HomeMy WebLinkAbout20042604.tiff Todd Hodges Design, LLC
Owl Creek Estates Minor Subdivision
United States Department of Agriculture
Soil Conservation Service
In Cooperation with Colorado Agricultural Experiment Station
Soil Survey or Weld County, Southern Part
Part of Sheet 9
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64 51
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Approxlm• ._ ,. T
Parcel Location
Applicable Soil Types: 4, 51, 64, 65. Narratives to Follow.
1269 North Cleveland Avenue • Loveland, Colorado 80537 • (970) 613-8556 • fax: (970) 613-8775
email: toddhodgesdesign@earthlink.net
2004-2604
Todd Hodges Design, LLC
Soil Survey of Weld County, Colorado excerpt (Southern Portion)
Published by the United States Department of Agriculture
Soil Conservation Service
In Cooperation with Colorado Agricultural Experiment Station
Issued September 1980
Soil Classification #4: Aquolls and Aquepts, flooded
4—Aquolls and Aquepts. flooded. This nearly level
map unit is in depressions in smooth plains and along the
bottoms of natural drainageways throughout the survey
area. Aquolls, which have a dark colored surface layer,
make up about 56 percent of the unit. Aquepts, which
have a lighter colored surface layer, make up about 25
percent. About 20 percent is soils that are well drained
and soils that have sandstone or shale within 46 inches of
the surface.
These are deep, poorly drained soils that formed in
recent alluvium. No one pedon is typical. Commonly the
soils have a mottled, mildly to moderately alkaline loamy
or clayey surface layer and underlying material that ex-
tends to a depth of 60 inches or more. In places they have
a gleyed layer in the underlying material.
Moat of the acreage is subject to excessive runoff.The
water table is at or near the surface in spring and during
the peak of the irrigation season.
These soils are used for rangeland and wildlife habitat.
Some small areas are irrigated pasture.
The potential native vegetation is dominated by
switchgrass, prairie cordgrass, aaltgrass, alkali sacaton,
big hluestem, indiangrass, western wheatgrass, slender
wheatgrass, sedge, and rush. Cattails and bulirush grow
in the swampy spots associated with these range sites.
Potential production ranges from 4,000 pounds per acre in
favorable years to 3,000 pounds in unfavorable years. As
range condition deteriorates, the tall and mid grasses
decrease,production drops,and saltgrass,sedge,and rush
increase.The farming and irrigation in adjacent areas has
increased the amount of salts on much of the acreage.
Management of vegetation on this soil should be based
on taking half and leaving half of the total annual produc-
tion. Switchgrass, big bluestem, indiangrass, western
wheatgrass, pubescent wheatgrass, intermediate wheat-
grass, tall wheatgrass, and tall fescue are suitable for
seeding. The plants selected should met the seasonal
requirements of livestock. For successful seeding, a fine
prepared seedbed is needed. A grass drill should be used.
Seeding early in spring has proven most successful. Til-
lage is needed to eliminate the undesirable vegetation.
Wetland wildlife, especially waterfowl, utilize this unit.
The wetland plants provide nesting and protective rover
as well as some food. The nearby irrigated cropland,
where wildlife obtain much of their food and find protec-
tive cover, makes this unit valuable to both wetland and
openland wildlife.
Openland wildlife,especially pheasant, use this unit for
cover and nesting. Deer find excellent cover in some
areas. These valuable wildlife areas should be protected
from fire and fenced to prevent encroachment and
overuse by livestock. They should not be drained. Capa-
bility subclass Vlw; Aquolls in Salt Meadow range site,
Aquepts in Wet Meadow range site.
1269 North Cleveland Avenue • Loveland, Colorado 80537 • (970)613-8556 • fax:(970)613-8775
email: toddhodgesdesign(it!,earthlink.net
Todd Hodges Design, LLC
Soil Survey of Weld County, Colorado excerpt (Southern Portion)
Published by the United States Department of Agriculture
Soil Conservation Service
In Cooperation with Colorado Agricultural Experiment Station
Issued September 1980
Soil Classification #51: Otero sandy loam, 1 to 3 percent slopes
51—Otero sandy loam, Ito 3 percent slopes-'MIS IS a and switchgrass decrease and blue grams-,sand dropseed,
deep, well drained soil on plains at elevations of 4,700 to and sand sage increase.Annual weeds'and grasses invade
5,250 feet- It finned In mixed outwash and eolun the site as range condition becomes poorer.
deposits Included in mapping are small areas of soils that Management of vegetation on this soil should be based
have loam and clay loam underlying material. on taking half and leaving half of the total annual produc-
Typically the surface layer is brown sandy loam about tion.Seeding is desirable if the range is In poor condition.
12 inches thick.The underlying material to a depth of 60 Sand bluestem, sand reedgrass, switchgrass, sideoala
inches is pale brown calcareous tine sandy loam. grams, blue grania, pubescent wheatgrass, and crested
Permeability is rapid. Available water capaeity is wheatgrass are suitable for seeding. The prase selected
moderate. The effective rooting depth is 60 inches or should meet the seasonal requirements of livestock. It can
more. Surface runoff is slow, and the erosion hazard is be seeded into a clean, ism stubble, or it can be drilled
low. into a Finn prepared seedbed. Seeding early in spring has
This soil is used almost entirely for irrigated crops. It proven most successful
is suited to all crops commonly grown in the area Land Windbreaks and environmental plantings are generally
leveling, ditch lining, and installing pipelines may be gaited to this soil. Soil blowing, the principal hazard in
needed for proper water application establishing trees and shrubs, can be controlled by cut
All methods of irrigation are suitable, but furrow ir- tinting only in the tree row and by leaving a strip of
rigatton is the most common. Barnyard manure and corn- vegetation between the rows. Supplemental irrigation
menial fertilizer are needed for top yields. may be needed at the time of planting and during dry
In nonirrigated areas thin soil is suited to winter wheat, periods Trees that are best suited and have good survival
barley, and sorghum. Most of the acreage u planted to are Rocky Mountain juniper,eastern redcedar,ponderosa
winter wheat. The predicted average yield is 28 bushels pine, Siberian elm, Ruselanolive, and hackberry. The
per acre. The sal is summer fathered in alternate years shrubs best suited are skonkbush sumac,lilac,and Siberi-
to allow moisture accumulation.Generally precipitaiton is an peaehreb.
too low for beneficial use of fertiliser. Wildlife is an important secondary use of this sod.
Stubble mulch fanning,stripwpping,and minimum tit- Ring-necked pheasant, mourning dove, and many non-
lage are needed to control water erosion. Terracing also game species can be attracted by establishing areas for
may be needed to control water erosion. nesting and escape cover. Per pheasants, undisturbed
The potential native vegetation on this range site is nesting cover is essential and should be included in plans
dominated by sand bluestem, sand reedgrass, and blue for habitat devekryment, especially in erne of intensivegrams. Needleandthread, awitchgrasa, aideoate grams, agriculture.
and western wheatgrass are also prominent Potential Rapid expansion of Greeley and the surrounding area
production ranges from 2,200 pounds per acre in favors- has reunited in urbanization of much of this Otero soil.
ble years to 1.800 pounds in unfavorable years. As range This soil has excellent potential for urban and reaes-
condition deteriorates,the sand bluestem,sand reedgrass, tiwl development. The only limiting feature is the
moderately rapid permeability in the subst»uim, which
muses a hazard of ground water contamination from
sewage lagoons. Lawns, shrubs, and trees grow well
Capability subclass Ille irrigated, We nonirrigated;
Sandy Plaine range site.
2412 Denby (bun • Fort Collins, Colorado 80526 • (970) 207-0272 • far: (561)828-8059
email: toddhodgesdesign(a-earthlink.net
Todd Hodges Design, LLC
Soil Survey of Weld County, Colorado excerpt (Southern Portion)
Published by the United States Department of Agriculture
Soil Conservation Service
In Cooperation with Colorado Agricultural Experiment Station
Issued September 1980
Soil Classification #64: Thedalund Loam, 1 to 3 percent slopes
44—Thedalund loam, 1 lo 3 percent slopes Thu is a The underlying shale la the moat limiting feature of
moderately deep, well lamed sal on plains at elevations this soil.Neither septic tank absorption fields nor sewage
of 4,900 to 6,2250 feet. It formed in realluum from shale lagoon.haietion properly- In places the underlying shale
Included in mapping are snail areas of sots that nave has high shrink-swell potential. Environmental and beau-
.hate and sandstone deeper than 40 mehe+ titivation plantings of trees and shrubs can be difficult to
7ypieally the surface toyer is brown loam about N eatabliah. Capability subclass Iva irrigated, lye nonir-
inches rims. The underlying material is and brown l rind foamy Plains range site.
very pale brown loam Shale is at a depth of about pe
inches
Penmeabihty and available water capacity are
moderate_The effective rooting depth IS 20 to 40 inches.
Suriare runoff is medium,and the erosion hazard is low
This soil is suited to limited cropping A suitable
cropping system is 3 to 4 yeah of alfalfa followed by 2
yeah of corn and small grain and alfalfa seeded with a
muse crop Incorporating plant residue and manure im-
proves filth and provides argseic mattes and plant
nutrients
Moot irrigation method.ere suitable,but the length of
runs should be short to prevent ear-irrigation. Light,
frequent irrigations are bet. Sprinkler irrigation is
desirable. Uommexml fertilisers inertia yields and add
to the value of the forage produced
In nomrrgated arena this soil as noted to winter wheat.
barley, and seghum. Moot of the acreage is planted to
wine wheat The predicted average yield n 22 bushels
per acre The sod is summer fallowed in alternate year.
to allow moisture aecumuLYon Generally precipitation is
too low for beneficial nee of fertilizer.
Stubble mnleh fanning,stripvropp,ng,and mmnmum til-
lage are needed to control sod blowing and water erosion
Terracing also may be needed to control water erosion
The potential native vegetation is dominated by blue
grams Several mid grasses,such as western wleatgraes
and needleandLuead, am also present. Potential produc-
tion ranges from 1,5(10 pounds per acre in favorable yearn
to 1,001 pounds in unfavorable yeah As range condition
deteriorates, the rind grasses decrease. blue gams. buf-
fabgrnss, sna*eweed, yucca, and fringed sage increase.
and forage production drops. Undesirable weeds and an-
nuals invade the site as range condition become.poorer.
Management of vegetation on this soil should be based
on taking half and Weemg bad of the total annual preda-
tion.Seeding is desirable if the tense is in poor condition
Sideoam grans,hale bluenem,western wheatgnom blue
grams,pubescent whetters,and created wheatgrsa are
mutable for seeding The grass selected should meet the
seasonal requirements of livestock It can be seeded into
a clean,firm sorghum stubble,or it can be drilled into a
firm prepared seedbed_ Seeding early In spring has
proven mast sumes,ful
Windbreaks and environmental planting.an generally
not milted to this soil Onus investigation is needed to
determine if plantings are feasible
Rangeland wildlife, such as antelope, cottontail, and
coyote,am best suited to this soil Bemuse forage praise.
non is typically low, grazing management is needed if
livestock and wildlife share the range Livestock watering
fatalities also are utilized by vanes wildlife species The
cropland tunas provide favorable habitat(or pheasant and
mourning dove Many nongame species can be attracted
by establishing areas for nesting and escape cover.
