HomeMy WebLinkAboutSite Certifications - 09/01/2017 (4)
EngineeringEngineeringEngineeringEngineering
908 Laporte Avenue Fort Collins, Colorado 80521 970.219.2834 bob@apex-engineer.com
AAAAugust 3ugust 3ugust 3ugust 31111, 2017, 2017, 2017, 2017
Ms. Heather McDowell, P.E.
City of Fort Collins, Water Utility Engineering
700 Wood Street
Fort Collins, CO 80521
RE:RE:RE:RE: Houska Automotive Expansion, BDR150010Houska Automotive Expansion, BDR150010Houska Automotive Expansion, BDR150010Houska Automotive Expansion, BDR150010
Site and Drainage CertificationSite and Drainage CertificationSite and Drainage CertificationSite and Drainage Certification
Dear Heather,
With this letter, we are submitting the Overall Drainage Certification and Utility Plan
Record Drawings for the above referenced project.
Attached please find the following:
1. Overall Site and Drainage Certification form, dated 8/31/2017, prepared by Apex
Engineering.
a. UDFCD design worksheets and volume calculations for Rain Gardens 1
and 2 and the Lemay Sub-basin Water Quality Pond, prepared by Apex
Engineering.
b. Bioswale checklist prepared by Heath Construction.
c. Construction phase photographs prepared by Heath Construction.
2. As-Built Topographic Drawing, dated 4/4/2017, prepared by Washburn Land
Surveying.
3. Drawings of Record, Utility Plans for Lot 1, Houska Automotive Repair, dated
8/31/2017, prepared by Apex Engineering.
The documents prepared by Apex Engineering are based on survey data provided by
Washburn Land Surveying. Apex cannot verify this survey data and assumes no liability
for its accuracy or completeness.
Please contact me at (970) 219-2834 if you have any questions or need additional
information.
Best Regards,
Bob Gowing, P.E.
APEX EngineeringAPEX EngineeringAPEX EngineeringAPEX Engineering
/15 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) Volume 1, Section 6.11, 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.)
x Use “Yes” for items completed as described.
x Use “N/A” for items that are not applicable to the site being certified.
x 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 Certification - FCSCM Vol.2, Ch.10
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
Lot 1, Houska Automotive Repair
8/31/2017
B1601649
Yes
Yes
Yes
Yes
Yes
Yes
/15 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.
x 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 Certification: 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.
N/A
N/A
N/A
N/A
Yes
Yes
Yes
Yes
Yes
Yes
Yes
concrete and asphalt
/15 Page 3
4.Outlet Structure Certification
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 Vol.1, Ch.7, Sect.3&4
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.)
N/A
4960.97
4960.97
Yes
Yes
Yes
Yes
Yes
N/A
Yes
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
/15 Page 4
III. Storm Pipes (aka storm drains) - FCSCM Vol.1, Ch.6, Sec. 4
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.
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 Vol.1, Ch.7, Sec.4.1.3.4
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.
Yes
Yes
Yes
Yes
Yes
Yes
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
/15 Page 5
V.Storm Drain Inlets - FCSCM Vol.1, Ch.6, Sec. 3
A.Construction/Installation: All storm drain inlets have been constructed in accordance with the
approved construction plans.
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 inlet covers are stenciled or stamped with the following designation: NO DUMPING – DRAINS
TO POUDRE RIVER.
VI. Culverts - FCSCM Vol.2, Ch.9
A.Construction/Installation: All culverts have been constructed and/or installed in accordance with
the approved construction plans.
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. 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.
Yes
Yes
Yes
N/A
Yes
Yes
N/A
Yes
Yes
Yes
Yes
N/A
N/A
N/A
N/A
/15 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.
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
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.
N/A
N/A
N/A
N/A
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
N/A
N/A
/15 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. Riprap - FCSCM Vol.1, Ch.7, Sec.4.4.4.3
A.Construction: All riprap has been installed in the locations and sizes indicated on the approved
construction plans.
XII. Permanent Erosion Control Fabric - FCSCM Vol.1, Ch.7
A.Construction: All fabric has been installed in the locations and sizes indicated on the approved
construction plans.
1. All fabric was installed per the details on the approved construction plans.
XIII. Post-Construction Site Cleanup - FCSCM Vol.3, Ch.7
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.
XIV. Certification of Other Permanent BMPs - FCSCM Vol.2, Ch.8, Sec.2 & FCSCM Vol.2, Ch.12
A. The construction of channel drop structures is in accordance with the approved plan both in
location, horizontal dimensions and cross-section.
XV. Certification of LID and Water Quality Facilities - FCSCM Vol.3, Ch.4
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.
