HomeMy WebLinkAboutUPTOWN PLAZA - PDP - PDP130025 - REPORTS - DRAINAGE REPORTConclusions
This design and the accompanying plan is in compliance with
the City of Fort Collins storm drainage requirements,, and
provides sufficient drainage control to mitigate any effects to
downstream sites. Sufficient detention has been provided onsite-
to reduce total 300 yr developed runoff to the 2'yr'historic
rate.
Street should be included in our report. However, we. are
ln requesting a ,.variance from City requirements since this roadway'
l was constructed before this.PUD was assembled, and thereforeshas
already been incorporated into other studys. Additionally, we
feel that in making the drainage work for this site, without..ahe,,.-
additional street area, we have already maximized detention
Runoff will be as follows: runoff from subbasin A (10`yr:'
1.06 cfs, 100. yr: 1.80 cfs) will be detained in a detention pond'
(645 cu ft) located in the paved drive on the north side._then
will discharge at a reduced rate 0.-8 cfs) into a second'pond
located. in the landscaped area to the south. Runoff -.from
subbasin C (10 yr: .1.31 cfs, 100 yr: 2.21 cfs) will be °detained
by a pond (1019 cu ft) again located in a drive, and also will
also discharge at a reduced rate o.5 cfs) into the south "•.!
detention pond.. Runoff from subbas:iL.I�will.not be detained... but.':.. -
will be directed to a trench drain at the southeast entrance .and
in turn into the south'pond. Flow-from'D into the pond will be
0 70:cfs for the 10 yr storm and .18 for the 100 yr storm.
Since the south pond 3s locat within subbasin E, runoff
frorq subbas' n E (10 yr 0:.30 cf.s, 100 yr: 0.57'cfs)-too will .be.
-_ _
detained in: this pond.. Spillage from the c wash will hot be
directed: into the .sanitary. system, but will be routed through
:
trench drains and into the pond. } - t0
g3f , t +
_ Total 10.0 yr.,flow into the south.pond, will be 3.10 cfs...
Pond.. volume will be 6994.cu ft. Discharge will be ;through a.
3 3/.16 inch orifice which will allow a 100. yr release of. 0.-42
cfs.. This flow will be channeled into an existing 12" storm
sewer on West 'Elizabeth the capacity of which is 4.07.cfs.-
.Runoff from subbasin F will flow undetained`,from the site at
C re leas C-
a 10.0; yr: rate of 0.35 'cfs.. Total 100 yr developed << i%al o.9£ will
thus. be 0.71 „cfs which compares favorably with the two year
tip'
historic rate of, .7: cfs:
Flow from the east landscaped area onto the adjacent site to
the.. east.'.will..be' .087 x .20 x 4.00 .07 cfs (AxCxI) for the; 10
year`itorm.and .087 x .'25 x 6.40 = .14 cfs for the 100. This.`
represents a substantial reduction from the existing since the '
�r� z o
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General Location..and_Description
The site is located on the south side of Elizabeth Street,
just west of -Shields and contains 1.465 acres. It is part of
Taco Bell to the west `'
..,:Fairvew.'Shoppng Center. with an existing. ,
a laundry ,mat and restaurant to the east, and:vacant property to
the`southc. Planned for this site is'a'Diamond Shamrock service
station, convenience store and car wash.
Drainage Design Criteria
This drainage stddy'has been prepared using. the...Rati'onal
Method since thesite is less thai 200 acres. Calculations have.
been performed for the ,2, 10 and lob year stormDeveloped flows.:_ p
from the site has been _;limited to 'the. two year,historic rate.
Drainage Facility_ Design
The site has been divided into five subbasinss A, C', D, E,
and F. All subbasinsp,except. for F, drain to detention ponds
located in three areas on the:. site. Total release has been
limited to the two year historic rate.
'Subbasins A, C and D'encompass'almost a11. the paved area of.
the site .in addition to the store.. ar
id, subbasin E.contains
:i
the car'wash and most of 'the landscaping including the large
detentionpond to the south, and subbasin F represents the
remainder'or.mostly landscaped fringes to the north and east`of
the property.,
According'to city requirements, the south half of Elizabeth
16MO l CO downloaded on Aug ]9 2013 froFn the C�ryyof Fort Collins Pu6he Recoiils,Wabsite http llcfrydocs fcgov comma
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litional"information or an official copy, please;conlact City,oFF,ort �ollms UniiGes,700pWootl Sireet FortColluis, CO SQ52,4:USA
Prepared For:
"Diamond Shamrock Refining And -.:Marketing Company
520 E. 56th Avenue
Denver,.Colorado '80216
Attn: Ed Kress.
Prepared',By
Gallocsay, Romero and Associates, Inc.
12449 E. 39th Avenue
Denver,.Colorado 80239
Attn- Roger Barrin'gerIV
BORING LOG NO. DP-2
Page 1 of 1
PROJECT: Uptown Plaza
CLIENT: D.K. Investments, Inc.
Windsor, Colorado
SITE: 1501 West Elizabeth Street
Fort Collins, Colorado
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ee LOCATION S6dtibK A-2
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Latitude: 40.573629' Longitude:-105.103103°
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Approximate Surface Elev: 5034.85 (FL)+/-
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PTH ELEVATION Ft
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SANDY LEAN CLAY, dark brown
3.0 5032+/
Boring Terminated at 3 Feet
Stratification lines are approximate. In -situ, the transition may be gradual.
Advancement Method:
See Exhibit A-3 for description of field
Notes:
34nch hand auger
procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
Abandonment Method:
Slotted PVC pipe vrith filter sand pack
abbreviations.
WATER LEVEL OBSERVATIONS
1 terra con
Boring Started: 6/20/2013
Boring Completed: 6/20/2013
-Si-7While drilling
Drill Rig: Hand auger
Driller. Bryce Johnson
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
lProject No.: 20135023
Exhibit: A-11
BORING LOG NO. DP-1
Page 1 of 1
PROJECT: Uptown Plaza
CLIENT: D.K. Investments, Inc.
Windsor, Colorado
SITE: 1501 West Elizabeth Street
Fort Collins, Colorado
LOCATION SeeExhbitA-2
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Latitude:40.573953° Longitude:-105.103496'
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Approximate Surface Elev: 5038.95 (Ft.) +/-
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DEPTH ELEVATION
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R1 I - LEAN CLAY with SAND and GRAVEL, brown
to dark brown
3.0 5036+/
Boring Terminates/ at 3 Feet
Stratification lines are approximate. In -situ, the transition may be gradual.
Advancement Method:
See Exhibit A-3 for description of field
Notes:
44nch solid -stem flight augers
procedures.
See Appendix B for description of laboratory
procedures and additional data (f any).
See Appendix C for explanation of symbols and
Abandonment Med)od:
Slotted PVC pipe with filter sand pack.
abbreviations.
WATER LEVEL OBSERVATIONS
�erra Co■ ■
1901 Sharp Point Drive, Suite C
Boring Started: 6/20/2013
Boring Completed: 6/20/2013
No free water observed while drilling.
Drill Rig: CME-45
Driller. Odell Drilling, Inc.
-
Fort Collins. Colorado
Project No.: 20135023
Exhibit: A-10
LEVEL
10
ONE WA-1 00
APPROXIMATE SCALE 1
+ Approximate Boring Location
01 20' 40' 4 Approximate Field Hydraulic ConductiAty Location
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT A& Approximate Location of Temporary Benchmark
INTENDED FOR CONSTRUCTION PURPOSES (Top Man Hole Lid —Elevation 5,041.2')
ProjectManager. Project No,
EDEI 2 135023 BORING LOCATION PLAN EXHIBIT
Drawn By: BCJ Scale; 1 0 1rerracon Uptown Plaza
Check By: EDB FtleNarne: Comulting I Enginmm & Scientists 1501 West Elizabeth Street A-2
App-,ed By: Dam: �d
EDB 6/20/2013 F. MM Fort Collins, Colorado
APPENDIX A
FIELD EXPLORATION
Geotechnical Engineering Report 1 f�rr�con
Uptown Plaza ■ Fort Collins, Colorado
July 24, 2013 ■ Terracon Project No. 20135023
Permeable pavements require periodic inspection and cleaning. Consideration should be given
to installing signage to restrict heavily loaded vehicles (i.e. trash trucks, delivery trucks, etc.)
from driving on permeable pavement areas. Also, maintenance of permeable pavements should
be completed by properly trained workers.
5.0 GENERAL COMMENTS
Terracon should be retained to review the final design plans and specifications so comments
can be made regarding interpretation and implementation of our geotechnical recommendations
in the design and specifications. Terracon also should be retained to provide observation and
testing services during grading, excavation, foundation construction and other earth -related
construction phases of the project.
The analysis and recommendations presented in this report are based upon the data obtained
from the borings performed at the indicated locations and from other information discussed in
this report. This report does not reflect variations that may occur between borings, across the
site, or due to the modifying effects of construction or weather. The nature and extent of such
variations may not become evident until during or after construction. If variations appear, we
should be immediately notified so that further evaluation and supplemental recommendations
can be provided.
The scope of services for this project does not include either specifically or by implication any
environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or
prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the
potential for such contamination or pollution, other studies should be undertaken.
This report has been prepared for the exclusive use of our client for specific application to the
project discussed and has been prepared in accordance with generally accepted geotechnical
engineering practices. No warranties, either express or implied, are intended or made. Site
safety, excavation support, and dewatering requirements are the responsibility of others. In the
event that changes in the nature, design, or location of the project as described in this report are
planned, the conclusions and recommendations contained in this report shall not be considered
valid unless Terracon reviews the changes and either verges or modifies the conclusions of this
report in writing.
