HomeMy WebLinkAbout20030450.tiff e Northam
tOlVlorado
Geotech
October 18, 2002 2956 29th Street,Unit 21
Greeley,Colorado 80631
Phone:(970)506-9244
Fax:(970)506-9242
Snowdance Development
1750 25th Avenue, Suite 305
Greeley, Colorado 80634
Attn: Mr. Jim Rawson
Re: Mineral and Aggregate Evaluation
Hill —Ault Project
Weld County Road 80 between Roads 27 and 29
Northern Colorado Geotech Project No. 029-02
Northern Colorado Geotech completed a preliminary geotechnical engineering Report for the proposed
9-Lot PUD at the above referenced site west of Ault, Colorado (Northern Colorado Geotech Project No.
029-02, dated March 19, 2002). The soils encountered at the site generally consisted of silty and/or
clayey sand to depths of 12% to greater than 15 feet. The silty and/or clayey sand is underlain by silty
r
sand with gravel that extends beyond the depths explored, 15 feet.
The proposed development is located within the Great Plains physiographic province. The Colorado
Piedmont is located near the western border of the Great Plains province and was formed during Late
Tertiary and Early Quaternary time (approximately 2,000,000 years ago). The Colorado Piedmont is a
broad, erosional trench which separates the Southern Rocky Mountains from the High Plains.
Structurally, the site lies near the axis of the Denver Basin. During the mountain building of the
Laramide Orogeny (approximately 70,000,000 years ago), intense tectonic activity occurred, causing the
uplifting of the Front Range and associated downwarping of the Denver Basin to the east Due to the
erosional action of wind and streams, relatively flat uplands and broad valleys characterize the present-
day topography of the Colorado Piedmont in this region. The site is likely underlain by the Cretaceous
Fox Hills and/or Laramie Formation. The Fox Hills consists of interbedded sandstone and siitstone
units. The Laramie is generally comprised of sandstone, siltstone and claystone units. The Laramie
also contains significant coal seams in southern Weld County and Boulder County.
Based on our borings and a literature review, it is our opinion that there are no economic sand or gravel
aggregate at the site. Due to the type of bedrock formations) which underlie the site, it is our opinion
that no economic quantities of quarry rock are available at the site. Based on the review of maps in the
area, we are unaware of coal mines in the immediate vicinity of the site. Therefore, it is our opinion that
there are no economic quantities of minerals or aggregate at the subject site.
2003-0450
Mineral and Aggregate Evaluation
Hill—Ault Project
Northern Colorado Gectech Project No.029-02
Page 2of2
If you have any questions concerning this report or any of our consulting services, please do not
hesitate to contact us at(970) 506-9244.
Sincerely,
NORTHERN COLORADO GEOTECH
Preparby:
Doug Leafgren,)P.G.
President `G
Copies to: Addressee (2)
r
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
PROPOSED HILL-AULT 9 LOT PUD
WELD COUNTY ROAD 80 BETWEEN ROADS 27 AND 29
WELD COUNTY, COLORADO
NORTHERN COLORADO GEOTECH
PROJECT NO. 029-02
March 1 ). 2002
Prepared ror:
Snowdance Dr.,elopment
1750 25th Averue, Suite 305
Greeley, Colorado 80634
Attn: Mr. Jib= Rawson
Northern
Colorado
Geotech
2956 29th Street, Unit 21
Greeley, Colorado 80631
Phone: (970) 506-9244
Fax: (970)506-9242
Northern
Colorado
Geotech
March 19, 2002 2956 29th Street, Unit 21
Greeley, Colorado 80631
Phone: (970)506-9244
Fax: (970)506-9242
Snowdance Development
1750 25th Avenue, Suite 305
Greeley, Colorado 80634
Attn: Mr. Jim Rawson
Re: Preliminary Geotechnical Engineering Report
Proposed Hill-Ault 9 Lot PUD
Northern Colorado Geotech Project No. 029-02
Northern Colorado Geotech has completed a preliminary geotechnical engineering exploration for
the proposed residential PUD to be located along Weld County Road 80 between roads 27 and 29
west of Ault, Colorado. This study was performed in general accordance with our proposal number
902012g dated February 21, 2002.
The subsurface soils at the site consisted of silty sand and silty clayey sand. The res ills of our field
exploration and laboratory testing indicate that the soils are non-expansive and have low load
hearing capab;:ities. Groundwater was encountered at depths of approximately 8% i,: 12 feet in
iarious locations at the she. Preliminary percolation tests show the so;!a exhibit gou, :;ercolation
characteristics.
Based on the anticipated construction and the results of our engineering exploration, it is our opinion
that proposed structures may be supported by spread footing foundations.
Th' recommendations contained in this report are preliminary in nature. Additional geotechnical
exploration is needed prior to residential construction at the site. If you have any questions or if we
may be or further service, please do not hesitate to contact us at(970) 506-9244.
Sincerely, ,
NORTHERN COLORADO GEOTECH \,
i
Prepared by:
•
Doug Leafgre , .G /
President
Reviewed by:
Gary G. Weeks, P.E.
r Vice President
Copies to: Addressee (4)
TABLE OF CONTENTS
Page No.
