HomeMy WebLinkAboutRIDGEWOOD HILL AMENDMENT TRACT B - MA210028 - SUBMITTAL DOCUMENTS - ROUND 4 - DRAINAGE REPORT
ADDENDUM TO FINAL DRAINAGE REPORT
Ridgewood Hills Sixth Filing
Tract “B”
Multi-Family Residential Development
North of Avondale Road and East of Triangle Drive
Fort Collins, Colorado
Prepared For:
M. Timm Development, Inc.
233 E. Carrillo St., Suite D
Santa Barbara, CA 93101
(805) 963-0358
Prepared By:
6112 E. Sienna Bouquet Pl.,
Cave Creek, AZ 85331
Phone: (303) 913-5382
Revised May 2023
Revised October 2022
December 2020
Proj. No.: 19-449
RIDGEWOOD HILLS SIXTH FILING
TRACT “B”
MULTI-FAMILY RESIDENTIAL DEVELOPMENT
ADDENDUM TO FINAL DRAINAGE REPORT
Table of Contents
ENGINEER’S CERTIFICATION .............................................................................................. 1
I INTRODUCTION AND BACKGROUND .................................................................................. 2
II PROPOSED MINOR AMENDMENT TO THE DEVELOPMENT PLAN .................................. 3
III DRAINAGE SYSTEM REVISIONS FOR THE NORTH PORTION OF THE SITE .................. 3
IV LOW IMPACT DEVELOPMENT (LID) REVISIONS ................................................................ 5
V CONCLUSIONS ...................................................................................................................... 6
A. COMPLIANCE WITH STANDARDS .................................................................................. 6
B. DRAINAGE CONCEPT ..................................................................................................... 6
VI REFERENCES ........................................................................................................................ 6
APPENDIX
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5/25/23 2
RIDGEWOOD HILLS FOURTH FILING
TRACT “B”
MULTI-FAMILY RESIDENTIAL DEVELOPMENT
ADDENDUM TO FINAL DRAINAGE REPORT
I. INTRODUCTION AND BACKGROUND
This report is an addendum to the Final Drainage Report for the Ridgewood Hills Fourth
Filing, dated October 2014, which was reviewed and approved by the City of Fort Collins in
January 2017. That Final Drainage Report assessed the potential drainage impacts of the
contemplated development of a 10.4-acre parcel, located east of Triangle Dr in the
southwest region of Fort Collins, CO. That parcel is bisected by what is to be the eastward
extension of Avondale Rd. The Final Drainage Report presented designs for stormwater
management improvements to mitigate any impacts. The site development contemplated at
the time of preparation of the Final Drainage Report consisted of a multi-family residential
complex, including 146 dwelling units in a mix of 6-unit, 8-unit, 16-unit and 24-unit buildings,
comprising a total of 11 buildings.
The drainage analysis in the Final Drainage Report addressed the requirements for on-site
stormwater management infrastructure, as well as any necessary upgrades to the two
existing detention basins located near the site, and which will serve the detention
requirements of the project. The design of on-site improvements also addressed facilities
necessary to comply with the City’s Low Impact Development (LID) criteria. The drainage
analysis also included an update of the findings of previous drainage studies for the
Ridgewood Hills subdivision, to reflect revisions that had been made to the City’s Storm
Drainage Design Criteria, subsequent to preparation of those previous reports and
construction of the existing detention facilities.
Among the findings of the drainage analysis documented in the Final Drainage Report for
the Ridgewood Hills Fourth Filing were the following:
• The drainage systems for the proposed development of the Fourth Filing would
effectively match the two geographic components of the site.
• The portion of the site north of Avondale Rd. would, for the most part, be collected
by one system, draining to the existing detention basin located north of Triangle Dr.
• The portion of the site south of Avondale Rd., and including Avondale Rd. and
portions of the existing single-family lots west and south of the south portion of the
development site, would be collected by a second system, draining to the existing
detention basin located south of Peyton Dr. and east of Fountain Dr.
• The two existing detention basins each have adequate capacity to also
accommodate the anticipated runoff from the proposed development of the Fourth
Filing, with only minor modifications required to the outlet control orifices in the
respective detention basins.
The reader is referred to the Final Drainage Report for the Ridgewood Hills Fourth Filing for
details of the assessment of the overall site, and for context for this Addendum.
5/25/23 3
II. PROPOSED MINOR AMENDMENT TO THE DEVELOPMENT PLAN
Subsequent to finalization of the Final Drainage Report for the Ridgewood Hills Fourth
Filing, the developer determined that it would be preferable to phase the development of the
site and to proceed first with construction of the south portion of the development (Tract A),
as well as Avondale Rd., and to delay develop the north portion of the site (Tract B). It was
also decided that minor revisions should be made to the building footprints in the respective
portions of the site, but with no increase in the development density, number or location of
buildings, and no significant change in the land-use percentages for the site. Minor
modifications to the parking configuration were determined to be necessary, in order to
ensure stand-alone compliance of each portion of the development with respect to the City’s
parking requirements for multi-family residential developments.
Development of the portion of the site north of Avondale Rd. was deferred, pending
reconsideration of the most appropriate style and scope of development for that property. It
was determined that no major revisions to the nature or scope of development of the north
portion of the site were warranted and, therefore, the revisions to the design of the
stormwater management system for that portion of the site were to be only those
appropriate to comply with recent revisions to City design criteria. It was further determined
that no further modifications would be necessary to the existing detention basin into which
Tract “B” will drain.
It has since been determined that the clubhouse and pool complex would be removed from
the Tract “B” development, and that alternate recreational amenities would be included
instead. This proposed substitution was discussed with City staff and approval to proceed
with the Minor Amendment application, on that basis, was received from the City on July 26,
2021.