Responsive a Resourceful ® Reliable 22
Geotechnical Engineering Report l��rracon
Uptown Plaza ® Fort Collins, Colorado
July 24, 2013 ■ Terracon Project No. 20135023
Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes
from the time the water is added to the mix.
Longitudinal and transverse joints should be provided_ as needed in concrete pavements for
expansion/contraction and isolation per ACI 325. The location and extent of joints should be
based upon the final pavement geometry. Joints should be sealed to prevent entry of foreign
material and doweled where necessary for load transfer.
Although not required for structural support, a minimum 4-inch thick aggregate base course
layer is recommended for the PCC pavements in heavy-duty areas to help reduce the potential
for slab curl, shrinkage cracking, and subgrade "pumping" through joints. Proper joint spacing
will also be required for PCC pavements to prevent excessive slab curling and shrinkage
cracking. All joints should be sealed to prevent entry of foreign material and dowelled where
necessary for load transfer.
For areas subject to concentrated and repetitive loading conditions such as dumpster pads,
truck delivery docks and ingress/egress aprons, we recommend using a portland cement
concrete pavement with a thickness of at least 6 inches underlain by at least 4 inches of
granular base. Prior to placement of the granular base the areas should be thoroughly
proofrolled. For dumpster pads, the concrete pavement area should be large enough to support
the container and tipping axle of the refuse truck.
Pavement performance is affected by its surroundings. In addition to providing preventive
maintenance, the civil engineer should consider the following recommendations in the design
and layout of pavements:
® Site grades should slope a minimum of 2 percent away from the pavements;
a The subgrade and the pavement surface have a minimum 2 percent slope to promote proper
surface drainage;
o Consider appropriate edge drainage and pavement under drain systems;
• Install pavement drainage surrounding areas anticipated for frequent wetting;
a Install joint sealant and seal cracks immediately;
a Seal all landscaped areas in, or adjacent to pavements to reduce moisture migration to
subgrade soils; and
® Placing compacted, low permeability backfill against the exterior side of curb and gutter.
4.7.3 Pavements — Maintenance
Preventative maintenance should be planned and provided for an ongoing pavement
management program in order to enhance future pavement performance. Preventive
maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching)
and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first
priority when implementing a planned pavement maintenance program and provides the highest
return on investment for pavements.
Responsive ® Resourceful o Reliable 21
Geotechnical Engineering Report
Uptown Plaza s Fort Collins, Colorado
July 24, 2013 a Terracon Project No. 20135023
Conventional Pavements
Merracon
Traffic Area
r
X-AltaffaMe.,
RecommentledPavement'Thickness(
,��kAsphaltrc
Concrete
°A re atefi�PortlandCement�
_,
Base Coursed
inc hes)
, Concrete
1Rtal, .a
Automobile Parking
(light duty)
A
3
4
-
7
B
-
-
5
5
Drive Lanes
and Loading Areas
(heavy duty)
A
4
6
-
10
B
-
4
5
9
Permeable Pavements
Ma,��ffiC
f-.
Y s �d �"
"M
B Recomm�. en
Ilk f 4 YS
ded Pid�
avement Thickness
fi ' i3de
(inches) g> p ` p
. „
Alternatives
Porous ar
Interlocking Concrete
re ate ' ` `
g -
Area
i As halt
Permeable
Corcrete
Paveme t
�
tal
Base tNull:
,z
��3
Course
A
3
6
9
Automobile
Parking
B
6
3
9
----
C
-
Typically 3'/8
3
6 Ye
Terracon recommends the design and construction of permeable pavements should be
completed by a specialty contractor who has demonstrated experience with placing,
compacting, finishing, edging, jointing, curing, and protecting permeable pavements. There are
several choices for base course depending upon which type of permeable pavement is chosen.
Terracon recommends constructing perimeter curbing around permeable pavements and
between conventional and permeable pavements to reduce infiltration of water below moisture
sensitive subgrades.
Where rigid pavements are used, portland cement concrete should be produced from an
approved mix design with the following minimum properties:
s�y L &'
�£P`
hViaileu-e ,G
i�, dMrtP
Compressive strength
4,000 psi (mimum)
Cement type
Type I or II cement
Entrained air content (%)
5 to 8
Concrete aggregate
ASTM C33 and CDOT Section 703
Responsive m Resourceful ■ Reliable 20
Geotechnical Engineering Report 1r�rrac®n
Uptown Plaza a Fort Collins, Colorado
July 24, 2013 a Terracon Project No. 20135023
evaluated at the time of pavement construction for signs of disturbance or instability. We
recommend the pavement subgrade be thoroughly proofrolled with a loaded tandem -axle dump
truck prior to final grading and paving. All pavement areas should be moisture conditioned and
properly compacted to the recommendations in this report immediately prior to paving.
4.7.2 Pavements — Permeable Pavement Subgrade Preparation
Unlike conventional pavements, permeable pavement subgrades are not compacted. When
preparing the subgrade for permeable pavements, care should be taken to excavate the
required reservoir storage volume without disturbing the underlying soils.
Groundwater was encountered at depths of about 3.5 and 3.7 feet below existing site grades in
the portion of the site planned for permeable pavements. Shallow groundwater conditions will
limit the thickness of the rock reservoir layer used to store the storm water runoff. Shallow
groundwater will also reduce infiltration rates as the water stored within the rock reservoir layer
infiltrates into the groundwater.
4.7.2 Pavements — Design Recommendations
Design of pavements for the project have been based on the procedures outlined in the 1993
Guideline for Design of Pavement Structures prepared by the American Association of State
Highway and Transportation Officials (AASHTO) and the Larimer County Urban Area Street
Standards (LCUASS).
A sample of the fill materials selected for swell -consolidation testing exhibited no movement when
wetted under an applied pressure of 200 psf which is less than the maximum 2 percent criteria
established for determining if swell -mitigation procedures in the pavement sections are required
per LCUASS standards. Therefore, we do not believe swell -mitigation of the subgrade materials
prior to pavement operations is necessary.
Traffic patterns and anticipated loading conditions were not available at the time that this report
was prepared. However, we anticipate that the new parking areas (i.e., light -duty) will be
primarily used by personal vehicles (cars and pick-up trucks). Delivery trucks and refuse
disposal vehicles will be expected in the drive lanes and loading areas (i.e., mediurr'-duty). A
maximum of 10 trucks per week were considered developing our recommendations. If heavier
traffic loading is expected, Terracon should be provided with the information and allowed to review
these pavement sections.
Rigid pavement design is based on an evaluation of the Modulus of Subgrade Reaction of the
soils (k-value), the Modulus of Rupture of the concrete, and other factors previously described.
A Modulus of Subgrade Reaction of 200 pci, and a Modulus of Rupture of 600 psi, were used
for pavement concrete. The rigid pavement thickness was determined on the basis of the
AASHTO design equation.
Recommended minimum pavement sections are provided in the table below.
Responsive o Resourceful a Reliable 19
Geotechnical Engineering Report lrorraeon
Uptown Plaza a Fort Collins, Colorado
July 24, 2013 a Terracon Project No. 20135023
moist. The soils encountered in DP-2 were also visually classified in the field and consisted of
native sandy lean clay. The soils encountered in DP-2 were very moist to wet.
Groundwater was not encountered in field hydraulic conductivity test boring DP-1. Groundwater
was encountered in field hydraulic conductivity test boring DP-2 at a depth of approximately 2.7
feet below existing site grade while drilling. During delayed groundwater measurements taken
in other borings completed on the site, groundwater was measured in Boring No. 5 (located
near hydraulic conductivity test boring DP-2) at a depth of approximately 3.8 feet below the
existing ground surface. The groundwater levels measured in our borings at the time of our field
study were used when calculating the field hydraulic conductivity at this site.
4.6.2 Hydraulic Conductivity - Discussion
The field hydraulic conductivity testing performed as part of our study was developed by the
U.S. Bureau of Reclamation and was referred to as the well permeameter method. The field
hydraulic conductivity tests were performed by adding water to the test holes to maintain a
constant water level (constant head test). The calculated hydraulic conductivity value for field
hydraulic conductivity test holes DP-1 and DP-2 were 3 feet per day (ft/day) and 108 May,
respectively. The calculated value for DP-1 is within the expected ranges for the soil types
encountered in our borings and is considered to be a representative value. The calculated
value for DP-2 is much higher than the expected ranges for the soil types (upper clays)
encountered in our borings. However, a layer of clean to silty gravel with sand was encountered
in some of the other borings completed at this site at a depth of approximately 6 feet below
existing site grades. It is likely the gravel layer extends below most of the site and would be
expected near the bottom of DP-2. We believe the comparatively higher field hydraulic
conductivity value measured in DP-2 is due to the higher flow rates that occur as water flows
into the gravel layer below the site. The test results and schematics of the field hydraulic
conductivity test hole details, Exhibit B-7 and B-8, are included in Appendix B.
The field hydraulic conductivity test results and soils encountered in our borings completed at
the site indicate infiltration of storm water retained in a reservoir below permeable pavements
into the soils underlying this site will be favorable for the design of permeable pavements.
However, shallow groundwater conditions may limit the allowable depth of the retention area
below permeable pavements. The slotted PVC pipe was left in place for future groundwater
readings.
4.7 Pavements
4.7.1 Pavements — Conventional Subgrade Preparation
On most project sites, the site grading is accomplished relatively early in the construction phase.
