HomeMy WebLinkAboutReports - Soils - 09/10/2025
CTL|Thompson, Inc.
Denver, Fort Collins, Colorado Springs, Glenwood Springs, Pueblo, Summit County – Colorado
Cheyenne, Wyoming and Bozeman, Montana
SOUTHEAST COMMUNITY CENTER
INTERSECTION OF ROCK CREEK DRIVE AND ZIEGLER ROAD
FORT COLLINS, COLORADO
Prepared for:
CITY OF FORT COLLINS
300 Laporte Avenue – East Building
Fort Collins, Colorado 80524
Attention:
Eric Cluver
Project No. FC11498.000-125-R1
September 10, 2025
GEOTECHNICAL INVESTIGATION
Table of Contents
CITY OF FORT COLLINS i
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
SCOPE ...................................................................................................................................... 1
SUMMARY OF CONCLUSIONS ................................................................................................ 1
SITE CONDITIONS ................................................................................................................... 3
PREVIOUS INVESTIGATION .................................................................................................... 3
PROPOSED CONSTRUCTION ................................................................................................. 4
INVESTIGATION ....................................................................................................................... 5
SUBSURFACE CONDITIONS ................................................................................................... 5
Fill Soil .................................................................................................................................... 6
Native Soil .............................................................................................................................. 6
Bedrock .................................................................................................................................. 6
Groundwater ........................................................................................................................... 7
GEOLOGIC HAZARDS .............................................................................................................. 7
Expansive Soil and Bedrock ................................................................................................... 7
Estimated Potential Heave ..................................................................................................... 8
Seismicity ............................................................................................................................... 8
SITE PREPARATION ................................................................................................................ 9
Excavation .............................................................................................................................. 9
Fill and Backfill ......................................................................................................................10
Over-Excavation ....................................................................................................................11
Construction Dewatering .......................................................................................................12
Utilities ...................................................................................................................................12
FOUNDATIONS ........................................................................................................................13
Drilled Piers Bottomed in Bedrock .........................................................................................13
Laterally Loaded Piers/Piles ..................................................................................................14
Closely Spaced Pier Reduction Factors .................................................................................15
LATERAL EARTH PRESSURES ..............................................................................................17
FLOOR SYSTEMS AND SLABS-ON-GRADE...........................................................................18
Slabs-On-Grade ....................................................................................................................18
Structurally Supported Floors ................................................................................................19
Exterior Flatwork....................................................................................................................20
POOL AND DECK CONSTRUCTION .......................................................................................20
BELOW-GRADE CONSTRUCTION ..........................................................................................21
SURFACE AND SUBSURFACE DRAINAGE ............................................................................22
PAVEMENTS ............................................................................................................................23
Table of Contents Cont.
CITY OF FORT COLLINS ii
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WATER-SOLUBLE SULFATES ................................................................................................25
SURFACE DRAINAGE .............................................................................................................27
CONSTRUCTION OBSERVATION ...........................................................................................27
GEOTECHNICAL RISK ............................................................................................................27
LIMITATIONS ...........................................................................................................................28
FIG. 1 – LOCATIONS OF EXPLORATORY BORINGS
APPENDIX A – SUMMARY LOGS OF EXPLORATORY BORINGS
APPENDIX B – LABORATORY TEST RESULTS AND TABLE B-I
APPENDIX C – SAMPLE SITE GRADING SPECIFICATIONS
APPENDIX D – PAVEMENT CONSTRUCTION RECOMMENDATIONS
APPENDIX E – PAVEMENT MAINTENANCE PROGRAM
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SCOPE
This report presents the results of our Geotechnical Investigation for the proposed
Southeast Community Center in Fort Collins, Colorado (Figure 1). The purpose of the investiga-
tion was to evaluate the subsurface conditions and provide geotechnical design and construc-
tion criteria for the project. The scope was described in a Service Agreement (No. PR-600523)
dated July 14, 2025. Evaluation of the property for the presence of potentially hazardous materi-
als was not included in our work scope.
The report was prepared from data developed during field exploration, field and labora-
tory testing, engineering analysis, and our experience. The report includes a description of sub-
surface conditions found in our exploratory borings and discussions of site development as influ-
enced by geotechnical considerations. Our opinions and recommendations regarding design cri-
teria and construction details for site development, foundations, floor systems, slabs-on-grade,
lateral earth loads, pavements, and drainage are provided. The report was prepared for the ex-
clusive use of the City of Fort Collins and your team in design and construction of the proposed
improvements. If the proposed construction differs from descriptions herein, we should be re-
quested to review our recommendations. Our conclusions are summarized in the following para-
graphs.
SUMMARY OF CONCLUSIONS
1. Strata encountered in our borings generally consisted of 5 to 20 feet of sandy
clay over 1 to 7 feet of sand that varied from clayey sand to poorly graded sand.
Claystone bedrock was encountered at depths between 22 to 29 feet below the
existing ground surface to the depths explored.
2. Groundwater was measured at approximate depths ranging from 17 to 23 feet in
16 borings during drilling. When measured several days later, groundwater was
encountered at depths of 16.2 to 18.2 feet in 16 borings. Groundwater levels may
fluctuate seasonally and rise in response to precipitation, irrigation and changes
in land-use. We recommend a minimum 3-foot, and preferably 5-foot, separation
between all foundation elements, including pool foundation components, and
groundwater.
3. The presence of expansive soils and bedrock constitutes a geologic hazard. We
calculated 1.5 inch to 3.5 inches of potential movement at the proposed ground
surface based on a 24-foot depth of wetting. It is not certain this movement will
occur. There is risk that improvements will heave or settle and be damaged. We
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believe the recommendations presented in this report will help to control risk of
damage; they will not eliminate that risk.
4. We estimate up to 3.5 inches of heave is possible at proposed grades with nor-
mal post-construction wetting. A slab-on-grade floor is suitable at this site pro-
vided potential movements of about 1 to 2 inches or less is acceptable after over-
excavation is performed. We recommend over-excavation to at least 5 feet below
slab, pavements and exterior flatwork, to reduce movements and provide more
uniform support subgrade. Over-excavation depths greater than 5 feet will reduce
potential movements and provide better long-term performance.
5. A memorandum provided by Counsilman-Hunsaker regarding Guidelines for Ge-
otechnical Investigations for Commercial Swimming Pools, dated May 8, 2025,
movements allowances ranged from approximately ½” to 1” are allowed for in-
door and outdoor pools, respectively. We judge that drilled piers bottomed in
bedrock are the safest foundation system for limiting movement potential in ex-
pansive soil and bedrock, for the proposed building and associated pool areas.
Complications for pier installation may include groundwater and potential hole
cave-in during drilled pier excavation. Design and construction criteria for founda-
tions are presented in the report.
6. Samples of the subgrade soils generally classified as AASHTO A-6 and A-7-6
soils, with a group index of 54. For the parking lot areas, we recommend 5 inches
of asphaltic concrete over 6 inches of aggregate base course or a full depth as-
phaltic concrete pavement with a thickness of 7 inches. Thicker sections are rec-
ommended for areas with heavier traffic.
7. Existing fill was encountered in borings TH-20 through TH-23 to depths of about
6 feet. The fill was likely placed during previous site grading activities and is des-
ignated as undocumented fill. Existing fill should not support foundations, floor
slabs or pavements.
8. Control of surface and subsurface drainage will be critical to the performance of
foundations, slabs-on-grade, pavements and other improvements. Overall sur-
face drainage should be designed, constructed, and maintained to provide rapid
removal of runoff away from the building and off pavements and flatwork. Water
should not be allowed to pond adjacent to the building or in pavement or flatwork
areas. Conservative irrigation practices should be employed to reduce the risk of
subsurface wetting.
9. Relatively soft soils were encountered in some of the borings. If soft soils are en-
countered, stabilization can likely be achieved by crowding 1½ to 3-inch nominal
size crushed rock into the subsoils until the base of the excavation does not de-
form by more than about 1-inch when compactive effort is applied.
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SITE CONDITIONS
The site is located at the intersection of Ziegler Road and Rock Creek Drive in Fort Col-
lins, Colorado (Figure 1, page 5). The vacant 10.5-acre lot is relatively flat and slopes down
very gradually to the southeast. The site appeared to have been previously utilized for crop pro-
duction. Muskrat ditch flows roughly ¼ mile south of the property.
Photo 1 – Google Earth Aerial Photo, October 1999
Based on earlier Google Earth images and samples from the south end of the property,
previous overlot grading appears to have occurred. The existing buildings to the south of the
site appears to be the original ranch. The ranch is now owned by the Poudre School District
along with Fossil Creek High School which is adjacent to the property and east of the site.
Groundcover consisted of natural grasses and weeds.
PREVIOUS INVESTIGATION
CTL|Thompson performed a preliminary geotechnical report for this site, Preliminary Ge-
otechnical Investigation, Project No. FC11498-115, dated February 6, 2025. The previous inves-
tigation appeared to be consistent with the soil and bedrock encountered for this geotechnical
investigation.
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PROPOSED CONSTRUCTION
The provided site plan (proceeding page, Figure 1) indicates the project will include the
construction of a community center building. We understand the proposed building will be a two-
story, wood and steel-framed structure with an approximate footprint of 96,000 square feet. The
building will include a lobby area, indoor basketball courts, an exercise area with equipment as
well as two pools. One pool will be a year-round indoor pool while the other pool being a sea-
sonal, outdoor pool. We have assumed the ground floor of the building will have a finished floor
elevation of 4,925 feet based on conversations with the client. We understand maximum column
loads will be on the order of 50 kips with wall loads expected to be between 500 to 3,000
pounds per lineal foot. Paved parking lots and access roads are planned and buried utilities will
be constructed. We anticipate site grading will be necessary and will likely involve elevating or
filling the site.
Figure 1 –Proposed Site Overlaid With Aerial Image (Approximate, Drawing Not To Scale)
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INVESTIGATION
The field investigation included drilling and sampling 23 exploratory borings at the ap-
proximate locations presented on Figure 1. The borings were drilled to depths of approximately
10 to 30 feet using 4-inch diameter continuous-flight augers, and a truck-mounted drill rig. Drill-
ing was observed by our field representative who logged the soils and bedrock and obtained
samples for laboratory tests. Summary logs of the exploratory borings, including results of field
penetration resistance tests and a portion of laboratory test data, are presented in Appendix A.
Boring location locations and elevations were acquired using a DJI Mavic 3E drone and real-
time kinematic (RTK) station. Existing ground elevations provided are considered to be approxi-
mate.
Soil and bedrock samples obtained during drilling were returned to our laboratory and
visually examined by our geotechnical engineer. Laboratory testing was assigned and included
moisture content, dry density, swell-consolidation, particle-size analysis, Atterberg limits, uncon-
fined compression, and water-soluble sulfate concentration. Swell-consolidation test samples
were wetted at a confining pressure which approximated the pressure exerted by the overbur-
den soils (overburden pressures). Results of the laboratory tests are presented in Appendix B
and summarized in Table B-I.