Letter of Transmittal
SCOPE 1
SITE CONDITIONS 1
PROPOSED CONSTRUCTION 2
SITE EXPLORATION 2
Laboratory Testing 2
SUBSURFACE CONDITIONS 3
Geology 3
Subsurface Conditions 3
Groundwater Conditions 3
Field Test Results 4
PRE,IMINARY DESIGN RECOMMENDATIONS 4
Fou;dation Dess i s 4
Footing Foundations 4
Below Grade Construction 5
Septic System Construction 5
General Earthwork 5
Site Preparation 5
Fill Materials aril Placement 6
GENERAL COMMENTS 7
ATTACHMENTS
Boring Location Plan
Logs of Borings
Laboratory Test Results
•
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
PROPOSED HILL-AULT 9 LOT PUD
WELD COUNTY ROAD 80 BETWEEN ROADS 27 AND 29
AULT, COLORADO
NORTHERN COLORADO GEOTECH
PROJECT NO. 029-02
MARCH 19, 2002
SCOPE
This report contains the results of our preliminary geotechnical engineering exploration for the
proposed residential 9 lot PUD to be located along Weld County Road 80 between Roads 27 and
29 west of Ault, Colorado.
This report includes descriptions of, and preliminary geotechnical engineering recommendations
relative to:
• subsurface soil and bedrock conditions
• groundwater conditions
• foundation design
• basement construction
• drainage
• septic systems
• earthwork
The recommendations contained in this report are preliminary and based upon the results of field
and laboratory testing, engineering analyses, and experience with similar soil conditions, structures
and our understanding of the proposed project.
SITE CONDITIONS
The site is currently divided into-several agricultural fields that have been recently used to grow
alfalfa. An existing residence and shed are located near the northwest corner of the property.
Weld County Road 80 is borders the site to the north. A small seepage ditch is located along the
eastern edge of the site. Agricultural ground is located south and west of the property. Surface
drainage is fair to good to the east.
r
Preliminary Geotechnical Engineering Report
Proposed Hill-Ault 9 Lot PUD
Northern Colorado Geotech Project No.029-02
PROPOSED CONSTRUCTION
As we understand it, the site will be developed for several residential estate style lots. The lots will
be serviced with on-site sewage disposal systems. We assume that minimal site grading will be
performed during the development of the site.
SITE EXPLORATION
A total of four test borings were drilled on March 6, 2002. The borings were drilled to an
approximate depth of 15 feet at the locations shown on the Site Plan, Figure 1. Additionally, one
preliminary percolation test boring was drilled adjacent to each soil test boring. All borings were
advanced with a truck-mounted drilling rig, utilizing 4- and 6-inch diameter solid stem augers.
The borings were located in the field by pacing from property lines and/or existing site features.
The accuracy of boring locations should only be assumed to the level implied by the methods used.
iithologic logs of each boring were recorded by an engineering geologist during the drilling
operations. At selected intervals, samples of the subsurface materials were taken by driving split-
^ swoon samplers. Standard penetration measurements were recorded while driving a spit-spoon
sampler into th,- subsurface materials. The standard penetration test is a useful index it etimating
'ne density of the materials encountered.
Groundwater conditions were evaluated in each boring at the time of subsurface exploration, and
:seven days after the drilling.
Laboratory Testing
The samples retrieved during the subsurface exploration were returned to our laboratory for
observation by the project manager. The soils were classified in general accordance with the
Unified Soil Classification System. At that time, the field descriptions were confirmed or modified
and an applicable laboratory testing program was formulated. Boring logs were prepared and are
attached with this report.
Laboratory tests were conducted on selected samples and are presented on the boring logs and
attached laboratory test sheets. The test results were used for the geotechnical engineering
analyses, and the development of foundation and earthwork recommendations.
Selected samples were tested for the following engineering properties:
2
Preliminary Geotechnical Engineering Report
Proposed Hill-Ault 9 Lot PUD
Northern Colorado Geotech Project No.029-02
• Water Content • Consolidation
• Dry Density • Expansion
• Compressive Strength • Sieve Analysis
SUBSURFACE CONDITIONS
Geology
The proposed area is located within the Great Plains physiographic province. The Colorado
Piedmont is located near the western border of the Great Plains province and was formed during
Late Tertiary and Early Quaternary time (approximately 2,000,000 years ago). The Colorado
Piedmont is a broad, erosional trench which separates the Southern Rocky Mountains from the
High Plains. Structurally, the site lies along the western flank of the Denver Basin. During the
mountain building of the Laramide Orogeny (approximately 70,000,000 years ago), intense tectonic
activity occurred, causing the uplifting of the Front Range and associated downwarping of the
Denver Basin to the east. Duo to the erosional action of wind and streams, relatively flat uplands
and broad valleys characterize the present-day topography of the Colorado Piedmont in this
region. Th. site is likely unde.;ain by the Cret.^_ceous Laramie Formation. The Laramie consists of
interbedded sal idctone, s;itstn,i and claystone units. Lo..ahzed coal beds can also be found in the
Laramie, although we are unaware of any coal mines in the immediate vicinity of the site.
Due to the relatively flat nature of the site, geologic hazards at the site are anticipated to be low.
Seismic activity in the area is anticipated to be low; and from a structural standpoint, the property
should be relatively stable With proper site grading around proposed structures, erosional
problems at the site should be minimal.
Subsurface Conditions
Soils at the site generally consist of silty sand and silty clayey sand. Summary boring logs are
attached with this report.
Groundwater Conditions
Groundwater was encountered in Test Borings 1 and 3 at approximate depths of 8% and 12 feet
when it was checked 7 days after the drilling. These observations represent groundwater
conditions at the time of the field exploration, and may not be indicative of other times, or at other
3
Preliminary Geotechnical Engineering Report
Proposed Hill-Ault 9 Lot PUD
Northern Colorado Geotech Project No.029-02
locations. Groundwater levels can be expected to fluctuate with varying seasonal and weather
conditions.