Further discussions with staff of the Stormwater Management Department indicated that
revisions to the nature and design of the LID facilities in Tract “B” should be made, which led
to some redesign of the grading in the eastern portion of the site and some minor revisions
to the delineation of the drainage sub-basin boundaries and the hydrologic analysis of the
stormwater regime in Tract “B”. This addendum addresses the minor modifications to the
stormwater management system for Tract “B” corresponding to the revisions in the site
development plan.
III. DRAINAGE SYSTEM REVISIONS FOR NORTH PORTION OF THE SITE
The overall area that will be drained by the system serving the north portion of the site will
be essentially as originally proposed. There will be a portion of the site, consisting of a band
of land extending along much of the southern perimeter of Tract “B” and identified as Sub-
basin 1, that cannot practicably be collected into and conveyed through the Tract “B”
drainage system. This portion of the site, located immediately north of the Avondale Rd.
right-of-way, includes approximately 50% of the footprints of the two buildings adjacent to
Avondale Rd., along with the landscaped areas between the buildings and the street, and
the temporary turn-around at the east end of the Avondale Rd. extension. This area will
drain onto Avondale Rd. and into the stormwater system serving the southern portion (Tract
“A”) of the site. The aggregate area of this sub-basin is 0.493 ac, which represents
5/25/23 4
approximately 5.9% of the previously proposed total catchment area of the south drainage
system (8.334 ac).
A significant portion of Tract ”B”, Sub-basin 1, was originally included as part of the
catchment area for the south drainage system, as delineated in the 2014 Final Drainage
Report for the Ridgewood Hills Fourth Filing, but was deleted from the catchment area
associated with the south drainage system, in the 2018 Addendum to the Final Drainage
Report, pending the reconsideration of the nature and scope of the development plans for
Tract “B”. The deleted catchment area amounted to 0.39 ac, representing approximately
79% of the 0.493 acres that is now proposed to be added back into the south drainage
system catchment area. Analysis of the anticipated runoff from this “added back” catchment
area indicates a Q2 of 0.62 cfs and a Q100 of 3.18 cfs. A review of the storm drain
improvements installed as part of the development of Tract “A” indicates that there is
adequate capacity in those improvements (the 5’ Type R inlet on the north side of Avondale
Rd. at the southeast corner of Tract “B” and the downstream piping from that inlet to the
existing detention pond south of Tract “A”) to accommodate the re-inclusion of the runoff
from Sub-basin 1 of Tract “B” into the aggregate stormwater flow to be collected and
conveyed by the Tract “A” drainage system. The installed 5’ Type R inlet will intercept 100%
of the minor storm flow and 71% of maximum design gutter flow of 3.2 cfs in the north gutter
of Avondale Rd., with a carry-over flow of less than one cfs, and there will continue to be
excess capacity in the piping runs downstream of the inlet, ranging from 53% to 214% of the
required capacity.
Based on the analyses conducted as part of the original design of the storm drain system for
both Tract “A” and Tract “B” of the development site (see the Final Drainage Report for
Ridgewood Hills Fourth Filing), it was concluded that the detention capacities of both
detention ponds are adequate to accommodate the expected runoff resulting from build-out
of Ridgewood Hills Fourth Filing (both north and south parcels, respectively), and that the
only warranted modification to Pond 2 (serving the south portion of the site) would be to
replace of the orifice plate at the outlet control works, reducing the diameter of the orifice
opening by 0.75”, in order to continue to restrict outflow from the detention pond to the
allowable, pre-development rate.
The maximum incremental inflow to the existing detention pond, due to the inclusion of this
sub-basin in the catchment area of the Tract “A” system, compared to the design inflow
indicated by the 2014 analysis for the entire Fourth Filing site, amounts to only 0.115 cfs
(0.14% of the total design discharge into the detention basin from the Fourth Filing), which
does not warrant any further revisions to the detention facility or outlet control works,
compared to those recommended in the 2014 Final Drainage Report.
The revised development layout for Tract “B” includes somewhat less impervious area than
originally proposed, and thus the design runoff from Tract “B” is somewhat less than set out
in the 2014 Final Drainage Report. The maximum design discharge from the site to the
existing inlet in Triangle Dr., near the north end of the site, and onward to the existing
Detention Pond 1, is calculated to be 21.95 cfs, compared to 28.97 cfs of collected on-site
runoff documented in the 2014 Final Drainage Report. Thus, consistent with the
recommendations of the 2014 Final Drainage Report, no revisions to Pond 1 appear to be
warranted, either to amend the operational capacity or to adjust the outflow restricting
orifice.
5/25/23 5
IV. LOW-IMPACT DEVELOPMENT (LID) REVISIONS
The previously approved stormwater management design for the north portion of the
proposed development (Tract “B”) included a pair of pea gravel-filled, curb-side sediment
traps, overflowing to grassed catchment / impoundment swales, each underlain by areas of
bio-treatment media. Runoff captured in the impoundment swales was to be discharged to
the downstream piped drainage system, either through the bio-treatment media and a
embedded perforated underdrain pipe, or via an outlet control structure designed to pass
flows in excess of the required Water Quality Capture Volume (WQCV).