SUBSURFACE CONDITIONS
Strata encountered in our exploratory borings generally consisted of 4 to 20 feet of sandy
clay over 3 to 17 feet of clayey sand to poorly graded sand. Claystone bedrock was encoun-
tered in 6 borings at 23 to 29 feet to the maximum depths explored. Samples of the clay soils
tested indicated up to 8.5 percent swell when the samples were wetted under surcharge pres-
sures that approximated overburden pressure. The higher swell values measured appeared to
be associated with the fill found predominantly located on the south side of the property. Sam-
ples of the claystone bedrock tested indicated up to 0.7 percent swell. Select pertinent engineer-
ing characteristics of the soils encountered are presented in the following paragraphs/sections.
Further descriptions of the subsurface conditions are presented on our boring logs and in our
laboratory test results.
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Fill Soil
It was difficult to discern fill from native soils in the samples obtained during drilling. Evi-
dence of previous earthwork is apparent from historical google earth aerial images. We estimate
that borings TH-20 through TH-23 have approximately 5 to 6 feet of fill and lie within the
planned parking lot area. Areas with deeper fill than that shown on our borings may be encoun-
tered during site development. The fill is of unknown origin and age and we have not been pro-
vided with records of compaction testing or fill placement conditions. The fill presents a risk of
settlement or heave to improvements constructed on the fill. We recommend the fill be removed,
moisture treated if necessary, and compacted in the pool building, swimming pool deck and
pavement area as discussed in Fill and Backfill and Over-Excavation sections of the report.
The fill is considered moderate to highly expansive.
Native Soil
Sandy clay was encountered in 23 of the borings in the planned building and parking lot
areas to depths of up to about 20 feet. The clay is soft to very stiff based on field penetration re-
sistance tests. Two clay samples swelled 1.3 to 6.3 percent when wetted. Four samples con-
tained 71 to 85 percent silt-and clay-sized particles and exhibited moderate plasticity. The clay
soil is judged to be highly expansive.
The clayey sand and sand was loose to medium dense. Samples of the clayey sand con-
tained 42 to 47 percent silt and clay-size particles (passing the No. 200 sieve). The clayey sand
has moderate plasticity. The natural sand is considered non-expansive or low-swelling based on
the results of laboratory testing and our experience.
Bedrock
Claystone bedrock was encountered in six of the sixteen borings drilled within the pro-
posed building area. Bedrock was encountered 23 to 28 deet below the existing ground surface.
The bedrock encountered was predominately claystone. The claystone was weathered to very
hard. Three claystone samples swelled up to 0.7 percent when wetted under surcharge pres-
sures that approximated overburden pressure. The claystone is judged to be expansive.
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Groundwater
Groundwater was estimated at depths ranging from 17 to 23 feet in 16 borings during
drilling. When measured several days later on July 31, 2025, water was measured at depths of
16.2 to 18.2 feet in 16 borings. Groundwater may develop on or near the bedrock surface or
other low permeable soil or bedrock when a source of water not presently contributing becomes
available. Groundwater levels may fluctuate seasonally and rise in response to precipitation,
landscape irrigation, changes in land-use or changes in water levels in the nearby Muskrat
Ditch. Groundwater is expected to affect below-grade construction at the site but may affect
drilled pier installation. We recommend a minimum separation of 3 feet, and preferably 5 feet,
from groundwater to foundations and floor systems.
GEOLOGIC HAZARDS
Geologic hazards and geotechnical concerns include expansive soils and bedrock. No
geologic hazards or geotechnical concerns that would preclude the proposed development were
noted. We believe potential hazards can be mitigated with proper engineering, design, and con-
struction practices, as discussed in this report.
Expansive Soil and Bedrock
Colorado is a challenging location to practice geotechnical engineering. The climate is
relatively dry, and the near-surface soils are typically dry and comparatively stiff. These soils
and related sedimentary bedrock formations tend to react to changes in moisture content. Some
of the soils and bedrock swell as they increase in moisture and are collectively referred to as ex-
pansive soils. Other soils can compress significantly upon wetting and are identified as com-
pressible soils. Much of the land available for development east of the Front Range is underlain
by expansive clay or claystone bedrock near the surface. The soils that exhibit compressible be-
havior are more likely west of the Continental Divide; however, both types of soils occur
throughout the state.
Covering the ground with buildings, streets, driveways, parking lots, etc., coupled with
lawn irrigation and changing drainage patterns, leads to an increase in subsurface moisture
conditions. As a result, some soil movement is inevitable. It is critical that all recommendations
in this report are followed to increase the chances that the foundations and slabs-on-grade will
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perform satisfactorily. Owners and/or property managers must assume responsibility for main-
taining structures and use appropriate practices regarding drainage and landscaping.
Based on our investigation, low to moderately expansive soils and bedrock are present
at this site at depths likely to influence performance of shallow foundations, floor slabs, pave-
ment, and other surface improvements. The presence of expansive soils constitutes a geologic
hazard. Existing fill, if encountered, may be poorly compacted and considered compressible
upon wetting or additional loading. There is risk that ground heave or settlement will damage
slabs-on-grade and foundations. The risks can be mitigated, but not eliminated, by proper de-
sign, construction, and maintenance procedures. We believe the recommendations in this report
will help reduce risk of foundation and/or slab damage; they will not eliminate risk. The owner(s)
should understand that improvements may be affected by movement of the subsoils. Slab-on-
grade and, in some instances, foundations may be affected. Maintenance and prudent irrigation
practices will be required to reduce risk.
Estimated Potential Heave
Based on the subsurface profiles, swell-consolidation test results and our experience,
we calculated the potential heave at the proposed ground surface for the building and surround-
ing parking areas. The analysis involves dividing the soil and bedrock profile into layers and
modeling the heave of each layer from representative swell tests. We estimated a potential
ground heave of 1.5 to 3.5 inches at the building borings. A depth of wetting of 24 feet below ex-
isting grades was considered for the analysis. It is not certain whether the estimated heave will
occur, and variations from our estimates should be anticipated.
Seismicity
According to the USGS, Colorado’s Front Range and eastern plains are considered low
seismic hazard zones. The earthquake hazard exhibits higher risk in western Colorado com-
pared to other parts of the state. The Colorado Front Range area has experienced earthquakes
within the past 100 years, shown to be related to deep drilling, liquid injection, and oil/gas ex-
traction. Naturally occurring earthquakes along faults due to tectonic shifts are rare in this area.
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The soil and bedrock at this site are not expected to respond unusually to seismic activ-
ity. The 2021 International Building Code (Section 16.13.2.2) defers the estimation of Seismic
Site Classification to ASCE7-22, a structural engineering publication. The table below summa-
rizes ASCE7-22 Site Classification Criteria.
ASCE7-22 SITE CLASSIFICATION CRITERIA
Seismic Site Class 𝑣̅𝑠, Calculated Using Measured or Estimated
Shear Wave Velocity Profile (ft/s)
A. Hard Rock >5,000
B. Medium Hard Rock >3,000 to 5,000
BC. Soft Rock >2,100 to 3,000
C. Very Dense Sand or Hard Clay >1,450 to 2,100
CD. Dense Sand or Very Stiff Clay >1,000 to 1,450
D. Medium Dense Sand or Stiff Clay >700 to 1,000
DE. Loose Sand or Medium Stiff Clay >500 to 700
E. Very Loose Sand or Soft Clay ≥500
F. Soils requiring Site Response Analysis See Section 20.2.1
Based on the results of our investigation, the reduced, empirically estimated average
shear wave velocity values for the upper 100 feet range between 753 and 1250 feet per second
with an average value of 1024 feet per second. We judge a Seismic Site Classification of D. The
field penetration test results along with the empirical estimates imply that shear-wave velocity
seismic tests to directly measure 𝒗̅𝒔 could result in a better Seismic Site Classification. The sub-
surface conditions indicate low susceptibility to liquefaction from a materials and groundwater
perspective.
SITE PREPARATION
Excavation
We believe the soils penetrated in our exploratory borings can generally be excavated
with conventional, heavy-duty excavation equipment. We recommend the owner and the con-
tractor become familiar with applicable local, state and federal safety regulations, including the
current OSHA Excavation and Trench Safety Standards. We believe the soils will classify as
Type C soils, which typically require maximum side slope inclinations of 1½:1 (horizontal:verti-
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cal) for temporary excavations in dry conditions. Flatter slopes will be required below groundwa-
ter or where seepage is present. The contractor’s “competent person” is required to review ex-
cavation conditions and refer to OSHA Standards when worker exposure is anticipated. Stock-
piles of soils and equipment should not be placed within a horizontal distance equal to one-half
the excavation depth, from the edge of the excavation. A professional engineer should design
excavations deeper than 20 feet, if any.
The drilled pier contractor should be selected based on experience with drilling or exca-
vating through comparatively soft, near-surface sandy material with groundwater present. Soft,
sandy soil close to measured groundwater levels suggests significant hole cave-in potential dur-
ing drilling. Casing may be required during drilling.
We recommend a minimum 5 feet of over-excavation, moisture-conditioning and re-com-
paction below pavements, slabs and exterior flatwork to reduce potential heave and improve
performance. The over-excavation should be extended beneath the adjacent sidewalks and im-
provements. Deeper over-excavation to 7 feet below pavements can be considered for better
performance. Pavement, slab and exterior flatwork preparation is discussed further in the report.
Fill and Backfill
The on-site soils are suitable for reuse as new fill, provided they are free of debris, vege-
tation/organics and other deleterious materials. Soil particles larger than about 3 inches in diam-
eter should not be used for fill unless broken down. Imported fill (if any) should have a maximum
particle size of 3 inches, between 40 and 60 percent passing the No. 200 sieve, a liquid limit
less than 40 and a plasticity index less than 20. Import soils consisting of material similar to
those found on-site may also be considered. Potential fill materials should be submitted to our
office for approval prior to import.
Prior to fill placement, debris, organics/vegetation and deleterious materials should be
substantially removed from areas to receive fill. The ground surface should be scarified to a
depth of at least 8 inches, moisture conditioned and compacted to the criteria below. Subse-
quent fill should be placed in thin (8 inches or less) loose lifts, moisture conditioned to within 2
percent of optimum moisture content for sand and between 1 and 4 percent above optimum for
clay and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D
698).
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We recommend utility trench backfill be placed and compacted as outlined above. Our
experience indicates use of self-propelled compactors results in more reliable performance
compared to fill compacted by an attachment on a backhoe or trackhoe. The upper portion of
the trenches should be widened to allow the use of a self-propelled compactor. The placement
and compaction of fill and backfill should be observed and tested by a representative of our firm
during construction.
Our experience indicates fill and backfill can settle, even if properly compacted to criteria
provided above. Factors that influence the amount of settlement are depth of fill, material type,
degree of compaction, amount of wetting and time. The degree of compression of properly com-
pacted fill under its own weight may be about 1 to 2 percent of the fill depth.
If loose or soft fill/soils are encountered during construction, they should be removed and
replaced with compacted fill or stabilized. Stabilization can likely be accomplished by crowding
1.5-inch to 3-inch nominal size crushed rock into the soft subsoils until the base of the excava-
tion does not deform significantly when compactive effort (a full-sized loader with full load) is ap-
plied. Geosynthetic grid or woven fabric can also be used in conjunction with the rock. Typically,
a biaxially woven fabric such as Mirafi 600x (or equal) or geogrid (such as Tensar BX1100 or
equal) topped with 8 to 12 inches of 1 to 5-inch crushed rock should provide a stable working
surface.