2412 Denby Court • Fort Collins, Colorado 80526 • (970) 207-0272 • fax: (561)828-8059
email: toddhodgesdesign(a)earthlink.net
Todd Hodges Design, LLC
Soil Survey of Weld County, Colorado excerpt (Southern Portion)
Published by the United States Department of Agriculture
Soil Conservation Service
In Cooperation with Colorado Agricultural Experiment Station
Issued September 1980
Soil Classification #85: Thedalund loam, 3 to 9 percent slopes
es—Thedatund loam. 3 to 9 percent slopes.This is o livestock and wildlife share the range.Livestock watering
moderately deep,well drained soil on plains at elevations facilities also are utilized by various wildlife species The
of 4,900 to 5250 feet It formed in residuum from shale.
Included m m ere snag areas of soils that have mourning oun areas provide a nongame habitat for pheasant and
aPWng by dove. s rove the species can be attracted
shale and sandstone deeper than 40 inches Some small by establishing areas for nesting and escape cover.
outcrops of shale and sandstone are also included. The underlying shale Is the most limiting feature of
Typically the surface layer of this Thedalund soil ki this soil. Neither septic tank absorption fields nor sewage
brown loam about S Inches thick The underlying material lagoons function properly. In places the underlying shale
is pale brown and very pale brown loam. Shale is at a has high shrink-swell potential Environmental and beau-
depth of about 26 inches tification plantings of trees and shrubs can he difficult to
Permeability end available water capacity are establish. Capability subclass 1Ve irrigated, Vie nonir-
moderate.The effective rooting depth is 20 to 40 inches. cleated;Loamy Plains range site.
Surface runoff is medium to rapid,and the erosion hazard
is moderate.
This soil Is sited to limited cropping. Intensive
cropping ie hazardous because of erosion. The cropping
system should be limited to such close grown crops as al-
falfa, wheat, and barley. The soil is also waked to ir-
rigated pasture. A suitable topping system is 3 to 4
years of alfalfa followed by 2 years of corn and small
grain and alfalfa seeded with a nurse crop.
Closely spaced contour ditches or sprinklers can be
used in irrigating close grown crops. Contour furrows or
sprinklers should be used for new crots. Application of
commercial fertilizer helps an maintaining good produc-
tion
The potential native vegetation is dominated by blue
grave.Several mid grasses,such as western wheatgraas
and needleandthread, are also present. Potential produc-
tion ranges from 1,600 pounds per acre in favorable years
to 1,000 pounds in unfavorable yeah. As range condition
deteriorates, the mid grasses decrease; blue grams, bnf-
Wogrsee, snake weed, yucca, end fringed sage increase;
and forage production drops Undesirable weeds and en-
neals invade the site as range condition becomes poorer.
Management of vegetation on this soil should be based
on taking half and leaving half of the total annual produe-
tion. Seeding is desirable if the range is in poor condition
Sideoatz mama,little bluestem,western wheatgrasa,blue
grams,pubescent wheatgrasa,and created wheatgrasa are
suitable for seeding_The grass selected should meet the
seasonal requirements of livestock It can be seeded Into
a clean, firm sorghum stubble,or It can be drilled Into a
firm prepared seedbed Seeding early in spring has
proven most successful
Windbreaks and environmental plantings are generally
not suited to this soil. Onsite investigation is needed to
determine if plantings are feasible.
Rangeland wildlife, such as antelope, cottontail, and
coyote,are best mated to this soil.Setasae forage produc-
tion is typically low, grazing management is needed if
2412 Denby Court • Fort Collins, Colorado 80526 • (970) 207-0272 • far: (561)828-8059
email: toddhodgesdesign(aIearthlink.net
•
FINAL DRAINAGE AND EROSION CONTROL REPORT
FOR
OWL CREEK ESTATES
Prepared for:
ED ORR
ORR LAND COMPANY
826 9th Street
Greeley, Colorado 80631
Prepared by:
North Star Design
700 Automation Drive, Unit I
Windsor, Colorado 80550
(970) 686-6939
May 21,2004
Job Number 101-07
_ North Star
3/4, design, inc.
May 21, 2005
Ms. Lisa Dunn
Larimer County Engineering
PO Box 1190 -
Fort Collins, CO 80522-1190
RE: Final Drainage Report for Owl Creek Estates
Dear Lisa: •
I am pleased to submit for your review and approval, this Final Drainage Report for Owl Creek
Estates. I hereby certify that this report for the drainage design of Owl Creek Estates was
prepared by me (or under my direct supervision) for the owners thereof and meet or exceed the
criteria in the Larimer County Storm-Water Management Manual.
I appreciate your time and consideration in reviewing this submittal. Please call if you have any
questions.
Prepared by: Reviewed By:
Yetib 41j
Shane Boyle, EIT Patricia Kroetch, PE
North Star Design, Inc. North Star Design, Inc.
7OO Automation Drive, Unit I Windsor, Colorado 8O55O
97O- 686 - 6939 Phone . 97O- 686 - 1 1 88 Fax
TABLE OF CONTENTS
TABLE OF CONTENTS iii
1. GENERAL LOCATION AND DESCRIPTION
1.1 Location 1
1.2 Description of Property 1
2. DRAINAGE BASIN
2.1 Basin Description 1
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations 2
3.2 Development Criteria Reference and Constraints 2
3.3 Hydrologic Criteria 2
4. DRAINAGE FACILITY DESIGN
4.1 General Concept 2
4.2 Specific Flow Routing 2
4.3 Drainage Summary 3
5. EROSION CONTROL
5.1 General Concept 3
6. CONCLUSIONS
6.1 Compliance with Standards 4
6.2 Drainage Concept 4
7. REFERENCES 4
APPENDICES
A Vicinity Map
B Hydrologic Computations
C Figures and Tables
— iii
1. GENERAL LOCATION AND DESCRIPTION
1.1. Location
Owl Creek Estates is located in Larimer County along Highway 392, between County
Roads 53 and 70. More specifically, the project site is located in the Southeast Quarter of
Section 16, Township 6 North, Range 64 West of the Sixth Principal Meridian, Larimer
County, Colorado. The site is bounded on the south by Highway 392, on the east by Owl
Creek, and on the north and west by undeveloped agricultural property. See the Vicinity
Map in Appendix A.
1.2. Description of Property
The project consists of approximately 75.6 acres of land. The proposed improvements on
this site consist of Owl Creek Lane and 9 lots, with a house, driveway, and walks on each
lot. Access is obtained on the south from Highway 392. No portion of the proposed
project is within a designated floodplain area. The site is currently undeveloped, with
existing vegetation consisting mainly of native grasses. The existing drainage pattern is
—
to the south into the Highway 392 roadside ditch, with an average slope of approximately
1.0%.
2. DRAINAGE BASIN
2.1. Basin Description
The existing drainage pattern for the site is to the south into the Highway 392 roadside
_ ditch. This drainage pattern will remain consistent with the proposed grading plan. A
portion of the site (Basins 2 and 4) will be collected in the Owl Creek Lane roadside
ditches and conveyed to the Highway 392 roadside ditch. The remainder of the site will
continue to utilize historic drainage paths to reach the Highway 392 roadside ditch. From
there the on-site runoff, along with the remainder of the runoff being carried by the
Highway 392 roadside ditch, will be released into Owl Creek, as is the historic drainage
pattern. Refer to Section 4 of this report for more specific sub-basin routing details.
1
3. DRAINAGE DESIGN CRITERIA
3.1. Regulations
This report was prepared to meet or exceed the specifications set forth in the "Larimer
County Storm-Water Management Manual". Where applicable, the criteria established in
the "Urban Storm Drainage Criteria Manual" (UDFCD), 2001 has been used.
3.2. Development Criteria Reference and Constraints
The runoff from this site has been routed to conform to the requirements of the County
Stormwater criteria. Neither storm water detention nor extended water quality detention
are proposed for this site.
3.3. Hydrologic Criteria
Runoff computations were prepared for the 2-year minor and 100-year major storm
frequencies utilizing the Rational Method. All hydrologic calculations associated with
the basins are included in Appendix B of this report.
4. DRAINAGE FACILITY DESIGN
4.1. General Concept
Runoff from the majority of the site will flow to the south via surface flow and will be
collected in the Highway 392 roadside ditch. From there, the runoff will be conveyed to
Owl Creek. Runoff from a portion of the site (Basin 3) will sheet flow directly to Owl
Creek. Neither storm water detention nor extended water quality-detention are being
proposed with this design.
4.2. Specific Flow Routing
A summary of the drainage patterns within each basin is provided in the following
paragraphs.
Basin 1 (6.86 acres) is located in the southwest corner of the site. Runoff from this basin
will be conveyed via sheet flow to the Highway 392 roadside ditch. Basin 1 runoff is 2.1
cfs for the 2-year minor storm and 7.5 cfs for the 100-year major storm.
2
Basin 2 (26.7 acres) contains the majority of the western portion of the site, including the
western half of Owl Creek Lane. Runoff from Basin 2 will be conveyed via surface flow
to the western Owl Creek Lane roadside ditch. From there, the runoff will be conveyed
via surface flow to the Highway 392 roadside ditch. Runoff from this basin is 7.7 cfs for
the 2-year storm and 26.9 cfs for the 100-year storm.
Basin 3 (4.27 acres) contains a small portion of the site along the northern site boundary.
Runoff from this basin will sheet flow to the east into Owl Creek. Runoff from Basin 3
is 1.3 cfs for the 2-year storm and 4.8 cfs for the 100-year storm.
Basin 4 (4.36 acres) contains the eastern half of Owl Creek Land and a small portion of
adjacent land. Runoff from Basin 4 will be collected in the eastern Owl Creek Lane
roadside ditch. From there, the runoff will be conveyed via surface flow to the Highway
392 roadside ditch. Runoff from this basin is 2.5 cfs for the minor storm and 8.3 cfs for
the major storm.
Basin 5 contains the majority of the eastern half of the site. Runoff from this basin will
flow to the south and east, following a historic drainage valley, to the Highway 392
roadside ditch. Runoff from Basin 5 is 8.5 cfs for the 2-year storm and 29.9 cfs for the
100-year storm.
4.3. Drainage Summary
The drainage plan for the site will maintain historic drainage patterns to the greatest
extent possible. Flow from Basins 1 and 5 will be conveyed to the Highway 392 roadside
ditch via historic surface flow drainage paths. Drainage from Basins 2 and 4 will be
collected in the Owl Creek Lane roadside ditches and then conveyed to the-Highway 392
roadside ditch. Runoff from Basin 3 will continue to sheet flow into Owl Creek. All on-
site drainage will be conveyed into Owl Creek, either via sheet flow or via the Highway
392 roadside ditch.
5. EROSION CONTROL
5.1. General Concept
Erosion and sedimentation will be controlled on-site by the use of silt fence, straw bales,
and a stabilized construction entrance. See the Erosion Control Plan in the back pocket
for details. These measures are designed to limit the overall sediment yield increase due
3
to construction. Silt fences or straw bale dikes will also be utilized in limited areas
adjacent to any stripping stockpiles that are created during grading. They will also be
used to slow runoff around the perimeter of the site as shown on the plan. During overlot
grading, disturbed areas are to be kept in a roughened condition and watered to reduce
wind erosion.