Subsequent revisions to the City’s LID Criteria (1-19-16) allow for treatment, using one or a
combination of LID techniques, designed to capture and treat not less than 75% of the
WQCV emanating from any newly developed impervious areas. The aggregate area of
impervious surface in Tract B (buildings, pavement, sidewalks and trash enclosures) is
2.389 ac. The revised design of the stormwater management system for the site captures
the runoff from 2.105 ac of roof and pavement area in Sub-basins 2 – 10, thus capturing
88.1% of the runoff from impervious areas of the site. The runoff from Sub-basins 2 and 3 is
captured and directed to a rain garden located along the downstream edge of Sub-basin 3,
designated as the Upper Rain Garden, and having capacity to detain and treat a WQCV
treatment volume of 1,194 c.f. (104% of the required capacity). The runoff from Sub-basins
2 – 10 is captured and directed to a rain garden located in Sub-basin 10, designated as the
Lower Rain Garden, and having capacity to detain and treat a WQCV treatment volume of
1,784 c.f. (101% of the required capacity). Design worksheets documenting the required
and provided capacities of the two rain gardens are included in the attachments to this
Addendum.
Runoff flows from the respective tributary drainage sub-basins that are in excess of the
calculated WQCV for each of the two rain gardens are passed through the rain garden
basins, over the top of the WQCV depth, and are conveyed out of the rain gardens ,via
appropriate outlet control structures and independent downstream piping, to discharge into
the existing Type “R” inlet in Triangle Drive, and from there to the existing Extended
Detention Pond facility west of Triangle Drive.
The two rain garden areas are designed in accordance with the guidelines set out in Volume
3 of the Mile High Flood District (MHFD) Criteria Manual and the City of Fort Collins
Bioretention standard cross-sections, details, and specifications. Each of the two rain
gardens includes a Bioretention sand media layer, a diaphragm aggregate layer, and a
reservoir aggregate layer enveloping a perforated PVC underdrain system. Consideration of
the nature of the native soils underlying the site led to a decision to include a geotextile
separator fabric beneath the reservoir aggregate layer, but not an impermeable geosynthetic
membrane. Details of the rain garden design are shown on the project drawings.
The table below presents a summary of the provided capacities of the two LID rain garden
facilities.
5/25/23 6
L.I.D. RAIN GARDEN VOLUME SUMMARY
Treatment Area Designation Required Provided
Volume (c.f.) Volume (c.f.)
Upper Rain Garden 1,147 1,194
Lower Rain Garden 1,763 1,784
Total available WQCV 2,910 2,978
V. CONCLUSIONS
A. COMPLIANCE WITH STANDARDS
The design of the stormwater management improvements to serve the development
of Ridgewood Hills Sixth Filing Tract “B” is in compliance with the City of Fort Collins
Storm Drainage Design Criteria and Construction Standards. The criteria and
recommendations of the Urban Storm Drainage Criteria Manual are also reflected in
the design of the drainage system.
B. DRAINAGE CONCEPT
The proposed drainage improvements for the development of Ridgewood Hills Sixth
Filing Tract “B” will effectively protect the proposed development, as well as
downstream properties, drainage facilities and natural waterways from the potential
impacts of stormwater runoff from the development, resulting in no adverse effects
due to the development of this site. Development of the site, as proposed, should
have a beneficial impact on water quality in downstream drainage facilities and
drainage ways, by reducing and/or delaying the initial discharge of runoff from the
site, such that sediments and other potential pollutants typically carried by this first
flush are removed from the flow.
VI. REFERENCES
“City of Fort Collins Stormwater Criteria Manual”, City of Fort Collins, Adopted December
2011
“Urban Storm Drainage Criteria Manual”, Volumes 1 & 2, UDFCD, Revised December 2012
“Urban Storm Drainage Criteria Manual”, Volume 3, UDFCD, Revised December 2012
APPENDIX
Drainage Area Summary - Entire Site
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.965 0.73 0.75 0.77 0.83 90
Pavement 1.424 0.89 0.90 0.92 0.96 100
Landscape 2.804 0.04 0.15 0.25 0.50 0
Total 5.193 0.40 0.47 0.53 0.69 44.15
Sub-Basin 1
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.136 0.73 0.75 0.77 0.83 90
Pavement 0.148 0.89 0.90 0.92 0.96 100
Landscape 0.209 0.04 0.15 0.25 0.50 0
Total 0.493 0.48 0.54 0.59 0.73 54.85
Sub-Basin 2
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.195 0.73 0.75 0.77 0.83 90
Pavement 0.468 0.89 0.90 0.92 0.96 100
Landscape 0.126 0.04 0.15 0.25 0.50 0
Total 0.789 0.71 0.74 0.77 0.85 81.56
Sub-Basin 3
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.026 0.73 0.75 0.77 0.83 90
Pavement 0.046 0.89 0.90 0.92 0.96 100
Landscape 1.009 0.04 0.15 0.25 0.50 0
Total 1.081 0.09 0.20 0.29 0.53 6.42
Sub-Basin 4
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.316 0.73 0.75 0.77 0.83 90
Pavement 0.672 0.89 0.90 0.92 0.96 100
Landscape 0.325 0.04 0.15 0.25 0.50 0
Total 1.313 0.64 0.68 0.72 0.81 72.84
Sub-Basin 10
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.016 0.73 0.75 0.77 0.83 90
Pavement 0.003 0.89 0.90 0.92 0.96 100
Landscape 0.171 0.04 0.15 0.25 0.50 0
Total 0.190 0.11 0.21 0.30 0.54 9.16
Ridgewood Hills 4th Filing - Tract "B"
TRIBUTARY AREAS, RUNOFF COEFFICIENTS,
AND PERCENT IMPERVIOUSNESS
Sub-Basin 5
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.072 0.73 0.75 0.77 0.83 90
Pavement 0.018 0.89 0.90 0.92 0.96 100
Landscape 0.103 0.04 0.15 0.25 0.50 0
Total 0.193 0.37 0.44 0.51 0.67 42.90
Sub-Basin 6
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.036 0.73 0.75 0.77 0.83 90
Pavement 0.006 0.89 0.90 0.92 0.96 100
Landscape 0.022 0.04 0.15 0.25 0.50 0
Total 0.064 0.50 0.55 0.61 0.73 60.00
Sub-Basin 7
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.070 0.73 0.75 0.77 0.83 90
Pavement 0.012 0.89 0.90 0.92 0.96 100
Landscape 0.062 0.04 0.15 0.25 0.50 0
Total 0.144 0.44 0.50 0.56 0.70 52.08
Sub-Basin 8
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.052 0.73 0.75 0.77 0.83 90
Pavement 0.034 0.89 0.90 0.92 0.96 100
Landscape 0.084 0.04 0.15 0.25 0.50 0
Total 0.170 0.42 0.48 0.54 0.69 47.53
Sub-Basin 9
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.046 0.73 0.75 0.77 0.83 90
Pavement 0.017 0.89 0.90 0.92 0.96 100
Landscape 0.053 0.04 0.15 0.25 0.50 0
Total 0.116 0.44 0.50 0.56 0.70 50.34
Sub-Basin 11
Surface Type Area C2 C5 C10 C100 % Imperv.