Over-Excavation
Over-excavation can be performed to provide a uniform, low swelling bearing stratum to
reduce differential movement on slabs, pavement and exterior flatwork areas. Our borings gen-
erally indicate low to moderate swell in the upper 5 to 10 feet of soil. Based on our understand-
ing of acceptable movement and our test results, we recommend over-excavation below slabs,
pavement and exterior flatwork areas.
Over-excavation has been used in the Front Range of Colorado with satisfactory perfor-
mance for the large majority of the sites where this ground modification method has been com-
pleted. Over-excavation across slab and pavement areas incorporates a uniform elevation low-
ering below grade or step-down consistent with the building foundations. The extent and depth
of over-excavation should be surveyed and an “as-built” plan of the over-excavated areas
should be prepared. We have seen isolated instances where settlement of over-excavation fill
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has led to damage. In most cases, the settlement was caused by wetting associated with poor
surface drainage and/or poorly compacted fill placed at the horizontal limits of the over-excava-
tion. The bottom of the over-excavation should extend laterally at least 5 feet outside the foun-
dation footprint to ensure the foundations are constructed over moisture-conditioned fill. Precau-
tions should be taken for compaction of fill at corners, access ramps and edges of the over-ex-
cavation due to equipment access constraints. The contractor should have the appropriate
equipment to reach and compact these areas. A conceptual over-excavation section of the
building is presented on Figure 4. Guideline specifications for over-excavation are provided in
Appendix C.
The excavation contractor should be chosen to assure they have experience with fill
placement at over-optimum moisture and have the necessary compaction equipment. Special
care should be taken to compact fill in corners and in and out of ramps. The contractor should
anticipate this and implement measures accordingly and have the proper equipment. The oper-
ation will be relatively slow. In order for the procedure to be performed properly, close contractor
control of fill placement to specifications is required. Over-excavation fill should be moisture-
conditioned between 1 and 4 percent above optimum moisture content for clay or within 2 per-
cent of optimum for sand. Fill should be compacted at least 95 percent of standard Proctor max-
imum dry density. Our representative should observe and test compaction of fill during place-
ment.
Construction Dewatering
Dewatering should consider how and where the pumped water will be disposed. The
City of Fort Collins, and/or the Colorado Department of Public Health may require dewatering
permits. Our experience indicates periodic environmental testing is usually required with these
permits, with reporting. Permitting requirements may also influence the construction schedule.
Utilities
Water, storm sewer and sanitary sewer lines are often constructed beneath slabs and
pavements. Compaction of utility trench backfill can have a significant effect on the life and ser-
viceability of floor slabs, pavements and exterior flatwork. Our experience indicates use of self-
propelled compactors results in more reliable performance compared to fill compacted by an at-
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tachment on a backhoe or trackhoe. The upper portion of the trenches should be widened to al-
low the use of a self-propelled compactor. During construction, careful attention should be paid
to compaction at curb lines and around manholes and water valves.
Special attention should be paid to backfill placed adjacent to manholes as we have ob-
served conditions where settlement in excess of 1 percent has occurred after completion of con-
struction. Flowable fill may be considered at critical utility crossings where it would be difficult to
achieve adequate compaction. Utility trench backfill should be moistened and compacted ac-
cording to the City of Fort Collins specifications. The placement and compaction of utility trench
backfill should be observed and tested by a representative of our firm during construction.
FOUNDATIONS
Based on movement guidelines provided for the pool areas, a deep foundation system
or drilled piers are considered the most reliable foundation system for addressing movement po-
tential. Due to expansive clay and claystone present drilled piers that are bottomed in bedrock
as recommended below, anchor foundations below the zone of moisture variation and resist
heave caused by swelling materials. Cave-in potential during drilling is significant. Zones of soft,
sandy soil with groundwater present are likely to be encountered during installation of deep
foundations. Casing may be required. Design and construction criteria for deep foundations are
presented below.
Drilled Piers Bottomed in Bedrock
1. Piers should be designed for the maximum allowable end pressure of 30,000 psf
and an allowable skin friction of 3,000 psf for the portion of pier in comparatively
unweathered bedrock.
2. Piers should have a minimum length of least 27 feet and must be extended
and/or penetrate at least 6 feet into the competent bedrock. Formation of
“mushrooms” or enlargements at the tops of piers should be avoided during pier
drilling and sub-sequent construction operations.
3. Piers should be designed to resist an ultimate uplift force calculated as (47 kips x
pier diameter in feet) to resist tension in the event of swelling. Reinforcement
should extend into grade beams and foundation walls.
4. The minimum diameter will depend upon the length-to-diameter ratio (L/D). We
recommend the piers be designed with a maximum L/D ratio not to exceed 30.
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5. Some pier-drilling contractors use casing with an I.D. equal to the specified pier
diameter. This practice results in a pier diameter less than specified. If full-diame-
ter casing is desired (I.D. of casing equal to specified pier diameter) it should be
clearly specified. If the design considers the reduction in diameter, then the spec-
ification should include a tolerance for smaller diameter for cased piers.
6. There should be a 4-inch (or thicker) continuous void beneath all grade beams
and foundation walls, between piers, to concentrate the deadload of the structure
onto the piers.
7. Pier drilling should produce shafts with relatively undisturbed bedrock exposed.
Excessive remolding and caking of bedrock on pier walls should be removed.
The bedrock surface should be rough or roughened. Pier drilling contractors
should be required to have properly sized augers. Use of side cutters or teeth to
increase the effective diameter should not be allowed.
8. Piers should have a center-to-center spacing of at least three pier diameters
when designing for vertical loading conditions, or they should be designed as a
group. Piers aligned in the direction of lateral forces should have a center-to-cen-
ter spacing of at least six pier diameters. Reduction factors for closely spaced
piers are provided in the following section.
9. Piers should be properly cleaned prior to placement of concrete. Concrete should
not be placed by free fall if there is more than about 3 inches of water at the bot-
tom of the hole. The piers may require underwater concrete placement.
10. Concrete should be on-site and placed in the pier holes immediately after the
holes are drilled, cleaned, and observed and reinforcing steel is set. Concrete
should have sufficient slump to fill the pier holes and not hang on the reinforce-
ment. We recommend a slump of 6 inches ± 1 inch.
11. Some movement of drilled pier foundations should be anticipated to mobilize the
skin friction. We estimate the movement will be on the order of ¼ to ½ inch. Dif-
ferential movement between adjacent piers may equal total movement.
12. Installation of drilled piers should be observed by a representative of our firm to
identify the proper bearing strata, confirm subsurface conditions are as antici-
pated from our borings, and observe the contractor’s installation procedures.
Laterally Loaded Piers/Piles
Lateral load analysis of piers can be performed with the software analysis package
LPILE by Ensoft, Inc. We believe this method of analysis is appropriate for piers with a pier
length to diameter ratio of seven or greater. Suggested criteria for LPILE analysis are presented
in the following table.
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SOIL INPUT DATA FOR “LPILE”
Soil Type Overburden Soil Unweathered Bedrock
Soil Model Type Stiff Clay w/o Free Water Hard Clay w/o Free
Water
Effective Unit Weight (pcf) 105 120
Undrained Shear Strength/Cohe-
sion‘c’ (psf) 750 8,000
Soil Strain, ε50 (in/in) 0.007 0.004
p-y Modulus, ks (pci) 500 2,000
p-y Modulus, kc (pci) 200 800
The ε50 represents the strain corresponding to 50 percent of the maximum principal
stress difference.
Closely Spaced Pier Reduction Factors
For axial loading, no reduction is needed for a minimum spacing of three diameters (cen-
ter to center). At one diameter (piers touching), the skin friction reduction factor for both piers
would be 0.5. End pressure values would not be reduced provided the bases of the piers are at
similar elevations. Interpolation can be used between one and three diameters.
For lateral loading, no reduction is needed for piers/piles in-line with the direction of lat-
eral loads with a minimum spacing of six diameters (center-to-center) based upon the larger
pier. If a closer spacing is required, the modulus of subgrade reaction for initial and trailing piers
should be reduced. At a spacing of three diameters, the effective modulus of subgrade reaction
of the first pier can be estimated by multiplying the given modulus by 0.6; for trailing piers in a
line at three-diameter spacing, the factor is 0.4. Linear interpolation can be used for spacing be-
tween three and six diameters.
Reductions to the modulus of subgrade reaction can be accomplished in LPILE by input-
ting the appropriate modification factors for p-y curves. Reducing the modulus of subgrade reac-
tion in trailing piers will result in greater computed deflections on these piers. In practice, a
grade beam can force deflections of all piers to be equal. Load-deflection graphs can be gener-
ated for each pier by using the appropriate p-multiplier values. The sum of the piers lateral load
resistance at selected deflections can be used to develop a total lateral load versus deflection
graph for the system of piers.
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For lateral loads perpendicular to the line of piers, a minimum spacing of three diameters
can be used with no capacity reduction. At one diameter (piers touching) the piers should be an-
alyzed as one unit. Interpolation can be used for intermediate conditions.
The above method has been used by our firm for years with success but sometimes re-
sults in overly conservative values. We believe the prediction equations proposed by Reese and
Van Impe1 result in more practical solutions for group efficiency. They were formulated by fitting
curves to data representing group efficiency versus pile spacing. No differentiation was made
between soil type, pile diameter, or penetration. The data indicates that for side-by-side piers,
group efficiency becomes unity at spacing of about 4 pier diameters. For in-line piers, the lead
piers were found to have efficiency of unity with spacing of about 4 diameters, and the trailing
piers were unity efficiency with spacing of 7 diameters. The equations for solving group effi-
ciency for side-by-side, leading and trailing piers are shown below, where the variable “s” is the
pile spacing and “b” is the pile diameter.
Side-by-side piers:
𝒆=𝟎.𝟔𝟒(𝒔
𝒃)𝟐 𝒇𝒐𝒓 𝟏≤ 𝒔
𝒃 ≤𝟑.𝟕𝟓,𝒆=𝟏.𝟎, 𝒔
𝒃 ≥𝟑.𝟕𝟓 (Equation 5.39)
Leading piers:
𝒆=𝟎.𝟔𝟒(𝒔
𝒃)𝟐 𝒇𝒐𝒓 𝟏≤ 𝒔
𝒃 ≤𝟑.𝟕𝟓,𝒆=𝟏.𝟎, 𝒔
𝒃 ≥𝟑.𝟕𝟓 (Equation 5.40)
Trailing piers:
𝒆=𝟎.𝟔𝟒(𝒔
𝒃)𝟐 𝒇𝒐𝒓 𝟏≤ 𝒔
𝒃 ≤𝟑.𝟕𝟓,𝒆=𝟏.𝟎, 𝒔
𝒃 ≥𝟑.𝟕𝟓 (Equation 5.41)
For piers that are skewed at an angle (i.e. between in-line and side-by-side), the group
efficiency is taken as a modification to shadow and edge effects. The efficiency can be esti-
mated by:
𝒆=(𝒆i𝟐𝐜𝐨𝐬𝟐∅+𝒆s𝟐𝐬𝐢𝐧𝟐∅)𝟐 ;𝐰𝐡𝐞𝐫𝐞 𝒆i = efficiency of pile in-line,
𝒆s = efficiency of pier side-by-side, and
∅ = angle between piers (Reese & Wang, 1996)
1“Single Piles and Pile Groups Under Lateral Loading,” Authored by Lymon C. Reese and William F. Van Impe, 2001; Section 5.7.5 ,
Pages 158 and 159.