Fills are typically placed and compacted in a uniform manner. However as construction
proceeds, the subgrade may be disturbed due to utility excavations, construction traffic,
desiccation, or rainfall/snow melt. As a result, the pavement subgrade may not be suitable for
pavement construction and corrective action will be required. The subgrade should be carefully
Responsive €a Resourceful a Reliable 18
Geotechnical Engineering Report
Uptown Plaza Fort Collins, Colorado
July 24, 2013 0 Terracon Project No. 20135023
should refer to ACI 302 for procedures and cautions regarding the use and placement
of a vapor retarder.
® Other design and construction considerations, as outlined in the ACI Design Manual,
Section 302.1 R are recommended.
4.5.2 Floor Systems - Construction Considerations
Movements of slabs -on -grade using the recommendations discussed in previous sections of this
report will likely be reduced and tend to be more uniform. The estimates discussed above
assume that the other recommendations in this report are followed. Additional movement could
occur should the subsurface soils become wetted to significant depths, which could result in
potential excessive movement causing uneven floor slabs and severe cracking. This could be
due to over watering of landscaping, poor drainage, improperly functioning drain systems,
and/or broken utility lines. Therefore, it is imperative that the recommendations presented in
this report be followed.
4.6 Hydraulic Conductivity Testing
Two (2) hydraulic conductivity borings, presented as Exhibits A-10 and A-11, and designated as
Boring DP-1 and DP-2, were performed to depths of approximately 3 feet below existing site
grades. Logs of the borings along with a Boring Location Plan (Exhibit A-2) are included in
Appendix A.
4.6.1 Hydraulic Conductivity— Field Investigation
We understand a carwash building previously occupying the site was demolished and removed
prior to our field investigation. During our field investigation, two (2) field hydraulic conductivity
test borings were completed to a depth of approximately 3 feet below existing site grades. The
field hydraulic conductivity test borings were completed in areas of. the site planned for
permeable pavements. One of the field hydraulic conductivity test borings (DP-1) was
completed in the area where the car wash building previously occupied the site. The second
field hydraulic conductivity test boring (DP-2) was completed in the area of the site where we
believe an existing detention area is present.
Field hydraulic conductivity test boring DP-1 was drilled with a CME-45 truck mounted drill rig with
4-inch outer diameter solid -stem augers. Field hydraulic conductivity test boring DP-2 was
completed with a 33/<-inch hand auger. During the drilling operations, lithologic logs of the borings
were recorded by the field engineer. Slotted PVC pipe was placed in each of the field hydraulic
conductivity test holes full -depth and the annulus surrounding the slotted PVC pipe was filled with
clean filter sand. The borings were then saturated with water and left to stabilize overnight.
The soils encountered in DP-1 were visually classified in the field and consisted of existing fill
materials comprised of lean clay with sand and gravel. The existing fill was slightly moist to
Responsive c Resourceful m Reliable 1 17
Geotechnical Engineering Report l�err�eon
Uptown Plaza a Fort Collins, Colorado
July 24, 2013 s Terracon Project No. 20135023
F
N�
Elevation of
3a
s
DepthAo groundwater ,> jDepth to groundwater,
.
P 9
Bonng�Nurriber s
ti 9 w _ ��
- groundwater 8,days k q
while dnllmg, ft �, � , 1 day after dnlhng, ft �
�� ,�� V
t <
�i a
after dnllmg ft �� 1
_
�
1
6 �--=-2.5
5,035.8
2
6 6.1
5,032.6
3
13.5 ! 4.9
5,034.9
4
6 3.2
5,035.7
5
Not encountered 3.8
5,034.5
6
Not encountered 3.5
5,035.9
DP-1
Not encountered i --
--
DP-2
2.7
-
These observations represent groundwater conditions at the time of the field exploration, and
may not be indicative of other times or at other locations. Groundwater levels can be expected
to fluctuate with varying seasonal and weather conditions, and other factors.
Groundwater level fluctuations occur due to seasonal variations in amount of rainfall, runoff and
other factors not evident at the time the borings were performed. Therefore, groundwater levels
during construction or at other times in the life of the structure may be higher or lower than the
levels indicated on the boring logs. The possibility of groundwater level fluctuations should be
considered when developing the design and construction plans for the project.
Fluctuations in groundwater levels can best be determined by implementation of a groundwater
monitoring plan. Such a plan would include installation of groundwater piezometers, and periodic
measurement of groundwater levels over a sufficient period of time.
4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION
4.1 Geotechnical Considerations
Based on subsurface conditions encountered in the borings, the site appears suitable for the
proposed construction from a geotechnical point of view provided certain precautions and
design and construction recommendations described in this report are followed. We have
identified geotechnical conditions that could impact design and construction of the proposed
structure, pavements, and other site improvements.
4.1.1 Existing, Undocumented Fill
As previously noted, existing undocumented fill was encountered to depths up to about 4 feet in
the borings drilled at the site. Deeper fills may be present on the site where buried tanks were
removed during demolition of the gas station previously occupying the site. We do not
recommend supporting shallow spread footing foundations or floor slabs on the existing fill
Responsive ® Resourceful a Reliable 4
Geotechnical Engineering Report
Uptown Plaza
1501 West Elizabeth Street
Fort Collins, Colorado
July 24, 2013
Terracon Project No. 20135023
Prepared for:
D.K. Investments, Inc.
Windsor, Colorado
Prepared by:
Terracon Consultants, Inc.
Fort Collins, Colorado
APPENDIX F
EXCERPTS FROM OTHER REPORTS
Attachment C
®i HEC-RAS CROSS SECTION
BASE FLOOD ELEVATION
1/2-FOOT FLOOOWAY BOUNDARY
100-YR FLOODPLAIN BOUNDARY
FLOW PATH DIVIDE
®AREAS OF FLOODING DETERMINED
BY APPROXIMATE METHODS
1501 W Elizabeth
Current Effective
Attachment 6
r'q 1 11
_... APPENDIX E.2
EUZABETH STREET/CONtiRTUT10N AVENUE FLOW PATH �' .
1"=200' N A W C raEx J mu, inc
Ow - 100-YEAR FLOODPLAIN MAP PLATE 8,
w"'m "' FULLY DEVELOPED CONDMONS WITH EXISTING FACILITIES
m �rr��.�rair..pa�mma o... w
t
M1.moa..o r.meumi
Attachment A
City Floodplain Waiver Form
(Based on City of Fort Collins Code, Section 10-114 or 10-144)
Sedlon A Property,lnformation
Property address or legal description 1501 West Elizabeth Street, Parcel # 9715440-001
Applicant name Patricia ICroetch, P.E. Phone 970-686-6939
Applicant address 700 Automation Dr., Windsor, CO 80550
Sedian B P! L60dsed Project Information'
r
• Description of proposed project (check all that apply):O new construction [I additionElremodel F—Iredevelopment
❑accessory structure ❑✓ fill ❑✓ excavation ❑change of use ❑other
(Attach additional descriptions and drawings as necessary.)
Current use (check one):❑residential ❑✓ non-residential ❑mixed-use❑vacantground
Proposed use (check one): ❑residential ✓❑non-residential ❑ mixed -use ❑other
If non-residential or mixed -use, describe use in more detail: Commercial use
• Foundation type (check one): Qslab on grade basement❑crawl space ❑enclosed area above grade
- ---
Section C Waiver Information
• Base flood elevation (100-year flood level): 5041.9ft NGV41(City) N/A (FEMA)
• Regulatory flood protection elevation: N/A
• Floodplain designation: ❑FEMA ✓❑City Floodplain name: Canal Importation Floodway:❑yes ❑✓ no
• Proposed lowest floor elevation (refer to city code io-37(d)): N/A (attach drawing)
• Name of capital project that will remove property from floodplain: CIPO
• Section(s) of City Code for which a waiver is being requested: 10- 1 39(1)and 10-37(C)(3)(a)
• What is the waiver request? Request to use post-CIPO construction hydrologic and hvdraulic information to
remove the parcel from the floodplain and from the standards of Chanter 10 of Citv Code.
The applicant hereby certifies that the above information, along with the attached plans and project descriptions, are correct.The applicant
agrees to comply with the provisions of the zoning ordinance, building code, all other applicable sections of City Code, Land Use Code, City
Plan and all other lays and ordinances affecting the construction and occupancy of the proposed building. The applicant understands that
if this waiver is approved, the structure and its occupants may be more susceptible to flood damage and, if in a FEMA floodplain, the cost of
flood insurance may increase for the property.
The applicant understands that new structures that are constructed pursuant to this waiver and upon completion of the relevant capital
project, are determined to not have been removed fro the floodway or flood fringe as anticipated at the time of said waiver and will be
deemed to benon-conforms u s nd all it
u activities and development shall be subject to the requirements of Chapter 10 of City
Code as the same would a ly to any co o g structure. //n
Signature of applicant: Date: l��Z3kt3
Capital project Notice to Proceed date: Expected capital project completion date:
Technical analysis for capital project:
.72
dCapital project will completely remove property from floodplain (check one) p yes 0 no ❑ unsure
ns Notes:
01
V
oWaiver.: ❑ approved ❑ denied�c.'i-11Jt3dEilities General Manager. ""r"r ; — ate:
floodptoin Waiver fa m 1106
be completed without elevating or floodproofing
City Municipal Code.
of
Port
°Colllns
per the floodplain standards of Chapter 10 of
CURRENT EFFECTIVE HYDRAULIC MODEL — 2001
Attachment B is Plate 8 of the 100-year floodplain in the Elizabeth Street/Constitution Avenue
Flow Path, and shows the BFE and the HEC-RAS cross -sections along Elizabeth Street. 1501
W. Elizabeth St. has been highlighted and cross -hatched, and as can be seen, a portion of the
property is in the current effective floodplain.