Roof 0.000 0.73 0.75 0.77 0.83 90
Pavement 0.000 0.89 0.90 0.92 0.96 100
Landscape 0.640 0.04 0.15 0.25 0.50 0
Total 0.640 0.04 0.15 0.25 0.50 0.00
Prepared by:L.C.O.Date:10/14/20
Final Tc Remarks
Basin Area C5 Length Slope Ti Length Slope Velocity Tt Comp Tc Tot. Length Tc =(L/180)+10
I.D.(ac)(ft)(%)(min)(ft)(%)(fps)(min)(min)(ft)(min)(min)
1 0.493 0.54 25 2.0%4.03 518 2.30%3.03 2.85 6.88 543 13.0 6.9
2 0.789 0.74 90 2.5%4.56 340 2.30%3.03 1.87 6.43 430 12.4 6.4
3 1.081 0.20 30 0.5%11.24 110 12.30%2.50 0.73 11.97 140 10.8 10.8
4 1.313 0.68 80 1.6%5.88 460 3.90%3.95 1.94 7.82 540 13.0 7.8
5 0.190 0.21 39 20.5%3.70 3 33.30%8.66 0.01 3.70 42 10.2 3.7
5 0.193 0.44 20 5.0%3.13 165 3.60%2.85 0.97 4.09 185 11.0 4.1
6 0.064 0.55 6 3.3%1.63 39 1.80%2.01 0.32 1.95 45 10.3 1.9
7 0.144 0.50 40 13.8%2.87 34 1.00%1.50 0.38 3.25 74 10.4 3.3
8 0.170 0.48 53 9.4%3.88 30 1.70%1.96 0.26 4.14 83 10.5 4.1
9 0.116 0.50 20 13.0%2.09 0.00 2.09 20 10.1 2.1
11 0.640 0.15 167 12.6%9.61 0.00 9.61 167 10.9 9.6
0 10.0
Total 5.193
Notes:
1. Channel flow velocity is a function of the channel slope and the channel conveyance factor (K). Vt = K(S^0.5).
K = 15 for grassed waterways and 20 for shallow paved swales.
2. Flow velocity across a non-channelized surface is a function of the slope and the nature of the surface. In the case of sub-basins 3, 7, 8 and 9,
where concentrated flow from a roof downspout is discharged onto a grassed slope, the distributed flow velocity is considered to range between
1.9 and 2.5 ft/sec.
Ridgewood Hills - Tract "B"
TIMES OF CONCENTRATION
Sub-Basin Data Initial / Overland Time Channel Travel Time Tc Check
Prepared by:L.C.O.Date:10/29/22
Basin Design Sub-Basin Runoff Time of C * A Rainfall Design Total Time Cumm.Rainfall Cumm.Design Pipe Pipe Pipe Length Velocity Time
I.D.Point Area Coeffic Concentr.Intensity Runoff of Conc.C*A Intensity Runoff Flow Slope Size Capacity
(ac)(min)(ac)(in/hr)(cfs)(min)(ac)(in/hr)(cfs)(cfs)(%)(in)(cfs)(ft)(ft/sec)(min)
Developed Condition
Upper LID System
1 1 0.493 0.48 6.9 0.24 2.60 0.62 6.9 0.24 2.60 0.62
2 2 0.789 0.71 6.4 0.56 2.65 1.49 6.4 0.56 2.65 1.49 1.49 2.92 12.00 7.93 63.3 11.51 0.09
1.49 7.53 12.00 12.73 111.8 17.68 0.11
3 3 1.081 0.09 10.8 0.10 2.21 0.22 10.8 0.66 2.20 1.46 1.46 1.22 15.00 9.29 109.7 4.94 0.37
1.46 1.22 15.00 9.29 161.2 4.94 0.54
1.46 Design 2-yr storm discharge from Upper LID system
Lower LID System
4 4 1.313 0.64 7.8 0.84 2.49 2.08 7.8 0.84 2.49 2.08 2.08 5.00 12.00 10.38 19.3 5.17 0.06
5 2.08
5 6 0.193 0.37 4.1 0.07 2.85 0.21 4.1 0.07 2.85 0.21 0.21 1.15 12.00 4.98 43.5 2.37 0.31
6 7 0.064 0.50 1.9 0.03 2.85 0.09 4.4 0.10 2.85 0.30 0.30 4.37 12.00 9.70 98.5 4.28 0.38
7 8 0.144 0.44 3.3 0.06 2.85 0.18 3.3 0.06 2.85 0.18 0.18 1.00 12.00 4.64 10.5 2.07 0.08
9 4.8 0.17 2.85 0.48 0.48 2.50 12.00 7.34 156.2 3.82 0.68
8 10 0.170 0.42 4.1 0.07 2.85 0.20 4.1 0.07 2.85 0.20 0.20 1.00 12.00 4.64 12.0 2.18 0.09
11 5.5 0.24 2.78 0.67 0.67 6.03 12.00 11.39 31.5 5.80 0.09
9a 12 0.033 0.44 2.1 0.01 2.85 0.04 5.6 0.25 2.77 0.70 0.70 2.04 12.00 6.63 78.4 3.90 0.33
9b 13 0.083 0.44 2.1 0.04 2.85 0.10 5.9 0.29 2.72 0.79 0.79 13.83 12.00 17.26 47.0 8.20 0.10
14 7.9 1.13 2.48 2.80 2.80 9.19 12.00 14.07 25.1 6.69 0.06
10 15 0.190 0.11 3.7 0.02 2.85 0.06 2.80 Design 2-yr storm discharge from Lower LID system
11 16 0.640 0.04 9.6 0.03 2.31 0.06 0.06 Design 2-yr storm undetained discharge from the site.