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LATERAL EARTH PRESSURES
Below-grade foundation walls, grade beams, and earth retention systems should be de-
signed to resist lateral earth pressures. The pressure is a function of the wall height, type of
backfill, drainage conditions, slope of the backfill surface, surcharge pressures, and the allowa-
ble rotation of the wall. The foundation walls will be essentially rigid and unable to rotate to mo-
bilize the strength of the backfill soils. Therefore, they should be designed for an "at rest" earth
pressure condition. For walls that are free to rotate an “active” earth pressure resistance can be
used. A “passive” earth pressure resistance can be used to resist sliding and overturning. Pas-
sive resistance requires movement to generate the resistance. We anticipate movement on the
order of 0.02 to 0.04 times the wall height will be required to mobilize passive resistance. Pas-
sive resistance should only be used when movement is tolerable and the soil is well-compacted
and will never be removed. We anticipate retained soil will consist sandy clay. Equivalent lateral
earth fluid pressures for retained soil have been tabulated below. The pressures provided below
do not include allowances for surcharge loads such as adjacent foundations, sloping backfill, ve-
hicle traffic, or hydrostatic pressure.
LATERAL EQUIVALENT FLUID DENSITY
Backfill Type On-Site Clayey Backfill
Active
Equivalent Fluid Density (pcf) 50
At Rest
Equivalent Fluid Density (pcf) 70
Passive
Equivalent Fluid Density (pcf)* 250*
*Assumes material will never be removed.
Backfill should be properly compacted as discussed in Fill and Backfill. The equivalent
fluid densities given above do not include allowances for surcharge loads such as adjacent
foundations, sloping backfill, vehicle traffic, or hydrostatic pressure. We can provide these allow-
ances upon request.
Drains are recommended behind all below-grade walls, including pool areas and crawl
spaces. The provision of a drain will not eliminate moist conditions in below-grade spaces. The
drain should lead to a positive gravity outlet, such as a proposed detention pond, or to a sump
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where water can be removed by pumping. Typical drain details are shown on Figures 5 and 6
for the various types of foundations and floor systems, Appendix C.
FLOOR SYSTEMS AND SLABS-ON-GRADE
Slabs-On-Grade
We anticipate the building main floor level will be used for indoor sports and general ac-
tivities, lobby/amenity, and other ancillary spaces. Subgrade will consist of clay and/or new fill of
similar composition. We estimate potential heave of up to about 1.5 to 3 inches for slabs-on-
grade. In order to reduce potential heave to less than 1 to 2 inches, we recommend performing
over-excavation to a depth of at least 5 feet below the slab. Deeper over-excavation would re-
sult in less potential heave. If floor movements cannot be tolerated, a structurally supported floor
system should be used. It is imperative that foundations, finishes and other items are isolated
from slab floors to prevent transferring slab movements to the structure.
1. Slabs should be separated from foundations, exterior walls and interior bearing
members with a slip joint that allows free vertical movement of the slabs. This de-
tail can reduce cracking if movement of the slab occurs.
2. Slabs should be placed directly on exposed subsoils or properly moisture condi-
tioned, compacted fill. The 2021 International Building Code (IBC) requires a va-
por retarder be placed between the base course or subgrade soils and the con-
crete slab-on-grade floor. The merits of installation of a vapor retarder below floor
slabs depend on the sensitivity of floor coverings and building use to moisture. A
properly installed vapor retarder (6 mil minimum, 10 mil for increased durability)
is more beneficial below concrete slab-on-grade floors where floor coverings,
painted floor surfaces or products stored on the floor will be sensitive to moisture.
The vapor retarder is most effective when concrete is placed directly on top of it,
rather than placing a sand or gravel leveling course between the vapor retarder
and the floor slab. The placement of concrete on the vapor retarder may increase
the risk of shrinkage cracking and curling. Use of concrete with reduced shrink-
age characteristics including minimized water content, maximized coarse aggre-
gate content, and reasonably low slump will reduce the risk of shrinkage cracking
and curling. Considerations and recommendations for the installation of vapor re-
tarders below concrete slabs are outlined in Section 5.2.3.2 of the 2015 report of
American Concrete Institute (ACI) Committee 302, “Guide for Concrete Floor and
Slab Construction (ACI 302.1R-15)”.
3. Use of slab-supported partition walls should be minimized. If slab-bearing parti-
tions are used, they should be designed and constructed with a minimum 3
inches space to allow for slab movement. Differential slab movements may
cause cracking of partition walls. If the void is provided at the top of partitions, the
connection between slab-supported partitions and foundation-supported walls
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should be detailed to allow differential movement. Doorways, wall partitions per-
pendicular to the exterior wall or walls supported by foundations should be de-
tailed to allow for vertical movement. Interior perimeter framing and finishing
should not extend onto slabs-on-grade, or if necessary, should be detailed to al-
low for movement.
4. Underslab plumbing (if any) should be pressure tested for leaks prior to slab con-
struction and be provided with flexible couplings. Pressurized water supply lines
should be brought above the floors as quickly as possible.
5. Plumbing and utilities that pass through the slabs should be isolated from the
slabs and constructed with flexible couplings. Utilities, as well as electrical and
mechanical equipment should be constructed with sufficient flexibility to allow for
movement.
6. Mechanical systems supported by the slabs should be provided with flexible con-
nections capable of at least 3 inches of movement.
7. Exterior flatwork and sidewalks should be separated from the structures. These
slabs should be detailed to function as independent units. Movement of these
slabs should not be transmitted to the foundations of the structures.
8. The American Concrete Institute (ACI) recommends frequent control joints be
provided in slabs to reduce problems associated with shrinkage cracking and
curling. To reduce curling, the concrete mix should have a high aggregate con-
tent and a low slump. If desired, a shrinkage compensating admixture could be
added to the concrete to reduce the risk of shrinkage cracking. We can perform a
mix design or assist the design team in selecting a pre-existing mix.
Structurally Supported Floors
If the risk of movement is not acceptable, we recommend a structurally supported floor.
To our knowledge, there are no soil treatments combined with slab-on-grade floors that will re-
sult in the same reduction in risk of floor movement (relative to the risk inherent for a floor slab
placed directly on the natural soils), as would be provided by a structurally supported floor.
A structural floor is supported by the foundation system. Design and construction issues
associated with structural floors include ventilation and lateral loads. Where structurally sup-
ported floors are installed over a crawl space, the required air space depends on the materials
used to construct the floor and the potential expansion of the underlying soils. Building codes
require a clear space of 18 inches between exposed earth and untreated wood floor compo-
nents. For non-organic floor systems, we recommend a minimum clear space of 10 inches. This
minimum clear space should be maintained between any point on the underside of the floor sys-
tem (including beams and floor drain traps) and the soils.
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Where structurally supported floors are used, utility connections including water, gas, air
duct, and exhaust stack connections to floor supported appliances should be capable of absorb-
ing some deflection of the floor. Plumbing that passes through the floor should ideally be hung
from the underside of the structural floor and not lain on the bottom of the excavation. It is pru-
dent to maintain the minimum clear space below all plumbing lines. This configuration may not
be achievable for some parts of the installation.
Control of humidity in crawl spaces is important for indoor air quality and performance of
wood floor systems. We believe the best current practices to control humidity involve the use of
a vapor retarder or vapor barrier (6 mil) placed on the soils below accessible subfloor areas.
The vapor retarder/barrier should be sealed at joints and attached to concrete foundation ele-
ments.
Exterior Flatwork
To increase performance of exterior flatwork, over-excavation to a minimum depth of 5
feet below flatwork can be performed to reduce potential damaging heave, similar to exterior
pavements. A 3-foot over-excavation could be considered for exterior flatwork areas but some
heave should be expected. Over-excavation to a depth of 5 feet will likely result in better perfor-
mance. We recommend exterior flatwork and sidewalks around the building be isolated to re-
duce the risk of transferring slab movement to the structure. One alternative would be to con-
struct the inner edges of the flatwork on haunches or steel angles bolted to the foundation walls
and detailing the connections such that movement will cause less distress to the building, rather
than tying the slabs directly into the building foundations. Construction on haunches or steel an-
gles and reinforcing the sidewalks and other exterior flatwork will reduce the potential for differ-
ential settlement and better allow them to span across foundation wall backfill. Frequent control
joints should be provided to reduce problems associated with shrinkage. Panels that are ap-
proximately square perform better than rectangular areas.
POOL AND DECK CONSTRUCTION
The pools will range in depth from 4 to 10 feet deep and be cast-in-place concrete/shot-
crete or gunite. Rigid concrete or gunite pools are brittle and can crack from shrinkage or move-
ment. Use of a well-reinforced gunite or concrete can reduce potential cracking.
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The pool deck is normally constructed as a slab-on-grade. The most common problem
with swimming pool performance in this area is heave or settlement and cracking of the deck
slabs surrounding the pool. Pool decks should be placed on at least 5 feet of low swelling fill.
Infiltration of surface water from precipitation or pool splash can cause moisture seepage
through cracks in the pool deck and the joints between the deck and pool. This wetting causes
the underlying soils to swell or compress and results in cracking and distress of the deck, and
potentially the nearby building foundations. In our opinion, the hazard can be reduced, but not
prevented, by construction considerations and maintenance.
The deck and surrounding areas should be sloped to provide positive drainage. We rec-
ommend slabs be isolated from building foundations and pool, and well-reinforced to function as
independent units. Cracking of the pool deck may occur and will require maintenance. Cracks
and joints in the deck should be sealed regularly. Cracking of the pool and pool deck can allow
water to infiltrate the subgrade soils which leads to soil movement problems and possibly hydro-
static uplift of the pool shell. This free water should be captured in a gravel drain to reduce the
potential for excessive heave or softening of the subsoils. The drain should be sloped to a sump
where the water can be removed by pumping. In addition, impermeable sheeting (20 mil or
thicker) should be placed between the gravel drain and the subgrade. Over-excavation should
be performed as recommended in Over-Excavation. Drains are recommended to control hydro-
static pressures. A typical pool wall drain and liner detail is shown on Figure 7, Appendix C.
BELOW-GRADE CONSTRUCTION
Foundation walls, pool walls and grade beams that extend below grade should be de-
signed to resist lateral earth pressures where backfill is not present to about the same extent on
both sides of the wall. Many factors affect the value of the design lateral earth pressure. These
factors include, but are not limited to, the type, compaction, slope and drainage of the backfill,
and the rigidity of the wall against rotation and deflection. For a very rigid wall where negligible
or very little deflection will occur, an “at-rest” lateral earth pressure should be used in design.