N/A
Yes
N/A
Yes
N/A
N/A
N/A
Yes
Yes
Yes
Yes
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =80.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 0.800
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.26 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 61,420 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =1,344 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum)DWQCV =8.0 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin =896 sq ft
D) Actual Flat Surface Area AActual =1254 sq ft
E) Area at Design Depth (Top Surface Area)ATop =2779 sq ft
F) Rain Garden Total Volume VT=1,351 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y =N/A ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =N/A cu ft
iii) Orifice Diameter, 3/8" Minimum DO =N/A in
Design Procedure Form: Rain Garden (RG)
BG
Apex Engineering
May 3, 2017
Houska Rain Garden 1 (Basin Q1A and Q1B) - As-Built
Fort Collins, CO
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
Houska Rain Garden 1 - UD-BMP_v3.03 RECORD, RG 5/3/2017, 2:35 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
BG
Apex Engineering
May 3, 2017
Houska Rain Garden 1 (Basin Q1A and Q1B) - As-Built
Fort Collins, CO
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
Houska Rain Garden 1 - UD-BMP_v3.03 RECORD, RG 5/3/2017, 2:35 PM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =100.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 1.000
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.40 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 12,600 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =420 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum)DWQCV =12.0 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin =280 sq ft
D) Actual Flat Surface Area AActual =336 sq ft
E) Area at Design Depth (Top Surface Area)ATop =764 sq ft
F) Rain Garden Total Volume VT=550 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y =N/A ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =N/A cu ft
iii) Orifice Diameter, 3/8" Minimum DO =N/A in
Design Procedure Form: Rain Garden (RG)
BG
Apex Engineering
May 3, 2017
Houska Rain Garden 2 (Basin Q2) - As-Built
Fort Collins, CO
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
Houska Rain Garden 2 - UD-BMP_v3.03 RECORD, RG 5/3/2017, 2:23 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
BG
Apex Engineering
May 3, 2017
Houska Rain Garden 2 (Basin Q2) - As-Built
Fort Collins, CO
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
Houska Rain Garden 2 - UD-BMP_v3.03 RECORD, RG 5/3/2017, 2:23 PM
Sheet 1 of 4
Designer:
Company:
Date:
Project:
Location:
1.Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =80.0 %
B) Tributary Area's Imperviousness Ratio (i = Ia / 100 )i =0.800
C) Contributing Watershed Area Area = 20.200 ac
D) For Watersheds Outside of the Denver Region, Depth of Average d6 = in
Runoff Producing Storm
E) Design Concept
(Select EURV when also designing for flood control)
F) Design Volume (1.2 WQCV) Based on 40-hour Drain Time VDESIGN=0.663 ac-ft
(VDESIGN = (1.0 * (0.91 * i3 - 1.19 * i2 + 0.78 * i) / 12 * Area * 1.2)
G) For Watersheds Outside of the Denver Region, VDESIGN OTHER= ac-ft
Water Quality Capture Volume (WQCV) Design Volume
(VWQCV OTHER = (d6*(VDESIGN/0.43))
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VDESIGN USER= ac-ft
(Only if a different WQCV Design Volume is desired)
I) Predominant Watershed NRCS Soil Group
J) Excess Urban Runoff Volume (EURV) Design Volume
For HSG A: EURVA = (0.1878i - 0.0104)*Area EURV = ac-f t
For HSG B: EURVB = (0.1178i - 0.0042)*Area
For HSG C/D: EURVC/D = (0.1043i - 0.0031)*Area
2.Basin Shape: Length to Width Ratio L : W =2.0 : 1
(A basin length to width ratio of at least 2:1 will improve TSS reduction.)
3.Basin Side Slopes
A) Basin Maximum Side Slopes Z =4.00 ft / ft
(Horizontal distance per unit vertical, 4:1 or flatter preferred)
4.Inlet
A) Describe means of providing energy dissipation at concentrated
inflow locations:
Design Procedure Form: Extended Detention Basin (EDB)
Lemay Sub-Basin Water Quality Pond - As-built
Apex Engineering
March 6, 2016
Fort Collins, CO
BG
Choose One
Excess Urban Runoff Volume (EURV)
Choose One
A
B
C / D
Water Quality Capture Volume (WQCV)
Lemay Sub-Basin Water Quality Pond - UD-BMP_v3.03 RECORD, EDB 5/9/2017, 6:48 PM
Sheet 2 of 4
Designer:
Company:
Date:
Project:
Location:
5.Forebay
A) Minimum Forebay Volume VFMIN =0.017 ac-ft
(VFMIN = 3%of the WQCV)
B) Actual Forebay Volume VF =0.000 ac-ft VF < MINIMUM VF
C) Forebay Depth DF = in
(DF = 18 inch maximum)
D) Forebay Discharge
i) Undetained 100-year Peak Discharge Q100 = cfs
ii) Forebay Discharge Design Flow QF = cfs
(QF = 0.02 * Q100)
E) Forebay Discharge Design
F) Discharge Pipe Size (minimum 8-inches)Calculated DP =in
G) Rectangular Notch Width Calculated WN = in
PROVIDE A CONSISTENT LONGITUDINAL
6. Trickle Channel SLOPE FROM FOREBAY TO MICROPOOL
WITH NO MEANDERING. RIPRAP AND
A) Type of Trickle Channel SOIL RIPRAP LINED CHANNELS ARE
NOT RECOMMENDED.