Ridgewood Hills - Tract "B"
STORM DRAINAGE SYSTEM DESIGN
(Rational Method Procedure)
2-YR STORM EVENT
Direct Runoff Cummulative Runoff Pipe Flow Travel Time
Prepared by:L.C.O.Date:10/29/22
Basin Design Sub-Basin Runoff Time of C * A Rainfall Design Total Time Cumm.Rainfall Cumm.Design Pipe Pipe Pipe Length Velocity Time
I.D.Point Area Coeffic Concentr.Intensity Runoff of Conc.C*A Intensity Runoff Flow Slope Size Capacity
(ac)(min)(ac)(in/hr)(cfs)(min)(ac)(in/hr)(cfs)(cfs)(%)(in)(cfs)(ft)(ft/sec)(min)
Developed Condition
Upper LID System
1 1 0.493 0.73 6.9 0.36 8.85 3.18 6.9 0.36 8.85 3.18
2 2 0.789 0.85 6.4 0.67 8.72 5.87 6.4 0.67 8.72 5.87 5.87 2.92 12.00 7.93 63.3 11.51 0.09
5.87 7.53 12.00 12.73 111.8 17.68 0.11
3 3 1.081 0.53 10.8 0.57 7.48 4.26 10.8 1.24 7.48 9.30 9.30 1.22 15.00 9.29 109.7 4.94 0.37
9.30 1.22 15.00 9.29 161.2 4.94 0.54
9.30 Maximum discharge from Upper LID system
Lower LID System
4 4 1.313 0.81 7.8 1.07 8.21 8.77 7.8 1.07 8.21 8.77 8.77 5.00 12.00 10.38 16.5 5.17 0.05
5 8.77 0.00 5.00 12.00 10.38 22.8 5.17 0.07
5 6 0.193 0.67 4.1 0.13 9.95 1.28 4.1 0.13 9.95 1.28 1.28 1.15 12.00 4.98 43.5 2.37 0.31
6 7 0.064 0.73 1.9 0.05 9.95 0.47 4.4 0.18 9.95 1.75 1.75 4.37 12.00 9.70 98.5 4.28 0.38
7 8 0.144 0.70 3.3 0.10 9.95 1.00 3.3 0.10 9.95 1.00 1.00 1.00 12.00 4.64 10.5 2.07 0.08
9 4.8 0.28 9.95 2.75 2.75 2.50 12.00 7.34 156.2 3.82 0.68
8 10 0.170 0.69 4.1 0.12 9.95 1.17 4.1 0.12 9.95 1.17 1.17 1.00 12.00 4.64 12.0 2.18 0.09
11 5.5 0.39 9.63 3.80 3.80 6.03 12.00 11.39 31.5 5.80 0.09
9a 12 0.033 0.70 2.1 0.02 9.95 0.23 5.6 0.42 9.57 3.99 3.99 2.04 12.00 6.63 78.4 3.90 0.33
9b 13 0.083 0.70 2.1 0.06 9.95 0.58 5.9 0.48 9.37 4.46 4.46 13.83 12.00 17.26 47.0 8.20 0.10
14 7.9 1.54 8.19 12.65 12.65 9.19 12.00 14.07 25.1 6.69 0.06
10 15 0.190 0.54 3.7 0.10 9.95 1.01 12.65 Maximum discharge from Lower LID system
11 16 0.640 0.50 9.6 0.32 8.17 2.61 2.61 Maximum undetained discharge from the site.
Ridgewood Hills - Tract "B"
STORM DRAINAGE SYSTEM DESIGN
(Rational Method Procedure)
100-YR STORM EVENT
Direct Runoff Cummulative Runoff Travel TimePipe Flow
Drainage Design Basin
Basin No.Point Area 2-Year 100-Year 2-Year 100-Year
(ac)(cfs)(cfs)
1 1 0.493 0.48 0.73 0.62 3.18
2 2 0.789 0.71 0.85 1.49 5.87
3 3 1.081 0.09 0.53 0.22 9.30
4 4 1.313 0.64 0.81 2.08 8.77
5 6 0.193 0.37 0.67 0.21 1.28
6 7 0.064 0.50 0.73 0.09 0.47
7 8 0.144 0.44 0.70 0.18 1.00
8 9 0.170 0.42 0.69 0.20 1.17
9 10, 11, 12, 13 0.116 0.44 0.70 0.14 0.81
10 5, 14 0.190 0.11 0.54 0.06 1.01
11 15 0.640 0.04 0.50 0.06 2.61
Ridgewood Hills - Tract B
DRAINAGE DATA SUMMARY TABLE
Design RunoffComp. Runoff Coeff.