Field Test Results
Field test results indicate that the sand soils vary from loose to medium dense in relative density.
Preliminary percolation testing is summarized as follows:
Preliminary Percolation Test Results
Test Hole Depth Soil Percolation Rate
(inches) Classification (minutes/inch)
1 36 SC-SM 13
2 36 SM 10
3 36 SM 9
4 36 SM 6
The soils in the proposed development have good percolation rates.
PRELIMINARY DEc•:GN RECOMMENDATIONS
Foundation Design
Based on the results of our preliminary subsurface exploration and laboratory testing, it is our
opinion that spread footing foundations may be used for support of proposed structures at the site.
The footings should be placed on undisturbed soils andlor engineered fill material. Relatively
shallow groundwater on the eastern portion of the site near the seepage ditch may require
attention in the final design and construction.
Footing Foundations -
Footings founded on the on-site soil may be preliminarily designed for maximum bearing pressures
of 1,000 to 2,000 psf. The design bearing pressure applies to dead loads plus design live load
conditions.
Exterior footings should be placed a minimum of 30 inches below finished grade for frost protection
and to provide confinement for the bearing soils. Finished grade is the lowest adjacent grade for
perimeter footings.
4
Preliminary Geotechnical Engineering Report
Proposed Hill-Ault 9 Lot PUD
Northern Colorado Geotech Project No.029-02
Below Grade Construction
Groundwater was encountered in Test Borings 1 and 3 at depths of 8% and 12 feet below existing
grade. Below grade construction is feasible provided the basement subgrade is placed a minimum
of 3 feet above the groundwater. Therefore, prior to the start of construction, site specific
explorations should be performed to establish more accurate groundwater information.
To reduce the potential for groundwater to enter the lower levels of proposed structures we
recommend that individual dewatering systems should be installed around the lower level of the
structures. The dewatering systems should, at a minimum, include a perimeter drainage pipe and
an underslab gravel drainage layer sloped to a suitable outlet, such as a sump and pump system.
Septic System Construction
Field test results indicate that standard septic systems are feasible for construction in the area of
the proposed lots. Complete percolation tests should be performed when proposed residences
and absorption beds have been sited. The system should ;be designed in accordance with
applicable state and county requirements and should be located at the minimum distances from all
prdiner:ground features described in Weld County regulations.
Gene-r4 Earthwork
All earthwork on the project should be observed and evaluated by Northern Colorado
Geotech. The evaluation of earthwork should include observation and testing of
engineered fill, subgrade preparation, foundation bearing soils, and other geotechnical
conditions exposed during the construction of the project.
Site Preparation
Strip and remove existing vegetation, debris, and other deleterious materials from proposed
building and pavement areas. All exposed surfaces should be free of mounds and
depressions which could prevent uniform compaction.
Stripped materials consisting of vegetation and organic materials should be wasted from the
site, or used to revegetate landscaped areas or exposed slopes after completion of grading
operations.
5
•
Preliminary Geotechnical Engineering Report
Proposed Hill-Ault 9 Lot PUD
Northern Colorado Geotech Project No.029-02
If unexpected fills or underground facilities are encountered, such features should be
removed and the excavation thoroughly cleaned prior to backfill placement and/or
construction.
Depending upon depth of excavation and seasonal conditions, groundwater may be
encountered in excavations on the site. Pumping from sumps may be utilized to control
water within excavations. Well points may be required for significant groundwater flow, or
where excavations penetrate groundwater to a significant depth.
The individual contractor(s) is responsible for designing and constructing stable, temporary
excavations as required to maintain stability of both the excavation sides and bottom. All
excavations should be sloped or shored in the interest of safety following local, and federal
regulations, including current OSHA excavation and trench safety standards.
Fill Materials and Placement
All exposed areas which will receive fill should be scarified to a minimum depth of eight
inches, conditioned to near optimum moisture content, and compacted.
The placement of soils on the s to should be observed by Northern Ccsiorado ' eotech. The
fill should be assessed for salability of use in the proposed fill and tested for placement
including compaction percentage and moisture content.
Engineered fill should be placed and compacted in horizontal lifts, using equipment and
procedures that will produce recommended moisture contents and densities throughout the
lift. Recommended compaction criteria for engineered fill materials are as follows:
Clean on-site soils or approved imported materials may be used as fill material.
Imported soils (if required) should conform to the following:
Percent fines by weight
Gradation fASTM C136)
6" 100
3" 70-100
No. 4 Sieve 50-100
No. 200 Sieve 50 (max)
• Liquid Limit 30 (max)
6
r•
Preliminary Geotechnical Engineering Report
Proposed Hill-Ault 9 Lot PUD
Northern Colorado Geotech Project No.029-02
• Plasticity Index 5 (max)
Minimum Percent
Material fASTM D698)
Scarified subgrade soils 95
On-site and imported fill soils:
Beneath foundations 95
Beneath slabs 95
On-site or imported sand soils should be compacted within a moisture range of 3 percent
below to 3 percent above optimum unless modified by the project geotechnical engineer.