_ 6. CONCLUSIONS
6.1. Compliance with Standards
All computations that have been completed within this report are in compliance with the
"Larimer'County Storm-Water Management Manual" and the "Urban Storm Drainage
Criteria Manual".
6.2. Drainage Concept
Conveyance elements have been designed to convey required flows to the existing
Highway 392 roadside ditch. If, at the time of construction, groundwater is encountered,
a Colorado Department of Health Construction Dewatering Permit will be required.
7. REFERENCES
1. Resource Consultants, Inc., "Larimer County Storm-Water Management Manual",
dated April 1979.
2. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated June 2001, and Volume 3 dated September
2001.
4
APPENDIX A
VICINITY MAP
721
1531
1701
PROJECT
LOCATION
r 1
1511 1 � 15
m GREE1£Y I HWY. 3921 a
20 21 22
SHEET 1 OF 1
DATE: 05/21/04 %North Star
SCALE: 1" = 2400' OWL CREEK ESTATES Ths, design, inc.
DRAWN BY: SB 700 Automation D ve,Unit I
VICINITY MAP Windsor,Colorado 80550
Phone: 970-686-6939
JOB NO.: 101-07 Fax: 970-686-1188
APPENDIX B
HYDROLOGIC COMPUTATIONS
-
- B
► 1 ► I I ► I I I I I I I I I I I I I
North Star ign,Inc.
700 AukDrive,Unit I )
\/
Windsor,.. 80550
RUNOFF COEFFICIENTS& % IMPERVIOUS
LOCATION: OWL CREEK ESTATES
PROJECT NO: 101-07
COMPUTATIONS BY: SB
DATE: 5/21/2004
Recommended%Impervious from Urban Storm Drainage Criteria Manual
% Runoff
Impervious Coefficient
C
Streets,parking lots(asphalt): 100% 0.90
Sidewalks(concrete): 90% 0.90
Roofs: 90% 0.90
Lawns(Average<2%,heavy soil): 0% 0.15
SUBBASIN TOTAL TOTAL ROOF PAVED CONCRETE LANDSCAPE % RUNOFF
DESIGNATION AREA AREA AREA AREA AREA AREA Impervious COEFF.
(ac.) (sq.ft) (sq.8) (sq.ft) (sq.ft) (sq.ft) (C)
1 6.86 298,703 0 0 0 298,703 0% 0.15
2 26.69 1,162,461 10,400 24,000 16,400 1,111,661 4% 0.18
3 4.27 186,061 0 0 0 186,061 0% 0.15
4 4.36 189,785 0 24,000 12,300 153,485 18% 0.29
5 33.40 1,454,769 13,000 0 8,200 1,433,569 1% 0.16
COMPOSITE 75.57 3,291,779 23,400 48,000 36,900 3,183,479 3% 0.17
EXISTING 75.57 3,291,779 0 0 0 3,291,779 0% 0.15
•
Flow.xls Cval
I I I I I I I I I I I I I I I I I I I
•
TIME OF CONCENTRATION
LOCATION: OWL CREEK ESTATES
PROJECT NO: 101-07
COMPUTATIONS BY: SB
DATE: 5/21/2004
SUB-BASIN DATA INITIAL/OVERLAND TIME TRAVEL TIME/CHANNEL FLOW t, CHECK FINAL REMARKS
(to (t,) (URBANIZED BASIN) t,
DESIGN SUBBASIN Area C.Cf Length Slope ti Length Slope V t, t, Total L tc---(L/ 180)+I0
POINT DESIGNATION (ac) (Cr=1.0) (ft) (%) (min) (ft) (%) (ft/s) (min) (min) (ft) (min) (min)
(I) (2) (3) (4) , (5) (6) (7) (8) (9) (10) (I1) (12) (13) (14)
1 1 6.86 0.15 400 1.5 31.04 700 1.0 2.0 5.83 36.9 1100 16.1 16.1
2 2 26.69 0.18 400 1.5 29.97 2500 0.7 1.7 24.90 54.9 2900 26.1 26.1
_
3 3 4.27 0.15 400 1.5 31.04 550 1.0 2.0 4.58 35.6 950 15.3 15.3
4 4 4.36 0.29 200 1.5 18.64 1525 1.0 2.0 12.71 31.3 1725 19.6 19.6
5 5 33.40 0.16 400 1.5 30.69_ 2400 0.8 1.8 22.36 53.0 2800 25.6 25.6
COMPOSITE 75.57 0.17 400 1.5 30.24 2500 0.7 1.7 24.90 55.1 2900 26.1 26.1
EXISTING 75.57 0.15 400 1.5 31.04 2500 0.7 _ 1.7 24.90 55.9 2900 ' 26.1 26.1
EQUATIONS:
4=4+t,
ti=[1.87(IA -C'COLo.51/Sin
t,=L/V where V=C,'S,,5 (C,from Table RO-2)
final te=minimum of t+t,and urbanized basin check •
i I I I I I I I I I I I I I I I I 1 1
) ) )
•
TIME OF CONCENTRATION
LOCATION: OWL CREEK ESTATES
PROJECT NO: 101-07
COMPUTATIONS BY: SB
DATE: 5/21/2004
SUB-BASIN DATA INITIAL/OVERLAND TIME TRAVEL TIME/CHANNEL FLOW t, CHECK FINAL REMARKS
(t) (4) (URBANIZED BASIN) 4
DESIGN SUBBASIN Area C.C1 Length Slope t1 Length Slope V 4 c Total L t=(L/ 180)+10
POINT DESIGNATION (ac) (Cr1.25) (ft) (%) (min) (ft) (%) (ft/s) (min) (min) (ft) (min) (min)
(I) (2) (3) (4) (5) (6) (7) (8) (9) (10) (II) (12) (13) (14)
1 1 6.86 0.19 400 1.5 29.82 700 1.0 2.0 5.83 35.7 1100 16.1 16.1
2 2 26.69 0.23 400 1.5 28.48 2500 0.7 1.7 24.90 53.4 2900 26.1 26.1
3 3 4.27 0.19 400 1.5 29.82 550 1.0 2.0 4.58 34.4 950 15.3 15.3
4 4 4.36 0.37 200 1.5 16.94 1525 1.0 2.0 12.71 29.6 1725 19.6 19.6
5 5 33.40 0.20 400 1.5 29.37 2400 0.8 1.8 22.36 51.7 2800 25.6 25.6
COMPOSITE 75.57 0.22 400 1.5 28.81 2500 0.7 1.7 24.90 53.7 2900 26.1 26.1
EXISTING 75.57 0.19 400 1.5 29.82 2500 0.7 1.7 24.90 54.7 2900 26.1 26.1
EQUATIONS:
4=4+4
t;=[1.87(1.1 -C5)O5]/S.V3
4=L/V where V=C,*S,;5 (C,from Table RO-2)
final tc=minimum of 4+4 and urbanized basin check
I lr I I I I I I I I I 1 I I I I 1 I I
North Star_.Ign,Inc.
700 Automation Drive,Unit I
Windsor,CO 80550
RATIONAL METHOD PEAK RUNOFF .
(2-YEAR)
LOCATION: OWL CREEK ESTATES
PROJECT NO: 101-07
COMPUTATIONS BY: SB
DATE: 5/21/2004
DIRECT RUNOFF CARRY OVER TOTAL Inlet Capacity REMARKS
Design SUBBASIN A C2 TOC5 i Q2 from Qr Q2 Total
Point DESIGNATION Design
(ac) (min) (in/hr) (cfs) Point (cfs) (cfs) (cfs)
I 1 6.86 0.15 16.1 2.06 2.11 2.11
2 2 26.69 0.18 26.1 1.58 7.70 7.70
3 3 4.27 0.15 15.3 2.09 1.34 134
4 4 4.36 0.29 19.6 1.92 2.45 2.45
5 5 33.40 0.16 25.6 1.59 8.54 8.54
COMPOSITE 75.57 0.17 26.1 1.58 20.83 20.83
EXISTING 75.57 0.15 26.1 I.58 17.88 17.88
Q=CiA
Q=peak discharge(cfs)
C=runoff cosfficient
i=rainfall intensity(in/hr)from IDF curve
•
A=drainage area(acres)
•
Flow.xls Q2
I I I I I I I I I I I I I I I I I 1 1
m
North sta in,Inc. )
700 Autome.an Drive,Unit I 1.
Windsor,CO 80550
RATIONAL METHOD PEAK RUNOFF
(100-YEAR)
LOCATION: OWL CREEK ESTATES
PROJECT NO: 101-07
COMPUTATIONS BY: SB
DATE: 5/21/2004
•
DIRECT RUNOFF CARRY OVER TOTAL Inlet Capacity REMARKS
Design SUBBASIN A Craa TOC. i Q1 from QQw (2100 Total
Point DESIGNATION Design
(ac) (min) (in/hr) (cfs) Point (cfs) (cfs) (cfs)
I 1 6.86 0.19 16.1 5.80 7.46 7.46
2 2 26.69 0.23 26.1 4.41 26.89 26.89
3 3 4.27 0.19 15.3 5.95 4.77 4.77
4 4 4.36 0.37 19.6 5.18 8.27 8.27
5 5 33.40 0.20 25.6 4.46 29.93 29.93
COMPOSITE 75.57 0.22 26.1 4.41 72.78 72.78
EXISTING 75.57 0.19 26.1 4.41 62.50 62.50
Q=CIA
Q=peak discharge(cfs)
C=runoff coefficient
i=rainfall intensity(in/hr)from IDF curve
A=drainage area(acres)
•
Flow.xls Q100
APPENDIX C
FIGURE AND TABLES
- C
i I I I 1 1 I I I I I I I I I I _ 1 I
9 lIIIIIIII
Fig. 3.3.1-I LARIMER COUNTY
RAINFALL INTENSITY-DURATION CURVE
8
AREA I-FORT COLLINS -AREA
•
T BASED ON DATA AND PROCEDURES FROM
N.O.A.A. ATLAS 2 , PRECIPITATION —
FREQUENCY ATLAS OF THE WESTERN
UNITED STATES-VOLUME III-COLORADO.
0
6
ANO
Y
a^.O9
Ftp
2 b -
J ?i r j..3/4
1 -
•
0 30 60 90 120 . I50 ISO
• STORM DURATION (Minutes )
].l-7
•
— Table 3.3.1-1
•
Area I - Fort Collins - Design Storms
—IC Total Precipitation
(in.)