For walls that can deflect or rotate 0.5 to 1 percent of the wall height (depending upon the back-
fill types), lower “active” lateral earth pressures are appropriate. Our experience indicates base-
ment walls can deflect or rotate slightly under normal design loads, and that this deflection typi-
cally does not affect the structural integrity of the walls. Thus, the earth pressure on the walls
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will likely be between the “active” and “at-rest” conditions. For pool walls that can not sustain
movement, earth pressure on the walls will likely be “at-rest” conditions.
Structural Design Parameters
Pool Slab
Modulus of Subgrade Reaction (k) 100 pci
Allowable Bearing Pressure 2,000 psf
Pool Walls
Lateral Earth Pressure Coefficient ‘Active’ Ka 0.5
Lateral Earth Pressure Coefficient ‘Passive’ Kp 3.0
Lateral Earth Pressure Coefficient ‘At-Rest’ Ko 0.75
Frequent control joints are recommended in concrete walls to control cracking. For lat-
eral load resistance, footings and slabs can be designed with a coefficient of friction between
the base of the footing/slabs and soils of 0.3. Lateral loads can be resolved by evaluating pas-
sive resistance using an equivalent fluid density of 250 pcf for backfill that is properly compacted
and will not be removed. The criteria do not include allowances for surcharge loads such as
sloping backfill, vehicle traffic, or hydrostatic pressure.
SURFACE AND SUBSURFACE DRAINAGE
Performance of flatwork will be influenced by changes in subsurface moisture con-
ditions. Properly planned and maintained surface drainage can reduce the risk of wetting of
the foundation soils. We recommend the following precautions be observed during construc-
tion and maintained after construction is completed:
1. Wetting or drying of the excavations should be avoided.
2. Positive drainage should be provided away from foundations, flatwork and pave-
ments. We recommend a minimum slope of at least 5 percent in the first 10 feet
away from the sports courts in landscaped areas, where possible. Pavements
and sidewalks adjacent to the structures should also be sloped for positive drain-
age. Water should not be allowed to pond adjacent to the improvements.
3. Backfill around structures (if any) should be moisture treated and compacted as
discussed in Fill and Backfill.
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4. Landscaping should be designed to minimize irrigation. Spray sprinklers should
not be located within 5 feet of structures and pool deck. Irrigation should be lim-
ited to the minimum amount sufficient to maintain vegetation. Application of more
water will increase likelihood of slab and foundation movements.
5. Impervious plastic membranes should not be used to cover the ground surface
immediately surrounding the structures. These membranes tend to trap moisture
and prevent normal evaporation from occurring. Geotextile fabrics can be used to
limit weed growth and allow for evaporation.
6. If interrupted footings are necessary to maintain deadload, a minimum 4-inch
thick void should be constructed below grade beams or foundation walls, be-
tween the pads.
7. The completed foundation excavation should be observed by a representative of
our firm to confirm subsurface conditions are as anticipated from our borings.
PAVEMENTS
Pavement areas will be used for automobile parking, access drives and truck/fire lanes.
We investigated subsurface conditions by obtaining shallow drive samples and disturbed bulk
samples from the auger cuttings within the upper 5 feet in all pavement borings (TH-17 through
TH-23). TH-20 through TH-23 appears to lie within the area where fill had previously been
placed. Our investigation indicates pavement subgrade will likely consist of expansive clay.
Pavements can experience heave due to expansive soils.
The samples were tested to classify the pavement subgrade and evaluate index proper-
ties for the soils that will influence pavement design. Five drive samples swelled 1.3 to 8.5 per-
cent when wetted under an applied pressure of 150 psf. Three samples contained 42 to 79 per-
cent silt and clay-sized particles and exhibited moderate plasticity. The bulk samples classify as
A-6 and A-7-6 soils based on criteria established by the American Association of State Highway
and Transportation Officials (AASHTO). The design CBR value was determined to be 6.0 and is
an implied value generated from measured R-values. We calculated a Resilient Modulus (MR) of
8,770 psi based on the soils encountered. These results are shown in Appendix B.
Clayey soil is considered to have poor pavement support characteristics. Samples in our
investigation swelled 1.3 to 8.5 percent. Per Larimer County Urban Area Street Standards
(LCUASS) Design Standards, over-excavation of at least 5 feet below pavements should be
performed to improve performance. We recommend the pavement subgrade be proof-rolled
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prior to paving to disclose soft areas. Soft areas should be reworked and compacted to specifi-
cations presented in Fill and Backfill. Subgrade areas that pass proof-roll should be stable
enough to pave.
We assume flexible hot mix asphalt (HMA) pavement is planned for the parking area.
Rigid portland cement concrete (PCC) pavement should be used for areas where the pavement
will be subjected to frequent turning of heavy vehicles. The table below summarizes alternatives
for the minimum recommended pavement sections.
RECOMMENDED PAVEMENT ALTERNATIVES
Traffic Classification
Full-Depth
Hot Mix Asphalt
(HMA)
Hot Mix Asphalt (HMA) +
Aggregate Base (ABC)
Portland Cement
Concrete (PCC)
Automobile Parking
Areas 6” HMA 5" HMA + 6” ABC 7” PCC
Access Drives and
Truck/Fire Lanes 7” HMA 6” HMA + 6” ABC 8” PCC
Our experience indicates problems with asphalt pavements can occur where heavy
trucks drive into loading and unloading zones and turn at low speeds. In areas of concentrated
loading and turning movements by heavy trucks, such as at entrances and trash collection ar-
eas, we recommend the consideration of an 8-inch or thicker portland cement concrete pad be
constructed at loading docks and dumpster locations, or other areas where trucks will stop or
turn. The concrete pads should be of sufficient size to accommodate truck turning, trash pickup
and delivery/loading areas.
The design of a pavement system is as much a function of paving materials as support-
ing characteristics of the subgrade. The quality of each construction material is reflected by the
strength coefficient used in the calculations. If the pavement system is constructed of inferior
materials, the life and serviceability of the pavement will be substantially reduced. We recom-
mend the materials, construction and maintenance methods conform to the requirements of the
City of Fort Collins. Materials planned for construction should be submitted and tested to con-
firm their compliance with these specifications.
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Control joints should separate concrete pavements into panels as recommended by ACI.
No de-icing salts should be used on paving concrete for at least one year after placement. Rou-
tine maintenance, such as sealing and repair of cracks annually and overlays at 2 to 5-year in-
tervals, are necessary to achieve the long-term life of an asphalt pavement. We recommend ap-
plication of a rejuvenating sealant such as fog seal after the first year. Deferring maintenance
usually results in accelerated deterioration of pavements leading to higher future maintenance
costs.
A primary cause of early pavement deterioration is water infiltration into the pavement
system. The addition of moisture usually results in heave and/or softening of subgrade and the
eventual failure of the pavement. We recommend drainage be designed for rapid removal of
surface runoff. Curb and gutter should be backfilled and compacted to reduce ponding adjacent
to pavements. Final grading of the subgrade should be carefully controlled so that design cross-
slope is maintained and low spots in the subgrade that could trap water are eliminated. A seal
should be provided between the curb and pavement and at joints to reduce moisture infiltration.
Irrigated landscaped areas in pavements should be avoided.
Material, construction and maintenance guidelines for flexible and rigid pavements are
provided in Appendix D. These criteria were developed from analysis of the field and laboratory
data, our experience, and LCUASS requirements. City of Fort Collins requirements should be
reviewed and followed. If materials cannot meet their recommendations, then the pavement de-
sign should be re-evaluated based upon available materials. Materials planned for construction
should be submitted and the applicable laboratory tests performed to verify compliance with the
specifications.
WATER-SOLUBLE SULFATES
Concrete in contact with soil can be subject to sulfate attack. We measured water-solu-
ble sulfate concentrations of < 0.01 to 0.01 percent in 7 samples. As indicated in our tests and
ACI 318-19, the sulfate exposure class is Not Applicable or S0.
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SULFATE EXPOSURE CLASSES PER ACI 318-19
Exposure Classes Water-Soluble Sulfate (SO4) in Soil A (%)
Not Applicable S0 < 0.10
Moderate S1 0.10 to 0.20
Severe S2 0.20 to 2.00
Very Severe S3 > 2.00
A) Percent sulfate by mass in soil determined by ASTM C1580
For the RS0 level of sulfate concentration, ACI 318-19 Code Requirements indicates
there are special no cement type requirements for sulfate resistance as indicated in the table
below.
CONCRETE DESIGN REQUIREMENTS FOR SULFATE EXPOSURE PER ACI 318-19
Exposure
Class
Maximum
Water/
Cement
Ratio
Minimum
Compressive
Strength
(psi)
Cementitious Material Types A Calcium
Chloride
Admixtures ASTM
C150/C150M
ASTM
C595/C595M
ASTM
C1157/C1157M
S0 N/A 2500 No Type
Restrictions
No Type
Restrictions
No
Type
Restrictions
No
Restrictions
S1 0.50 4000 IIB Type with (MS)
Designation MS No
Restrictions
S2 0.45 4500 V B Type with (HS)
Designation HS Not
Permitted
S3 Option
1 0.45 4500 V + Pozzolan or
Slag Cement C
Type with (HS)
Designation plus
Pozzolan or
Slag Cement C
HS + Pozzolan or
Slag Cement C
Not
Permitted
S3 Option
2 0.4 5000 V D Type with (HS)
Designation HS Not
Permitted
A) Alternate combinations of cementitious materials shall be permitted when tested for sulfate resistance meeting the criteria in
section 26.4.2.2(c).
B) Other available types of cement such as Type III or Type I are permitted in Exposure Classes S1 or S2 if the C3A contents
are less than 8 or 5 percent, respectively.
C) The amount of the specific source of pozzolan or slag to be used shall not be less than the amount that has been determined
by service record to improve sulfate resistance when used in concrete containing Type V cement. Alternatively, the amount
of the specific source of the pozzolan or slab to be used shall not be less than the amount tested in accordance with ASTM
C1012 and meeting the criteria in section 26.4.2.2(c) of ACI 318.
D) If Type V cement is used as the sole cementitious material, the optional sulfate resistance requirement of 0.040 percent
maximum expansion in ASTM C150 shall be specified.
Superficial damage may occur to the exposed surfaces of highly permeable concrete,
even though sulfate levels are relatively low. To control this risk and to resist freeze-thaw deteri-
oration, the water-to-cementitious materials ratio should not exceed 0.50 for concrete in contact
with soils that are likely to stay moist due to surface drainage or high-water tables. Concrete
CITY OF FORT COLLINS 27 of 28
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
should have a total air content of 6 percent ± 1.5 percent. We advocate damp-proofing of all
foundation walls and grade beams in contact with the subsoils.
SURFACE DRAINAGE
Performance of foundations, flatwork, and pavements is influenced by changes in sub-
grade moisture conditions. Carefully planned and maintained surface grading can reduce the
risk of wetting of the foundation soils and pavement subgrade. We recommend a minimum
slope of 5 percent in the first ten feet outside foundations in landscaped areas. Backfill around
foundations should be moisture treated and compacted as described in Fill Placement. Roof
drains should be directed away from buildings. Downspout extensions and splash blocks should
be provided at discharge points, or roof drains should be connected to solid pipe discharge sys-
tems. We do not recommend directing roof drains under buildings.