GENERAL COMMENTS
The analysis and recommendations presented in this report are based upon data obtained from
borings performed to obtain representative subsurface conditions at the site. Variations in the soil
--- between borings will occur Northern Colorado C'aotech should be present during construction to
obsen-3 `he excavation and construction procedures and confirm or:.nrdify our recommendations
The scope of services for this project does not include either specifically or by implication any
environmental assessment of the site.
This report has been prepared in accordance with generally accepted geotechnical engineering
practices in this area at this time. No warranties, either express ,r implied, are intended or made.
7
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11VELi2{>DU.(iY Ttrar 60
OUTLOT
LOT 1 No,1 an A
LOT 6
LOT 9
_ J LOT T
LOT 2
No.2
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71 S
C LOT 4 LOT 6
/LOT 6
LOT B
No.4 5
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BORING LOCATION PLAN
PROPOSED 9-LOT HILL AULT PUD
WEL N D COUNTY ROAD 60 BOWEN ROME 27&n
ALLY,COLORADO
FOR,314
Northam
0M82ANCE DEVELOPMENT
02402
Colorado OS r•am
Geobech Da3.1602
MOROI D FOR Mat L0CMOI a d.Y. Phone p70) oai4 PMtAlyl DIALA C S C WTP .d OOMQmCTO 81222886 Fc 6068242 Aw�
LOG OF BORING No. 1 Sheet 1 of 1
CLIENT ARCHRECT/ENGINEER
Snowdance Development
SrrEWeld County Road 80, Between Roads 27 and 29 PROJECT
Auk,Colorado Hill-Auk Project
SAMPLES TESTS
O _ w tie a4 w e
U sw z Wce
O tr 2 wW
NJ m LLIRW 0
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w
o< n. oz
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6"TOPSOIL ::i,_;a' 13 1 SS 18 9
0.5
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SILTY CLAYEY SAND
Tan, moist to wet,very loose to medium dense —
3 2 RS 12 12 100 7,000
•
•
5-i
3 3 SS 0/12
s 0%
• •
10._,
13.0
SILTY SAND WITH GRAVEL
Tan,wet, medium dense —
^C —\) 10 4 SS 12 18
15.0 . '• 15
BOTTOM OF BORING
•
-•••••-. WATER LEVEL OBSERVATIONS sNo�rthern STA'1'!ED 3/6/02 FINISHED 3/6/02
i
Colorado
WL 4 8.8 W.D. DRILL u _DRILL Dco. Drilling Eng RIG CME-75
a WL = 8.7 A.B. 2956 29th Street,Unit 21 LOGGED BY DML APPROVED DML
u Greeley,Cokxado 80631
506- 44
6 When Checked 7 Days A.B. Pt 977x0-.506-9 42 NCG PROJECT NO. OZ9-0Z
0
40
LOG OF BORING No. 2
Sheet 1 of 1
CLIENT ARCHITECT/ENGINEER
Snowdance Development _
srrEWeld County Road 80, Between Roads 27 and 29 PROJECT
Ault,Colorado Hill-Ault Project
SAMPLES TESTS
0
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≥ > w a~
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SILTY SAND
Tan,moist, loose —
5 2 SS 12 9
e.
-
3 3 RS 12 23 93 7,000
10-
12.5 —
SILTY SAND WITH GRAVEL ! '
Tan,moist, medium dense —
re,.>'.
.' 18 4 SS 12 9
Pa'r
15.0 *lilt 15 I
BOTTOM OF BORING
WATER LEVEL OBSERVATIONS N
orthern STARTED 3/6/02 FINISHED 3/6/02
WL None W.D. Geotech Mu_co. Drilling Eng DRILL RIG CME-75
uWL None A.B. 2956 2901 Street,unit 21 LOGGED BY DML APPROVED DML
n _ Greeley,Colorado 80631
S♦ When Checked 7 Days A.B. Phone:
976506-92 NCCi PROJECT NO. 029-02
LOG OF BORING No. 3 Sheet t or 1
�.., CLIENT ARCHITECT/ENGINEER
e Snowdance Development _
sITEWeId County Road 80,Between Roads 27 and 29 PROJECT
Ault,Colorado Hill-Ault Project
SAMPLES TESTS
0
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-' 1.4z> W m z�
9 t. W K W0 D: 2 WF
≥ > w Cluj
a F- 3Q m WWI" N O 0
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t -:-•
SILTY SAND
Tan, moist to wet,loose —
9 2 RS 12 9 96 7,500
_
9999 f __ 5— s
I
I
\ 7 3 SS 12 11
10-
13.0 : :.:. __
SILTY SAND WITH GRAVEL
Tan,wet, medium dense " : —
>q.a 22 4 SS 12 22
:, V. -(
15.0 n .- 15
BOTTOM OF BORING
WATER LEVEL OBSERVATIONS Northern STARTED 3/6/02 FINISHED 3/6/02
W.a ,/�OlOrado
WL None
Geotech DwuDRILL RIG
Drilling Eng c CME-75
WL 2 12.0 A B. 2956 29th street,Unit 21 LOGGED BY DML APPROVED DML
Greeley,Colorado 80631
lil When Checked 7 Days A.B. Phone: 970-506-9244PROJECT No. 029-02
0 >s Fax:
ax: 970.506--9242 �y
LOG OF BORING No. 4 Sheet 1 of
�„• CLIENT ARCHITECT/ENGINEER
Snowdance Development _
sITEWeld County Road 80, Between Roads 27 and 29 PROJECT
Ault,Colorado HiII-Auk Project
SAMPLES TESTS
0
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=
. >� m w KW I 0 Of
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6"TOPSOIL 9 1 SS 18 8
0.5
SILTY SAND
Tan, moist,loose to medium dense
7 2 SS 12 6
5
•
I I 10 3 RS 12 7 100 9,000
10-
7 4 SS 12 14
15.0
BOTTOM OF BORING
/•� WATER LEVEL OBSERVATIONS Northern STARTED 3/6/02 FINISHED 3/6/02
WL None W.D. iI�OjOf2C/O
Geotech DRILL coDRILL w Drilling Eng D CME-75
WL None A.B. 2956 29th Street,unit 21
LOGGED By DML APPROVED DML
Greeley,Colorado 80631
oWhen Checked 7 Days A.B. Far 970-506-9242244 NCO PROJECT NO. 029-02 J
-4 - r
