HomeMy WebLinkAboutSite Certifications - 12/11/2024N ISSAN D EALERSHIP
S ITE C ERTIFICATION N ARRATIVE
F ORT C OLLINS , CO
19 OLD TOWN SQUARE #238 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com
October 18, 2024
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Nissan Dealership
Fort Collins, CO
Project Number: U21004
Dear Staff:
United Civil has completed the Overall Site and Drainage Certification for the Nissan Dealership project and is providing this
narrative in support of the certification form for items that have been altered during construction and/or are not in strict
conformance with the approved Utility Plans or Drainage Report for the project.
For the certification process, United Civil has reviewed the as-built topographic survey provided by Northern Engineering and
performed multiple independent site visits to review as-constructed conditions. During this process, certain items have been
modified in the field during construction and the following documents those as-constructed conditions.
Bioretention, Water Quality, and Detention Ponds
The following table provides a summary of the as-constructed ponds provided for the project:
Pond Designation WQCV
Required
(cf)
WQCV
Provided
(cf)
WQCV
WSEL
Provided
Detention
Volume Required
(ac-ft)
Detention
Volume Provided
(ac-ft)
100-year
WSEL
Provided*
Pond A1 939 2,544 5006.8 3.03 3.40 5011.0
Bioretention Pond A2 7,220 12,904 5010.1 - - 5011.0
Bioretention Pond A3 2,802 6,067 5007.4 - - 5011.0
Underground Pond C1 2,775 3,171 5004.3 0.67 0.83 5005.5
Underground Pond C2 1,487 1,567 5004.7 - - -
* As calculated using the as-constructed detention pond and considering the required design volume.
As constructed, Pond A1 is provided with up to 2,544 cubic feet of water quality treatment. The required WQCV for this pond
was 939 cubic feet. Therefore, a significant increase in volume of water quality treatment is provided in the as constructed
state. This trend of providing additional volume is consistent for each of the Bioretention Ponds and Underground Ponds on
site as well. As shown in the table above, required water quality and LID volumes are met with additional capacity in
Bioretention Pond A2 and A3, and Underground Ponds C1 and C2.
Extended detention was also associated with this project, provided with Pond A1 and Underground Pond C1. The volume
provided for Pond A1 in the as constructed state was 3.40 ac-ft as compared to the required 3.03 ac-ft. The Underground
Pond C1 was also in a surplus of detention volume as 0.67 ac-ft was required in the design and the constructed detention
volume provides 0.83 ac-ft. Because as constructed volumes exceed that of the required, no negative impacts are foreseen
to the overall function of the drainage system and downstream infrastructure should only be alleviated by the constructed
ponds.
12/11/2024
Grading/Stormwater Certification Accepted
(Certificate of Occupancy Released)
Acceptedby:
Date:
Escrow was held for CO and is now released
we
N ISSAN D EALERSHIP
S ITE C ERTIFICATION N ARRATIVE
F ORT C OLLINS , CO
19 OLD TOWN SQUARE #238 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com
Underground Detention
The underground detention systems (i.e., Pond C1 and Pond C2) for the development appear to have been constructed in
compliance with the approved utility plans. Specifically, the size and number of chambers, the size and number of drainage
basins and inspection ports, and the size and number of underdrains with appropriate cleanouts have all been installed on
the site. Additionally, as the entire system provides water quality, all have been wrapped per manufacturer
recommendations and backfilled. Finally, the weirs in structures STMH A3.1, Basin A6, Inlet A7, Basin A10, and Inlet A13 2
have been constructed in conformance with the design. In general, Pond C1 infrastructure was constructed slightly lower
than designed; however, the associated structures and weirs also reflect this as-built condition. Weirs have been installed
such that required water quality and detention volumes are achieved per the approved design. It is not anticipated that the
lower nature of underground Pond C1 will have a negative impact on the storm system during the 100-year storm event.
Bioretention
The Bioretention systems (i.e., Pond A2 and Pond A3) for the development appear to have been constructed in compliance
with the approved utility plans. Each pond was designed and constructed with appropriate Bioretention sand media and
perforated underdrains. Moreover, both Pond A2 and Pond A3 were designed and constructed with additional capacity above
the required WQCV (see table on the prior page).
Forebays
Four forebay structures were constructed with the Nissan-Kia project. All forebays were designed with additional capacity
and were constructed as such. Below is a summary regarding the required volumes relative to the as-built capacities.
Level Spreader
The on-site level spreader associated with the Pond A1 outfall was constructed in compliance with the approved utility plans.
Moreover, additional erosion control measures were installed downstream of the level spreader. Turf reinforcement matting
was originally the only material found necessary for the level spreader outfall; however, buried riprap was also installed below
the specified turf reinforcement matting.