2 hr - 5 min Storms
—
Time 12-EE 25 yr SO yr 100
5 0.27 0.39 0.47 0.57 0.66 0.75-
10 - 0.42 0.60 0.73 0.88 1.03 1.17
15 0.53 0.77 0.92 1.12 1.30 1.48
20 0.61 0.90 " 1.10 1.31 1.50 1.73
- 25 0.68 0.99 1.20 1.44 1.67 1.91
30 0.73 1.06 1.28 1.55 1.81 2.05
35 0.77 1.12 1.35 1.64 1.93 2.18
- 40 ' 0.80 1.17 1.41 1.72 2.02 2.30
45 0.84 1.22 1.47 .1.79 2.10 2.40
50 0.87 1.26 1.52 1.85 2.17 . 2.48
55 0.90 1.30 1.57 1.91 2.23 - 2.55
-
60 0.93 1.34 1.62 1.97 2.29 2.60
65 0.96 1.37 1.66 2.01 2.34 2.65
70 0.98 1.40 1.70 2.05 2.38 2.69
- 75 1.00 1.43 1.73 2.08 2.41 2.72
80 1.02 1.45 1.75 2.11 2.44 2.75
85 1.03 1.47 1.77 2.14 2.46 2.77
90 1.04 1.49 1.78 2.17 2.48 2.79
95 1.05 1.50 1.79 2.19 2.50 2.81
C 100 1.06 1.51 1.80 2.21 2.52 2.83
105 1.07 1.52 1.81 2.22 2.54 2.85
-
110 1.08 1.53 1.82 2.23 2.56 2.87
115 1.09 1.54 1.83 2.24 • 2.56 2.88
120 1.10 1.55 1.84 2.25 2.57 2.89
3 hr - 10 min Storms
_ 10 0.42 0.60 0.73 0.88 1.03 1.17
20 0.61 0.90 1.10 1.31 1.50 1.73
30 0.73 -. 1.06 1.28 1.55 1.81 2.05
40 0.80 1.17 1.41 1.72 2.02 2.30
-
50 0.87 1.26 1.52 1.85 2.17 2.48
60 0.93 1.34 1.62 1.97 2.29 2.60
70 0.98 1.40 1.70 2.05 2.38 2.69
- 80 1.02 1.45 - 1.75 2.11 2.45 2.75
90 1.05 1.49 1.79 2.17 2.50 2.79
100 1.07 1.52 : 1.82 2.21 2.54 2.83
_ 110 1.09 1.55 1.85 ' 2.25 2.57 2.87
120 1.11 1.58 1.88 2.29 2.60 2.91
130 1.13 1.61 1.91 2.33 2.63 2.95
140 1.15 1.63 1.93 2.36 2.66 2.99
-
150 1.17 1.65 1.95 2.39 2.69 3.02
160 1.19 1.67 1.97 2.42 2.72 3.05
170 1.21 ' 1.69 1.99 2.44 2.75 3.08
-C ) 180 1.23 1.71 2.01 2.46 2.77 3.11
LCS-WM Manual 3.3--4 April 1979
9I I I I
Fig. 3.3.1-2 LARIMER COUNTY
RAINFALL INTENSITY-DURATION CURVE
6 AREA II:- LOVELAND AREA
T BASED ON DATA AND PROCEDURES FROM
N.O.A.A. ATLAS 2, PRECIPITATION -
FREOUENCY ATLAS OF-THE WESTERN
UNITED STATES-VOLUME III-COLORADO.
0
x6
Y
n
b
O
u
e5
y
W4
J _
u. 3
44,
4y
/pY
2 J
j.
pie+p
I _ 0 30 -60 90 120 150 180
STORM DURATION (Minutes )
— Table 3.3.1-3
^ Area II - Loveland - Design Storms
- ( / Total Precipitation
(in.)
2 hr - 5 min Storms
-
Time LIE syr l2_E. 22_XL 5__a 100 yr
5 0.29 0.41 0.49 0.59 0.68 0.77
- = 10 0.45 - 0.64 0.76 0.92 1.06 1.20
15 0.57 0.81 0.96 1.16 1.34 1.52
20 0.66 0.94 1.12 1.36 1.54 1.78
25 . 0:73 1.04 1.24 1.50 1.71 1.98
30 0.79 1.12 1.33 1.61 1.86 2.10
35 0.83 1.19 1.41 1.70 2.00 2.30
40 -•0.87 1.25 1.48 1.78 2.10 2.39
-
45 0.91 1.30 1.54 1.85 2.18 2.47
50 0.94 1.34 1.60 1.91 2.25 2.54
•
55 0.97 1.38 1.65 1.97 2.31 2.60
- 60 1.00 1.41 1.69 2.03 2.36 2.66
65 1.03 1.44 1.73 2.08 2.40 2.71
70 1.06 1.47 1.76 2.12 2.44 2.75
75 1.08 1.50 1.79 2.16 2.48 2.79
80 1.10 1.52 1.81 2.18 2.52 2.82
85 1.11 1.54 1.83 2.22 2.55 2.85
90 1.12 1.55 1.85 2.25 2.58 2.88
95 1.13 1.56 1.87 2.27 2.60 2.91
j 100 1.14 1.57 1.89 2.29 2.61 2.93
105 1.15 1.58 1.91 2.30 2.62 2.95
- 110 1.16 1.59 1.92 2.31 2.63 2.97
115 1.17 1.60 1.93 2.32 2.64 2.99
120 1.18 1.61 1.94 2.33 2.65 3.01
-
3 hr - 10 min Storms
10 0.45 0.64 0.76 0.92 1.06 1.20
- _ 20 0.66. 0.94 1.12 1.36 1.54 1.78
30 0.79 - 1.12 1.33 1.61 1.86 2.10
40 0.87 1.25 1.48 1.78 2.10 2.39
- 50 0.94 1.34 1.60 1.91 2.25 2.54
60 1.00 1.41 1.69 2.03 2.36 2.66
70 1.06 1.47 1.76 2.12 2.44 2.75
- 80 1.10 1.52 - 1.81 2.19 2.52 2.82
90 1.13 1.56 1.85 2.25 2.57 2.88
100 1.17 1.59 1.89 2.30 2.62 2.94
110 1:20 1.62 1.93 . 2.34 2.66 - 3.00
120 1.23 1.65 1.97 2.38 2.70 3.05
130 1.25 1.67 2.01 2.42 2.74 3.10
140 1.27 1.69 2.04 2.45 2.77 3.15
- 150 1.29 1.71 2.07 2.48 2.80 3.19
160 1.30 1.73 2.09 2.51 2.83 3.23
170 1.31 1.75 2.11 2.53 2.85 3.25
180 1.32 1.76 2.12 2.55 2.87 3.27
- LCS-WM Manual 3.3-- 7 April 1979
DRAINAGE CRITERIA MANUAL �� •- r
TABLE RO-3
Recommended Percentage Imperviousness Values
Land Use or Percentage
Surface Characteristics Imperviousness
Business:
Commercial areas 95
Neighborhood areas 85
Residential:
Single-family •
Multi-unit(detached) 60
Multi-unit(attached) 75
Half-acre lot or larger •
Apartments 80
Industrial:
Light areas 80
Heavy areas 90
Parks, cemeteries 5
Playgrounds 10
Schools 50
Railroad yard areas 15
Undeveloped Areas:
Historic flow analysis 2
Greenbelts, agricultural 2
Off-site flow analysis 45
(when land use not defined)
Streets:
Paved 100 •
Gravel (packed) 40
Drive and walks 90
Roofs 90•
Lawns, sandy soil 0
Lawns,clayey soil 0
See Figures RO-3 through RO-5 for percentage imperviousness.
Based in part on the data collected by the District since 1969,an empirical relationship between C and
the percentage imperviousness for various storm return periods was developed. Thus,values for C can
be determined using the following equations(Urbonas, Guo and Tucker 1990).
•
CA =KA + (1.31i' —1.442 +1.135i—0.12)for CA≥0,otherwise CA=0 (RO-6)
C� =Kco + (0.8581' -0.78612 +0.774i+0.04) (RO-7)
Ce =(CA + Ccn)/2
in which:
i=%imperviousness/100 expressed as a decimal(see Table RO-3)
06/2001 RO-9
Urban Dryings and Flood Control District
—
Table 4.2.6-1
Runoff Coefficients for Rational Method
(Prom: American Soc. of Civil Engineers and Mater !\
—
Pollution Control Fad. [1970] and Seely. [1960])
—
Character of surface Runoff coefficients
Rana. Recommended
•
Pavement--asphalt or concrete 0.70-0.95 0.90 =
Gravel, from clean and Zoos.
to clayey and compact 0.25-0.70 0.50
— Roofs 0.70-0.95 0.90
Lawns (irrigated) sandy soil
Flat,--2.percent 0.05-0.15 0.10
— Average, 2 to 7 percent 0.15-0.20 0.17
Steep, 7 percent or more 0.20-0.30 0.25
Lawns (irrigated) heavy soil
— Flat, 2 percent ' 0.13-0.17 0.15
Average, 2 to 7 percent 0.18-0.22 0.20
Steep, 7 percent 0.25-0.35
0.30
Pasture and non-irrigated lawns
Sand •
Bare 0.15-0.50 0.30
Light vegetation 0.10-0.40 0.25 i
Loam F
Bare 0.20-0.60 0.40
— Light vegetation 0.10-0.45 0.30
Clay
Bare 0.30-0.75 0.50
_ Light vegetation 0.20-0.60 0.40
Composite areas
Urban
— Single-family. 4-6 units/acre 0.25-0.50 0.40
Multi-family. >6 units/acre - 0.50-0.75 0.60
Rural (mostly non-irrigated lawn area)
-
<1/2 acre - 1 acre 0.20-0.50 0.35
1 acre - 3 acres 0.15-0.50 0.30
Industrial
Light 0.50-0.80 0.65
Heavy 0.60-0.90 0.75
Business
Downtown 0.70-0.95 0.85
- Neighborhood 0.50-0.70 0.60
Parks 0.10-0.40 0.20
Rural open space
es--
-
- LCS-WM Manual 4.2--4 April 1979
Final Drainage and
Erosion Control Report
contains oversized
Grading , Drainage and
r Erosion Control Plan Map
Please see Original File
_ t
- PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
OWL CREEK PLANNED UNIT DEVELOPMENT - LOTS 3, 4, 5, & 6
- NORTHEAST OF WELD COUNTY ROAD 53
AND COLORADO HIGHWAY 392
WELD COUNTY, COLORADO
TERRACON PROJECT NO. 21995117
May21, 2004
Prepared for:
— Orr Land Company
826 9th Street
Greeley, Colorado 80631
Prepared by:
Terracon
1289 First Avenue
— Greeley, Colorado 80631
Telephone (970) 351-0460
Fax(970) 353-8639
- lierracon
lierracon
1289 First Avenue
May 21, 2004 Post Office Box 1744
Greeley,Colorado 80632-1744
(970)351-0460 Fax:(970)353-8639
Orr Land Company
826 9th Street
Greeley, Colorado 80631
Attn: Ms. Tammy Ellerman
Re: Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development— Lots 3, 4, 5, & 6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117
Terracon has completed a preliminary geotechnical engineering exploration for the proposed
planned unit development to be located northwest of Weld County Road 53 and Colorado
Highway 392. This study was performed in general accordance with our proposal number
P2104044g dated April 12, 2004.
The results of our engineering study, including the boring location diagram, laboratory test
results, test boring records, and the geotechnical recommendations needed to aid in the design
and construction of foundations and other earth connected phases of this project are attached.
The subsurface soils at the site generally consisted of clayey sand and sandy lean clays
underlain by claystone, siltstone, and sandstone bedrock. The results of our field exploration
and laboratory testing indicate that the soils and bedrock at the site have low to high expansion
potential. The soils and bedrock at anticipated foundation bearing depth have moderate load
^
bearing capability.