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4
H
6
8 I -- 1
10 - -
12
0.1 1 10
STRESS,ksf
Specimen Identification Classification Yd MC%
• 1 3.0 Silty Clayey Sand 100 12
CONSOLIDATION TEST
Northern 2956 29th street,Unit 21 Client: Snowdance Development Number:029-02
>�6orado Greeley,Cdorada AtioSikGeotech Fax: 970-506-9242 80631
Phone: 97asos 9244 Project: Hill Ault Project
Location: Weld County Road 80, Between Roads 27 and 2f
U.S.SIEVE OPENING IN INCHES I U.i, SIEVE NUMBERS I HYDROMETER
6 4 3 2 1.5 1 3/4 1/2, 3 4 6 810 1416 20 30 40 50 60 1001200
100 I I I I I : 11111 III
�-. 95
90
85 '
75 ___ __.. k
70 -
65
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100 10 1 0.1 0.01 0.001
GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL SANDSILT OR CLAY
coarse I fine cau I se medium I fine
Specimen Identification Classification LL PL PI Cc Cu
_
• 3 3.0 - Silty Sand
Specimen Identification D100 D60 D30 D10 %Gravel %Sand %Silt I %Clay
• 3 3.0 9.5 0.112 2.0 56.9 41.1
GRAIN SIZE DISTRIBUTION
Northern 2956 29th Street,Unit 21
Colorado Greeley,cnlorado80631 Client: Snowdance Development Number:029-02
Phone: 970-506-9244
u Project: Hill-kilt Project
0 Geotech Fax: 970-506-9242
o
ce Location: Weld County Road 80, Between Roads 27 and
Drainage Report
For
- W.B. Farms Estates Subdivision
Greeley, Colorado
_ Prepared for:
Snowdance Development Co.
_ 1750 25th Ave., Suite 305
Greeley CO 80634
Prepared by:
- Diane M Houghtaling, P.E.
1119 12th Street
• Greeley CO 80631
August, 2002
W.B. Farms Estates Subdivision
Drainage Report
Weld County, Colorado
Final Drainage Report
Certification of Engineer
I hereby attest that this report for the final drainage design for W.B. Farms Estates Subdivision
was prepared by me, or under my direct supervision, in accordance with the provisions of the
Weld County Storm Drainage Design criteria for the responsible parties thereof. I understand
that the Weld County does not and shall not assume responsibility for the drainage facilities
designed by others.
Diane M. Houghtaling, Registered Professional Engineer
State of Colorado Registration No. 22809
Certification of Developer
Snowdance Development Company hereby certifies that the drainage facilities for W.B. Farms
_ Estates Subdivision shall be constructed according to the design presented in this report. I
understand that the Weld County does not and will not assume liability for drainage facilities
designed and/or certified by my engineer. I also understand that the Weld County relies on the
representations of others to establish that drainage facilities are designed and constructed in
compliance with County guidelines, standards, or specifications. Review by the Weld County can
therefore in no way limit or diminish any liability which I or any other party may have with respect
to the design or construction of such facilities.
Attest: Charles Hill
Notary Public
W.B. Farms Estates Subdivision
Drainage Report
Weld County, Colorado
I. General Location and Description
A. Location
The property is located in the northwest quarter of Section 20, Township 7 North, Range 66 East
of the 6th Principal Meridian, Weld County, Colorado. It is physically located south of WCR 80
between WCR 27&WCR 29(see Figure 1). WCR 80 is a local gravel road in the Weld County
Transportation Plan and requires 60' of right-of-way.
The proposed development is bounded on all sides by farmland. A tributary to Coal Creek and the
Eaton ditch lies on the east boundary of the site.
B. Description of Property
The total site is 30.4 acres and is currently cultivated. The site will be developed into 9 single-
family lots containing 2.5 acres and an outlot for the existing wetlands. The topography is gently
rolling with grades as low as 1%to as steep as 2.5. A site map is included as Figure 2. The
existing soils consist of kim loam. The water table is over 6 feet below the existing ground.
A outlot is being created on the north boundary of the site. Jurisdictional wetlands exist in this
area. No work will be allowed within this area. In addition, silt fence will be provided during any
_ grading operation to protect the wetland plants and water quality.
Historically this site has been irrigated with junior water rights. There is a waste ditch crossing
this site. The center section of this ditch will be eliminated. The flows will be intercepted by the
road ditches and directed to the low point on the WB Farm Road cul-de-sac. The final section of
the waste ditch will be maintained and used for storm runoff.
All internal streets will have a right-of-way of 60 feet and a road surface 26 feet wide.
IL Drainage Basins and Sub-Basins
A. Major Basin Description
_ As stated this site drains into a tributary of Coal Creek. No existing drainage studies of the area
were found.