Storm Sewers
The Overall Site Certification form notes that all storm sewers shall be provided with minimum slopes of 0.4%. The approved
utility plans provided for several storm sewers below this minimum slope noted. Additionally, although the storm sewer for
the development has been constructed in substantial compliance with the approved utility plans, there are certain sections
of the storm sewer system that have been constructed below the design slopes provided in the approved plans. For this
reason, the storm sewer systems with sections constructed with slopes less than the design slopes provided have been
modeled using the as-constructed invert elevations. The modeling for this is attached to this narrative. Although the as-
constructed slopes may provide for less capacity and velocities during low flow conditions, the impact to the 100-year flows
in each system are negligible and are not anticipated to negatively impact they system.
Site Grading
The site grading for the development has been constructed in substantial compliance with the approved utility plans for the
project. There are, however, areas that have been graded with a difference to the design elevations of greater than 0.2-feet.
These elevations are noted in the provided record drawings and none of the as-constructed as-built elevations are anticipated
to have negative impacts to function of drainage infrastructure for the development.
Forebay Designation
Volume Required
(cf)
Volume Provided
(cf)
Forebay E1 35 47
Forebay H1 157 190
Forebay G1 17 26
Forebay F1 11 21
N ISSAN D EALERSHIP
S ITE C ERTIFICATION N ARRATIVE
F ORT C OLLINS , CO
19 OLD TOWN SQUARE #238 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com
Based upon the review of the as-built conditions and information made available to United Civil by the contractor, including
the topographic survey and as-built plans, United Civil does not believe that any of the revisions noted in this narrative will
negatively impact the drainage system for the development, the safety of the development or public, or downstream private
or public infrastructure.
If you should have any questions or comments as you review this certification, please feel free to contact us at your
convenience.
Sincerely,
United Civil Design Group, LLC
Brady Kirkbride, EI Colton Beck, PE Sam Eliason, PE
Design Engineer Project Manager Principal
Attachments:
Pond Stage-Storage Calculations
Storm Sewer Hydraulic Calculations
Page 1
OVERALL SITE and DRAINAGE CERTIFICATION
Commercial, Multi-Family and Subdivision Certification Form and Checklist
Project Name:
Date:
Building Permit Numbers:
(Commercial or multi-family)
Per the requirement in Fort Collins Stormwater Criteria Manual (FCSCM) Chapter 3, Section 3.0 to certify as-
built construction to the approved drainage and grading plans, please fill in all applicable items in this
Certification Form for Commercial, Multi-Family and Overall Single Family sites. NOTE: several items must be
verified during construction.A copy of the approved grading plan must be submitted with the as-built grading
plan. (As-built elevations must be written in red next to the approved elevations.)
Use “Yes” for items completed as described.
Use “N/A” for items that are not applicable to the site being certified.
If any blanks are “No,” attach an explanation referencing the item number below.
Attach an explanation or description of the as-built condition for any items listed or for anything not listed but
shown on the approved construction plans.
Provide an as-built redline or Mylar drawing with the following:
I. Water Quality and Quantity Detention Basin - FCSCM Ch. 6 and 7
For multiple detention basins on a site, provide the following for each basin separately:
A.Volume: As-built topographic verification is attached at 1-foot (or less) contour intervals and
volume verification calculations for the water quality capture volume and the 100-year detention storage
volume.
1. Detention basin topography was prepared by a professional land surveyor registered in the state
of Colorado.
2. Both proposed and as-built contours are shown on the same plan sheet (dashed lines for
proposed and solid lines for as-built).
3. All critical spot elevations as shown on the approved construction plans have been verified and
the as-built elevations are shown on the plan sheet.
4. Stage-storage-discharge tables are provided on a separate document.
5. Verification that designed drain time is in compliance with Colorado Revised Statute § 37-92-
602(8) is attached and has been uploaded to the Statewide Compliance Portal
(tinyurl.com/COCompliancePortal) for approval. Uploaded documents must include:
a. The cover sheet from the approved drainage report
b. The stamped certification page from the approved drainage report
c. As-built topographic survey
d. Stamped certification page from the Overall Site & Drainage Certification
e. PDF output from the Stormwater Detention and Infiltration Design Data Speadsheet
1 /19
Page 2
B.Water Quality and Quantity Detention Basin Grading: Attached is as-built verification that there is
a minimum 2% positive fall into the concrete trickle pans or flow-line(s) from all areas in the bottom of
the detention pond. If there is a “soft pan” in the flow-line, all areas still must meet the minimum 2%
grade requirement.