MINIMUM DEPTH OF 1.5 FEET
F) Slope of Trickle Channel S = 0.0010 ft / ft
7.Micropool and Outlet Structure
A) Depth of Micropool (2.5-feet minimum)DM = ft
B) Surface Area of Micropool (10 ft2 minimum)AM = sq ft
C) Outlet Type
D) Depth of Design Volume (EURV or 1.2 WQCV) Based on the Design H =4.45 feet
Concept Chosen Under 1.E.
E) Volume to Drain Over Prescribed Time WQCV =0.553 ac-ft
F) Drain Time TD =40 hours
(Min TD for WQCV= 40 hours; Max TD for EURV= 72 hours)
G) Recommended Maximum Outlet Area per Row, (Ao)Ao =1.53 square inches
H) Orifice Dimensions:
i) Circular Orifice Diameter or Dorifice =1 - 3 / 8 inches
ii) Width of 2" High Rectangular Orifice Worifice =inches
I) Number of Columns nc =1 number
J) Actual Design Outlet Area per Row (Ao)Ao =1.48 square inches
K) Number of Rows (nr)nr =13 number
L) Total Outlet Area (Aot)Aot =19.8 square inches
M) Depth of WQCV (HWQCV)HWQCV =feet
(Estimate using actual stage-area-volume relationship and VWQCV)
N) Ensure Minimum 40 Hour Drain Time for WQCV TD WQCV =hours
(flow too small for berm w/ pipe)
Fort Collins, CO
BG
Lemay Sub-Basin Water Quality Pond - As-built
March 6, 2016
Apex Engineering
Design Procedure Form: Extended Detention Basin (EDB)
Choose One
Wall with Rect. Notch
Berm With Pipe
Choose One
Orifice Plate
Other (Describe):
Choose One
Concrete
Soft Bottom
Wall with V-Notch Weir
Lemay Sub-Basin Water Quality Pond - UD-BMP_v3.03 RECORD, EDB 5/9/2017, 6:48 PM
Sheet 3 of 4
Designer:
Company:
Date:
Project:
Location:
8.Initial Surcharge Volume
A) Depth of Initial Surcharge Volume DIS = in
(Minimum recommended depth is 4 inches)
B) Minimum Initial Surcharge Volume VIS = cu ft
(Minimum volume of 0.3% of the WQCV)
C) Initial Surcharge Provided Above Micropool Vs=cu ft
9.Trash Rack
A) Type of Water Quality Orifice Used
B) Water Quality Screen Open Area: At = Aot * 38.5*(e-0.095D)At =670 square inches
C) For 1-1/4"", or Smaller, Circular Opening (See Fact Sheet T-12):
i) Width of Water Quality Screen and Concrete Opening (Wopening) Wopening =inches
ii) Height of Water Quality Screen (HTR) HTR =inches
iii) Type of Screen, Describe if "Other"
D) For Circular Opening (greater than 1-1/4" diameter)
OR 2" High Rectangular Opening (See Fact Sheet T-12):
i) Width of Water Quality Screen Opening (Wopening) Wopening =ft
ii) Height of Water Quality Screen (HTR) HTR =ft
iii) Type of Screen, Describe if "Other"
v) Cross-bar Spacing inches
vi) Minimum Bearing Bar Size
Apex Engineering
March 6, 2016
Lemay Sub-Basin Water Quality Pond - As-built
Fort Collins, CO
BG
Design Procedure Form: Extended Detention Basin (EDB)
Choose One
Circular (up to 1-1/4" diameter)
Circular (greater than 1-1/4" diameter) OR Rectangular (2" high)
Choose One
S.S. Well Screen with 60% Open Area*
Other (Describe):
Choose One
Aluminum Amico-Klemp SR Series (or equal)
Other (Describe):
Lemay Sub-Basin Water Quality Pond - UD-BMP_v3.03 RECORD, EDB 5/9/2017, 6:48 PM
Sheet 4 of 4
Designer:
Company:
Date:
Project:
Location:
10.Overflow Embankment
A) Describe embankment protection for 100-year and greater overtopping:
B) Slope of Overflow Embankment ZE =0.02 ft / ft TOO STEEP (< 3)
(Horizontal distance per unit vertical, 4:1 or flatter preferred)
11.Vegetation
AVOID PLACING IRRIGATION HEADS
IN THE BOTTOM OF THE BASIN
12.Access
A) Describe Sediment Removal Procedures