According to the Community Panel No. 080266-0475-D dated September 22. 1999, the subject
site is located in Zone C, which is an"Area designated as Minimal Flooding."
W.B. Farms Estates Subdivision
Drainage Report
Weld County, Colorado
B. Sub-Basin Description
Historically, this site has used a sheet flow across the field to drain to the Coal Creek tributary.
Development of this site will add very little impervious area to this site creating an insignificant
increase in the runoff. For this reason, a request was made to waive the requirement for a
detention pond. This request was granted by the Weld County Public Works Department.
However, the new roadways and ditches will interrupt and concentrate these historic flows and
the Weld County Public Works Department requested that all cross culverts and ditches be sized
to carry the 100-year storm.
III. Drainage Design Criteria
A. Regulations
This project will follow the Weld County' Storm Drainage Design Criteria. The developed storm-
water conditions were developed using information and criteria from the Urban Drainage Flood
Control Manual, and the City of Greeley Storm Drainage Manual.
B. Development Criteria Reference and Constraints
Since the single-family portion of this site is less than 90 acres, the Rational Method was used to
calculate on-site developed storm water runoff. The runoff coefficients and time-intensity-
frequency curves were from the City of Greeley Storm Drainage Criteria Manual.
To determine the water surface in the tributary the USGS"Techniques for Estimating regional
Flood Characteristics of Small Rural Watersheds in the plains Region of Eastern Colorado" was
used to determine the peak flow. Civiltools software was used for the pipe and channel sizing
analysis. The calculations are included in the appendix. Based on these calculations the 100-year
storm will inundate 47 feet of the easterly lots; no homes or septic systems will be allowed with
75 feet of the easterly property boundary.
C. Hydrological Criteria
As stated earlier the runoff will be routed to the tributary via the proposed streets side ditches and
the irrigation waste ditches.
There are two culvert crossings. .The first is near the north boundary and the second is at the
intersection of Hill Drive and WB Farm Road. These culverts are designed to convey the 100-
year storm. Culvert calculations are included in the appendix.
W.B. Farms Estates Subdivision
Drainage Report
Weld County, Colorado
D. Hydraulic Criteria
Storm-water quality will be mitigated on-site during construction with the use of silt fencing.
Running the storm-water through grassed areas will provide long-term storm-water quality.
D. Waivers/Variances Requests
Due to the small increase in runoff of the site, a waiver of the requirement for a detention pond to
limit the discharge to the 5-year historic rate is requested. This request has the verbal approval of
Drew Scheltinga of the Weld County, Public Works Department.
E. Storm-water Quality Considerations
The site has been designed to use open ditches and natural wetland areas as water quality
measures
IV. Wetland Preservation and Mitigation
No grading is anticipated in the tributary or wetland areas.
All disturbed areas for roadways will be re-seeded as soon as possible. As grading is expected to
occur during the summer, reseeding may be delayed until fall. Silt Fence, soil roughening and
watering shall be employed to reduce the fugitive dust prior to re-seeding.
V. Drainage Facility Maintenance
The HomeOwners Association will provide maintenance of the streets, culverts and ditches.
VL Conclusions
This project is in compliance will all Weld County drainage criteria, Comprehensive Drainage
plans and USDCM
W.B. Farms Estates Subdivision
Drainage Report
Weld County, Colorado
VII. References
A. Weld County Code
B. Design Criteria Manual, Urban Drainage Flood Control District.
VIII. Appendices
A. Existing Studies
Fema Map
Weld County Soil Survey
Cover Sheet from Soils Report
B. Off-Site Basin Calculations
Off-Site Basin Map
Tributary Peak Flows and Channel Calculations
C. On-Site Basins
— Urban Drainage and Food Control District Runoff Coefficients
Time of Concentration Calculations
Intensity-Frequency-Duration Curves—City of Greeley
Peak flow calculations
C. Hydrologic Computations
D. Culvert sizing
Road Side Ditch and Waste Ditch sizing
Pocket
Drainage Plan
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DIANE M. HOUGHTALING SrOVDANCE DEVELDPIUNT ca \/ ,,,,,,i-, IVkc.
1119 12TH STREET 1750 25TH AVE„ STE 305 SCALE. N TS SHEET
GREELEY, COLORADO, 80631 GREELEY, COLORADO, 80634 DATE. 7-I ti -O 2
970-378-7220 FAX 970-378-7220 970-356-9787 FAX 970-353-4 DRAVN DY. nm 11 I
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DIANE M. HOUGHTALING SNDVDANCE DEVEOP ENT CO. SITE PLAN
1119 12TH STREET 1750 25TH AVE., STE 305 RCALEi 1• - aotv FIGURE
GREELEY, COLORADO, 80631 GREELEY, COLORADO, 80634 DATE' 7-19-x8
970-378-7220 FAX 970-378-7220 970-356-9787 FAX 970-333-4 4,, YI
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- FIRM `'
FLOOD INSURANCE RATE NAP
— WELD COUNTY, .•s,.Yt A'° '� r„� I ` .
COLORADO $
(UNINCORPORATE AREAS)
� u wa •-
PANEL 175 OF 1015
-
— ".; GREAT WESTERN
Ill COMMUMIIT•PANEL NUMBER .I I 1 I I I I I I I I I I I I I I I 1 1 1 1 1 1 1 1 1 +1 1 1 1 1 4 1
08021E 0475 0 '' HURRICH
x 32
MAP REVISED: _
Ty SEPTEMBER ii,1999
....