1.Low Flow: Choose one of the following detention basin low flow options as applicable:
a. Turf swale for low flow path in detention basin.
There is a minimum 2% grade in the flow-line(s) of the detention basin. The flattest as-built grade
is .
b. Concrete pan for low flow in detention basin.
There is a concrete pan installed that meets the grades as shown on the approved construction
plans. (Show as-built spot elevations.)
c. Soft pan for low flow in detention basin.
Verify and document the soft pan material gradation, trench width and depth - to be verified
during construction by engineer. Picture documentation is preferred or engineer’s statement of
visual inspection and compliance. (Choose one below.)
o There is a soft pan with an underdrain installed that meets the design on the approved
construction plans. (Show the underdrain grades, bedding material, geotextile, spot elevations,
bends, cleanouts, etc.)
o There is soft pan installed without an underdrain but there is a type A or B soil. The soil
type must be documented by supplying verification from a registered professional geotechnical
engineer.
NOTE: Spot elevations are to be within 0.2 ft. +/-.
2. Side Slopes: The as-built side slopes of the detention basin have been calculated and are shown.
Indicate the side slope with an arrow and a numerical value (e.g., 6.25:1). The maximum slope allowed
is 4:1. Small areas of 3:1 may be acceptable, but slopes steeper than 3:1 must be stabilized or re-
graded. Provide documentation if a variance was granted for steeper slopes during the design process.
3.Spillway: The following items must be field verified:
a. The location of the spillway is indicated on the as-built plan.
b. The width of the spillway is indicated on the as-built plan.
c. The elevation(s) of the spillway is shown on the as-built plan.
d. A concrete ribbon defines the location and grade of the spillway.
e. There is downstream scour protection in the spillway as per the construction plans. Indicate
type: (riprap size “D50” gradation and bedding type, geotextile, buried
riprap with inches of bury, etc.).
f. There are no obstructions in the spillway, such as trees, bushes, sidewalks, landscape
features, rocks, etc.
1 /19
As constructed
ponds include
both bioretention
media (flat
bottom of pond)
or a wetland
area. These
water quality
features do not
meet the 2%
flowline criteria.
UCDG-CDB
Page 3
4.Outlet Structure:
a. The orifice plate for the approved release rate is installed with the correct size and location of
the orifice.
b. The orifice plate for the water quality outlet is installed with the correct hole size, number of
rows and columns of holes.
c. The bottom hole on both the water quality and quantity outlets are at the bottom of the plate
so no water ponds in front of the plate.
d. The well screen is the correct material and is installed as shown on the construction plans.
e. 100-year overflow grate elevation is . (Elev. A on detail D-46)
f. The top elevation of the water quality capture volume is . (Elev. B on detail
D-46)
g. Overflow grate is made of the correct material, has the correct bar spacing, is hinged at the
top and bolted at the bottom.
h. The bottom of the outlet box has no obstructions or misalignments that will cause it to retain
runoff water and is sloped at 2% towards outlet.
II. Channels/Swales - FCSCM Ch. 8, Sec. 2.0 and Ch. 9, Sec. 5.0
A. Capacity: The as-built capacity of all the major channels and swales has been verified. They meet
or exceed capacity requirements shown in the approved drainage study for this project.
1. All swales are located within the drainage easements as shown on the construction plans.
2. Longitudinal slopes and side-slopes (cross-sections) have been verified. Design criteria requires
longitudinal slopes of 2% min. (on vegetated swales) and side-slopes no steeper than 4:1. If these
criteria are not met, the certification engineer will write a justification and propose mitigation for each
instance or have the issues corrected. If variances to these criteria have previously been approved and
are shown on the construction plans, no justification is needed.
3. As-built spot elevations on channels/swales are shown that correspond to spot elevations
shown on the approved construction plans.
4. All permanent erosion control measures are installed as shown on the approved construction
plans (e.g., drop structures, riprap, TRMs, etc.). (Include pictures and verification of the materials used
as part of this verification.)
5. All pans, curbs, storm pipes or other appurtenances appropriately tie into each other in the
system. (Pictures at tie-in points suggested.)
6. The minimum freeboard is provided for all channels and swales as shown on the approved
construction plans or as identified in the approved drainage study. (Show the freeboard provided on
the cross-sections as on the construction plan set or attached as separate documentation.)
7. The low flow portion of all channels or swales is clear of obstructions. (No landscaping, trees,
shrubs, sod, etc. infringe on the low flow portion of channels or swales.)