Based on the preliminary geotechnical engineering analyses, subsurface exploration and
laboratory test results, it is our opinion that proposed residences could be supported on spread
footing or drilled pier foundation systems. Spread footing foundations appear suitable in
conditions where proposed foundations are anticipated to bear upon soils of low expansion
potential a minimum of 4 feet above highly expansive claystone bedrock. Spread footing
foundations could also be used in conditions where non-expansive siltstone/sandstone bedrock is
encountered within 4 feet of the anticipated foundation bearing elevation. In addition, spread
footing foundations anticipated to bear on portions of materials that approach moderate expansion
potentials could require as much as 3 to 4 feet of overexcavation and replacement with non-
expansive engineered fill. Drilled pier foundations appear to be suitable in conditions where low to
moderately expansive bedrock is encountered within 4 feet of the anticipated foundation bearing
elevation. According to the Colorado Association of Geotechnical Engineers (CAGE) a swell
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Consulting Engineers&Scientists Since 1965
www.terracon.com
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development—Lots 3,4, 5, & 6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
_ potential of 3% to 5% is considered moderately expansive. A swell potential greater than 5% is
considered highly expansive.
Subsurface conditions vary significantly across the site. Accordingly, particularly due to the size of
the proposed lots, subsurface conditions can be expected to vary across each lot. Terracon
recommends subsurface exploration and geotechnical evaluation at each lot at the location of the
proposed residence to verify subsurface conditions and foundation recommendations for each
residence prior to development of foundation plans.
Slab on grade could be used at the site in areas where proposed slabs are anticipated to bear a
minimum of 4 feet above the highly expansive claystone bedrock, however, portions of
materials that approach or exceed moderate expansion potentials could require as much as 3
to 4 feet of overexcavation and replacement with non-expansive, low permeability engineered
fill. This alternative would not eliminate the possibility of slab heave but movements would tend
to be reduced and tend to be more uniform. The use of structural floor systems, structurally
supported independent of subgrade soils, would be a positive means of eliminating the potential
detrimental effects of floor movement. Structural floors are likely to be necessary when the
planned floor elevation is within 4 feet of the highly expansive claystone bedrock.
Groundwater was encountered on the site at depths of 14% to 19% feet below existing grade,
therefore, full-depth basement construction appears to be feasible on the site.
_ The expansive properties of the claystone bedrock encountered at the site can result in damage
to the proposed pavements at the site. Pavements bearing directly on unmitigated claystone
bedrock could result in excessive cracking, which could result in increased pavement
maintenance costs, a reduced pavement life, or pavement failure. Terracon recommends
consideration be given to placing pavements a minimum of 3 feet above the claystone bedrock
stratum. Based on the current site conditions, this may require overexcavation and
replacement of the claystone bedrock on the southern portion of the site to maintain the
minimum recommended separation of 3 feet. In addition, due to the presence of moderately
expansive clayey sand soils (under light loading conditions such as those imposed by pavement
structures) Terracon recommends consideration be given to moisture conditioning and
replacing the subgrade soils to a minimum depth of 2 feet. Backfill beneath the pavements
should be placed in accordance with the recommendations outlined in this report.
Other preliminary design and construction recommendations, based upon preliminary
geotechnical conditions, are presented in the report.
iii
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development— Lots 3, 4, 5, &6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
We appreciate being of service to you in the preliminary geotechnical engineering phase of this
project, and are prepared to assist you during the comprehensive geotechnical engineering and
construction phases as well. If you have any questions concerning this report or any of our
testing, inspection, design and consulting services, please do not hesitate to contact us.
Sincerely, `.. pti REG/
TERRACON CONSULTANTS, Inc. `,�� pQ,P p�ExgyTF9F
e").:iV. OE9•0
�s 1A.
,
Andrei Bedoya, E.I. Ty G. Alexander, P.E. %.A�.orvb. .oy
Staff Engineer Office Manager °'� s�ONALENG'C.``��
Copies to: Addressee (3)
iv
TABLE OF CONTENTS
Page No.
Letter of Transmittal
INTRODUCTION 1
PROPOSED CONSTRUCTION 1
SITE EXPLORATION 2
Field Exploration 2
Laboratory Testing 3
SITE CONDITIONS 3
Soil and Bedrock Conditions 4
Field and Laboratory Test Results 4
— Groundwater Conditions 4
ENGINEERING ANALYSES AND RECOMMENDATIONS 5
Geotechnical Considerations 5
Foundation Systems— Drilled Piers 6
Foundation Systems — Spread Footings 6
Pavement Design and Construction 7
Septic System Construction 8
Earthwork 8
— General Considerations 8
Site Preparation 9
Fill Materials and Placement 9
Excavation and Trench Construction 10
Additional Design and Construction Considerations 10
Underground Utility Systems 10
Surface Drainage 11
GENERAL COMMENTS 11
— APPENDIX A
Boring Location Plan
Logs of Borings
APPENDIX B
Laboratory Test Results
APPENDIX C
General Notes
General Notes — Sedimentary Bedrock Classification
Unified Soil Classification
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
OWL CREEK PLANNED UNIT DEVELOPMENT- LOTS 3, 4, 5, & 6
NORTHEAST OF WELD COUNTY ROAD 53
AND COLORADO HIGHWAY 392
WELD COUNTY, COLORADO
TERRACON PROJECT NO. 21995117
MAY 21, 2004
INTRODUCTION
This report contains the results of our preliminary geotechnical engineering exploration for the
proposed planned unit development to be located northeast of Weld County Road 53 and Colorado
Highway 392 in Weld County, Colorado.
The purpose of these services is to provide information and preliminary geotechnical engineering
recommendations relative to:
• subsurface soil and bedrock conditions
• groundwater conditions
• preliminary foundation design and construction
• basement construction
• floor slab design and construction
• pavement design and construction
• septic systems
• earthwork
• drainage
The recommendations contained in this report are based upon the results of field and laboratory
testing, preliminary engineering analyses, and experience with similar soil conditions, structures and
our understanding of the proposed project.
PROPOSED CONSTRUCTION
Terracon understands the site layout has been modified from the layout indicated during our original
subsurface exploration performed at the site, Terracon Project No. 21995117 dated October 1, 1999.
The site has been increased in size and reconfigured to support 3 additional lots for a total of 9 lots.
Each residence will be supported by an individual septic system on each lot. Additional infrastructure
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development—Lots 3,4, 5, & 6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
at the site will include construction of an access road. Loads for the proposed residences were not
available, however, Terracon assumes wall and column loads will not exceed 3 kips per lineal foot and
40 kips, respectively. Site grading plans were not available, however Terracon assumes site grading
cuts and fills will not exceed 3 feet.
SITE EXPLORATION
The scope of the services performed for this project included a site reconnaissance by a geotechnical
engineer, a subsurface exploration program, laboratory testing and engineering analyses.
Field Exploration
Six test borings were drilled on May 5, 2004. The borings were drilled to approximate depths of 5 to
25 feet at the locations shown on the Site Plan, Appendix A. Four borings were drilled within the
proposed lots, and 2 borings were drilled in the area of proposed pavements. Four percolation test
holes were drilled adjacent to the test borings on proposed lots. Percolation tests were conducted in
general accordance with Weld County requirements. All borings were advanced with a truck-mounted
— drilling rig utilizing 4-inch diameter solid stem augers.
The borings were located in the field by pacing measurements from property lines and existing site
features. Ground surface elevations at each boring location were obtained by measurements with an
engineer's level from a temporary bench mark (TBM) shown on the Site Plan. The accuracy of boring
locations and elevations should only be assumed to the level implied by the methods used to
determine each.
Lithologic logs of each boring were recorded by the field representative during the drilling operations.
At selected intervals, samples of the subsurface materials were taken by driving split-spoon and ring-
barrel samplers.
Penetration resistance measurements were obtained by driving the split-spoon and ring-barrel
samplers into the subsurface materials with a 140-pound hammer falling 30 inches. The penetration
resistance value is a useful index in estimating the consistency, relative density or hardness of the
materials encountered.
Groundwater conditions were evaluated in each boring at the time of site exploration, and one day
after completion of drilling.
2
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development—Lots 3, 4, 5, &6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
Laboratory Testing
All samples retrieved during the field exploration were returned to the laboratory for observation by the
project geotechnical engineer and were classified in accordance with the Unified Soil Classification
System described in Appendix C. Samples of bedrock were classified in accordance with the general
notes for Bedrock Classification. At that time, the field descriptions were confirmed or modified as
— necessary and an applicable laboratory testing program was formulated to determine engineering
properties of the subsurface materials. Boring logs were prepared and are presented in Appendix A.
Laboratory tests were conducted on selected soil and bedrock samples and are presented on the
boring logs and in Appendix B. The test results were used for the geotechnical engineering analyses,
and the development of foundation and earthwork recommendations. All laboratory tests were
performed in general accordance with the applicable local or other accepted standards.
Selected soil and bedrock samples were tested for the following engineering properties:
• Water Content
• Dry Density
• Consolidation/Expansion
• Grain Size
• Plasticity Index
SITE CONDITIONS
The site was located in an agricultural area and was undeveloped at the time of our site visit. The site
was vegetated with alfalfa, native weeds, and grasses. Various large deciduous trees were observed
near the northeast portion of the site. Several small, unlined irrigation ditches were observed at the
site. The ditches were dry at the time of our field exploration and appeared to be abandoned. Two oil
'- and gas well heads were observed at the site in the northeast and southwest portions. Surface
drainage sloped gently to the east. The site is bordered to the north, east, and west by agricultural
land, and to the south by Colorado Highway 392.
3
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development— Lots 3, 4, 5, & 6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
SUBSURFACE CONDITIONS
Soil and Bedrock Conditions
As presented on the Logs of Boring, surface soils at the site generally consisted of clayey sand and
_ sandy lean clay. The materials underlying the surface soils and extending to the maximum depth of
exploration consisted of claystone, siltstone, and sandstone bedrock.
— Field and Laboratory Test Results
Field test results indicate that the clay soils vary from stiff to very stiff in consistency. The sand soils
vary from medium dense to very dense in relative density. The underlying bedrock varies from soft to
hard in hardness. Laboratory test results indicate that subsoils at shallow depth have a low to
moderate expansion potential. The claystone bedrock encountered is highly expansive.
Percolation Test Results
— . Percolation testing conducted in the area of the proposed soil absorption bed are summarized as
follows:
li
11i' t,t f�{ tl
li0at,o} T #S €siettlt' G ,G'i j 1,€,i �e
ta €t "fi' ! tna atogrA ti 1 i ll t��4'€Rgt
Test Ijoie' _ jti , r ,, , S� �k , 3 fi r' 6406 €04' e�.'
;t€€�� , t � �dal N, @4t
�tt,�.ufjtFann1ti1 j1.,,,Cti1ss ai!,9 Hlminutesj,4ni,:;'y
B-7 30 CL 23
B-8 30 CL 13
B-9 30 CL 31
B-10 30 SC 12
Field test results appear to indicate that the soils at the site have good percolation characteristics.
Groundwater Conditions
Groundwater was encountered at approximate depths of 16 to 24 feet in test borings B-7, B-8, and B-9
_ at the time of field exploration. When checked one day after the drilling, groundwater was measured
at approximate depths of 14'/2 to 19'/2 feet in the same test borings. Groundwater was not
encountered in the other test borings drilled for this phase. These observations represent groundwater
conditions at the time of the field exploration, and may not be indicative of other times, or at other
4
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development—Lots 3, 4, 5, &6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
locations. Groundwater levels can be expected to fluctuate with varying seasonal and weather
conditions.