POST PROJECT (CIPO) HYDRAULIC MODEL — 2013
Attachment C is Plate 8 of the 100-year floodplain in the Elizabeth Street Channel Flow Path,
and shows the BFE and the HEC-RAS cross -sections that remain along the Elizabeth Street
flow path, after updating the hydraulic model to reflect the improvements made as part of the
CIPO project. 1501 W. Elizabeth St. has been highlighted and cross -hatched. Please note that
the entire lot has been completely removed from the 100-year post project floodplain.
FLOODPLAIN DOCUMENTATION
In addition to the attachments, the following documents are available for review and inspection
in the Stormwater Master Planning and Floodplain Administration office:
"Volume III, Technical Appendix E, F Canal Importation Basin Master Drainage Plan";
Anderson Consulting Engineers; May 11. 2001
"As -Built Design Summary and Floodplain Modeling Report for Canal Importation Ponds
and Outfall Project (CIPO)"; Ayres Associates; February, 2013
APPLICABLE CODE
• 10-140(1) —new mixed -use construction is permitted in the flood fringe of a City basin,
as long as the standards of 10-37 or 10-38 are satisfied.
• 10-37(c)(3)(a) — new structures must be elevated eighteen inches above the base flood
elevation.
WAIVER AUTHORITY
• 10-144 — The General Manager may waive floodplain requirements if he is satisfied that
there is sufficient degree of certainty that the property will be removed from the
floodplain as a result of a City funded capital project. The construction of the project and
the hydraulic analysis are complete and accepted by City staff and awaiting adoption by
City Council.
FLOODPLAIN WAIVER
Stormwater staff recommends that the floodplain waiver be approved.
If there are any questions, or if additional information is needed, please contact Stormwater
staff.
cc: Jon Haukaas, Water Engineering and Feld Operations Manager
Brian Varrella, Floodplain Administrator
Utilities
City
electric o wastewater water
Of
F AM,
d Street
PO Box 580
Collins
Fart Collins. CO 80522
For700 t Collins.
970.221.6700
970-221.6619619 —fax
970.224.6003 — Too
utiliBes@fcgov corn
kgov.com/utiflues
MEMORANDUM
DATE: November 1, 2013
TO: Brian Janonis, Utilities Executive Director
FROM: Mark Taylor, Civil Engineer IIA*
Ken Sampley, Stormwater and Floodplain Program Manager�k
RE: Floodplain waiver request for 1501 West Elizabeth Street
PURPOSE/EXECUTIVE SUMMARY
A proposed redevelopment (mixed use with multi -family over commercial) project at 1501 W
Elizabeth Street can benefit from a City floodplain waiver. The project is located in the Canal
Importation Basin Floodplain and downstream of the capital improvements associated with the
Canal Importation Ponds and Outfall Project (CIPO) project.
The CIPO project has completely removed this property from the 100-year floodplain. The
effect of these improvements on flood hazard mapping, as studied and documented in
February, 2013 by Ayres Associates, have not been adopted into the Stormwater Master Plan
by City Council. Your review and/or approval of the waiver is requested to allow the
development to move forward with the benefit of more accurate flood risk information, consistent
with the standards of Section 10-144 of Chapter 10 of City Municipal Code. This will remove
requirements to elevate mixed -use residential structures in the City flood fringe currently
outlined in Sections 10-37 and 10-140.
BACKGROUND
A proposal to construct a new 2-story mixed use building with multi -family residential on the
second floor and commercial use on the first floor is in the process of being reviewed by City
staff. The previous structure, formerly operated as service station/convenience store, has been
demolished. A portion of the property is within the flood fringe of the City -regulated 100-year
Canal Importation Basin floodplain, as shown in Attachment B.
The current effective hydraulic model on West Elizabeth Street was established by Anderson
Consulting Engineers as part of the Canal Importation Basin Master Plan, in 2001. The City
contracted with Ayres Associates to update the hydraulics and hydrology in the Canal
Importation Basin following the completion of the CIPO improvements. The updated hydraulic
model, which was completed in February, 2013, has been reviewed and accepted by City staff,
but has not been adopted by City Council at this time.
REQUEST
The developer of 1501 W. Elizabeth Street has requested that the City grant a floodplain waiver,
included as Attachment A, so that the most up-to-date hydraulic data may be used, which
completely removes the property from the 100-year floodplain and enables the development to
APPENDIX E
FLOODPLAIN WAIVER
SEDIMENT/EROSION CONTROL
BEST MANAGEMENT PRACTICES (BMPs)
COST OPINION SPREADSHEET
1501 West Elizabeth (Uptown Plaza)
Item
No.
BMP
ID
Unit
Installation
Unit Cost
Quantity
Cost
1
Check Dam
CDR
LF
$0.00
2
Check Dam (Reinforced)
CDR
LF
$0.00
3
Concrete Washout Area
CWA
EA
$1,200.00
1
$1,200.00
4
Construction Fence
CF
I LF
$0.00
5
Construction Markers
CM
LF
$0.00
6
Culvert Inlet Filter
CIF
LF
$0.00
7
Dewatering
DW
EA
$0.00
8
Diversion Ditch (Unlined)
DD
LF
$0.00
9
Diversion Ditch (ECM or plastic)
DD
LF
$0.00
10
Sediment/Erosion Control Matting
ECM
SY
$0.00
11
Inlet Protection
IP
LF
$10.00
16
$160.00
12
Reinforced Rock Berm
RRB
LF
$0.00
13
Sediment Basin(')
SB
LF
$0.00
14
Sediment Control Log (Wattle)
SCL
LF
$0.00
15
Seeding and Mulching
SM
AC
$0.00
16
Sift Fence
SF
LF
$3.00
885
$2,655.00
17
Rock Sock
RS
LF
$10.00
35
$350.00
18
Stabilized Staging Area
SSA
SY
$0.00
19
Surface Roughening
SR
AC
$0.00
20
Temporary Stream Crossing
TSC
EA
$0.00
21
Topsoil (6-inch Lift)
TSL
AC
$0.00
22
Vehicle Tracking Control(2)
VTC
EA
$1,500.00
1
$1,500.00
Subtotal $5,865.00
Maintenance & replacements (50%) $2,932.50
#1 Erosion control amount 1 $8,797.50
#2 Reseeding AC $1,200 1.28 $1,536.00
Erosion control escrow (greater of #1 & #2) $8,797.50
CONSTRUCTION SEQUENCE
PROJECT: 1501 W ELIZABETH (UPTOWN PLAZA) DATE: 1/29/14
CONSTRUCTION PHASE (MONTH)
1
2
3
4
5
6
7
8
9
10
11
12
DEMOLITION
GRADING INCLUDES OVERLOT
OVERLOT
DETENTION / WO PONDS
SWALES, DRAINAGEWAYS, STREAMS
PIPELINE INSTALLATION INCLUDES OFFSITE
WATER
SAINITARY SEWER
STORM SEWER
CONCRETE INSTALLATION (INCLUDES OFFSITE)
AREA INLETS
CURB INLETS
CURB AND GUTTER
PAVEMENT INSTALLTATION
FINE GRADING BASE COURSE INSTALL
PAVEMENT
BEST MANAGEMENT PRACTICES
APPENDIX D
BMP SCHEDULE & COST ESTIMATE
f7
Detention Pond Outlet Sizing
100-YEAR
LOCATION:
1501 West Elizabeth
PROJECT NO:
350-01
COMPUTATIONS BY:
PPK
DATE:
1/28/2014
Submerged Orifice Outlet:
release rate is described by the orifice equation,
Qo = Ck sgrt( 2g(h-E.))
where Qo = orifice outflow (cfs)
Ca = orifice discharge coefficient
g = gravitational acceleration = 32.2 ft/s
A, = effective area of the orifice (ft`)
Eo = greater of geometric center elevation of the orifice or d/s HGL (ft)
h = water surface elevation (ft)
Qmax =
outlet pipe dia = D =
Invert elev. =
Ea =
h=
Co =
0.45
cfs
12.0
in
5033.47
ft
5033.61
ft
5036.00
ft - 100 yr WSEL
0.6
solve for effective area of orifice using the orifice equation
Ao = 0.060 ft`
= 8.7 in`
orifice dia. = d = 3.33 in
Check orifice discharge coefficient using Figure 5-21 (Hydraulic Engineering)
d / D = 0.28
kinematic viscosity, v = 1.22E-05 ftZ/s
Reynolds no. = Red = 4Q/(pdv) = 1.69E+05
Co = (K in figure) = 0.6 check
Use d =
Ao =
Qo =
Detention.xls
3.300 in
0.059 ff` _
0.44 cfs
8.55 in
LOCATION:
PROJECT NO:
COMPUTATIONS BY
DATE:
STAGE - STORAGE TABLE
100-YEAR
1501 West Elizabeth
350-01
PPK
1/28/2014
POND 1 Extended Water Quality Volume Required =
WQCV
100 year WSEL
Spillway Elevation
100 yr Detention Volume Required =
Total 100 yr Volume Required =
With 0.40 porosity
0.042 0.105 ac ft
0.319 0.799 ac ft
0.361 0.904 ac ft
Stage
(ft)
Surface
Area
(ft`)
Incremental
Storage
(ac-ft)
Total
Storage
(ac-ft)
5033.47
0
5034.50
13,888
0.109
0.109
5035
20,630
0.242
0.242
5036
20,630
0.474
0.715
5036.40
20,630
0.189
0.905
5037
20,630
0.284
1.189
WATER QUALITY CALCULATIONS
LOCATION:
PROJECT NO:
COMPUTATIONS BY:
DATE:
1501 West Elizabeth
350-01
PPK
1 /28/2014
Use 24-hour brim -full volume drain time for extended detention basin
Required Storage = a ' ( 0.91 ' 13 - 1.19 ` I2 + 0.78 ' 1)
Water Quality Capture Volume = WQCV = (required storage/12)'(tributary drainage area)
SUB BASIN
Trib.
area
(ac)
% Imperv.