1 /19
(No major channels/swales were provided for the development. UCDG-BJK)
Page 4
III. Storm Pipes (aka storm drains) - FCSCM Ch. 9, Sec. 4.0
A. Storm Drain Pipe Capacity: The as-built capacity of all pipes installed on this project has been
verified and meets or exceeds the capacity requirements shown in the approved drainage study for this
project.
1. All storm drain pipe sizes and materials have been verified and are in conformance with the
approved construction plans. (Indicate on the plan and profile sheets that they have been verified.)
Material and size substitutions must be approved prior to installation. If a pipe size or material was
changed during construction, the certification engineer must attach the approval documents or supply
them with this certification. Approval documents must include a calculation documenting the capacity
equivalency (equal or greater) of the substituted size.
2. The longitudinal slope of the pipe is as shown on the approved construction plans. The
acceptable minimum slope is 0.4%. All slopes flatter than the designed slope on the construction plans
must be justified with capacity calculations on an attached sheet.
3. The as-built invert elevations have been verified and are shown on the plan and profile sheets of
the approved construction plans.
B.Storm Drain Pipe Installation Requirements: All pipes are installed in accordance with the
approved construction plans and construction specifications.
1. The minimum cover requirements for all pipes have been met as shown on the approved
construction plans. These will be called out in critical locations.
2. All encasements and clearances as specified on the approved construction plans have been met.
3. Any specific joint types or construction methods specified on the approved construction plans
have been met. (List on a separate sheet and attach to this certification.)
IV. Concrete Pans - FCSCM Ch. 8, Sec. 2.0
A. Construction/Installation: All concrete pans have been constructed in accordance with the
approved construction plans.
1. The concrete pans are the correct size/width as shown on the approved construction plans.
2. The longitudinal slopes of the pans are as shown on the approved construction plans. The
certification engineer must justify or mitigate longitudinal slopes less than the minimum of 0.4% unless
a flatter slope was approved and is shown on the approved construction plans. Provide mitigation or
justification by separate document.
3. The cross-section of the pan is as shown on the construction plans. (Specifically, the pan cross-
section is “V” shaped and meets the side slope shown on the detail.)
4. The concrete pans are a minimum of 6 inches thick without reinforcement and a minimum of 4
inches thick with a minimum of 6X6-W14xW14 reinforcement per detail D20B and D20C. (Provide
documentation of the reinforcement used if different than shown on the details or on the approved
construction plans.)
5. The spot elevations shown on the concrete pan(s) have been verified and are shown on the as-
built drawings.
1 /19
(As constructed
pipes include
multiple locations
with slopes less
than 0.4%, see
the attached
narrative.
Hydraulic
calculations are
provided for all
storm sewer that
has been
installed flatter
than designed.
UCDG-BJK)
Page 5
V.Storm Drain Inlets - FCSCM Ch. 9, Sec. 3.0
A. Construction/Installation: All storm drain inlets have been constructed in accordance with the
approved construction plans and construction specifications.
1. The size and type of inlets are consistent with the inlets shown on the approved construction
plan. Indicate by writing “Verified” on each inlet on the plan sheet or list on a separate document the
inlet number(s), type and size (length). If the inlet installed is other than the one on the approved
construction plan detail sheet, provide the name and source of the detail with justification for equal or
better capacity.
2. The size of the inlet opening is consistent with the approved detail. (Check height and width.)
3. The elevation of the grate (if applicable) is at the elevation shown on the street profile or as
indicated by a spot elevation on the construction plans.
4. The as-built invert elevations of all pipes entering and leaving the inlet are shown on the plan
and profile sheets within construction tolerance of 0.2 feet. If substantially different, provide
justification and capacity calculations to show the capacity is not affected or propose mitigation.
5. The as-built size of the inlet box is as shown on the construction plans or an explanation or
justification is attached.
6. All Type C, R, 13 and 16 inlet covers are stenciled or stamped with the following designation (or
an equivalent): NO DUMPING – DRAINS TO POUDRE RIVER.
VI. Culverts - FCSCM Ch. 9, Sec. 4.0
A. Construction/Installation: All culverts have been constructed and/or installed in accordance with
the approved construction plans and construction specifications.
1. All culvert sizes have been verified as indicated on the as-built construction plans as correct.
2. The culvert material type for all culverts installed is as on the approved construction plans and is
indicated on the as-built plans.
3. The as-built invert “in and out” elevations have been verified and are indicated on the as-built
construction plans.
4. The culvert headwalls or wing walls have been installed as shown on the approved construction
plans. Headwalls or wing walls may be needed in the as-built conditions onsite if the slopes adjacent to
the culvert are greater than 4:1. Please note areas needing stabilization in the certification narrative.
An alternative to consider is a turf reinforcement mat (TRM).