ENGINEERING ANALYSES AND RECOMMENDATIONS
Geotechnical Considerations
Based on the preliminary geotechnical engineering analyses, subsurface exploration and laboratory
test results, it is our opinion that proposed residences could be supported on spread footing or drilled
pier foundation systems. Spread footing foundations appear suitable in conditions where proposed
foundations are anticipated to bear upon soils of low expansion potential a minimum of 4 feet above
highly expansive claystone bedrock. Spread footing foundations could also be used in conditions
where non-expansive siltstone/sandstone bedrock is encountered within 4 feet of the anticipated
foundation bearing elevation. In addition, spread footing foundations anticipated to bear on portions of
materials that approach moderate expansion potentials could require as much as 3 to 4 feet of
overexcavation and replacement with non-expansive engineered fill. Drilled pier foundations appear to
be suitable in conditions where low to moderately expansive bedrock is encountered within 4 feet of
the anticipated foundation bearing elevation. According to the Colorado Association of Geotechnical
Engineers (CAGE) a swell potential of 3% to 5% is considered moderately expansive. A swell
potential greater than 5% is considered highly expansive.
Subsurface conditions vary significantly across the site. Accordingly, particularly due to the size of the
proposed lots, subsurface conditions can be expected to vary across each lot. Terracon recommends
subsurface exploration and geotechnical evaluation at each lot at the location of the proposed
residence to verify subsurface conditions and foundation recommendations for each residence prior to
development of foundation plans.
Slab on grade could be used at the site in areas where proposed slabs are anticipated to bear a
minimum of 4 feet above the highly expansive claystone bedrock, however, portions of materials
that approach or exceed moderate expansion potentials could require as much as 3 to 4 feet of
overexcavation and replacement with non-expansive, low permeability engineered fill. This
alternative would not eliminate the possibility of slab heave but movements would tend to be
reduced and tend to be more uniform. The use of structural floor systems, structurally supported
independent of subgrade soils, would be a positive means of eliminating the potential detrimental
effects of floor movement. Structural floors are likely to be necessary when the planned floor
elevation is within 4 feet of the highly expansive claystone bedrock.
5
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development—Lots 3, 4, 5, &6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
Groundwater was encountered on the site at depths of 14%2 to 1972 feet below existing grade,
therefore, full-depth basement construction appears to be feasible on the site.
The expansive properties of the claystone bedrock encountered at the site can result in damage to the
proposed pavements at the site. Pavements bearing directly on unmitigated claystone bedrock could
result in excessive cracking, which could result in increased pavement maintenance costs, a reduced
pavement life, or pavement failure. Terracon recommends consideration be given to placing
pavements a minimum of 3 feet above the claystone bedrock stratum. Based on the current site
conditions, this may require overexcavation and replacement of the claystone bedrock on the southern
portion of the site to maintain the minimum recommended separation of 3 feet. In addition, due to the
presence of moderately expansive clayey sand soils (under light loading conditions such as those
imposed by pavement structures) Terracon recommends consideration be given to moisture
conditioning and replacing the subgrade soils to a minimum depth of 2 feet. Backfill beneath the
pavements should be placed in accordance with the recommendations outlined in this report.
Preliminary design and construction recommendations for foundation systems and other earth
connected phases of the project are outlined below.
Foundation Systems— Drilled Piers
Due to the presence of highly expansive claystone bedrock on the site, grade beam and drilled pier
foundation systems could be used for support of proposed residences. Drilled pier foundations appear
to be suitable in conditions where moderately to highly expansive bedrock is encountered within 4 feet
of the anticipated foundation bearing elevation. For axial compression loads, maximum end-bearing
pressures could range from 10,000 to 30,000 pounds per square foot (psf), and skin friction could
range from 1,000 to 3,000 psf. In addition, there may be uplift forces that should be balanced with
either or a combination of minimum penetration and dead load.
Foundation Systems—Spread Footings
Due to the properties of the on-site soils and anticipated loading conditions, spread footing foundations
bearing upon undisturbed subsoils and/or engineered fill could be used for support for the proposed
residences. Spread footing foundations appear suitable in conditions where proposed foundations are
anticipated to bear upon soils of low expansion potentials a minimum of 4 feet above bedrock. Spread
footing foundations could also be used in conditions where non-expansive bedrock is encountered
within 4 feet of the anticipated foundation bearing elevation. In addition, spread footing foundations
anticipated to bear on portions of materials that approach moderate expansion potentials could require
as much as 3 to 4 feet of overexcavation and replacement with non-expansive engineered fill.
6
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development—Lots 3, 4, 5, & 6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
Maximum net allowable bearing pressures could range from 1,500 to 3,000 psf. In addition, the
footings could require a minimum dead-load pressure that could range from 500 to 1,000 psf.
Pavement Design and Construction
The expansive properties of the claystone bedrock encountered at the site can result in damage to the
proposed pavements at the site. Pavements bearing directly on unmitigated claystone bedrock could
result in excessive cracking, which could result in increased pavement maintenance costs, a reduced
pavement life, or pavement failure. Terracon recommends consideration be given to placing
pavements a minimum of 3 feet above the claystone bedrock stratum. Based on the current site
conditions, this may require overexcavation and replacement of the claystone bedrock on the southern
_ portion of the site to maintain the minimum recommended separation of 3 feet. In addition, due to the
presence of moderately expansive clayey sand soils (under light loading conditions such as those
imposed by pavement structures) Terracon recommends consideration be given to moisture
conditioning and replacing the subgrade soils to a minimum depth of 2 feet. Backfill beneath the
pavements should be placed in accordance with the recommendations outlined in this report.
— Design of pavements for the project have been based on the procedures outlined in the 1993
Guideline for Design of Pavement Structures by the American Association of State Highway and
Transportation Officials (AASHTO) as well as Colorado Department of Transportation (CDOT) design
procedures.
Traffic criteria assumed for pavement thickness design includes 18-kip equivalent single axle loads
(ESAL's) of 36,500 for local residential streets.
Local drainage characteristics of proposed pavement areas are considered to vary from fair to good
depending upon location on the site. For purposes of this design analysis, fair drainage characteristics
are considered to control the design. These characteristics, coupled with the approximate duration of
saturated subgrade conditions, results in a design drainage coefficient of 0.8 when applying the
AASHTO criteria for design.
_ For flexible pavement design, a terminal serviceability index of 2.0 was utilized along with an inherent
reliability of 85% and a design life of 20 years. Using the correlated design R-value of 5, appropriate
ESAL, environmental criteria and other factors, the structural numbers (SN) of the pavement sections
were determined on the basis of the 1993 AASHTO design equation.
The required total thickness for the pavement structure is dependent primarily upon the foundation soil
or subgrade and upon traffic conditions. Based on the soil conditions encountered at the site, the
following pavement thickness is recommended:
7
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development—Lots 3, 4, 5, & 6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
Recommended Pavement Thickness(Inches)
Traffic Area Asphalt Concrete Surface Aggregate Base Course Total
Local Street 4 8 12
_ Aggregate base course should consist of a blend of sand and gravel that meets specifications for
quality and gradation. Use of materials meeting Colorado Department of Transportation (CDOT)
Class 5 or 6 specifications is recommended for base course. Aggregate base course should be
placed in lifts not exceeding six inches and should be compacted to a minimum of 95% Standard
Proctor Density (ASTM D698).
Asphalt concrete should be composed of a mixture of aggregate, filler and additives, if required, and
approved bituminous material. The asphalt concrete should conform to approved mix designs stating
the Marshall or Superpave properties, optimum asphalt content, job mix formula and recommended
mixing and placing temperatures. Aggregate used in asphalt concrete should meet particular
gradations. Material meeting Colorado Department of Transportation Grading S or SX specification is
_ recommended for asphalt concrete. Mix designs should be submitted prior to construction to verify
their adequacy. Asphalt material should be placed in maximum 3-inch lifts and should be compacted
to within a range of 92% to 96% of maximum theoretical specific gravity.
Septic System Construction
Field test results indicate that a standard septic system and leach field (soil absorption bed) could
be feasible for construction at the site provided the bottom of the absorption bed is placed a
minimum of 4 feet above bedrock. Comprehensive percolation testing will be necessary at the time
of design for proposed residences. Percolation testing should be conducted in accordance with
Weld County regulations.
Earthwork
General Considerations
The following presents recommendations for site preparation, excavation, subgrade preparation and
placement of engineered fills on the project.
All earthwork on the project should be observed and evaluated by Terracon. 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.
8
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development—Lots 3, 4, 5, &6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
Site Preparation
Strip and remove existing vegetation, debris, and other deleterious materials from proposed building
and pavement areas. Stripped materials consisting of vegetation and organic materials should be
wasted from the site.
Subgrade soils beneath proposed pavements, as well as all exposed areas which will receive fill, once
properly cleared, should be scarified to a minimum depth of 8 inches, conditioned to near optimum
moisture content, and compacted.
Although evidence of fills or underground facilities such as septic tanks, cesspools, basements, and
_ utilities was not observed during the site reconnaissance, such features could be encountered during
construction. 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.
It is anticipated that excavations for the proposed construction can be accomplished with conventional
earthmoving equipment.
Based upon the subsurface conditions determined from the geotechnical exploration, subgrade soils
exposed during construction are anticipated to be relatively stable. However, the stability of the
subgrade may be affected by precipitation, repetitive construction traffic or other factors. If unstable
conditions develop, workability may be improved by scarifying and drying.
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
Clean on-site soils or approved imported materials may be used as fill material. On-site claystone
bedrock materials are not recommended for use as compacted fill.
Imported soils (if required) should conform to the following:
Percent fines by weight
Gradation (ASTM C136)
3" 100
No. 4 Sieve 70-100
9
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development—Lots 3,4, 5, & 6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
No. 200 Sieve 50 (max)
• Liquid Limit 30 (max)
• Plasticity Index 15 (max)
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 is 95% of maximum dry density as determined by the
standard Proctor method ASTM D698.
On-site clay and sand soils should be compacted within a moisture content range of 2 percent below
to 2 percent above optimum. Imported sand soils should be compacted within a moisture range of 4
percent below to 2 percent above optimum unless modified by the project geotechnical engineer.
Excavation and Trench Construction
Excavations into the on-site soils will encounter a variety of conditions, including caving soils and
possibly groundwater. The individual contractor(s) should be made 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.
_ The soils to be penetrated by the proposed excavations may vary significantly across the site. The
preliminary soil classifications are based solely on the materials encountered in widely spaced
exploratory test borings. The contractor should verify that similar conditions exist throughout the
proposed area of excavation. If different subsurface conditions are encountered at the time of
construction, the actual conditions should be evaluated to determine any excavation modifications
necessary to maintain safe conditions.
As a safety measure, it is recommended that all vehicles and soil piles be kept to a minimum lateral
distance from the crest of the slope equal to no less than the slope height. The exposed slope face
should be protected against the elements.
