HomeMy WebLinkAboutDrainage Reports - 06/19/2025 (2)
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February 24, 2025
Wes Lamarque
Stormwater Engineer
City of Fort Collins
700 Wood Street
Fort Collins, Colorado 80524
Re: First Presbyterian Church Minor Amendment – Drainage Memo
We are pleased to submit for your review and approval this drainage letter showing the drainage
impacts from the proposed building addition at the First Presbyterian Church.
The project is located at 531 South College Avenue and currently has an existing structure and an
asphalt parking lot on the site. The project will build an addition for a new elevator and will include
the abandonment of the westerly sanitary sewer run towards South Mason Street. The manhole
adjacent to the elevator footprint will be flowfilled a minimum of 20’ west of the manhole and may be
replaced with a cleanout. All sanitary sewer and appurtenances near the area will be private moving
forward. The elevator footprint is 211 square feet. Of these 211 square feet, 55 square feet is new
impervious area and the remaining area of the new structure will be over existing paved areas.
Because the increase in impervious area is less than 1,000 square feet and the disturbed area is
less than 10,000 square feet, the City of Fort Collins does not require water quality treatment,
additional onsite detention nor erosion control materials. The four-step process for selecting
structural BMPs is also not required and will not be presented in this letter.
The existing flow patterns will not be changed with the project and the addition will have a negligible
impact to the site's stormwater runoff.
The project exists in the City Floodplain area. The ground floor of the e xisting building is 0.3’ below
the floodplain, therefore the elevator wall is to be floodproofed to 12 Inches above the base flood
elevation (BFE) to 4997.00’. Exhibits are attached to show the limits of the floodway and details the
structure cross section.
We appreciate your time and consideration in reviewing this submittal. If you have any questions or
need additional information please feel free to call at any time (970) 834-6385.
Sincerely, Reviewed by,
Abigail Wright, E.I.T. Michael Oberlander, P.E.
Colorado Engineer in Training 0079259 Colorado Professional Engineer 34288
City of Fort Collins Approved Plans
Approved by:
Date:
Wes Lamarque
06/19/2025
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EX VS PROP
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EXISTING IMPERVIOUS AREA
157 SF
PROPOSED IMPERVIOUS AREA
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PROJECT NO:
DESIGNED BY:
SHEET NO:
SHEET TITLE
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BY
FLOODPLAIN PLAN
4
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AGW
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24-000-559-00
FEBRUARY 2025
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811
NOTES:
1. A FEMA ELEVATION OR FLOODPROOFING CERTIFICATE WILL BE
COMPLETED AND APPROVED BEFORE THE CO IS ISSUED. THIS IS
REQUIRED EVEN IF PROPERTY IS ONLY IN A CITY FLOODPLAIN.
2. THERE WILL BE NO FILL IN THE FLOODWAY UNLESS A HYDRAULIC
ANALYSIS SHOWS "NO-RISE".
3. NO MANUFACTURED HOMES, EXCEPT IN AN EXISTING PARK CAN BE
PLACED IN THE FLOODWAY.
4. NO CHANGING A NONCONFORMING NON-RESIDENTIAL OR MIXED USE
STRUCTURE TO A RESIDENTIAL STRUCTURE.
5. LANDSCAPING MEETS REQUIREMENTS FOR NO ENCROACHMENT IN
THE FLOODWAY WITHOUT A HYDRAULIC ANALYSIS TO SHOW "NO-RISE".
NO LANDSCAPE CHANGES ARE PROPOSED WITH THE PROJECT.
6. NO STORAGE OF MATERIALS OR EQUIPMENT IN THE FLOODWAY.
7. A FLOODPROOFING CERTIFICATE WILL BE COMPLETED AND APPROVED
BEFORE THE CO IS ISSUED.
8. FLOODPROOFING INFORMATION WILL BE SUBMITTED AT THE TIME OF
THE BUILDING PERMIT APPLICATION.