VII. Sub-Drains
A. Construction/Installation: All sub-drains shown on the construction plans have been installed in
accordance with those plans and the construction specifications. Sub-drains installed with the sanitary
sewer are to be verified on the sanitary sewer plan and profile sheets of the construction plans. (NOTE:
Indicate any sub-drains installed after the plans were approved on the as-built plans.)
1. The size of the sub-drains are as approved on the construction plans and are indicated on the as-
built plans.
2. The type of sub-drain, in particular the perforated and non-perforated sections of the drain, are
as indicated on the approved construction plans.
1 /19
(As constructed
pipes include
multiple inlets
with elevations
varying by more
than 0.2', see
the attached
narrative.
UCDG-BJK)
(Please also refer to contractor's During Construction Checklist. UCDG-CDB)
Page 6
3. The cover requirements per the construction plans are provided.
4. The cleanouts have been installed at the locations shown on the construction plans and are
accessible for cleaning. (Cleanouts can be buried a maximum of 6 inches deep with their locations
marked.)
5. The backfill materials for sub-drains are as shown on the approved construction plans. (This
includes the type, depth and width.)
6. The geo-textile liner completely wraps the sub-drain and the permeable backfill material unless
shown otherwise on the approved construction plans. (Sub-drain pipe wrapped in a sock filter material
is accepted only if approved prior to installation.)
VIII. Curb Cuts
A. Construction: All curb cut openings are constructed in accordance with the approved construction
plans and construction specifications.
1. The size (width) of the curb cut opening is as shown on the approved construction plans.
2. The curb cut openings tie into a downstream swale, pipe, or other appurtenances with a smooth
transition and there no obstructions such as riprap or sod impeding the flow downstream of the curb
cut.
IX. Sidewalk Culverts & Chases
A. Construction/Installation: All sidewalk culverts have been installed at the locations shown on the
approved construction plans.
1. The size (width and length) of the culverts are as shown on the approved construction plans.
2. The cover plate is a minimum 5/8-inch galvanized plate bolted to a galvanized angle iron per the
detail shown on the approved construction plans or per the City’s detail.
3. The sidewalk culvert invert “in and out” elevations have been verified and are indicated on the
as-built plans.
4. The sidewalk culvert opening is as shown on the approved construction plans or per the City’s
detail.
5. There is a smooth transition both on the inlet and outlet ends of the sidewalk culvert with no
obstructions such as riprap or sod impeding the flow into or out of the sidewalk culvert.
X. Site Grading - FCSCM Ch. 8
A. Construction: All common open spaces have been graded in accordance with the approved
construction plans.
1. The grading on all common open spaces bordering private lots has been verified as correct and
the as-built rear lot corner elevations have been shown on the as-built plans.
1 /19
Page 7
2. The as-built contours for “overlot grading” are shown on the as-built construction plans for all
common open spaces, tracts, outlots, etc. If not in compliance, please attach a narrative describing the
situation for noncompliance and when it may be corrected. An escrow for overlot grading may be
required. (NOTE: Residential Lot Grading Certification is a separate process from this Overall Site
Certification. It is understood that residential lots will be brought to final grade once the foundation is
backfilled so they may be lower than the plan shows at this Overall Site Certification stage.)
3. All turf reinforcement mats (TRMs) have been installed as shown on the approved construction
plans and the slopes are stabilized.
XI. Permanent Erosion Control BMPs - FCSCM Ch. 9, Sec. 7.0
A. Construction: All permanent erosion control BMPs have been installed per the approved
construction plans.
1. All riprap has been installed in the locations and sizes indicated on the approved construction
plans.
2. All fabric has been installed in the locations and sizes indicated on the approved construction
plans.
a. All fabric was installed per the details on the approved construction plans.
XII. Post-Construction Site Cleanup - FCSCM Ch. 3, Sec. 2.0
A. Construction: All construction debris and obstructions of any kind have been removed from
drainage paths.
1. All construction debris has been removed except in staging area(s).
2. All ruts have been smoothed out in all construction areas.
3. All areas needing reseeding have been identified and future stabilization goals have been
coordinated with the Erosion Control Inspector and in accordance with FCSCM Vol.2 Chapter 12. Note
the area needing stabilization in the narrative.
XIII. Certification of LID and Water Quality Facilities - FCSCM Ch. 7
A. Attached are the During Construction Inspection Checklist for Low Impact Development (LID) and
other items to be verified during construction, along with pictures and other required documentation.
B. Attached is verification of the rain garden and/or sand filter flat surface area(s) and ponding
volume(s). This verification includes survey of critical elevations.