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rewriter- EKE \\ t
DIANE M. HDUGHTALING SNOVDANCE DEVELOPMENT CO. F 1 bod N\c
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—
1119 12TH STREET 1750 25TH AVE., STE 305 SCALD %° =2coc ' SHEET
GREELEY, COLORADO, 80631 GREELEY, COLORADO, 80634 DATE' 1 - I ci -O 2
970-378-7220 FAX 970-378-7220 970-356-9797 FAX 970-353-49 DpAVPI We p'n1i
• [91ECYEN RY' 0
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
PROPOSED HILL-AULT 9 LOT PUD
WELD COUNTY ROAD 80 BETWEEN ROADS 27 AND 29
WELD COUNTY, COLORADO
NORTHERN COLORADO GEOTECH
PROJECT NO.029-02
March 19,2002
Prepared for:
Snowdance Development
1750 25th Avenue, Suite 305
Greeley, Colorado 80634
Mn: Mr.Jim Rawson
Northern
Colorado
Geotec '
2956 29th Sfreett UnIt 21
• Greeley,Colorado 60M1
Phone:(970)5014244
Fax: (970)501-9242
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DIANE M. HOUGHTALING EFT SITE BASINS
1119 12TH STREET SCALE, 1•A : 20001 ISHEET
`
— GREELEY, COLORADO, 80631 DATE, 1-4-0 2
970-378-7220 FAX 97O-378-7220 DRAyw D r.n N
•
NON URBAN EASTERN COLORADO BASINS ONLY 192 AC-12,800 AC
II III I I
BASIN , AREA PEAK DISCHARGE/FLOOD VOLUME
SQ MI 5 10 25 50 100
Q V Q V Q V Q V Q V
0.5275 131 15 204 22 315 32 414 41 532 51
DISCHARGE CONSTANT 2 3 5 7 9
TIME CONSTANT 5.19 4.89 4.61 4.44 4.30
HYDROGRAPH TIME Q TIME Q TIME Q TIME Q TIME Q
0 0 0 0 0 0 0 0 0 0
16 12 15 19 14 29 13 39 13 50
_ 26 28 24 44 23 88 22 90 21 115
36 55 34 85 32 131 31 173 30 222
52 107 49 168 48 257 44 338 43 435
57 124 54 194 51 299 49 393 47 506
82 131 59 204 55 315 53 414 52 532
67 129 84 200 60 309 58 407 56 524
73 120 68 187 65 288 62 380 60 488
93 83 88 129 83 199 80 282 77 337
119 50 112 78 108 121 102 159 99 204
156 26 147 41 138 63 133 83 129 106
207 11 195 18 184 27 178 38 172 48
259 4 244 7 230 10 222 14 215 18
311 1 293 2 277 3 267 3 258 4
363 0 342 0 323 0 311 0 301 0
CIvIlTools TRAPEZOIDAL CHANNEL HYDRAULICS
b) Sows far depth given 0 and channel dimensions
Bass Width(B):10 ft.
Side Slopes(SS):20 H:1V
Manning.W:0.05
Bad Slaps(S):2.200%
_ Flow Rds(O): • di
Mow Depth(d 3D 2 VVGEer S.r�GCF
Ftow Area(A):100.27 sq.ft. q 4 41 eGOA
Wetted perimeter('):04.13 S. Side,
Plow Velocity(V):4.57 Ns
Flaw ls:SubwOiwt
Critical Depth(Ye):1.90 S.
Sediment transport size p76):3.4 Less than 0.25 Yoh
BASED ON
PREPARED BY TECHNIQUES FOR ESTIMATING REGIONAL FLOOD
DIANE M. HOUGHTALING CHARATERICTICS OF SMALL RURAL WATERSHEDS IN THE
8/7/02 PLAINS REGION OF EASTERN COLORADO
DRAINAGE CRITERIA MANUAL RUNOFF
so
TABLE 3-1 (42)
RECOMMENDED .RUNOFF COEFFICIENTS AND PERCENT IMPERVIOUS
LAND USE OR PERCENT FREQUENCY
-
SURFACE CHARACTERISTICS IMPERVIOUS 2 5 10 100
Business:
—
Commercial Areas 95 .87 .87 .88 .89
Neighborhood Areas 70 . 60 .65 .70 .80
— Residential :
Single-Family * .40. .45 .50 .60
— Multi-Unit (detached) 50 .45 .50 .60 .70
Multi-Unit (attached) 70 .60 .65 .70 .80
1/2 Acre Lot or Larger * .30 .35 .40 .60
—
Apartments 70 .65 .70 .70 .80
Industrial :
- Light Areas 80 .71 .72 .76 .82
Heavy Acres 90 .80 .80 .85 .90
Parks , Cemetaries: 7 . 10 .18 .25 .45
Playgrounds: 13 . 15 .20 .30 .50
Schools: 50 .45 .50 .60 .70
-
Railroad Yard Areas 20 .20 .25 .35 .45
Undeveloped Areas:
- Historic Flow Analysis- 2 (See "Lawns")
Greenbelts, Agricultural
- Offsite Flow Analysis 45 .43 .47 .55 o' .65
(when land use not defined)
Streets:
-
Paved 100 .87 .88 .90 .93
Gravel (Packed) 40 .40 .45 .50 .60
- Drive and Walks: 96 .87 .87 .88 .89
Roofs: 90 .80 .85 .90 .90
Lawns, Sandy Soil 0 .00 .01 .05 .20
Lawns, Clayey Soil 0 .05 .15 .25 .50
_ NOTE: These Rational Formula coefficients may not be valid for large basins.