Req. Storage
tin, of runoff)
from Fig. SQ-2
WQCV
(ac-ft)
req. vol
WQCV'1.2
(ac-ft)
DwQ
(ft)
req. area/row
from Fig. EDB-3
(in Z/row)
POND 3
1.28
80
0.33
0.035
0.042
1.00
0.381
WQ outlet sizing for pond 1
From Figure 5, for 314 in. hole diameter
Area of hole =
0.442 in
# of columns =
1
Area provided/row =
0.442 in
Area Required/row =
0.381 in
Use 1 columns of 3/4" diam holes
100-YEAR DETENTION VOLUME REQUIRED
UNDER PARKING LOT DETENTION POND
FAA METHOD
LOCATION:
1501 West Elizabeth
PROJECT NO:
350-01
COMPUTATIONS BY:
PPK
DATE:
1 /28/2014
Equations:
A trib. To pond =
1.28 acre
Qp = CIA
C100 =
1.00
Vi = T C I A= T Qp
Developed C A=
1.3 acre
Vo =K QPo T
QPo =
0.45 cfS
S=Vi -Vo
K=
0.9
Rainfall intensity from City of Fort Collins IDF Curve
Storm
Duration, T
(min)
Rainfall
Intensity, i
(in/hr)
Qp
(cfs)
Vol. In
Vi
(ft)
Vol. Out
Vo
(ft)
Storage
S
(ft)
Storage
S
(ac-ft)
5
9.95
12.7
3821
0
3821
0.088
10
7.72
9.9
5929
0
5929
0.136
20
5.60
7.2
8602
243
8359
0.192
30
4.52
5.8
10414
486
9928
0.228
40
3.74
4.8
11489
729
10760
0.247
50
3.23
4.1
12403
972
11431
0.262
60
2.86
3.7
13179
1215
11964
0.275
70
2.62
3.4
14085
1458
12627
0.290
80
2.38
3.0
14623
1701
12922
0.297
90
2.22
2.8
15345
1944
13401
0.308
100
2.05
2.6
15744
2187
13557
0.311
110
1.93
2.5
16305
2430
13875
0.319
120
1.80
2.3
16589
2673
13916
0.319
130
1.60
2.0
15974
2916
13058
0.300
140
1.40
1.8
15053
3159
11894
0.273
150
1.20
1.5
13824
3402
10422
0.239
160
1.15
1.5
14131
3645
10486
0.241
170
1 1.10
1.4
14362
3888
10474
0.240
180 1
1.05
1.3
14515
4131
1 10384
0.238
Required Storage Volume: 13916 ft'
0.319 acre-ft
APPENDIX C
DETENTION POND CALCULATIONS
North,Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
LOCATION:
PROJECT NO:
COMPUTATIONS BY:
DATE:
100-yr storm, Cf =
1501 West Elizabeth
350-01
ppk
1/28/2014
1.25
RATIONAL METHOD PEAK RUNOFF
(100-YEAR)
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Design
Point
Subbasin
ID
A
(ac)
C'Cf
tc
(min)
i
(in/hr)
Q (100)
(cfs)
Design
Point
Q (100)
(cfs)
Q(100)tot
(cfs)
1 Historic
1 Historic
1.28
0.28
7.8
8.19
2.9
2.9
Pre Development
1
1
1.28
1.00
5.0
9.95
12.8
12.8
Post Development
Q = C iA Q = peak discharge (cfs)
C = runoff coefficient
I = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
FlowAs Q100
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
LOCATION:
PROJECT NO:
COMPUTATIONS BY:
DATE:
10-yr storm, Cf =
1501 West Elizabeth
350-01
ppk
1/28/2014
1.00
RATIONAL METHOD PEAK RUNOFF
(10-YEAR)
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Design
Point
Subbasin
ID
A
(ac)
C"Cf
tc
(min)
i
(in/hr)
Q (10)
(cfs)
Design
Point
Q (10)
(cfs)
Q(10)tot
(cfs)
1 Historic
1 Historic
1.28
0.22
8.1
3.91
1.1
1.1
Pre Development
1
1
1.28
0.82
5.0
4.87
5.1
5.1
Post Development
Q = C iA Q = peak discharge (cfs)
C = runoff coefficient
I = rainfall intensity (in/hr) from OF curve
A = drainage area (acres)
Flow.xls Q10
North Star Design, Inc.
700 Automation Drive, Unit
Windsor, CO 80550
LOCATION:
PROJECT NO:
COMPUTATIONS BY:
DATE:
2-yr storm, Cf =
1501 West Elizabeth
350-01
ppk
1/28/2014
RATIONAL METHOD PEAK RUNOFF
(2-YEAR)
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Design
Point
Subbasin
ID
A
(ac)
C'Cf
tc
(min)
i
(in/hr)
Q (2)
(cfs)
Design
Point
Q (2)
(cfs)
Q(2)tot
(cfs)
1 Historic
1 Historic
1.28
0.22
12.1
1.57
0.45
0.45
Release Rate
1
1
1.28
0.82
6.4
2.60
2.7
2.7
Post Development
Q = C iA Q = peak discharge (cfs)
C = runoff coefficient
I = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
Flow.xls Q2
North Star Design, Inc.
700 Automation Drive,
Unit I
Windsor, CO 80550
TIME OF CONCENTRATION - 100 YR
LOCATION:'
1501 West Elizabeth
PROJECT NO:
350-01
COMPUTATIONS BY:
ppk
DATE:
1/28/2014
100-yr storm Cf = 1.25
SUB -BASIN DATA
INITIAL I OVERLAND TIME
(u)
TRAVEL TIME / GUTTER OR CHANNEL FLOW
(tt)
tc CHECK
(URBANIZED BASIN)
FINAL
tc
REMARKS
DESIGN
POINT
SUBBASIN
ID
1)
Area
(ac)
(2)
C
(3)
C'Cf
Length
(ft)
(4)
Slope
(%)
(5
ti
(min)
(6)
Length
(ft)
(7)
Slope
(%)
(8)
n
Manning
rough.
Val.
(ft/s)
(9)
tt
(min)
(10)
to =
ti + tt
(11)
Total L
(ft)
12
tc=(1/180)+10
(min)
(13)
(min)
(14
1 Historic
1 Historic
1.28
0.22
0.28
20
2.0
5.3
300
1.00
0.016
2.0
2.49
7.8
320
11.8
7.8
Pre Development
i
1
1.28
0.82
1.00
50
15.0
0.5
0
1.00
0.016
2.0
0.00
0.5
50
10.3
5.0
IPost Development
::
Eq
-
I
I
EQUATIONS:
tc=ti+tt
ti = (1.87 (1.1 - CCt ) Lo.5 ) / s. 1/3
It = Wel.
Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + tt and urbanized basin check
minimum tc = 5 minutes
Flow.xls TOC-100
North Star Design. Inc.
700 Automation Drive, Unit I
Wndsor, CO 80550
LOCATION: 1501 West Elizabeth
PROJECT NO: 350-01
COMPUTATIONS BY: ppk
DATE: 1 /28/2014
10-yr storm Cf = 1.00
TIME OF CONCENTRATION - 10 YR
SUB -BASIN DATA
INITIAL / OVERLAND TIME
(tl)
TRAVEL TIME / GUTTER OR CHANNEL FLOW
(tt)
tc CHECK
(URBANIZED BASIN)
FINAL
tc
REMARKS
DESIGN
POINT
SUBBASIN
ID
(1)
Area
(ac)
(2)
C
(3)
C'Cf
Length
(ft)
(4
Slope
(°/a)
5
ti
(min)
(6)
Length
(ft)
(7)
Slope
(%)
(8)
n
Manning
rough.
Val.
(ft/s)
(9)
It
(min)
(10)
tc =
ti + It
(11)
Total L
(ft)
(12)
tc=(1/180)+10
(min)
(13)
(min)
(14)
1 Historic
1 Historic
1.28
0.22
0.22
20
2.0
5.6
300
1.00
0.016
2.0
2.5
8.1
320
11.8
8.1
Pre Development
�31
1
- 1
1.28
0.82
0.82
50
15.0
1.4
0
1.00
0.016
2.0
0.0
1.4
50
10
5.0
jPost Development
EQUATIONS:
tc=ti+It
tl=[1.87(1.1- CCt) La.51/ S 113
it = L/Vel.
Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + It and urbanized basin check
minimum tc = 5 minutes
Flow.xls TOC-10
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
LOCATION: 1501 West Elizabeth
PROJECT NO: 350-01
COMPUTATIONS BY: ppk
DATE: 1 /28/2014
2-yr storm Cf = 1.00
TIME OF CONCENTRATION - 2 YR
SUB -BASIN DATA
INITIAL / OVERLAND TIME
(ti)
TRAVEL TIME / GUTTER OR CHANNEL FLOW
(tt)
tc CHECK
(URBANIZED BASIN)
FINAL
tc
REMARKS
DESIGNbSUBBASIN
POINT(ac)
Area
(2)
C
(3
C'Cf
Length
(ft)
(4)
Slope
N
(5
li
(min)
(6)
Length
(ft)
(7)
Slope
(%)
(8)
n
Manning
rough.
Vel.
(fUs)
(9)
tt
(min)
(10)
tc=
ti + tt
(11)
Total L
(ft)
(12
tc=(U180)+10
(min)
(13)
(min)
14)
1 Historic
1.28
0.22
0.22
187
0.7
24.4
190
0.50
0.030
0.8
4.2
28.5
377
12.1
12.1
Pre Develo ment
1.28
0.82
0.82
118
1.1
5.2
186
1.20
0.013
2.7
1.1
11.7
6.4
Post Develo ment
Ps�.
EQUATIONS:
tc = ti + tt
ti = [1.87 (1.1 - CC1) 1-0.5 ] / S 15
It= LNel.
Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + ft and urbanized basin check
minimum tc = 5 minutes
Flow.als TOC-2
North Star Design, Inc.
700 Automation Drive, Unit 1
Windsor, CO 80550
LOCATION:1501,WestElizabeth
PROJECT NO: 350-01
COMPUTATIONS BY: ppk
DATE: 1/28/2014
RUNOFF. COEFFICIENTS & % IMPERVIOUS
Recommended Runoff Coefficients from Table 3-3 of City of Fort Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
Streets, parking lots (asphalt)
Sidewalks (concrete)
Roofs:
Lawns (flat <2%, heavy soil;
Runoff
%
coefficient
Impervious
C
0.95
100
0.95
96
0.95
90
0.20
0
SUBBASIN
ID
-
TOTAL
AREA
(ac.)
TOTAL
AREA
(sq.ft)
ROOF
AREA
(sq.ft)
PAVED
AREA
(sq.ft)
SIDEWALK
AREA
(s .ft)
LANDSCAPE
AREA
(sq.ft)
RUNOFF
COEFF.
(C)
%
Impervious
REMARKS
1 Historic
1.28
55,864
0
1,565,
0
54,299
0.22
3
Pre Development
1
1.28
55,864
17,000
21,950
7,520
9,394
0.82
80
Past Development
EEc uations
Calculated C coefficients & % Impervious are area weighted
C=£(Ci Ai) /At
Ci = runoff coefficient for specific area, Ai
Ai = areas of surface with runoff coefficient of Ci
n = number of different surfaces to consider
At = total area over which C is applicable; the sum of all Ai's
Flow.xls Cval
APPENDIX B
HYDROLOGIC COMPUTATIONS
R3
./.mot•om�omi
n FONT FLpODNAN soMDMY
■N..we
FLOODPLAN NOTES
1, PORYONS OF THIS PROJECT WERE LOCATED IN THE CITY REGULATORY 100-YEAR CANAL IMPORTATION BASIN
FLOOOPWN BUT THE SITE HAS BEEN REMOVED NA THE FLOCDPLNN WAIVER PROCESS BASED ON WFORIATON
CONTAINED W THE 'AS -BUILT OESICN SUMMARY k iLOCKI MODELING REPORT FOR CANAL IMPORTATION
PONDS AND WITALL' BY ACRES ASSOCIATES DATED FEBRUARY 2013. THE CHAPTER 10 REQUIREMENTS OF CITY
MUNICIPAL CODE NO LONGER APPLY.
2, WFORMATON SHOWN IS BASED W THE CURRENT EFFECTIVE MODEL MAP BY ANDERSON CWSULPNG
,. ENGINEERS DATED 2001,
QTDCCT
-' CALL UTILITY NOTIFICATION
CENTER OF COLORADO
1-800-922-1987 (811)
E,sL 2-BU9NEBs DAYS W NDVANCE
BEFORE You Oy WNDE. OR EXCAVATE
I'M THE MARNWG CF UNDERG4WNO
MEMBER WIJTIES.
20 10 0 20 40
SILT R TO BE eR PLACE OYMNO
ObWTId a OJERLOT pUOPT
REMOVE MIDI TO SIIBBAY
MSTAwTRON t PAYING
OPERATIOIIS
ROTOR W NUT SHEET now, UNDER
PAYtmIT eI:TENTIDN DETAI
SCALE, V • 20'
EROSION comma NOTES:
1) The City Stormwater, Department erosion control inspector must be notified at
least 24 hours prior to: any construction on this site.
2) All required SNIPS shall be installed prior to any land disturbing octivity
j c:,
(stockpiling, stripping, grading, etc). All of required erosion control measures must
p rn
be installed t (Ile appropriate time in lM1e COn9Ir11 [lion 9egU<nC< 03 in divot <tl Irl the
approved project Kch<dule, construction plans, and erasion control report
I Lc ra
O m
a
3) Pre -disturbance vegetation shall be protected and retained wherever possible.
U
a G
Removal or disturbance. at existing vagelolion shall be limited to the area required
}� C ry Od-
for immediate construction operations, and for the shortest practical period of time.
U l-
0
All soils exposed during land activity (stripping, eroding, utility
C o 0
ti 2
m y rn
in stocetc.) shall by
Riling, etc.) shall be kept N a rouon, then
�.N
Q
ripping or along; per
ripping disking along land contours until mulch, vegetation, tr other permanent
or
N C 0
S t W
ntolI.
erosion cannel is in.toll.d.la No soils in areas Outside project street right) Of way
CD
' � I�
> G. LL
shall remain exposed by land activity for more than thirty (30) tloys
before required temporary Or p
permanent erosion (e.g. seed/mulch,
mess of
etc. is installed. unless otherwise approved by
approved
lanthe �epOrimen
Staying,
the StormWaler t.
,
5) The properly must be watered and maintained of all times during construction
,w I�
activities ea as to prevent wind-coused erosion. All land disturbing activities east be
`
Immediately discontinued "an fugitive dust impacts adjacent properties, as
determined by the City Engineering Department.
6) All temporary (structural) erosion control measures must be inspected and
W
doffer each runoff event every 14 days in
Or r,.
order t
Order continued p for ante
assure continued performance of their surfaces. function. retained
O
n shalaAll
slspaxe le, Particularly a those on Dowd roadway surfaces. cau shall removed and
manner
dlaposed of in a manner and location so as not !o cause their release into any
r
>
m
droinogeway.
7) No soil stockpile shall exceed ten (10) feet In height. All sail stockpiles shall be
Protected from sediment tmnspwt by surface roughening, watering, and perimeter
sip fencing. Any sail stockpia remaining otter 30 days shell be seeded and mulched.
8) City Ordinance prohibits the tracking, dropping, or depositing of soils or any other
material onto city street$ by Or from any vehicle. Any inadvertent deposited material
Shall be cleaned immediately by the contractor.
Z
O
N
W
K
LEGEND, 1 11111111
= _ = = = _ = CMSTING PIPES
-..._..-4905 - -. ••_ ELSTWG 5' CONTOUR
EMSTWG ICONTOUR
-,go- PROPOSED 5' CONTOUR
PROPOSED t' CONTOUR
A3 DESIGN POINT
BASIN CRITERIA
4�EEAREA
10 WR RUNOPE CEROnOENT M ACRES
^ nos ORECnw
as as wo As wo WW as BASIN BOUNDARY
®—SF—SF— SILT FENCE
® �:•Y VENICLE TRACKING PAID
® El CONCRETE WASIrOUT AREA
OROOK YYX
IP r0 INLET PROTECTW
CONSTRUCTION SEQUENCE
eeeeeeeon
e
-----_---
-
------------
---
--------
---
--------
----
-------
-41.111-1
---------
--
------------
--------ILO---
------------
----__==----
------------
---------
--
Milli
---------
--
---------
--
MM
mm
------
—
—
--
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL
APPROVED:
ntr Env^.-
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CHECKED BY:
Welw a AwAr l.r alxlly
INKY
CHECKED BY:
Sldm.... WFily
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CHECKED BY:
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CHECKED BY:
iroih Engiyer
PAU,
CHECKED BY:
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5 OF 8
No. 350-01
PROJECT
in 0
vision
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VICINITY MAP
APPENDIX A
VICINITY MAP
A
7. REFERENCES
City of Fort Collins, "Storm Drainage Criteria Manual", (SDCM), dated March,
1986.
2. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated March, 1969, and Volume 3 dated September,
1992.
13
All computations that have been completed within this report are in compliance with the
City of Fort Collins Storm Drainage Design Criteria Manual and the Canal Importation
Master Drainage Plan. The site was removed from the City regulatory 100 year Canal
Importation Basin floodplain by the waiver process which was justified based on the
information contained in the "As -Built Design Summary & Floodplain Modeling report
for Canal Importation Ponds and Outfall" by Ayres Associates dated February 2013.
Since the property was removed from the floodplain, there will be no Chapter 10
compliance issues.
6.2 Drainage Concept
The proposed drainage concepts presented in this report and on the construction plans
adequately provide for conveyance of runoff to the detention areas. Conveyance
elements have been designed to pass required flows and to minimize future maintenance.
If, at the time of construction, groundwater is encountered, a Colorado Department of
Health Construction Dewatering Permit would be required.
12
5) Waste Management and Disposal:
Portable toilets will be anchored & periodically maintained by waste management company.