Additional Design and Construction Considerations
Underground Utility Systems
All piping should be adequately bedded for proper load distribution. It is suggested that clean, graded
gravel compacted to 75 percent of Relative Density ASTM D4253 be used as bedding. Utility trenches
10
Preliminary Geotechnical Engineering Report
Owl Creek Planned Unit Development— Lots 3, 4,5, &6
Northeast of Weld County Road 53 and Colorado Highway 392
Terracon Project No. 21995117 Terracon
should be excavated on safe and stable slopes in accordance with OSHA regulations as discussed
above. Backfill should consist of the on-site soils or existing bedrock. If bedrock is used, all plus 6-
inch material should be removed from it prior to its use. Claystone bedrock should not be placed with
4 feet of pavements, floor slabs, or spread footing foundations. The pipe backfill should be compacted
to a minimum of 95 percent of Standard Proctor Density ASTM D698.
Surface Drainage
_ Positive drainage should be provided during construction and maintained throughout the life of the
proposed project. Planters and other surface features which could retain water in areas adjacent to
pavements should be sealed or eliminated.
GENERAL COMMENTS
_ Terracon should be retained to review the preliminary design plans and specifications so comments
can be made regarding interpretation and implementation of our preliminary geotechnical
recommendations in the design and specifications. Terracon also should be retained to provide
— testing and observation during excavation, grading, and construction phases of the project.
The preliminary 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 weather. This report is for preliminary information regarding
budget and planning purposes, and is not intended for final design or construction. Additional
borings will be required when building locations and roadway elevations are determined.
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 outlined 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 verifies or modifies the conclusions of this report in writing.
11
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—
LOT 1 B-2 i
L 11.53*Acm
B-1® a 8-12
L J
STATE HIGHWAY 392
J FGEND
— IQ, TEST BORINGS DRILLED ON 5/5/04
® TEST BORINGS DRILLED ON 8/24/99N
FIGURE I: SITE PLAN
OWL CREEK PUD
—' 4 , TEMPORARY BENCH MARK = NORTHEAST OF WELD COUNTY ROAD 53 AND HIGHWAY 392
WELD COUNTY, COLORDO
TEST BORING B-7 Project Mngr. TGA Project No. 21995117
ASSUMED EL. = 100' P Designed By: irerracon Scale: t' = 500'
Checked By: TGA Date: 5/20/04
1289 FIRST AVENUE
Approved By: TGA GREELEY. COLORADO 80631 Drown By: AB
DIAGRAM IS FOR GENERAL LOCATION ONLY,
AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES. File Name: 21995117.dwg Figure No. 1
- jLOG OF BORING NO. B-07 Page 1 of 1 ,
CLIENT
Orr Land Company
— SITE Highway 392 and WCR 55 PROJECT
Weld County, CO Owl Creek PUD
SAMPLES TESTS
o DESCRIPTION m r z n
r F z=
U ± 1 w LLl cc 2 z 7
- a H y m w O 3 air- D 0W
oQ w 0 7 >- w .1 a00 ZI�-
Approx. Surface Elev.: 100.0 ft o o z i- rx also o[Cr) Do
..... .F.,"" i TOPSOIL
SANDY LEAN CLAY,very stiff, light brown — CL 1 SS 22 6.3
/%, (CL)
_ //J%4.5 95.5
2 RS 49 11.8 118
II BEDROCK, claystone with occasional 5
sandstone/siltstone lenses, soft to hard, tan —
to gray with iron staining
— 3 RS 50/0.7 4.8
10
1 - 4 SS 23 19.7
15
—
—
(Lignite lenses from 20 to 24 feet) 20 -
25 75 - 5 SS 28 16.7
25
— END OF BORING
o
i-
0
0
z
0
0
1
K
W
H
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS,ft BORING STARTED 5-5-04
It
Y 16.0 WD Y 14.5 AB lierracon RIG
CME55OREMAN
BORING CEF D 5-5-04
JSD
L AB checked after 48 hours. JOB# 21995117,
LOG OF BORING NO. B-08 Page 1 of 1
CLIENT
Orr Land Company
SITE Highway 392 and WCR 55 PROJECT
Weld County, CO Owl Creek PUD
SAMPLES TESTS
O -J 0
DESCRIPTION 2 w z .r Z -
U r
U
Z
Q W co j LIJ a. > O [KW
K ZOLIF
O
ZH
0 Approx.Surface Elev.: 104.0 ft o D Z F- t m LIJ 3 U o a D CO
L'n, 00 5 ,TOPSOIL 103
- , SANDY LEAN CLAY, stiff, brown (CL) - CL 1 SS 15 8.4
(Poorly graded sand lenses at 4 feet) —SP 2 RS 24 2.1 109
• 5 SM
10 - CL 3 RS 50/0.8 5.0 113
//,13
91
BEDROCK, claystone/siltstone,firm to
hard, light brown/tan/gray with minor iron 4 SS 38 16.8
staining 15
1 _
20—
24.8 (Gypsum crystals observed at 24 feet) 79 — 5 SS 50/0.8 18.1
END OF BORING
0
0
O
QU
W
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 5-5-04
W WL 24.0 WD Y 16.0 AB lrerr acon RIG CME-55 FOREMAN BORING COMPLETED
5-5-04
JSD
SA/L_ AB checked after 48 hours. JOB# 21995117
LOG OF BORING NO. B-09 Page 1 of 1
CLIENT
Orr Land Company
SITE Highway 392 and WCR 55 PROJECT
Weld County, CO Owl Creek PUD
SAMPLES TESTS
O
17)
DESCRIPTION °' >2 W a-
IT
U > K W Z
r ~ LLI
Q H co CO W O WI- U W
W D } W OJ a0 �r zi
o Approx. Surface Elev.: 106.0 ft o D Z m0 U o a CO
Liz °05 TOPSOIL 1055
SANDY LEAN CLAY,very stiff, brown (CL) - CL 1 SS 19 7.4
- CL 2 RS 27 7.0 109
5
49 97
BEDROCK, sandstone, firm, light — 3 RS 37 4.4 114
brown/tan 10
12 94 —
.-. BEDROCK, claystone/siltstone, gray/brown —
with iron staining —
4 SS 16 19.0
15
1 20
24.8 81 - 5 SS 50/0.8 19.6
END OF BORING
O
.— 0
0
0
QU
w
W
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 5-5-04
BORMPLETD5-04
IL
24.0 WD Y19.5 AB1ierracon RG ING COME55EFFOREMAN 5 JSD
L AB checked after 48 hours. JOB# 21995117
LOG OF BORING NO. B-10 Page 1 of 1
CLIENT
Orr Land Company
SITE Highway 392 and WCR 55 PROJECT
Weld County,CO Owl Creek PUD
SAMPLES TESTS
DESCRIPTION
r _ z=
U D' w w 1 ~ -H
LL
C�
a I— co m us o 3 wi- D 00W
a
o Approx. Surface Elev.: 88.0 ft o co z m CO o a z ti
;x;05 TOPSOIL , a75-
CLAYEY SAND, medium dense to very —SC 1 SS 26 5.8
dense, brown/light brown (SC) -
SC 2 RS 22 5.4 117
5
(Poorly graded sand at 9 feet) —SC 3 RS 50/0.9 5.1
io
(Reddish brown at 11 feet)
/1/:%13 75
BEDROCK, sandstone/siltstone, firm, light
_ brown/tan 4 SS 34 19.2
15 73 15
END OF BORING
0
0
0
O
aU
K
W
_ F
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
r WATER LEVEL OBSERVATIONS, ft BORING STARTED 5-5-04
BOOMPLETD o 5-04
WL Y None WD Y None AB lierracon R GRING COME 55E FOREMAN 5 JSD
WL AB checked after 48 hours. JOB# 21995117
LOG OF BORING NO. B-11 Page 1 of 1
CLIENT
Orr Land Company
SITE Highway 392 and WCR 55 PROJECT
Weld County,CO Owl Creek PUD
SAMPLES TESTS
DESCRIPTION m } o o a
U W
_ Z LL C7
a
n O co a. > wZ D pW
w vUi 2 a. w a J ¢O Ems- z�
0 Approx. Surface Elev.: 96.0 ft o � z � m m 3 v ER �m
7/-�-05 \TOPSOIL
CLAYEY SAND,with lean clay lenses, —SC 1 RS 20 6.9
medium dense, brown (SC)
j91 5 -SC 2 RS 24 4.1 115
END OF BORING
a
z
a
0
U¢
W
ti
S- The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 5-5-04
WL 4 None WD = None AB lierracon
BORING COMPLETED 5-5-04
° WL Y RIG CME-55 FOREMAN JSD
_ m WL AB checked after 48 hours. JOB# 21995117
LOG OF BORING NO. B-12 Page 1 of 1
CLIENT
Orr Land Company
SITE Highway 392 and WCR 55 PROJECT
Weld County, CO Owl Creek PUD
SAMPLES TESTS
0 O e p n
DESCRIPTION w z Zr
U
a. • I— CO CO W uf > co W i- 0 w
o Approx. Surface Elev.: 91.0 ft o D D � CO 50 L1J
o o. DO
0 5 ,TOPSOIL 90.5.
CLAYEY SAND, medium dense, brown —SC 1 RS 17 7.6 104
(SC)
ll/4 3 88 —
BEDROCK, claystone/siltstone, hard,
tan/light brown 4.9 86 — 2 RS 50/0.9 7.9 109
END OF BORING
a
0
0
— 0
0
QU
W
ti
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 5-5-04
5-04
IL
None WD None AB lierracon R GRING CO CME55EFFOREMAN BOMPLETD5 JSD
— L AB checked after 48 hours. JOB# 21995117
-14
-12
-10
-8
-6
0
z
a
y -4
J
Qx_
-2
0 •
2
4
6
0.01 0.1 1 10 100
PRESSURE, KSF
Specimen Identification Classification Yd pcf WC,%
• B-07 4.0ft CLAYSTONE 118 12
0
U
0
g Notes: Water added at 0.5 ksf.
F-
a
_ U
CONSOLIDATION TEST
Project: Owl Creek PUD
0 lierracon Highway 2 9951392 and WCR 55 Weld County, CO
b
Date: 5-20-04
-14
-12
-10
-8
-6
0
- z
-4
-2
2
4
6
0.01 0.1 1 10 100
PRESSURE,KSF
Specimen Identification Classification Yd, pcf WC,%
• B-09 4.0ft SANDY LEAN CLAY(CL) 109 7
O
Notes: Water added at 0.5 ksf.
0
N.
N.
_ a
CONSOLIDATION TEST
zir
erracon Project: Owl Creek PUD
Site: Highway 392 and WCR 55 Weld County, CO
O Job#: 21995117
Date: 5-20-04
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PRESSURE, KSF
Specimen Identification Classification Yd, pcf WC,%
• B-12 0.5ft CLAYEY SAND (SC) 104 8
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Notes: Water added at 0.1 ksf.
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CONSOLIDATION TEST
Project: Owl Creek PUD
1 rerracon Site: Highway 392 and WCR 55 Weld County, CO
o Job#: 21995117
Date: 5-21-04
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-12
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PRESSURE,KSF
Specimen Identification Classification Yd, pcf WC,%
• B-12 4.0ft CLAYSTONE/SILTSTONE 109 8
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Notes: Water added at 0.1 ksf.