Rain Garden Analysis Worksheet - Sub-Basins 2 & 3 (Upper RG) 10-19-22.xlsm, RG 10/31/22, 11:19 AM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1.Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =40.7 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i =0.407
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV =0.15 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area)Area =81,486 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 =0.50 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =1,147 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 =6.00 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 =663 sq ft
D) Actual Flat Surface Area AActual =2001 sq ft
E) Area at Design Depth (Top Surface Area)ATop =2776 sq ft
F) Rain Garden Total Volume VT=1,194 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3.Growing Media
4.Underdrain System
A) Are underdrains provided?1
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y =1.958 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =1,147 cu ft
iii) Orifice Diameter, 3/8" Minimum DO =13/16 in
Design Procedure Form: Rain Garden (RG)
Larry Owen
Owen Consulting Group, Inc.
October 31, 2022
Ridgewood Hills Tract B (Drainage Sub-Basins 2 & 3)
Fort Collins, CO
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
Rain Garden Analysis Worksheet - Sub-Basins 2 & 3 (Upper RG) 10-19-22.xlsm, RG 10/31/22, 11:19 AM
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)
Larry Owen
Owen Consulting Group, Inc.
October 31, 2022
Ridgewood Hills Tract B (Drainage Sub-Basins 2 & 3)
Fort Collins, CO
Temporaty irrigation will be provided until such time as the native grasses in the rain garden become established. Subsequent to vegetation establishment, the temporary
irrigation improvements will be remove and reliance will be upon rainfall and snow events.
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
Rain Garden Analysis Worksheet - Sub-Basins 4 - 10 (Lower RG) 10-19-22.xlsm, RG 10/31/22, 11:20 AM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1.Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =60.9 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i =0.609
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV =0.19 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area)Area =95,040 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 =0.50 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =1,763 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 =9.00 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 =1158 sq ft
D) Actual Flat Surface Area AActual =2001 sq ft
E) Area at Design Depth (Top Surface Area)ATop =2756 sq ft
F) Rain Garden Total Volume VT=1,784 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3.Growing Media
4.Underdrain System
A) Are underdrains provided?1
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y =1.962 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =1,763 cu ft
iii) Orifice Diameter, 3/8" Minimum DO =1 in
Design Procedure Form: Rain Garden (RG)
Larry Owen
Owen Consulting Group, Inc.
October 31, 2022
Ridgewood Hills Tract B (Drainage Sub-Basins 4 - 10)
Fort Collins, CO
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
Rain Garden Analysis Worksheet - Sub-Basins 4 - 10 (Lower RG) 10-19-22.xlsm, RG 10/31/22, 11:20 AM
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:Temporaty irrigation will be provided until such time as the native grasses in the rain garden become established. Subsequent to vegetation establishment, the temporary
irrigation improvements will be remove and reliance will be upon rainfall and snow events.
Design Procedure Form: Rain Garden (RG)
Larry Owen
Owen Consulting Group, Inc.
October 31, 2022
Ridgewood Hills Tract B (Drainage Sub-Basins 4 - 10)
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
Gutter & Inlet Analysis.xlsm, Q-Allow 10/14/20, 12:31 PM
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK =13.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.020
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =25.0 ft
Gutter Width W =2.00 ft
Street Transverse Slope SX =0.020 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.028 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.015
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =19.5 25.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 6.0 inches
Allow Flow Depth at Street Crown (leave blank for no)check = yes
MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =19.3 19.3 cfs
Major storm max. allowable capacity GOOD - greater than flow given on sheet 'Q-Peak'
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
Ridgewood Hills Tract B
Gutter Analysis D/S of DP 1
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Minor storm max. allowable capacity GOOD - greater than flow given on sheet 'Q-Peak'
Gutter & Inlet Analysis 10-15-20.xlsm, Inlet On Grade 1/6/21, 10:32 AM
Project:
Inlet ID:
Design Information (Input)MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow')aLOCAL =3.0 3.0 inches
Total Number of Units in the Inlet (Grate or Curb Opening)No =2 2
Length of a Single Unit Inlet (Grate or Curb Opening)Lo =10.00 10.00 ft
Width of a Unit Grate (cannot be greater than W from Q-Allow) Wo =N/A N/A ft
Clogging Factor for a Single Unit Grate (typical min. value = 0.5)Cf-G =N/A N/A
Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1)Cf-C =0.10 0.10
Street Hydraulics: OK - Q < maximum allowable from sheet 'Q-Allow'MINOR MAJOR
Total Inlet Interception Capacity Q =0.6 3.2 cfs
Total Inlet Carry-Over Flow (flow bypassing inlet)Qb =0.0 0.0 cfs
Capture Percentage = Qa/Qo =C% =100 100 %
INLET ON A CONTINUOUS GRADE
Ridgewood Hills Tract B
Inlet Analysis at DP 1
CDOT Type R Curb Opening
Gutter & Inlet Analysis.xlsm, Q-Allow 10/15/20, 10:23 AM
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK =4.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.020
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =24.0 ft
Gutter Width W =1.50 ft
Street Transverse Slope SX =0.020 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.000 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.015
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =24.0 24.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 6.0 inches
Allow Flow Depth at Street Crown (leave blank for no)check = yes
MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs
Major storm max. allowable capacity GOOD - greater than flow given on sheet 'Q-Peak'
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
Ridgewood Hills Tract B
Gutter Analysis at DP 2
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Minor storm max. allowable capacity GOOD - greater than flow given on sheet 'Q-Peak'
Gutter & Inlet Analysis.xlsm, Inlet In Sump 10/15/20, 10:21 AM
Project =
Inlet ID =
Design Information (Input)MINOR MAJOR
Type of Inlet Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow')alocal =3.00 3.00 inches
Number of Unit Inlets (Grate or Curb Opening)No =2 2
Water Depth at Flowline (outside of local depression)Ponding Depth =6.0 6.0 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo (G) =N/A N/A feet
Width of a Unit Grate Wo =N/A N/A feet
Area Opening Ratio for a Grate (typical values 0.15-0.90)Aratio =N/A N/A
Clogging Factor for a Single Grate (typical value 0.50 - 0.70)Cf (G) =N/A N/A
Grate Weir Coefficient (typical value 2.15 - 3.60)Cw (G) =N/A N/A
Grate Orifice Coefficient (typical value 0.60 - 0.80)Co (G) =N/A N/A
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo (C) =5.00 5.00 feet
Height of Vertical Curb Opening in Inches Hvert =6.00 6.00 inches
Height of Curb Orifice Throat in Inches Hthroat =6.00 6.00 inches
Angle of Throat (see USDCM Figure ST-5)Theta =63.40 63.40 degrees
Warning 1 Side Width for Depression Pan (typically the gutter width of 2 feet)Wp =9.00 9.00 feet
Clogging Factor for a Single Curb Opening (typical value 0.10)Cf (C) =0.10 0.10
Curb Opening Weir Coefficient (typical value 2.3-3.6)Cw (C) =3.60 3.60
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70)Co (C) =0.67 0.67
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition)Qa =11.2 11.2 cfs
Inlet Capacity IS GOOD for Minor and Major Storms (>Q PEAK)Q PEAK REQUIRED =1.4 6.3 cfs
Warning 1: Dimension entered is not a typical dimension for inlet type specified.