Dumpsters on site will be covered & periodically emptied by waste management company.
Concrete waste will be allowed to harden and then will be removed from site.
No washing activities will occur on site.
Location of the concrete washout is shown on the site map. The washout will be sufficiently
deep to accommodate all anticipated concrete truck wash water. Waste concrete will be
allowed to harden and be removed from site periodically as the washout reaches 50% of its
capacity. Truck wash water will not be allowed to reach the curb & gutter or any other water
course.
6) Groundwater and Stormwater Dewatering:
No groundwater was encountered during soils exploration therefore ground water is not
_anticipated to be an issue. If groundwater is encountered a groundwater discharge permit
shall be obtained and a detailed report shall be completed describing the location and the
route of where pumped groundwater will be conveyed and the measures taken to prevent the
transport of any pollutants to downstream waters.
7) Inspection & Maintenance:
It is required that routine site inspections are performed to effectively address maintenance
and repair of Best Management Practices (BMP's). The site inspections are to performed by
the contractor or an inspector designated by the administrator at a minimum of once every
fourteen (14) calendar days on active construction sites and after any significant storm event
(an event causing runoff). As part of the site inspections the inspector is required to keep
documentation of
all inspections and BMP maintenance, including an updated Site Map indicating new BMP's
or the removal of BMP's since the previous inspection.
Any maintenance, repair, or necessary installation of BMP's that are noted during the
inspection must be completed within seven (7) calendar days from the date of the inspection.
6. CONCLUSIONS
6.1 Compliance with Standards
11
2 Materials Handling and S ill Prevention:
g of -aria yea �:,
Materials Handljng &Spilt r
e Eater �.M M'
�� h A 1t
�Ap rmamatetlocationU site
^'�eSY t r
E1RPlwable to thas
NVN& w6��
P.reventromBivlP�
,� ;
a Project
Portable toilets, anchored &
Contractor to determine
X
located away from drainages
Fuel storage located in bulk tanks
with secondary containment &
spill kit
Mobile fueling performed at least
200 feet away from drainages &
Contractor to determine
X
fully attended
Fertilizers, form oil, solvents,
cleaners, detergent stored in 55 gal
Contractor to determine
X
or smaller containers, kept in
storage units
Dumpsters containing used
chemicals containers & liquid
Contractor to determine
X
wastes kept covered
Equipment cleaning (on site) uses
no detergents & flows to onsite
retention basin
In case of a release of fuel or other
chemicals, absorbent booms or
earthen berms will be immediately
Location of spill
X
constructed to contain the spill &
prevent runoff to adjacent surface
waters
MSDS sheets for onsite chemicals
will be kept at the construction
Contractor to determine
X
trailer to facilitate spill response &
cleanup
3) Dedicated Asphalt or Concrete Batch Plant:
Not proposed with this development
4) Vehicle Tracking Pad:
Vehicle tracking control pad shall be installed wherever construction vehicle access routes
intersect paved public roads. Vehicle tracking control pads shall be installed to minimize the
transport of sediment (mud) by runoff or vehicles tracking onto the paved surface. Any mud
tracked to public roads shall be removed on a daily basis and after any significant storm that
causes sediment to be transported. It is unlawful to track sediment/mud onto public streets
and may be enforced by the City of Fort Collins or by the State of Colorado.
10
5.5 BMP Implementation
1) Phased BMP Implementation
BMP's are expected to change as the construction progresses and it is the responsibility of
the contractor to ensure appropriate BMP's are in place and/or removed at the appropriate
time in the construction sequence. A construction sequence schedule has been included on
the Drainage & Erosion Control Plan and included in the construction plans for this site.
All BMP's shall be inspected and repaired or replaced as required to satisfy the conditions of
the Stormwater Discharge Permit. All BMP's must be maintained and repaired as needed to
assure continued performance of their intended function.
Refer to Appendix D for BMP Implementation Schedule
Refer to Appendix D for BMP Estimated Costs
9
Non -Structural Practices for Erosion and Sediment Control:
Soils exposed during the earthwork phase and landscape prep phase shall be kept in a roughened
condition by ripping or disking along land contours until mulch, vegetation, or other permanent
erosion control is installed. No large amount of soils (in excess of 15 yards) will be allowed to be
stock piled on site. Overburden from the utility pipe trenching will be piled adjacent to trenches
upstream of sediment controls and will be replaced in the trenches within 72 hours.
Excess excavated materials from the demolition and grading phases of the project that cannot be
reused on site will be exported as it is excavated. This includes any asphalt pavement from the
existing site that is to be removed.
A vehicle tracking pad will be installed at a location most beneficial to the site construction as
determined by the contractor. Vehicles will not be permitted in the excavated area if soil is
muddy. Gravel sub base will be placed and compacted in the areas indicated for pavement
following excavation. In the current pre construction state the site enables tracking of silt onto
the adjacent streets during wet conditions. During construction activities the street will be
monitored for foreign debris tracked out of the site and mechanical sweeping and clean up will
be performed as needed.
No area shall remain exposed by land disturbing activity for more than thirty (30) days before
required temporary or permanent erosion control (e.g. seed/mulch, landscaping, etc.) is installed.
Temporary & Permanent non-structural BMP's:
_ �.
on Structural
�n�z
Appoxtmate
A l�cable this
poaect
BMP;
¢ location on srte
r gym`
Surface roughening
Entire site
X
Soil stockpile height limit (less
than 10')
Perimeter vegetative butler
West boundary of site
X
Minimization of site disturbance
Mulch
Seed & mulch stockpiles after 30
days
Stockpile toe protection (silt fence,
wattles or ditch)
Preservation & protection of
West boundary of site
X
existing vegetation & trees
Good site housekeeping (routine
Entire Site
X
cleanup of trash & constr debris)
Heavy equip staged on site,
properly maintained & inspected
Staging area
X
daily (no onsite maintenance)
8
5.4 Best Management Practices (BMP's) for Stormwater Pollution Prevention
Structural Practices for Erosion and Sediment Control
Structural practices for the site will consist mainly of silt fence and rock sock filters and are
described in detail in the following paragraphs. These BMP's are expected to change as the
construction progresses and it is the responsibility of the contractor to ensure appropriate BMP's
are in place and/or removed at the appropriate time in the construction sequence. All temporary
and permanent erosion and sediment control practices must be maintained and repaired as
needed to assure continued performance of their intended function.
Silt fence and rock sock filters shall be in place prior to.commencement of construction
activities. During clearing and grubbing necessary for silt fence installation, all cleared material
shall be placed on the uphill side so that if erosion occurs from the cleared material, the sediment
will be trapped and not transported downstream. Rock socks shall be implemented in the existing
curb line as shown on the Drainage & Erosion Control Plan.
All BMP's shall be installed per the details shown on the construction plan set.
Temporary & Permanent Structural BMP's:
St utural BMP�a
. -" s
f,
Approx�imaCe location on site a�aa
4 Applicable to thtsE
Project rt+
4;
Z
Silt Fence
Site perimeter, refer to site map
X
Straw bale dams
Rock Socks
At proposed sidewalk culverts, refer to site
map
X
Earthen diversion dams
Vegetated swales
Sediment trap/pond
Pipe slope drains
Geogrid
Inlet/outlet protection
Culverts
Riprap
Erosion control mats
Inlet protection
7
5.2 SWMP contact information
Permit holder:
Name:
Address:
Phone Number:
Email Address:
Appointed agent:
Name:
Address:
Phone Number:
Email Address:
5.3 Identification and location of all potential pollution sources
Potenttial PPbllutdht-Source�A�ctti°ity � ��
h�.i
a.
gPotenttal`Pollptant GeneratedAppcable
�
34`'0 Sri srs . %a=Ti^^°maL4 v...ua Xa=ry
h. tom
prOJOet y
Disturbed Areas
Sediment
X
Soil stockpiles
Sediment
X
Travel to adjacent public streets
Tracked sediment
X
Contaminated soils
Sediment, chemicals
Loading and unloading chemicals
Chemicals
Outdoor storage of chemicals
Chemicals
On site equipment maintenance
Oil, grease
On site equipment fueling
Diesel, gasoline
X
Dust generating activities
Particulates, sediment
X
Use of fertilizer, pesticides, herbicides
Fertilizer, pesticides
Use of detergents, solvents, oils
Detergents, solvents, oil
X
Waste dumpsters, waste piles
Chemicals
X
Concrete washout
Concrete, sediment
X
On site equipment washing
Detergents, oil
On site asphalt batch plant
Asphaltic cement, sediment
On site concrete batch plant
Cement, sediment
Portable toilets
Domestic sewage
X
5. STORMWATER MANAGEMENT CONTROLS.
5.1 Written Analysis
The soils on this site are classified by the USGS Soil Survey as Altvan-Santana Loams
and are classified in the hydrologic group B. The soils are described as being well
drained and having a moderately high to high ability to transmit water (0.6 to 2.0 inches
per hour). The geotechnical report indicates that the soils on site have a porosity as high
as 108 feet per day. The rainfall and wind erodibility is deemed to be moderate.
The site is. surrounded by developed sites including streets and paved areas. The
construction shall utilize silt fence around the perimeter to control sediment transport
from rainfall and from wind. The silt fence that is located in the proposed pavement areas
will be removed prior to placing new pavement. Rock socks will be utilized in the
existing curb to capture sediments that are not fully contained by the silt fence placement.
The locations of the rock socks will be in the areas of concentrated flow such as the
existing curb and on the existing concrete sidewalks.