C. Attached is verification of the underground infiltration required volume(s), weir elevations,
orifices, inspection ports and filtering fabric. This verification includes survey of critical elevations.
D. All visible LID design features were verified as part of the engineer's site visit.
1 /19
(Installed riprap at downstream end of Storm Line A buried per contractor coordination with a
City of Fort Collins Stormwater Inspector. Plans did not call out buried riprap. UCDG-CDB)
(TRM and Shoremax matting to be installed after seeding. UCDG-BJK)
(Final site cleanup to be completed with erosion control installation noted above. UCDG-CDB)
(TRM to be installed after seeding. UCDG-BJK)
(Refer to narrative for Bioretention and Underground Detention Ponds. UCDG-CDB)
(TRM and Shoremax matting to be installed after seeding. UCDG-BJK)
1 /19 Page 8
XIV. Certification of Other Permanent BMPs
A. The construction of other permanent BMPs not specifically addressed in this certification is in
accordance with the approved plan. This may include grade control structures, rundowns, bridges, stream
access/improvements, etc.
Please specify other permanent BMPs included on this site:
XV. Certification and Erosion Control Measures - FCSCM Ch. 3
A.All temporary erosion control measures shall be removed upon stabilization. If at the time of preparing
this certification there are any erosion control measures still remaining on the site, please note them in
the narrative and verify that they need to remain at this time. If in doubt as to the need for any control
measure, please consult with the Erosion Control Inspector at erosion@fcgov.com.
XVI. Statement of Compliance - FCSCM Ch. 3
A.This certification is signed and stamped. By signing this form, the engineer(s) attests that he/she has
visited and observed the site, and to the best of his/her knowledge, the as-built conditions of the drainage
facilities are as described in the above form and in the enclosed as-built plans.
B. Failure to properly disclose all known information could result in the rejection of this certification and
prevent the release of any and all Stormwater Utility permit holds on Building Permits and/or Certificates
of Occupancy within this development.
XVII.Signature and Stamp by a Colorado-Registered Professional Engineer
Engineer’s contact information:
Name:
Email:
Phone:
Company:
Address:
PE Stamp
Sign and date over stamp
10-18-2024
//1 Page 1
CERTIFICATION OF LOT GRADING
Pursuant to Fort Collins City Code § 26-544 & City Land Use Code § 3.3.2 (e)
Date:
Address:
Lot: Block:
Subdivision:
Permit Application #:
Larimer County Parcel #:
Larimer County Reception #:
(on development agreement)
I, (print) , a Colorado registered professional engineer, verify that construction
of all stormwater facilities and grading is complete and hereby submit this certification.
Please answer the following questions by initialing the appropriate response. For each question initialed “No,” attach an
explanation detailing how this will affect stormwater drainage for this lot and any adjacent lots.
1. Certification includes attached Stormwater-approved grading plan. (NOTE: City’s
Building Department does not approve grading plans).
2. Certification includes the attached as-built survey dated (must be within 60
days of the date the certification is submitted) accurately and truthfully depicting
elevations for:
Top of foundation/finished floor
Finished grade on each side of the structure
Quarter points along each lot line (not more than 50 feet apart)
Break points/high points
Swales
Berms
Retaining walls
Air conditioning pads
Window wells
Any other appurtenance(s) within an easement
All elevations are within a 0.2 foot tolerance of the approved grading plan.
The top of foundation is at least 6 inches above the highest grade surrounding the
structure.
There is a minimum grade of 5% away from the structure within the first 5 to 10 feet
adjacent to the residence.
All slopes meet or exceed the minimum requirement of 2% (1% is acceptable on single
family lots when the swale is draining the runoff from only two adjoining properties)
and are not steeper than % (:1).
All flow lines of stormwater drainage swales are a minimum of 6 inches below the
elevation of ground adjacent to the structure and will direct drainage as shown on the
Stormwater-approved grading plan.
All downspout locations and discharge directions are shown on the as-built survey.
Runoff is directed into an appropriate drainage system or lot line swale, and it is not
directed onto neighboring properties.
No Yes
No Yes
No Yes
No Yes
No Yes
No Yes
No Yes
No Yes
(Minor deviations only as shown on the attached record drawing. No negative impacts are
anticipated due to deviations. UCDG-BJK)
//1 Page 2
9. A smooth transition with no vertical offset (step) in grade is provided at the lot line to all
adjacent properties.
10. The grading of this lot does not adversely affect neighboring properties or City
infrastructure.
11. Landscaping has been completed prior to survey. If not, please indicate who will be
responsible for completing landscaping:
12. Final site cleanup has been completed.
13. I personally visited the site as part of the certification process, and in my professional
opinion, the as-built survey is an accurate representation of the site conditions..