CONSTRUCTION OBSERVATION
We recommend that CTL|Thompson, Inc. provide full-time construction observation ser-
vices to allow us the opportunity to ensure drilled pier construction and over-excavation efforts
are executed consistent with recommendations herein. Other observations are recommended to
review general conformance with design plans. If others perform these observations, they must
accept responsibility to judge whether the recommendations in this report remain appropriate.
GEOTECHNICAL RISK
The concept of risk is an important aspect with any geotechnical evaluation, primarily be-
cause the methods used to develop geotechnical recommendations do not comprise an exact
science. We never have complete knowledge of subsurface conditions. Our analysis must be
tempered with engineering judgment and experience. Therefore, the recommendations pre-
sented in any geotechnical evaluation should not be considered risk-free. Our recommendations
represent our judgment of those measures that are necessary to increase the chances that the
structures and improvements will perform satisfactorily. It is critical that all recommendations in
this report are followed during construction. Owners or property managers must assume re-
sponsibility for maintaining the structures and use appropriate practices regarding drainage and
landscaping. Improvements after construction, such as construction of additions, retaining walls,
TH-1
TH-2 TH-3
TH-4
TH-5
TH-6
TH-7
TH-8
TH-9
TH-10
TH-11
TH-12
TH-13
TH-14
TH-15
TH-16
TH-17
TH-18
TH-19
TH-20
TH-21
TH-22
TH-23
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL I T PROJECT NO. FC11,498.000-125-R1
FIGURE 1
Locations of
Exploratory Borings
NOT TO SCALE
CITY OF FORT COLLINS
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
APPENDIX A
SUMMARY LOGS OF EXPLORATORY BORINGS
4,885
4,890
4,895
4,900
4,905
4,910
4,915
4,920
4,925
4,930
4,885
4,890
4,895
4,900
4,905
4,910
4,915
4,920
4,925
4,930
15/12
11/12
9/12
36/12
23/12
WC=9.1DD=106LL=37 PI=20-200=68SS=<0.01
WC=10.6DD=122SW=0.0
WC=9.1DD=106LL=37 PI=20-200=68SS=<0.01
WC=10.6DD=122SW=0.0
TH-1
El. 4922.1
Prop. FG 4925.0
10/12
20/12
9/12
29/12
30/12
50/7
WC=10.2DD=108SW=3.6pF=4.64
WC=21.9DD=104SW=0.4pF=4.41
WC=18.9DD=109pF=4.23-200=77
WC=9.5DD=129SW=0.0pF=2.03
WC=16.4DD=116SW=0.7
WC=10.2DD=108SW=3.6pF=4.64
WC=21.9DD=104SW=0.4pF=4.41
WC=18.9DD=109pF=4.23-200=77
WC=9.5DD=129SW=0.0pF=2.03
WC=16.4DD=116SW=0.7
TH-2
El. 4921.1
Prop. FG 4925.0
11/12
25/12
11/12
24/12
WC=10.0DD=106SW=1.6
WC=20.4DD=108SW=2.1
WC=10.0DD=106SW=1.6
WC=20.4DD=108SW=2.1
TH-3
El. 4920.4
Prop. FG 4925.0
14/12
15/12
9/12
6/12
WC=10.0UC=15,680
WC=12.3DD=118-200=51
WC=14.0DD=115LL=27 PI=12-200=42
WC=10.0UC=15,680
WC=12.3DD=118-200=51
WC=14.0DD=115LL=27 PI=12-200=42
TH-4
El. 4922.2
Prop. FG 4925.0
11/12
10/12
11/12
10/12
14/12
50/4
WC=10.5DD=107SW=2.1
WC=12.5DD=115SW=0.0
WC=18.3DD=118SW=0.7
WC=10.5DD=107SW=2.1
WC=12.5DD=115SW=0.0
WC=18.3DD=118SW=0.7
TH-5
El. 4922.0
Prop. FG 4925.0
14/12
10/12
31/12
15/12
18/12
WC=18.2UC=6,720
WC=4.5DD=114-200=13
WC=18.2UC=6,720
WC=4.5DD=114-200=13
TH-6
El. 4920.4
Prop. FG 4925.0
EL
E
V
A
T
I
O
N
-
F
E
E
T
FIGURE 1-A
DRIVE SAMPLE. THE SYMBOL 15/12 INDICATES 15 BLOWS OF A 140-POUND HAMMER
FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES.
EL
E
V
A
T
I
O
N
-
F
E
E
T
WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING.
SAND, CLEAN TO SILTY, OCCASIONAL GRAVEL, MOIST , DENSE TO VERY DENSE, BROWN
(SP)
2.
3.
CLAY, SANDY, SLIGHTLY MOIST TO MOIST, LOOSE TO VERY STIFF, BROWN, (CL)
THE BORINGS WERE DRILLED ON JULY 22, 2025 TO JULY 24, 2025 USING 4-INCH DIAMETER
CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG.
1.
LEGEND:
NOTES:
SAND, CLAYEY, SLIGHTLY MOIST TO MOIST, LOOSE TO MEDIUM DENSE, BROWN (SC)
BEDROCK CLAYSTONE, SLIGHT MOIST, HARD, BROWN
FILL, CLAY, SANDY, SLIGHTLY MOIST, STIFF TO VERY STIFF, BROWN (FILL)
WATER LEVEL MEASURED AT TIME OF DRILLING.
BORING ELEVATIONS WERE SURVEYED BY A REPRESENTATIVE OF OUR FIRM
REFERENCING THE TEMPORARY BENCHMARK SHOWN ON FIGURE 1.
THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN
THIS REPORT.
4.
Summary Logs of
Exploratory Borings
INDICATES PROPOSED FINAL GRADE.
-
-
-
-
-
-
-
-
-
INDICATES MOISTURE CONTENT (%).
INDICATES DRY DENSITY (PCF).
INDICATES SWELL WHEN WETTED UNDER OVERBURDEN PRESSURE (%).
INDICATES PASSING NO. 200 SIEVE (%).
INDICATES LIQUID LIMIT.
INDICATES PLASTICITY INDEX.
INDICATES UNCONFINED COMPRESSIVE STRENGTH (PSF).
INDICATES SOLUBLE SULFATE CONTENT (%).
INDICATES SOIL SUCTION (pF).
WC
DD
SW
-200
LL
PI
UC
SS
pF
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL | T PROJECT NO. FC11498.000-125
BULK SAMPLES COLLECTED FROM THE AUGER CUTTINGS.
4,890
4,895
4,900
4,905
4,910
4,915
4,920
4,925
4,930
4,895
4,900
4,905
4,910
4,915
4,920
4,925
4,930
13/12
18/12
11/12
9/12
WC=10.8DD=115SW=3.7
WC=12.3DD=121SW=1.9
WC=10.8DD=115SW=3.7
WC=12.3DD=121SW=1.9
TH-7
El. 4920.0
Prop. FG 4925.0
11/12
18/12
9/12
14/12
50/7
50/7
WC=8.0DD=93SW=0.0pF=4.76SS=<0.01
WC=13.1DD=110SW=2.0pF=4.41
WC=18.3DD=111pF=2.49
WC=8.5DD=108pF=4.57-200=12
WC=18.0DD=113SW=0.3pF=3.31
WC=15.9DD=116 pF=3.89-200=91
WC=8.0DD=93SW=0.0pF=4.76SS=<0.01
WC=13.1DD=110SW=2.0pF=4.41
WC=18.3DD=111pF=2.49
WC=8.5DD=108pF=4.57-200=12
WC=18.0DD=113SW=0.3pF=3.31
WC=15.9DD=116pF=3.89-200=91
TH-8
El. 4919.7
Prop. FG 4925.0
11/12
3/12
9/12
11/12
9/12
50/7
WC=10.0DD=106LL=39 PI=21-200=82
WC=11.0DD=127-200=36
WC=10.0DD=106LL=39 PI=21-200=82
WC=11.0DD=127-200=36
TH-9
El. 4920.1
Prop. FG 4925.0
17/12
6/12
7/12
19/12
19/12
WC=7.8DD=102SW=0.1
WC=9.5DD=119
WC=7.8DD=102SW=0.1
WC=9.5DD=119
TH-10
El. 4920.8
Prop. FG 4925.0
20/12
6/12
7/12
19/12
WC=9.6DD=92LL=41 PI=29-200=66SS=<0.01
WC=12.0DD=104
WC=18.4DD=112SW=0.0
WC=9.6DD=92LL=41 PI=29-200=66SS=<0.01
WC=12.0DD=104
WC=18.4DD=112SW=0.0
TH-11
El. 4921.7
Prop. FG 4925.0
22/12
9/12
4/12
27/12
37/12
50/7
WC=10.3DD=127SW=5.2
WC=19.0DD=103SW=0.7
WC=10.3DD=127SW=5.2
WC=19.0DD=103SW=0.7
TH-12
El. 4921.5
Prop. FG 4925.0
11/12
14/12
14/12
14/12
WC=10.8DD=102SW=2.4
WC=19.3DD=109SW=0.0
WC=10.8DD=102SW=2.4
WC=19.3DD=109SW=0.0
TH-13
El. 4920.6
Prop. FG 4925.0
10/12
20/12
8/12
12/12
WC=12.0DD=98LL=40 PI=20-200=81
WC=12.3DD=120SW=0.2
WC=12.0DD=98LL=40 PI=20-200=81
WC=12.3DD=120SW=0.2
TH-14
El. 4920.1
Prop. FG 4925.0
16/12
13/12
8/12
18/12
WC=11.3DD=98SW=1.3
WC=13.3DD=113
WC=11.3DD=98SW=1.3
WC=13.3DD=113
TH-15
El. 4921.1
Prop. FG 4925.0
EL
E
V
A
T
I
O
N
-
F
E
E
T
EL
E
V
A
T
I
O
N
-
F
E
E
T
4,890
Summary Logs of
Exploratory Borings
FIGURE 2-A
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL | T PROJECT NO. FC11498.000-125
4,890
4,895
4,900
4,905
4,910
4,915
4,920
4,925
4,930
4,890
4,895
4,900
4,905
4,910
4,915
4,920
4,925
4,930
15/12
19/12
14/12
15/12
50/11
WC=8.7DD=112SW=5.3
WC=18.2DD=109SW=0.1
WC=8.7DD=112SW=5.3
WC=18.2DD=109SW=0.1
TH-16
El. 4919.7
Prop. FG 4925.0
13/12
10/12
28/12
WC=10.4DD=102LL=40 PI=26-200=83
WC=10.4DD=102LL=40 PI=26-200=83
TH-17
El. 4919.6
16/12
12/12
13/12
WC=6.2DD=113SW=2.0SS=0.01
WC=6.2DD=113SW=2.0SS=0.01
TH-18
El. 4916.7
12/12
12/12
6/12
WC=7.9DD=92SW=1.3SS=<0.01
WC=10.7DD=95LL=41 PI=27-200=79
WC=7.9DD=92SW=1.3SS=<0.01
WC=10.7DD=95LL=41 PI=27-200=79
TH-19
El. 4919.0
15/12
14/12
10/12
WC=8.8DD=98LL=39 PI=26-200=77
WC=8.6DD=121SW=7.5SS=0.01
WC=8.8DD=98LL=39 PI=26-200=77
WC=8.6DD=121SW=7.5SS=0.01
TH-20
El. 4919.1
21/12
13/12
13/12
WC=10.0DD=118SW=8.5SS=<0.01
WC=7.3DD=108LL=31 PI=19-200=47
WC=10.0DD=118SW=8.5SS=<0.01
WC=7.3DD=108LL=31 PI=19-200=47
TH-21
El. 4916.9
19/12
22/12
9/12
WC=8.0DD=120SW=7.3SS=<0.01
WC=8.0DD=120SW=7.3SS=<0.01
TH-22
El. 4915.0
22/12
29/12
10/12
WC=10.4DD=118SW=5.9SS=<0.01
WC=9.0DD=113LL=33 PI=0-200=42
WC=10.4DD=118SW=5.9SS=<0.01
WC=9.0DD=113LL=33 PI=0-200=42
TH-23
El. 4914.0
EL
E
V
A
T
I
O
N
-
F
E
E
T
EL
E
V
A
T
I
O
N
-
F
E
E
T
Summary Logs of
Exploratory Borings
FIGURE 3-A
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL | T PROJECT NO. FC11498.000-125
CITY OF FORT COLLINS
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
APPENDIX B
LABORATORY TEST RESULTS AND TABLE B-I
%%
pcf pF
CLAY, SANDY (CL)
TH-1 AT 9 FEET
SILT AND CLAY:
SOIL SUCTION:
10.6
122
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited no movement when wetted under an applied pressure of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-1
%%
pcf pF
CLAY, SANDY (CL)
TH-2 AT 4 FEET
4.64
SILT AND CLAY:
SOIL SUCTION:
10.2
108
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 3.6 percent when wetted under an applied pressure
of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-2
%%
pcf pF
CLAY, SANDY (CL)
TH-2 AT 9 FEET
4.41
21.9
104
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 0.4 percent when wetted under an applied pressure
of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-3
%%
pcf pF
Swell Consolidation
Test Results
2.03
9.5
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:129
LIQUID LIMIT:
PLASTICITY INDEX:
SILT AND CLAY:
SOIL SUCTION:
SAND, CLEAN TO SLIGHTLY SILTY (SP, SP-SM)
TH-2 AT 24 FEET
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited no movement when wetted under an applied pressure of 3000.0
psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-4
%%
pcf pF
Swell Consolidation
Test Results
16.4
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:116
LIQUID LIMIT:
PLASTICITY INDEX:
SILT AND CLAY:
SOIL SUCTION:
CLAYSTONE
TH-2 AT 29 FEET
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 0.7 percent when wetted under an applied pressure