The site may also utilize a vehicle tracking control pad to minimize sediment from being
tracked onto adjacent pavements. Sediment that is tracked will be removed and placed
within the site or permanently disposed of offsite. A concrete washout will be used on
site during the concrete placement. All hardened concrete will be disposed of offsite.
These BMP's have not been located on the site map due to the fact that the site is very
small and these BMP's will need to be placed by the contractor in locations that are most
beneficial and will minimize disruption of adjacent traffic.
Permanent erosion control consists of covering the soils with a building, concrete walks,
concrete drives and sod. No soil will be left exposed to erosion after the construction is
complete. Refer to the landscape plan for areas of and instructions for placement of sod
and soil amendments required prior to placement of soda
Refer to Appendix D for the timing of the construction phases and the sequential
installation of all BMP phasing for this site.
Refer to the end of Appendix D for the Erosion Control Surety calculations.
5
Basin I encompasses the majority of the proposed development including the entire
building, parking lot, private drives and the landscaping on the west side of the site. A
majority of the runoff flows to the parking lot in the south half of the site which will
convey the flows beneath the parking lot to the proposed detention pond. This detention
pond will have a small release rate (0.45 cfs) which equate to the 2 year undeveloped
runoff. The water quality extended detention is incorporated into the subsurface
detention system. The detention system will have an overflow to the east along the
private drive that extends into the adjacent property.
This site is being developed under the City criterion that requires that 25% of the site
pavements be pervious. This site has approximately 21,950 square feet of proposed
parking lot pavement on site which is entirely within Basin 1. Of the 28,700 square feet,
25% of this area would equate to 5490 square feet of required pervious pavement and
with this proposed development, approximately 5650 square feet of pervious pavements
are being proposed and will be located in the parking spaces as shown on the grading and
drainage plan.
4.3 Drainage Summary
All runoff from this site and the adjacent sites will be safely conveyed via surface flow to
the detention pond. The site will generally conform to the Canal Importation Master
Drainage plan which this site is included in.
The City of Fort Collins will be responsible for maintenance of the existing storm
drainage facilities located within the right-of-way. The drainage facilities located outside
of the right of way (including the detention pond) will be maintained by the property
owner.
4
3.3 Hydrologic Criteria
Runoff coefficients calculations were prepared for the 2 and 10-year minor and 100-year
major storm frequency utilizing the rational method. Detention is proposed on site under
the parking lot with a release rate equal to the 2 year historic runoff rate. The amount of
detention provided under the parking lot was based on an assumed porosity of the chosen
aggregate of 0.4.
3.4 Hydraulic Criteria
The onsite collection system is 4" perforated pipe which is collect in a larger pipe and
conveyed to the outlet point with a restriction to the historic runoff rate. An inlet is
located in the parking lot which will act as a collection point if the porous pavements
cannot intercept all of the site runoff. Sizes for the inlet and pipes have not been
calculated as the amount of runoff expected in these conveyances are difficult to predict.
Stormwater will also infiltrate into the groundwater as indicated by the geotechnical
report, portion of which are included in the appendix.
4. DRAINAGE FACILITY DESIGN
4.1 General Concept
The runoff from this site will flow into the parking lot which will be constructed using
75% conventional materials (asphalt or concrete) and 25% porous pavement (concrete or
pavers). The runoff from the site will enter the subsurface material (3/4" poorly graded
angular rock) via the porous pavements. In a situation where the porous pavements are
clogged, the runoff will flow to the proposed inlet in the southeast corner of the site and
enter the subsurface material.
A small amount of flow from the patio on the north is anticipated to enter West Elizabeth
Street without detention. No offsite flows will enter this site.
4.2 Specific Flow Routing
A summary of the drainage patterns within each basin is provided in the following
paragraphs.
3
on the information contained in the "As -Built Design Summary & Floodplain Modeling
report for Canal Importation Ponds and Outfall" by Ayres Associates dated February
2013. Since the property was removed from the floodplain by the waiver process, there
will be no Chapter 10 compliance issues.
2.2 Sub -basin Description
This site was included in the "Final Drainage Report for Diamond Shamrock Gas Station,
Convenience Store and Car Wash, Lot 2 Fairview Shopping Center II" by Galloway,
Romero & Associates dated February 6, 1989 and revised May 16, 1989. Portions of this
report are included in the Appendix.
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations
This report was prepared to meet or exceed the "City of Fort Collins Storm Drainage
Design Criteria Manual' specifications. Where applicable, the criteria established in the
"Urban Storm Drainage Criteria Manual" (UDFCD), developed by the Denver Regional
Council of Governments, has been used.
3.2 Development Criteria Reference and Constraints
The runoff from this site has been routed to maintain the same patterns as previously
established. The site is restricted to a 2 year historic release rate with this development.
The historic condition for this site is an undeveloped condition without regard to the
previous development condition. The runoff from the entirety of the site, including the
entire proposed building, will be directed to the parking lot where the water will enter the
under parking lot detention area via the proposed porous pavements or via an inlet
proposed near the southeast corner of the site. The release rate for the detention pond has
been calculated to be 0.45 cfs which is equivalent to the 2 year historic runoff rate for this
site in an undeveloped condition.
The detention pond will release to the north into an existing storm manhole as the site
previously has done.
1. GENERAL LOCATION AND DESCRIPTION
1.1 Location
The site is located on the Lot 20, Block 11 Fairview 9h Filing in the Southeast'/4 of
Section 15, Township 7 North, Range 68 West of the Sixth Principal Meridian, in the
City of Fort Collins, Larimer County, Colorado. The address of the existing site is 1501
West Elizabeth Street. See the location map in Appendix A.
The project is located on the south side of West Elizabeth Street between South Bryan
Avenue and City Park Avenue. The project is bounded on all sides by existing
commercial development.
1.2 Description of Property
The entire site consists of approximately 1.46 acres of land. The land was previously
developed with a c-store and car wash which were destroyed in a fire. The buildings
have been removed from the site but some pavement and utilities currently remain on the
site. The site currently drains to a detention pond on the south portion of the site. Slopes
on site range from approximately 1% to 2%. This site is currently located in the City
regulatory 100 year Canal Importation Basin floodplain but will be removed in
conjunction with this proposed development via the City Floodplain Waiver process.
This project will include the development of a single building that has commercial and
retail on the main floor and residential units on the upper floors located in the north half
of the site. There will be private drives, parking and landscaping on the remainder of the
site. The site will provide detention storage under the parking lot with a combination of
infiltration and collection in a system of perforated pipes.
2. DRAINAGE BASINS AND SUB -BASINS
2.1 Major Basin Description
The proposed development lies within the Canal Importation Drainage Basin. The site is
also located in a 100 year floodplain. With this proposed development, an application for
a City Floodplain Waiver was approved to remove this site from the 100 year floodplain
(refer to Appendix E for a copy of this approved waiver). The waiver was justified based
TABLE OF CONTENTS
..
TABLE OF CONTENTS............................................................................................................... ii�
GENERAL LOCATION AND DESCRIPTION
1.1 Location...................................................................................................................1
1.2 Description of Property ............................................................................................I
2. DRAINAGE BASINS AND SUB -BASINS
2.1 Major Basin Description..........................................................................................1
2.2 Sub -Basin Description.............................................................................................2
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations..............................................................................................................2
3.2 Development Criteria Reference and Constraints...................................................2
3.3 Hydrologic Criteria..................................................................................................3
3.4 Hydraulic Criteria....................................................................................................3
4. DRAINAGE FACILITY DESIGN
4.1 General Concept.......................................................................................................3
4.2 Specific Flow Routing.............................................................................................3
4.3 Drainage Summary..................................................................................................4
5. STORMWATER MANAGEMENT CONTROLS
5.1 Written Analysis.....................................................................................................5
5.2 SWMP Contact Information...................................................................................6
5.3 Identification and location of all potential pollution sources..................................6
5.4 Best Management Practices (BMP's) for Stormwater Pollution Prevention ........... 7
5.5 BMP Implementation...............................................................................................9
6. CONCLUSIONS
6.1 Compliance with Standards..................................................................................12
6.2 Drainage Concept..................................................................................................12
7. REFERENCES..................................................................................................................13
APPENDICES
A Vicinity Map
B Hydrologic Computations
C Detention Pond Calculations
D BMP Schedule and Cost Estimate
E Floodplain Waiver
F Excerpts from Other Reports
ftti
North Star
design
700 Automation Drive, Unit I
Windsor, CO 80550
Phone:970-686-6939
Fax:970-686-1188
January 29, 2014
Glen Schlueter
City of Fort Collins Stormwater
700 Wood Street
Fort Collins, CO 80522-0580
RE: Final Drainage and Erosion Control Study for
1501 West Elizabeth Street
Dear Glen,
I am pleased to submit for your review and approval, this Final Drainage and Erosion Control
Study for 1501 West Elizabeth Street. I certify that this report for the drainage design was
prepared in accordance with the Master Plan and the criteria in the City of Fort Collins Storm
Drainage Manual.
I appreciate your time and consideration in reviewing this submittal. Please call if you have any
questions.
Sincerely,
CM
Patricia Kroetch, P.E. '.,'i%p:
����4iuiupt llI
it
FINAL DRAINAGE AND EROSION
CONTROLSTUDY
1501 WEST ELIZABETH STREET
Prepared for:
Jim Hillhouse
Hillhouse Architects
Windsor, CO 80550
Prepared by:
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, Colorado 80550
(970)686-6939
January 29, 2014
Job Number 350-01