INLET IN A SUMP OR SAG LOCATION
Ridgewood Hills Tract B
Inlet Analysis at DP 2
CDOT Type R Curb Opening
H-VertH-Curb
W
Lo (C)
Lo (G)
Wo
WP
Override Depths
Gutter & Inlet Analysis.xlsm, Q-Allow 10/15/20, 10:27 AM
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK =4.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.020
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =16.7 ft
Gutter Width W =1.50 ft
Street Transverse Slope SX =0.030 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.000 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.015
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =16.7 16.7 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 6.0 inches
Allow Flow Depth at Street Crown (leave blank for no)check = yes
MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs
Major storm max. allowable capacity GOOD - greater than flow given on sheet 'Q-Peak'
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
Ridgewood Hills Tract B
Gutter Analysis at DP 4
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Minor storm max. allowable capacity GOOD - greater than flow given on sheet 'Q-Peak'
Gutter & Inlet Analysis.xlsm, Inlet In Sump 10/15/20, 10:29 AM
Project =
Inlet ID =
Design Information (Input)MINOR MAJOR
Type of Inlet Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow')alocal =3.00 3.00 inches
Number of Unit Inlets (Grate or Curb Opening)No =2 2
Water Depth at Flowline (outside of local depression)Ponding Depth =6.0 6.0 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo (G) =N/A N/A feet
Width of a Unit Grate Wo =N/A N/A feet
Area Opening Ratio for a Grate (typical values 0.15-0.90)Aratio =N/A N/A
Clogging Factor for a Single Grate (typical value 0.50 - 0.70)Cf (G) =N/A N/A
Grate Weir Coefficient (typical value 2.15 - 3.60)Cw (G) =N/A N/A
Grate Orifice Coefficient (typical value 0.60 - 0.80)Co (G) =N/A N/A
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo (C) =5.00 5.00 feet
Height of Vertical Curb Opening in Inches Hvert =6.00 6.00 inches
Height of Curb Orifice Throat in Inches Hthroat =6.00 6.00 inches
Angle of Throat (see USDCM Figure ST-5)Theta =63.40 63.40 degrees
Warning 1 Side Width for Depression Pan (typically the gutter width of 2 feet)Wp =9.00 9.00 feet
Clogging Factor for a Single Curb Opening (typical value 0.10)Cf (C) =0.10 0.10
Curb Opening Weir Coefficient (typical value 2.3-3.6)Cw (C) =3.60 3.60
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70)Co (C) =0.67 0.67
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition)Qa =11.2 11.2 cfs
Inlet Capacity IS GOOD for Minor and Major Storms (>Q PEAK)Q PEAK REQUIRED =2.2 10.2 cfs
Warning 1: Dimension entered is not a typical dimension for inlet type specified.
INLET IN A SUMP OR SAG LOCATION
Ridgewood Hills Tract B
Inlet Analysis at DP 4
CDOT Type R Curb Opening
H-VertH-Curb
W
Lo (C)
Lo (G)
Wo
WP
Override Depths
DRAWINGS
AV
O
N
D
A
L
E
R
O
A
D
WOO
D
R
O
W
DRI
V
E
T
R
I
A
N
G
L
E
D
R
I
V
E
EXISTING INLET CORE
SOUTH WALL OF INLET BOX
TO ACCEPT PIPING FROM
PROPOSED DEVELOPMENT
PIPE ELEVATION AT
ENTRANCE TO STORM INLET
APPROXIMATELY 5070.69'
BUILDING
B
BUILDING
C
BUILDING
D
BUILDING
E
BUILDING
F
10' TYPE 'R' INLET
INLET
STRUCTURE
MANHOLE LID-2
DAYLIGHT HDPE STORM DRAIN IN EROSION
PROTECTED RUNDOWN TO RAIN GARDEN, (TYP)
SEE AREA DRAINAGE PLAN.