Notes:
Fort Collins, CO
Design Procedure Form: Extended Detention Basin (EDB)
March 6, 2016
Apex Engineering
BG
Lemay Sub-Basin Water Quality Pond - As-built
Choose One
Irrigated
Not Irrigated
Lemay Sub-Basin Water Quality Pond - UD-BMP_v3.03 RECORD, EDB 5/9/2017, 6:48 PM
Extended Detention Calculations:Extended Detention Calculations:Extended Detention Calculations:Extended Detention Calculations:Notes:Notes:Notes:Notes:
WQCV = a(0.91i^3-1.19i^2+0.78i)
where a =1.0 (from Table 3-2)
where I =80%(assumed for site)
where A =20.20 acre (assumed for site)
WQCV =0.394 inch (from Equation 3.1)
WQCV =28889 cubic feet (from Equation 3-3)
WQCV =0.663 acre feet
Stage/Storage Calculations:Stage/Storage Calculations:Stage/Storage Calculations:Stage/Storage Calculations:
Input:Input:Input:Input:
WQCV Required = 0.663 acre feet (per above calculations)
Where:Where:Where:Where:
Volume = ((A+B)/2)D (average end area method)
D = elevationn - elevationn-1
A = area of elevationn-1 contour
B = area of elevationn contour
Calculations:Calculations:Calculations:Calculations:
Cumulative Cumulative Cumulative Cumulative
Elev.Elev.Elev.Elev. AreaAreaAreaArea AreaAreaAreaArea StorageStorageStorageStorage StorageStorageStorageStorage
(feet)(feet)(feet)(feet) (SF)(SF)(SF)(SF) (acre)(acre)(acre)(acre) (acre-ft)(acre-ft)(acre-ft)(acre-ft) (acre-feet)(acre-feet)(acre-feet)(acre-feet)
4956.52 0 0.000 0.000 0.000
4957.00 1,538 0.035 0.008 0.008
4958.00 5,239 0.120 0.078 0.086
4959.00 7,509 0.172 0.146 0.233
4960.00 9,449 0.217 0.195 0.427
4961.00 11,702 0.269 0.243 0.670
4962.00 14,597 0.335 0.302 0.972
Results:Results:Results:Results:
WQ WSEL = 4960.97 (interpolated)
Note: As-built topographic information provided by Washburn Surveying
Detention/WQL Pond Calculations - As-BuiltDetention/WQL Pond Calculations - As-BuiltDetention/WQL Pond Calculations - As-BuiltDetention/WQL Pond Calculations - As-Built
Houska Regional WQL PondHouska Regional WQL PondHouska Regional WQL PondHouska Regional WQL Pond
4/27/20174/27/20174/27/20174/27/2017
STMH RIM = 4959.89
INV N = 4957.09
STMH RIM = 4960.06
INV = 4956.56
INLET RIM = 4960.97
INV = 4956.52
STMH RIM = 4960.61
INV SE = 4954.86
INV W = 4954.76
INV NE = 4954.96
INLET RIM = 4959.49
INV = 4955.39
495
9
.
9
495
9
.
6
495
9
.
5
495
9
.
4
1
495
9
.
3
495
9
.
3
495
9
.
4
495
9
.
6
496
0
495
8
4957
495
7
496
0
496
2
496
0
495
9
496
0
496
1
4962
49
6
1
496
1
496
2
4961
4963
4962
49
6
1
496
2
4962
4961
496
1
4962
INV FES = 4957.75
berm
4962.02
berm
4962.15
berm
4962.33
berm
4962.08
berm
4962.03
berm
4962.07
berm
4962.12
berm
4962.47
berm
4962.38
berm
4962.13
berm
4961.89
3621 Muskrat Creek Drive
Fort Collins, CO 80528
970-232-9645
www.WashburnSurveying.com
Sheet 1 of 2 Project #: 2016-0032 Date: March 21, 2017 Scale: 1"=15' Drawn: ABS
0'15'30'45'
INLET RIM = 4961.65
INV = 4957.50 INLET RIM = 4962.00
INV NW = 4959.00
INV S = 4959.05
ADS RIM = 4962.82
INV = 4959.52
ADS RIM = 4963.77
INV = 4960.27
FF ELEV = 4963.29
496
0
495
8
496
2
496
0
495
9
496
0
496
1
4962
49
6
1
496
1
496
2
4961
4963
4962
49
6
1
496
2
4962
4961
496
1
4962
49
6
2
49
6
1
49
6
1
49
6
3
49
6
2
49
6
1
49
6
1
49
6
2
4963
49
6
4
3621 Muskrat Creek Drive
Fort Collins, CO 80528
970-232-9645
www.WashburnSurveying.com
Sheet 2 of 2 Project #: 2016-0032 Date: March 21, 2017 Scale: 1"=15' Drawn: ABS
0'15'30'45'