detailed in the
attached Memo dated January 23, 2019.
We have completed a City of Fort Collins Certification of Lot Grading, which is also attached.
Because of the uniqueness of the project, several items in the standard form are not applicable,
deviate from standards, or require further explanation. Comments on questions 1 through 8 are
as follows
1. Attached is the Memo approved by the Stormwater Engineering & Development Review
Division.
2. Elevations for the drainage around the new swimming pool structure are shown along
with the direction of drainage for the lot showing that runoff from the addition is now
directed to the front of the lot rather than the historical drainage to the rear of the lot.
3. Only spot elevations were made prior to landscaping. The slope of the drainage swale is
equal to or greater than the approved plan.
4. In order to fit the drainage swale to the lot and get it to drain to the front of the lot, the
sides of the swale begin at the elevation of the concrete pool apron. Had the swale began
six-inches below the pool apron, there would not have been enough elevation change to
direct water to the front of the lot. If the water depth in the swale exceeds the depth of
the swale water may seep under the structure and into the pool. The structure is
constructed entirely of aluminum and glass so there is no danger of rotting or
deterioration.
5. There is minimum 5% grade away from the structure beyond the drainage swale.
6. The maximum slope of the drainage swale that would fit on the lot is 0.6% as approved in
the drainage memo.
7. As discussed in question 4, the flow line of the drainage swale is not 6-inches below the
ground adjacent to the structure.
8. There are no downspouts on the new structure. The drainage swale does however pick up
the drainage from the two downspouts on the back of the house. There were no changes
to the existing drainage or elevations in the front of the house. Water leaving the
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drainage swale at the southeast corner of the new structure will follow the new flagstone
walkway to the front (east) of the house and then across the grass lawn to the street.
Calculations were made as to the depth of water on the flagstone walkway for the design
storm and found to be less 0.1 feet in depth. It is possible that some of this runoff could
spill onto the neighboring lot but the neighboring lot in this area is xeriscape rock and
concrete driveway, both sloping to Hiawatha Court.
Questions 9 through 12 were applicable and answered on the form.
Please contact me if you have any further questions.
Sincerely,
Ron Slosson, P.E.