No Yes
No Yes
No Yes
No Yes
No Yes
14. Based on this information, I certify that (check one):
The elevations and drainage patterns of the lot/site are in substantial conformance with the City
approved drainage and grading plan for the property (information attached).
The elevations and drainage patterns of the lot/site as measured are in general conformance with the
City approved drainage plan with exceptions (information attached). In my professional judgment the
elevations and grading of the lot/site as constructed are functionally adequate and equivalent to the
specifically approved drainage plan, and will affect stormwater drainage on and off the lot/site in a
manner consistent with the approved drainage plan.
Name:
Email:
Phone:
Company:
Address:
NOTE:A complete certification must be submitted at least two weeks prior to a request for a Certificate of Occupancy
for the lot/site, including, but not limited to, drawings of the lot/site showing the approved design and as-built surveyed
elevations of all structures, drainage and grading features, written information/explanation of discrepancies, and other
information necessary to confirm the above certification to:
Email (preferred)
WaterUtilitiesEng@fcgov.com
Mailing Address
Fort Collins Utilities
ATTN: Water Utilities Engineering
281 North College Avenue
Fort Collins, CO 80521
Questions?
970-221-6700
PE Stamp
Sign and date
DETENTION POND STAGE STORAGE
Nissan - Kia Dealership, Fort Collins, CO
POND ID: Detention Pond A1
Stage Storage Calculations
Elevation Area (sf) Depth (ft)
Incremental
Volume (cf) Volume total (cf)
Volume total (ac-
ft)
5,006.00 55.16 0.00 0 0 0.00
5,006.20 193.02 0.20 23 23 0.00
5,006.40 3,060.44 0.20 268 292 0.01
5,006.60 7,231.23 0.20 1,000 1,291 0.03
5,006.80 10,637.10 0.20 1,776 3,067 0.07
5,007.00 12,703.90 0.20 2,331 5,398 0.12
5,007.20 14,654.87 0.20 2,734 8,132 0.19
5,007.40 16,290.77 0.20 3,093 11,225 0.26
5,007.60 24,887.11 0.20 4,088 15,312 0.35
5,007.80 26,554.11 0.20 5,143 20,456 0.47
5,008.00 27,964.96 0.20 5,451 25,907 0.59
5,008.20 29,193.92 0.20 5,715 31,622 0.73
5,008.40 30,391.01 0.20 5,958 37,581 0.86
5,008.60 31,590.89 0.20 6,198 43,778 1.01
5,008.80 32,791.69 0.20 6,438 50,216 1.15
5,009.00 33,993.12 0.20 6,678 56,894 1.31
5,009.20 35,195.53 0.20 6,919 63,813 1.46
5,009.40 36,408.59 0.20 7,160 70,973 1.63
5,009.60 37,636.26 0.20 7,404 78,377 1.80
5,009.80 38,882.79 0.20 7,652 86,029 1.97
5,010.00 40,152.89 0.20 7,903 93,932 2.16
5,010.20 41,585.75 0.20 8,173 102,105 2.34
5,010.40 58,033.52 0.20 9,916 112,022 2.57
5,010.60 59,779.04 0.20 11,781 123,802 2.84
5,010.80 61,549.59 0.20 12,132 135,935 3.12
5,011.00 63,378.61 0.20 12,492 148,427 3.41
Date: 10/16/2024 C:\United Civil Dropbox\Projects\U21004 - Nissan Dealership\Construction\Drainage Certification\Ponds\Stage Storage
BIORETENTION POND STAGE STORAGE
Nissan - Kia Dealership, Fort Collins, CO
POND ID: Bioretention Pond A2
Stage Storage Calculations
Elevation
Area
(sf)
Depth
(ft)
Incremental Volume
(cf)
Volume total
(cf)
Volume total
(ac-ft)
5,009.00 11,884.00 0.00 0 0 0.00
5,009.20 12,293.00 0.20 2,418 2,418 0.06
5,009.40 12,700.00 0.20 2,499 4,917 0.11
5,009.60 13,108.00 0.20 2,581 7,497 0.17
5,009.80 13,516.00 0.20 2,662 10,160 0.23
5,010.00 13,931.00 0.20 2,745 12,904 0.30
Date: 10/16/2024 C:\United Civil Dropbox\Projects\U21004 - Nissan Dealership\Construction\Drainage Certification\Ponds\Stage Storage
BIORETENTION POND STAGE STORAGE