of 3000.0 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-5
%%
pcf pF
CLAY, SANDY (CL)
TH-3 AT 4 FEET
SILT AND CLAY:
SOIL SUCTION:
10.0
106
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 1.6 percent when wetted under an applied pressure
of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-6
%%
pcf pF
CLAY, SANDY (CL)
TH-3 AT 9 FEET
20.4
108
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 2.1 percent when wetted under an applied pressure
of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-7
%%
pcf pF
CLAY, SANDY (CL)
TH-5 AT 4 FEET
SILT AND CLAY:
SOIL SUCTION:
10.5
107
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 2.1 percent when wetted under an applied pressure
of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-8
%%
pcf pF
CLAY, SANDY (CL)
TH-5 AT 9 FEET
12.5
115
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited no movement when wetted under an applied pressure of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-9
%%
pcf pF
Swell Consolidation
Test Results
18.3
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:118
LIQUID LIMIT:
PLASTICITY INDEX:
SILT AND CLAY:
SOIL SUCTION:
CLAYSTONE
TH-5 AT 29 FEET
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 0.7 percent when wetted under an applied pressure
of 3000.0 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-10
%%
pcf pF
CLAY, SANDY (CL)
TH-6 AT 4 FEET
SILT AND CLAY:
SOIL SUCTION:
8.2
106
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 4.0 percent when wetted under an applied pressure
of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-11
%%
pcf pF
CLAY, SANDY (CL)
TH-7 AT 4 FEET
SILT AND CLAY:
SOIL SUCTION:
10.8
115
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 3.7 percent when wetted under an applied pressure
of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-12
%%
pcf pF
CLAY, SANDY (CL)
TH-7 AT 9 FEET
12.3
121
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 1.9 percent when wetted under an applied pressure
of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-13
%%
pcf pF
CLAY, SANDY (CL)
TH-8 AT 4 FEET
4.76
SILT AND CLAY:
SOIL SUCTION:
8.0
93
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited no movement when wetted under an applied pressure of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-14
%%
pcf pF
CLAY, SANDY (CL)
TH-8 AT 9 FEET
4.41
13.1
110
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 2.0 percent when wetted under an applied pressure
of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-15
%%
pcf pF
Swell Consolidation
Test Results
2.49
18.3
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:111
LIQUID LIMIT:
PLASTICITY INDEX:
SILT AND CLAY:
SOIL SUCTION:
CLAY, SANDY (CL)
TH-8 AT 14 FEET
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited compression of 0.1 percent when wetted under an applied
pressure of 1800 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-16
%%
pcf pF
Swell Consolidation
Test Results
3.31
18.0
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:113
LIQUID LIMIT:
PLASTICITY INDEX:
SILT AND CLAY:
SOIL SUCTION:
CLAYSTONE
TH-8 AT 24 FEET
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 0.3 percent when wetted under an applied pressure
of 3000.0 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-17
%%
pcf pF
CLAY, SANDY (CL)
TH-10 AT 2 FEET
SILT AND CLAY:
SOIL SUCTION:
7.8
102
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 0.1 percent when wetted under an applied pressure
of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-18
%%
pcf pF
SAND, CLAYEY (SC)
TH-10 AT 9 FEET
9.5
119
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited compression of 0.1 percent when wetted under an applied
pressure of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-19
%%
pcf pF
CLAY, SANDY (CL)
TH-11 AT 9 FEET
SILT AND CLAY:
SOIL SUCTION:
12.0
104
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited compression of 0.7 percent when wetted under an applied
pressure of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-20
%%
pcf pF
CLAY, SANDY (CL)
TH-11 AT 14 FEET
18.4
112
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited no movement when wetted under an applied pressure of 1800 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-21
%%
pcf pF
CLAY, SANDY (CL)
TH-12 AT 2 FEET
SILT AND CLAY:
SOIL SUCTION:
10.3
127
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 5.2 percent when wetted under an applied pressure
of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-22
%%
pcf pF
CLAY, SANDY (CL)
TH-12 AT 9 FEET
19.0
103
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 0.7 percent when wetted under an applied pressure
of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-23
%%
pcf pF
CLAY, SANDY (CL)
TH-13 AT 4 FEET
SILT AND CLAY:
SOIL SUCTION:
10.8
102
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 2.4 percent when wetted under an applied pressure
of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-24
%%
pcf pF
CLAY, SANDY (CL)
TH-13 AT 9 FEET
19.3
109
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited no movement when wetted under an applied pressure of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-25
%%
pcf pF
CLAY, SANDY (CL)
TH-14 AT 9 FEET
SILT AND CLAY:
SOIL SUCTION:
12.3
120
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 0.2 percent when wetted under an applied pressure
of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-26
%%
pcf pF
CLAY, SANDY (CL)
TH-15 AT 4 FEET
SILT AND CLAY:
SOIL SUCTION:
11.3
98
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 1.3 percent when wetted under an applied pressure
of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-27
%%
pcf pF
CLAY, SANDY (CL)
TH-15 AT 9 FEET
13.3
113
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited compression of 0.5 percent when wetted under an applied
pressure of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-28
%%
pcf pF
CLAY, SANDY (CL)
TH-16 AT 2 FEET
SILT AND CLAY:
SOIL SUCTION:
8.7
112
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 5.3 percent when wetted under an applied pressure
of 500 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-29
%%
pcf pF
CLAY, SANDY (CL)
TH-16 AT 9 FEET
18.2
109
SILT AND CLAY:
Swell Consolidation
Test Results
SOIL SUCTION:
SAMPLE OF:
FROM:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 0.1 percent when wetted under an applied pressure
of 1100 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-30
%%
pcf pF
CLAY, SANDY (CL)
TH-17 AT 1 FEET
SILT AND CLAY:
SOIL SUCTION:
8.9
102
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 3.2 percent when wetted under an applied pressure
of 150 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-31
%%
pcf pF
CLAY, SANDY (CL)
TH-18 AT 4 FEET
SILT AND CLAY:
SOIL SUCTION:
6.2
113
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 2.0 percent when wetted under an applied pressure
of 150 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-32
%%
pcf pF
CLAY, SANDY (CL)
TH-19 AT 2 FEET
SILT AND CLAY:
SOIL SUCTION:
7.9
92
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 1.3 percent when wetted under an applied pressure
of 150 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-33
%%
pcf pF
CLAY, SANDY (CL)
TH-20 AT 4 FEET
SILT AND CLAY:
SOIL SUCTION:
8.6
121
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 7.5 percent when wetted under an applied pressure
of 150 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-34
%%
pcf pF
FILL, CLAY, SANDY
TH-21 AT 2 FEET
SILT AND CLAY:
SOIL SUCTION:
10.0
118
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 8.5 percent when wetted under an applied pressure
of 150 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-35
%%
pcf pF
FILL, CLAY, SANDY
TH-22 AT 4 FEET
SILT AND CLAY:
SOIL SUCTION:
8.0
120
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 7.3 percent when wetted under an applied pressure
of 150 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-36
%%
pcf pF
FILL, CLAY, SANDY
TH-23 AT 2 FEET
SILT AND CLAY:
SOIL SUCTION:
10.4
118
Swell Consolidation
Test Results
FROM:
SAMPLE OF:
MOISTURE CONTENT:
DRY UNIT WEIGHT:
LIQUID LIMIT:
PLASTICITY INDEX:
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0.1 1 10 100
Co
m
p
r
e
s
s
i
o
n
(
-)
o
r
E
x
p
a
n
s
i
o
n
(
+
)
—
%
Applied Pressure -KSF
Sample exhibited expansion of 5.9 percent when wetted under an applied pressure
of 150 psf.
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL l T PROJECT NO. FC11498.000-125
FIGURE B-37
Specification Title:Onsite/Native (Clay or Silt)
ASTM D75 / AASHTO T2 / CDOT CP30
Material Description:
Sample Location:FC114998, S-1
R-Value (ASTM D2844)
34
25
10
0100200300400500600700
Exudation Pressure (psi)
0
20
40
60
80
100
R-
V
a
l
u
e
Test
Point
Moisture
(%)
Exudation
Pressure
(psi)
R-Value
1 17.3 442 34
2 18.6 292 25
3 20.6 183 10
R- Value at 300 psi
Exudation Pressure
25
Remarks:
17.3 18.6 20.6
0100200300400500600700
Exudation Pressure (psi)
0
10
20
30
40
50
Mo
i
s
t
u
r
e
C
o
n
t
e
n
t
(
%
)
Sampling Method:
CTL Thompson
400 North Link Lane
Fort Collins, CO 80524
Craig Ellis
2025-2026 Miscellaneous Services (CTL)
Client:
Report Date:
Soil/Aggregate Laboratory Summary
25-0505.SoilSampling.0024; ver: 1Aug 5, 2025 Work Order No.:
Work Order Date:Jul 24, 2025 Reviewed by:Joe Zorack
Results apply only to the specific items and locations referenced and at the time of testing, observations or special inspections. Unless noted otherwise, samples were received in adequate condition.