*See Figure 2-1 for percent impervious.
11-1-90
URBAN DRAINAGE AND FLOOD CONTROL DISTRICT
I I I I I I I I I I I I I I I I I I I
) )
TIME OF CONCENTRATION
SUBDIVISION MOUNTAIN SHADOWS
CALCULATED BY DMH DATE 11-12-01
SUB-BASIN INITIAUOVERLAND TRAVEL TIME Tc CHECK FINAL REMARKS
DATA TIME(T1). Tt) URBANIZED BASINS Tc
TOTAL
DESIGN AREA Cs LENGTH SLOPE TI LENGTH SLOPE VEL Tt COMP LENGTH Tc•(U180)+10
AC FT % MIN FT % FPS MIN fc CHECI0 FT MIN MIN
(1) (2) (3) (4) (5) (8) (7) (8) (9) (70) (11) (12) (19) (14) )
eccs.)-e 337.6 0.15 100 2.5 12.6 9400 2.5 2.5 82.7 N/A 75.3
# 1 24.08 0.15 100 2.5 12.8 800 2.5 2.5 5.3 17.9
2 0.8 0.15 100 1.2 16.1 600 1.2 1.2 8.3 24.4
3 3.32 0.15 100 2.5 12.8- 400 2.5 2.5 2.7 15.3
4 11.06 0.15 100 2.5 12.8 1200 2.5 2.5 8.0 20.8
5 0.72 0.15 100 1.0 17.1 1000 1.0 1.0 18.7 33.8
8 9.88 0.15 100 2.5 12.8 1300 2.5 2.5 8.7 21.3
41 inc.\N At. S.Mt Oi}4.fke.. V0.LuN
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Prepared by DIANE M HOUGHTALING 7/18/02 Page 1
LIDSTONE & ANDERSON, INC. 1994 (BASED UN NOAA ATLAS, 19737)
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TIME IN MINUTES
INTENSITY-DURATION-FREQUENCY CURVES
GREELEY, COLORADO
FIGURE 3-I
Publlo •orla
RUNOFF
BASIN AREA TOC INTENSITY Q
ACRES MIN INMR CFS
1 24.06 17.9 2.37 28.5
2 0.6 24.4 2.00 0.6
3 3.32 15.3 2.37 3.9
4 11.06 20.6 2.00 11.1
5 0.72 33.8 1.64 0.6
6 9.68 21.3 2.00 9.7
TIME OF CONCENTRATION ROUNDED DOWN 5 MIN INCREMENTS
I 1 I I I 1 I I I I I I I I I I I 1 1
Civil; 1
CivilTools ROUND CULVERT DESIGN CivilTools TRAPEZOIDAL CHANNEL HYDRAULICS
Calculate the headwater depth required for a round drainage culvert to pass the design flow b) Eolw for doh given Q and channel dimensions
Headwater Depth Calculation for a Round Pipe Culvert
Base Width(B):1 n.
INPUT DATA 7 Side Slopes(SS):4 H:1V
Pipe Diameter(D):36 Inches W Rennin's'n': .01
C Bed Slops(S):1.000%
Pipe Length (L):60 feet C9 Flow Rate(Q),28.8 ds
Pipe Slope:0.63% Flow Depth(d):1.02 ft < z'o t<
D n O Q 29.00 cfs FgowArea(A):5.1s aq.n.
ft-
Design ( d): Wetted perimeter(P):928 n.
Pipe and Entrance Type: on red to select V d Flaw Velocity(V):5S3 tJs
Pipe and Entrance Type:Concrete pipe with bell end projecting F'°" e s 7°''°" )
c- CriticalDepth(W):1.14 It
Manning's'n':0.016 Sediment tran dsize(D76):0.7 Inches,approx.
Tailwater Depth (TW):0 feet
2- b) Solve for depth given O end charnel dimensions
OUTPUT SUMMARY is
Bea WWII(B):1 it.
Culvert is flowing:Part Full std.Slopes(SS):+ H:1V
Headwater Depth (Hw)is:2.53 feet on
Manning.'n':0216
Slope
Culvert will operate under Inlet control s w Flow Rale(O):33 ere
Normal Flow Depth (Dn)is:21 Inches . IV Flaw Depth(d):1.20 ft. < 2' c.k.
Flow velocity in culvert is:6.87 ft./s "� — "Ants(A):6.96 0. ft.
Wetted perimeter(P):10.80 n.
Flow velocity at outlet is:6.87 ftJs To r. Few Velocity M:4.74 We
Flow Is:Supercritical
Crawl Depth(Vo):122 n.
Sediment transport size(O75):0.6 Less than 0.25 inch
b) Solve for depth given Q end channel dimensions )
Base Width(B):2 It.
Side Slopes(SS):S H:1V
Runnings'n':0.018
Bed Stops(S):2200%
Flow Rate(0):$8.8 ds
Flow Depth(4):0.78 R. < i 'oh
() j Flow Aree(A):4.98 sq.f.
j Xy wined l� a(P):1122 n.
y y+ Flow Velocity(V):8.78 tie
...1 Flow Is:Supercritical
el Critical Depth etc):0.99 8.
Sediment transport size(D76):12 Inches.apples.
Date: 8/7/2002 Time: 10:9 9
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