Nissan - Kia Dealership, Fort Collins, CO
POND ID: Bioretention Pond A3
Stage Storage Calculations
Elevation Area (sf)
Depth
(ft)
Incremental
Volume (cf)
Volume total
(cf)
Volume total
(ac-ft)
5,006.20 0.08 0.00 0 0 0.00
5,006.40 4,809.00 0.20 322 322 0.01
5,006.60 5,202.00 0.20 1,001 1,323 0.03
5,006.80 5,563.00 0.20 1,076 2,399 0.06
5,007.00 5,927.00 0.20 1,149 3,548 0.08
5,007.20 6,297.00 0.20 1,222 4,770 0.11
5,007.40 6,672.00 0.20 1,297 6,067 0.14
Date: 10/16/2024 C:\United Civil Dropbox\Projects\U21004 - Nissan Dealership\Construction\Drainage Certification\Ponds\Stage Storage
Stormwater Facility Name:
Facility Location & Jurisdiction:
User Input: Watershed Characteristics User Defined User Defined User Defined User Defined
Selected BMP Type = EDB Stage [ft] Area [ft^2] Stage [ft]Discharge [cfs]
Watershed Area = 13.35 acres 0.00 0 0.00 0.000
Watershed Length =970 ft 0.50 4,733 0.50 0.030
Watershed Length to Centroid = 515 ft 1.00 11,804 1.00 0.060
Watershed Slope =0.030 ft/ft 1.50 15,818 1.50 1.120
Watershed Imperviousness = 65.0%percent 2.00 26,966 2.00 1.370
Percentage Hydrologic Soil Group A = 0.0%percent 2.50 30,135 2.50 1.620
Percentage Hydrologic Soil Group B = 60.0%percent 3.00 33,140 3.00 1.800
Percentage Hydrologic Soil Groups C/D = 40.0%percent 3.50 36,152 3.50 2.08
Target WQCV Drain Time = 40.0 hours 4.00 39,241 4.00 2.27
4.50 57,523 4.50 2.42
User Input 5.00 61,925 5.00 2.67
After completing and printing this worksheet to a pdf, go to:
https://maperture.digitaldataservices.com/gvh/?viewer=cswdif
Create a new stormwater facility, and attach the PDF of this
worksheet to that record.
Routed Hydrograph Results
Design Storm Return Period =WQCV 2 Year 5 Year 10 Year 50 Year 100 Year
One-Hour Rainfall Depth =N/A 0.82 1.13 1.40 2.39 2.86 in
CUHP Runoff Volume =0.283 0.523 0.781 1.048 2.172 2.731 acre-ft
Inflow Hydrograph Volume =N/A 0.523 0.781 1.048 2.172 2.731 acre-ft
Time to Drain 97% of Inflow Volume =40.0 38.5 36.8 35.6 31.8 30.3 hours
Time to Drain 99% of Inflow Volume =45.2 45.6 45.5 45.6 46.3 46.8 hours
Maximum Ponding Depth =1.51 1.72 2.10 2.46 3.80 4.34 ft
Maximum Ponded Area =0.37 0.47 0.63 0.69 0.87 1.19 acres
Maximum Volume Stored =0.283 0.369 0.590 0.826 1.869 2.404 acre-ft
Once CUHP has been run and the Stage-Area-Discharge
information has been provided, click 'Process Data' to
interpolate the Stage-Area-Volume-Discharge data and
generate summary results in the table below. Once this
is complete, click 'Print to PDF'.
Stormwater Detention and Infiltration Design Data Sheet
Pond A1 - Nissan-Kia
Fort Collins
Location for 1-hr Rainfall Depths (use dropdown):
After providing required inputs above including 1-hour
rainfall depths, click 'Run CUHP' to generate runoff
hydrographs using the embedded Colorado Urban
Hydrograph Procedure.
SDI_Design_Data_v2.00-As-built, Design Data 10/16/2024, 10:44 AM
Booleans for Message Booleans for CUHP
Watershed L:W 1 CUHP Inputs Complete
Watershed Lc:L 1 CUHP Results Calculated
Watershed Slope FALSE Time Interval
RunOnce 1
CountA 1
Draintime Coeff 1.0
User Precip 1
Equal SA Inputs 1
Equal SD Inputs 1
Stormwater Detention and Infiltration Design Data Sheet
0
10
20
30
40
50
60
0.1 1 10TIME [hr]
100YR IN
100YR OUT
50YR IN
50YR OUT
10YR IN
10YR OUT
5YR IN
5YR OUT
2YR IN
2YR OUT
WQCV IN
WQCV OUT
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0.1 1 10 100
DRAIN TIME [hr]
100YR
50YR
10YR
5YR
2YR
WQCV
SDI_Design_Data_v2.00-As-built, Design Data 10/16/2024, 10:44 AM