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FIRST PRESBYTERIAN
CHURCH
20.0' UE
PROPERTY BOUNDARY (TYP)
FF = 4995.70
ANY CONCRETE WALK
REMOVED FOR ELEVATOR
INSTALLATION SHALL BE
REPLACED MATCHING
EXISTING CONDITIONS
NEW TRANSFORMER PAD
ELEVATION 4997.0
NEW ELEVATOR ADDITION (DOORS ON
INTERIOR OF EXISTING BUILDING)
BFE = 4996.0
EX GROUND FLOOR = 4995.7
EDUCATION WING FLOOR (S) = 4990.7
BASEMENT FLOOR (N) = 4985.7
PROPOSED ELEVATOR PIT FLOOR = 4981.7
EXTERIOR WALLS TO BE FLOODPROOFED
TO ELEVATION 4997.0
REMOVE EXISTING CONCRETE FOR
ELEVATOR INSTALLATION
EXISTING TREE TO
REMAIN
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DATE:
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PROJECT NO:
DESIGNED BY:
SHEET NO:
SHEET TITLE
RE
V
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BY
GRADING PLAN
5
MPO
AGW
MPO
24-000-559-00
FEBRUARY 2025
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811
NOTES:
1. THE PROJECT IS A BUILDING ADDITION FOR A NEW ELEVATOR. THE
ELEVATOR FOOTPRINT IS 211 SQUARE FEET. OF THIS 211 SF, 55 SF IS
NEW IMPERVIOUS AREA AND THE REMAINING AREA IS EXISTING
CONCRETE. DETENTION, WATER QUALITY, AND LID ARE NOT REQUIRED.
2. THE EXISTING GROUND FLOOR ELEVATION OF THE BUILDING IS LOWER
THAN THE BFE IN THE AREA. THE NEW ELEVATOR CONSTRUCTION SHALL
BE FLOODPROOFED TO 4997.0 (12" ABOVE 100-YR BFE) ON ITS EXTERIOR
WALLS.
3. ALL GRADING SHALL BE CONFINED TO THE PROPERTY BEING
DEVELOPED OR ADJACENT PUBLIC RIGHT-OF-WAY. NO GRADING SHALL
BE DONE OUTSIDE OF PROPERTY LINES UNLESS OTHERWISE SHOWN.
4. THE PROJECT DISTURBS LESS THAN 10,000 SF AND EROSION CONTROL
DOCUMENTATION AND DESIGN IS NOT REQUIRED.
5. ANY DAMAGED CURB, GUTTER AND SIDEWALK EXISTING PRIOR TO
CONSTRUCTION, AS WELL AS STREETS, SIDE3WALKS, CURBS, AND
GUTTERS, DESTROYED, DAMAGED OR REMOVED DUE TO CONSTRUCTION
OF THIS PROJECT, SHALL BE REPLACED OR RESTORED TO CITY OF FORT
COLLINS STANDARDS AT THE DEVELOPER'S EXPENSE PRIOR TO THE
ACCEPTANCE OF COMPLETED IMPROVEMENTS AND/OR PRIOR TO THE
ISSUANCE OF THE FIRST CERTIFICATE OF OCCUPANCY.
EXISTING MAJOR CONTOUR
LEGEND
EXISTING MINOR CONTOUR
PROPOSED MINOR CONTOUR
PROPOSED MAJOR CONTOUR
XX.XX PROP SPOT ELEVATION (FT)
EX SPOT ELEVATION (FT)
STRUCTURES IN FLOODPLAIN
CITY BFE AT UPSTREAM END OF
STRUCTURE 4996.00
REGULATORY FLOOD PROTECTION
ELEVATION 4997.00
LOWEST FLOOR ELEVATION 4981.70
FLOODPROOFING ELEVATION 4997.00
FLOOD PROTECTION
ELEV = 4997.0
GROUND FLOOD ELEVATOR
OPENING = 4997.0
BASEMENT ELEVATOR
OPENING = 4997.0
ELEVATOR PIT ±4981.7
12 FLOOR DOWN ELEVATOR
OPENING ±4990.7
ELEVATOR SHAFT CROSS
SECTION