TEE INVERT ELEV. = 5081.15
8.6 LF 12" HDPE
N-12 STORM
DRAIN @ 2.33%
APPROX. CENTERLINE OF
DRAINAGE SWALE @ 2.0% +/-
SLOPE (TYP)
43.7 LF 12" HDPE N-12 STORM
DRAIN @ 1.20%
98.1 LF 12" HDPE N-12
STORM DRAIN @ 4.43%
TEE INVERT EL. = 5086.05
INLET INV. EL. = 5091.2
NYLOPLAST AREA INLET W/ 12" SQ. STD.
GRATE (TYP) SEE DETAIL SHT. 12
INLET INV. EL. = 5087.0
156.5 LF HDPE N-12
STORM DRAIN @ 3.13%
12.0 LF 12" HDPE N-12
STORM DRAIN @ 0.80%
31.4 LF 12" HDPE N-12
STORM DRAIN @ 1.59%
123.5 LF 12" HDPE N-12
STORM DRAIN @ 6.5% +/-
40.5 LF HDPE N-12
STORM DRAIN
@ 0.5% +/-
INLET INVERT
ELEV. = 5092.0
EXISTING 24" RCP
EXISTING 36" RCP
FOREBAY OVERFLOW WEIR, 12" TALL, WITH 1"
WIDE, FULL-DEPTH DRAINAGE SLOTS @ 1.5' +/-
CENTERS. KEY WEIR INTO SIDE EMBANKMENTS.
RAIN GARDEN CONCRETE FOREBAY WITH OVERFLOW WEIR,
FOR DETAILS, SEE SHEET 13
FOREBAY OVERFLOW WEIR, 12" TALL, WITH 1"
WIDE, FULL-DEPTH DRAINAGE SLOTS @ 1.5' +/-
CENTERS. KEY WEIR INTO SIDE EMBANKMENTS.
RAIN GARDEN CONCRETE FOREBAY WITH OVERFLOW WEIR,
FOR DETAILS, SEE SHEET 13
LOWER RAIN GARDEN OUTLET
CONTROL STRUCTURE. FOR
DETAILS, SEE SHEET 13
INDICATED INVERT OF EXISTING INLET = 7070.69
TO BE CONFIRMED PRIOR TO COMMENCEMENT
OF CONSTRUCTION.
MANHOLE LID-1
INFLOW ENERGY
DISSIPATION STRUCTURE - 1
LID SYSTEM PIPING
(SEE PROFILE ON SEPARATE SHEET)
BUILDING
A
32.7 LF HDPE
N-12 STORM
DRAIN @ 1.2% ±
TEE INV. EL. = 5086.40
106.1 LF 12" HDPE N-12
STORM DRAIN @ 4.7% +/-
TEE INVERT ELEV. = 5081.00
24.6 LF HDPE N-12 STORM
DRAIN @ 1.22%
OUTLET CONTROL
STRUCTURE - 1
107.0 LF 12" HDPE N-12
STORM DRAIN @ 1.9% +/-
4" DIA. SLOTTED PVC SUB-DRAIN PIPES
FOR DETAILS, SEE SHEET 13
4" DIA. SLOTTED PVC SUB-DRAIN PIPES
FOR DETAILS, SEE SHEET 13
10.6 LF 12" HDPE N-12
STORM DRAIN @ 1.00%
EXISTING INLET CORE
SOUTH WALL OF INLET BOX
TO ACCEPT PIPING FROM
PROPOSED DEVELOPMENT
PIPE ELEVATION AT
ENTRANCE TO STORM INLET
APPROXIMATELY 5070.69'
UPPER RAIN GARDEN
LOWER RAIN
GARDEN
SHELTER
SPORT
COURT
DOG PARK
TOT-LOT
FL
O
W
T
O
E
X
.
P
O
N
D
1
EXISTING DETENTION
POND
11b
1
2
5
15
6
12
1
2
4
5
6
9
11
0.493 0.48
0.789 0.71
1.313 0.64
0.193 0.37
0.064 0.50
0.116 0.44
0.640 0.04
11
14
8
0.170 0.42
10
0.190 0.11
13
4
10
8
9
7
3
1.081 0.09
3
FFE
5100.30
FFE
5092.50
FFE
5095.50
FFE
5094.20
FFE
5089.00
FFE
5084.35
7
0.144 0.44
NORTH
0
SCALE:1" = 30'
15'30'60'90'
Sheet:
Of:
Date:
Job No:
Drawn:
Design:
Scale:
Checked:
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BY
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05
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MAY 30, 2023
RI
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295
NOTES
1.SEE SHEETS 13-14 FOR STORM DRAIN
PLANS & PROFILES.
LEGEND
DRAINAGE BASIN I.D.
DESIGN POINT
OVERLAND
FLOW DIRECTION
#
#
0.000.000 MINOR STORM RUNOFF COEFFICIENT
DRAINAGE BASIN AREA (AC)
DRAINAGE BASIN
61
1
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1
Ridgewood Hills Fifth Filing
DRAINAGE DATA SUMMARY TABLE
Drainage Basin
No.Design Point Basin Area (ac)
Comp. Runoff Coeff.Design Runoff
2-Year 100-Year 2-Year 100-Year
(cfs)(cfs)
1 1 0.493 0.48 0.73 0.62 3.18
2 2 0.789 0.71 0.85 1.49 5.87
3 3 1.081 0.09 0.53 0.22 9.30
4 4 1.313 0.64 0.81 2.08 8.77
5 6 0.193 0.37 0.67 0.21 1.28
6 7 0.064 0.50 0.73 0.09 0.47
7 8 0.144 0.44 0.70 0.18 1.00
8 9 0.170 0.42 0.69 0.20 1.17
9 10, 11, 12, 13 0.116 0.44 0.70 0.14 0.81
10 5, 14 0.190 0.11 0.54 0.06 1.01
11 15 0.640 0.04 0.50 0.06 2.61
05
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