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CONSOLIDATION TEST
Project: Owl Creek PUD
1 lerracon Site: Highway 392 and WCR 55 Weld County, CO
0 Job#: 21995117
Date: 5-21-04
U.S.SIEVE OPENING IN INCHES U.S.SIEVE NUMBERS HYDROMETER
6 4 3 2 1.5 1 314 1/2 3 4 6 8101416 20 30 40 5060 100140200
100 T I I
95
90
85
80
75
70
65
T 60
co 55
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cC
z 50
i-
z 45
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0-
35
30
25
20
15
10
5
0
_ 100 10 1 0.1 0.01 0.001
GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL SAND SILT OR CLAY
coarse I fine coarse I medium fine
Specimen Identification Classification LL PL PI Cc Cu
• B-12 0.5ft CLAYEY SAND(SC) 28 12 16
§ Specimen Identification D100 D60 D30 D10 %Gravel %Sand %Silt I %Clay
6 • B-12 0.5ft 9.525 0.134 0.5 66.2 33.3
0
QU
Cl
_ GRAIN SIZE DISTRIBUTION
lierracon Project:I- Owl Creek PUD
Site: Highway 392 and WCR 55 Weld County, CO
Job#: 21995117
Date: 5-20-04
GENERAL NOTES
_
DRILLING&SAMPLING SYMBOLS:
SS: Split Spoon- 1-3/8"I.D.,2"O.D.,unless otherwise noted HS: Hollow Stem Auger
ST: Thin-Walled Tube-2"O.D.,unless otherwise noted PA: Power Auger
RS: Ring Sampler-2.42"I.D.,3"O.D.,unless otherwise noted HA: Hand Auger
DB: Diamond Bit Coring-4",N, B RB: Rock Bit
BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary
The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch
penetration with a 140-pound hammer falling 30 inches is considered the"Standard Penetration"or"N-value".
WATER LEVEL MEASUREMENT SYMBOLS:
— WL: Water Level WS: While Sampling
WCI: Wet Cave in WD: While Drilling
DCI: Dry Cave in BCR: Before Casing Removal
— AB: After Boring ACR: After Casing Removal
Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other
times and other locations across the site could vary. In pervious soils,the indicated levels may reflect the location of groundwater. In
— low permeability soils,the accurate determination of groundwater levels may not be possible with only short-term observations.
DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have
more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine
— Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are
plastic,and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be
added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis
of their in-place relative density and fine-grained soils on the basis of their consistency.
—
CONSISTENCY OF FINE-GRAINED SOILS RELATIVE DENSITY OF COARSE-GRAINED SOILS
Standard
— Unconfined Penetration or Standard Penetration
Compressive N-value(SS) or N-value(SS)
Strength,Qu,psf Blows/Ft. Consistency Blows/Ft. Relative Density
<500 <2 Very Soft 0—3 Very Loose
— 500 - 1,000 2-3 Soft 4—9 Loose
1,001 - 2,000 4-6 Medium Stiff 10—29 Medium Dense
2,001 - 4,000 7-12 Stiff 30-49 Dense
4,001 - 8,000 13-26 Very Stiff 50+ Very Dense
8,000+ 26+ Hard
RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY
— Descriptive Term(s)of other Percent of Major Component
constituents Dry Weight of Sample Particle Size
Trace <15 Boulders Over 12 in.(300mm)
— With 15—29 Cobbles 12 in.to 3 in.(300mm to 75 mm)
Modifier >30 Gravel 3 in.to#4 sieve(75mm to 4.75 mm)
Sand #4 to#200 sieve(4.75mm to 0.075mm)
RELATIVE PROPORTIONS OF FINES Silt or Clay Passing#200 Sieve(0.075mm)
Descriptive Term(s)of other Percent of PLASTICITY DESCRIPTION
constituents Dry Weight
Term Plasticity Index
Trace <5 Non-plastic 0
With 5-12 Low 1-10
Modifiers > 12 Medium 11-30
High 30+
-
— lierracon _
Form 108-9-00
UNIFIED SOIL CLASSIFICATION SYSTEM
- [
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests• Soil Classification
Group
Symbol Group Name°
Coarse Grained Soils Gravels Clean Gravels Cu≥4 and 1 s Cc s 3° GW Well-graded gravel`
More than 50%retained More than 50%of coarse Less than 5%fines` Cu<4 and/or 1 >Cc>3` GP Poorly graded gravel`
fraction retained on
on No.200 sieve No.4 sieve Gravels with Fines Fines classify as ML or MH GM Silty graven"
More than 12%fines` Fines classify as CL or CH GC Clayey gravel`°"
Sands Clean Sands Cu≥6 and 1s Cc s 3° SW Well-graded sand'
50%or more of coarse Less than 5%fines° Cu<6 and/or 1>Cc>3° SP Poorly graded sand'
— fraction passes
No.4 sieve Sands with Fines Fines classify as ML or MH SM Silty sand's"
More than 12%fines° Fines Classify as CL or CH SC Clayey sand°""'
Fine-Grained Soils Silts and Clays inorganic PI>7 and plots on or above"A"line' CL Lean Uay"`M
— 50%or more passes the Liquid limit less than 50 PI<4 or plots below"A"line' ML Silt"`"'
No.200 sieve
organic Liquid limit-oven dried <0.75 OL Organic dal.'"
— Liquid limit-not dried Organic silt"'M0
Silts and Clays inorganic PI plots on or above"A"line CH Fat clay""
Liquid limit 50 or more
PI lots below"A"line MH Elastic Silt"`"
organic Liquid limit-oven dried Organic clay"""
<0.75 OH
Liquid limit-not dried Organic silt"`.Mo
Highly organic soils Primarily organic matter,dark in color,and organic odor PT Peat
"Based on the material passing the 3-in.(75-mm)sieve "If fines are organic,add"with organic fines"to group name.
B If field sample contained cobbles or boulders,or both,add"with cobbles ' If soil contains≥15%gravel,add"with gravel"to group name.
— or boulders,or both"to group name. J If Atterberg limits plot in shaded area,soil is a CL-ML,silty clay.
-Gravels with 5 to 12%fines require dual symbols: GW-GM well-graded K If soil contains 15 to 29%plus No.200,add"with sand"or"with
gravel with silt,GW-GC well-graded gravel with clay,GP-GM poorly gravel,"whichever is predominant.
graded gravel with silt,GP-GC poorly graded gravel with clay. L If soil contains≥30%plus No.200 predominantly sand,add
— °Sands with 5 to 12%fines require dual symbols: SW-SM well-graded "sandy"to group name.
sand with silt,SW-SC well-graded sand with clay,SP-SM poorly graded m
sand with silt,SP-SC poorly graded sand with Gay If soil contains≥30%plus No.200,predominantly gravel,
add"gravelly"to group name.
z
— ECu=Deo/D1e Cc= (D'o) "PI≥4 and plots on or above"A"line.
Die x Deo ° PI<4 or plots below"A"line.
E If soil contains≥15%sand,add"with sand"to group name. PPI plots on or above"A"line.
°If fines classify as CL-ML,use dual symbol GC-GM,or SC-SM. ° PI plots below"A"line.
60 i I I
For classification of fine-grained
soils and tine-grained fraction
'
— 50 —of coarse-grained soils Jc&/ �\cm
Equation of"A"-line J, +t^
a Horizontal at PI=4 to LL 25.5.
X 40 -- then PI-0.73(LL 20) '''+o
'' �� -- ---
O
p Equation of"U"-line
? Vertical at LL=16 to PI=7, G
30 — then P1=0.9(LL-8) /
V
— N o<O i
co 20 _ V
5 G MH or OH
10 / .
—
41-- ML orOL
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0 10 16 20 30 40 50 60 70 80 90 100 110
LIQUID LIMIT(LL)
�+/9e 1 lerracon _
Form 111
•
GENERAL NOTES
_ i
Sedimentary Rock Classification
DESCRIPTIVE ROCK CLASSIFICATION:
Sedimentary rocks are composed of cemented clay, silt and sand sized particles.The most
common minerals are clay, quartz and calcite. Rock composed primarily of calcite is called
limestone; rock of sand size grains is called sandstone, and rock of clay and silt size grains
is called mudstone or claystone,siltstone,or shale. Modifiers such as shaly,sandy,dolomitic,
— calcareous,carbonaceous,etc.are used to describe various constituents. Examples: sandy
shale; calcareous sandstone.
LIMESTONE Light to dark colored, crystalline to fine-grained texture, composed of CaCo3, reacts readily
with HCI.
DOLOMITE Light to dark colored, crystalline to fine-grained texture, composed of CaMg(CO3)2, harder
than limestone, reacts with HCI when powdered.
CHERT Light to dark colored, very fine-grained texture, composed of micro-crystalline quartz(Si02),
— brittle, breaks into angular fragments, will scratch glass.
SHALE Very fine-grained texture, composed of consolidated silt or clay, bedded in thin layers. The
unlaminated equivalent is frequently referred to as siltstone, claystone or mudstone.
SANDSTONE Usually light colored,coarse to fine texture,composed of cemented sand size grains of quartz,
feldspar,etc.Cement usually is silica but may be such minerals as calcite, iron-oxide,or some
other carbonate.
CONGLOMERATE Rounded rock fragments of variable mineralogy varying in size from near sand to boulder size
-- but usually pebble to cobble size(1/2 inch to 6 inches).Cemented together with various cemen-
ting agents. Breccia is similar but composed of angular, fractured rock particles cemented
together.
PHYSICAL PROPERTIES:
DEGREE OF WEATHERING BEDDING AND JOINT CHARACTERISTICS
-
Slight Slight decomposition of parent Bed Thickness Joint Spacing Dimensions
material on joints. May be color Very Thick Very Wide >10'
change. Thick Wide 3' • 10'
Moderate Some decomposition and color Medium Moderately Close 1' - 3'
c Thin Close 2"• 1'
change throughout.
Very Thin Very Close .4" • 2"
High Rock highly decomposed,may be ex• Laminated — .1"- .4"
tremely broken.
—
Bedding Plane A plane dividing sedimentary rocks of
the same or different lithology.
HARDNESS AND DEGREE OF CEMENTATION Joint Fracture in rock, generally more or
— Limestone and Dolomite: less vertical or transverse to bedding,
Hard Difficult to scratch with knife. along which no appreciable move-
ment has occurred.
Moderately Can be scratched easily with knife, Seam Generally applies to bedding plane
Hard cannot be scratched with fingernail. with an unspecified degree of
— Soft Can be scratched with fingernail. weathering.
Shale, Siltstone and Claystone
Hard Can be scratched easily with knife, SOLUTION AND VOID CONDITIONS
—
cannot be scratched with fingernail. Solid Contains no voids.
Moderately Vuggy (Pitted) Rock having small solution pits or
Hard Can be scratched with fingernail. cavities up to 1 inch diameter, fre-
- Soft Can be easily dented but not molded quently with a mineral lining.
with fingers. Porous Containing numerous voids,pores,or
other openings, which may or may
Sandstone and Conglomerate not interconnect.
— Well Capable of scratching a knife blade. Cavernous Containing cavities or cavems,some-
Cemented times quite large.
Cemented Can be scratched with knife.
— Poorly Can be broken apart easily with
Cemented fingers.
— 1 rerracon
Form 110-6.85
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