This report should not be reproduced, except in full, without the written permission of GROUND Engineering Consultants, Inc.
41 Inverness Drive East, Englewood, Colorado www.groundeng.com 303-289-1989
Englewood | Commerce City | Loveland | Granby | Gypsum | Colorado Springs Page 2 of 3
Specification Title:Onsite/Native (Clay or Silt)
ASTM D75 / AASHTO T2 / CDOT CP30
Material Description:
Sample Location:FC11498: S-2
R-Value (ASTM D2844)
21
13
5
0100200300400500600700
Exudation Pressure (psi)
0
20
40
60
80
100
R-
V
a
l
u
e
Test
Point
Moisture
(%)
Exudation
Pressure
(psi)
R-Value
1 19.5 394 21
2 22.2 280 13
3 25.3 179 5
R- Value at 300 psi
Exudation Pressure
14
Remarks:
19.5 22.2
25.3
0100200300400500600700
Exudation Pressure (psi)
0
10
20
30
40
50
Mo
i
s
t
u
r
e
C
o
n
t
e
n
t
(
%
)
Sampling Method:
CTL Thompson
400 North Link Lane
Fort Collins, CO 80524
Craig Ellis
2025-2026 Miscellaneous Services (CTL)
Client:
Report Date:
Soil/Aggregate Laboratory Summary
25-0505.SoilSampling.0024; ver: 1Aug 5, 2025 Work Order No.:
Work Order Date:Jul 24, 2025 Reviewed by:Joe Zorack
Results apply only to the specific items and locations referenced and at the time of testing, observations or special inspections. Unless noted otherwise, samples were received in adequate condition.
This report should not be reproduced, except in full, without the written permission of GROUND Engineering Consultants, Inc.
41 Inverness Drive East, Englewood, Colorado www.groundeng.com 303-289-1989
Englewood | Commerce City | Loveland | Granby | Gypsum | Colorado Springs Page 3 of 3
UNCONFINED PASSING WATER-
MOISTURE DRY LIQUID PLASTICITY APPLIED COMPRESSIVE NO. 200 SOLUBLE
DEPTH CONTENT DENSITY LIMIT INDEX SWELL COMPRESSION PRESSURE SUCTION STRENGTH SIEVE SULFATES
BORING (FEET)(%)(PCF)(%)(%)(PSF)(PF)(PSF)(%)(%)DESCRIPTION
S-1 0-5 8.8 42 26 72 CLAY, SANDY (CL)
S-2 0-5 9.8 64 CLAY, SANDY (CL)
TH-1 2 9.1 106 37 20 68 <0.01 CLAY, SANDY (CL)
TH-1 9 10.6 122 0.0 500 CLAY, SANDY (CL)
TH-2 4 10.2 108 3.6 500 4.64 CLAY, SANDY (CL)
TH-2 9 21.9 104 0.4 1100 4.41 CLAY, SANDY (CL)
TH-2 14 18.9 109 4.23 77 CLAY, SANDY (CL)
TH-2 24 9.5 129 0.0 3000 2.03 SAND, CLEAN TO SLIGHTLY SILTY (SP, SP-SM)
TH-2 29 16.4 116 0.7 3000 CLAYSTONE
TH-3 4 10.0 106 1.6 500 CLAY, SANDY (CL)
TH-3 9 20.4 108 2.1 1100 CLAY, SANDY (CL)
TH-4 4 10.0 15680 CLAY, SANDY (CL)
TH-4 9 12.3 118 51 CLAY, SANDY (CL)
TH-4 14 14.0 115 27 12 42 CLAY, SANDY (CL)
TH-5 4 10.5 107 2.1 500 CLAY, SANDY (CL)
TH-5 9 12.5 115 0.0 1100 CLAY, SANDY (CL)
TH-5 29 18.3 118 0.7 3000 CLAYSTONE
TH-6 4 8.2 106 4.0 500 0.04 CLAY, SANDY (CL)
TH-6 9 18.2 6720 CLAY, SANDY (CL)
TH-6 14 4.5 114 13 SAND, CLEAN TO SLIGHTLY SILTY (SP, SP-SM)
TH-7 4 10.8 115 3.7 500 CLAY, SANDY (CL)
TH-7 9 12.3 121 1.9 1100 CLAY, SANDY (CL)
TH-8 4 8.0 93 0.0 500 4.76 <0.01 CLAY, SANDY (CL)
TH-8 9 13.1 110 2.0 1100 4.41 CLAY, SANDY (CL)
TH-8 14 18.3 111 0.1 1800 2.49 CLAY, SANDY (CL)
TH-8 19 8.5 108 4.57 12 SAND, CLEAN TO SLIGHTLY SILTY (SP, SP-SM)
TH-8 24 18.0 113 0.3 3000 3.31 CLAYSTONE
TH-8 29 15.9 116 3.89 91 CLAYSTONE
TH-9 4 10.0 106 39 21 82 CLAY, SANDY (CL)
TH-9 14 11.0 127 36 CLAY, SANDY (CL)
TH-10 2 7.8 102 0.1 500 CLAY, SANDY (CL)
TH-10 9 9.5 119 0.1 1100 SAND, CLAYEY (SC)
TH-11 4 9.6 92 41 29 66 <0.01 CLAY, SANDY (CL)
TH-11 9 12.0 104 0.7 1100 CLAY, SANDY (CL)
TH-11 14 18.4 112 0.0 1800 CLAY, SANDY (CL)
TH-12 2 10.3 127 5.2 500 CLAY, SANDY (CL)
TH-12 9 19.0 103 0.7 1100 CLAY, SANDY (CL)
TH-13 4 10.8 102 2.4 500 CLAY, SANDY (CL)
TH-13 9 19.3 109 0.0 1100 CLAY, SANDY (CL)
TH-14 4 12.0 98 40 20 81 CLAY, SANDY (CL)
TH-14 9 12.3 120 0.2 1100 CLAY, SANDY (CL)
TH-15 4 11.3 98 1.3 500 CLAY, SANDY (CL)
TABLE B-I
SUMMARY OF LABORATORY TESTING
ATTERBERG LIMITS SWELL TEST RESULTS
Page 1 of 2
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL|T PROJECT NO. FC11,498.000-125-R1
UNCONFINED PASSING WATER-
MOISTURE DRY LIQUID PLASTICITY APPLIED COMPRESSIVE NO. 200 SOLUBLE
DEPTH CONTENT DENSITY LIMIT INDEX SWELL COMPRESSION PRESSURE SUCTION STRENGTH SIEVE SULFATES
BORING (FEET)(%)(PCF)(%)(%)(PSF)(PF)(PSF)(%)(%)DESCRIPTION
TABLE B-I
SUMMARY OF LABORATORY TESTING
ATTERBERG LIMITS SWELL TEST RESULTS
TH-15 9 13.3 113 0.5 1100 CLAY, SANDY (CL)
TH-16 2 8.7 112 5.3 500 CLAY, SANDY (CL)
TH-16 9 18.2 109 0.1 1100 CLAY, SANDY (CL)
TH-17 1 8.9 102 3.2 150 0.01 CLAY, SANDY (CL)
TH-17 4 10.4 102 40 26 83 CLAY, SANDY (CL)
TH-18 1 9.0 103 43 29 82 CLAY, SANDY (CL)
TH-18 4 6.2 113 2.0 150 0.01 CLAY, SANDY (CL)
TH-19 2 7.9 92 1.3 150 <0.01 CLAY, SANDY (CL)
TH-19 4 10.7 95 41 27 79 CLAY, SANDY (CL)
TH-20 2 8.8 98 39 26 77 CLAY, SANDY (CL)
TH-20 4 8.6 121 7.5 150 0.01 CLAY, SANDY (CL)
TH-21 2 10.0 118 8.5 150 <0.01 CLAY, SANDY (CL)
TH-21 4 7.3 108 31 19 47 CLAY, SANDY (CL)
TH-22 1 11.5 120 38 25 65 CLAY, SANDY (CL)
TH-22 4 8.0 120 7.3 150 <0.01 CLAY, SANDY (CL)
TH-23 2 10.4 118 5.9 150 <0.01 CLAY, SANDY (CL)
TH-23 4 9.0 113 33 0 42 SAND, CLAYEY (SC)
Page 2 of 2
CITY OF FORT COLLINS
SE COMMUNITY CENTER
CTL|T PROJECT NO. FC11,498.000-125-R1
CITY OF FORT COLLINS
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
APPENDIX C
SAMPLE SITE GRADING SPECIFICATIONS
CITY OF FORT COLLINS C-1
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
SAMPLE SITE GRADING SPECIFICATIONS
1. DESCRIPTION
This item shall consist of the excavation, transportation, placement, and compaction of
materials from locations indicated on the plans, or staked by the Engineer, as necessary
to achieve building site elevations.
2. GENERAL
The Geotechnical Engineer shall be the Owner's representative. The Geotechnical Engi-
neer shall approve fill materials, method of placement, moisture contents and percent
compaction, and shall give written approval of the completed fill.
3. CLEARING JOB SITE
The Contractor shall remove all trees, brush and rubbish before excavation or fill place-
ment is begun. The Contractor shall dispose of the cleared material to provide the
Owner with a clean, neat appearing job site. Cleared material shall not be placed in ar-
eas to receive fill or where the material will support structures of any kind.
4. SCARIFYING AREA TO BE FILLED
All topsoil and vegetable matter shall be removed from the ground surface upon which
fill is to be placed. The surface shall then be plowed or scarified to a depth of 8 inches
until the surface is free from ruts, hummocks, or other uneven features, which would pre-
vent uniform compaction by the equipment to be used.
5. COMPACTING AREA TO BE FILLED
After the foundation for the fill has been cleared and scarified, it shall be disked or
bladed until it is free from large clods, brought to the proper moisture content and com-
pacted to not less than 95 percent of maximum dry density as determined in accordance
with ASTM D 698 or AASHTO T 99.
6. FILL MATERIALS
On-site materials classifying as CL, SC, SM, SW, SP, GP, GC, and GM are acceptable.
Fill soils shall be free from organic matter, debris, or other deleterious substances, and
shall not contain rocks or lumps having a diameter greater than three (3) inches. Fill ma-
terials shall be obtained from the existing fill and other approved sources.
7. MOISTURE CONTENT
Fill materials shall be moisture treated. Clay soils placed below the building envelope
should be moisture-treated to between optimum and 3 percent above optimum moisture
content as determined from Standard Proctor compaction tests. Clay soil placed exterior
to the building should be moisture treated between optimum and 3 percent above opti-
mum moisture content. Sand soils can be moistened to within 2 percent of optimum
moisture content. Sufficient laboratory compaction tests shall be performed to determine
the optimum moisture content for the various soils encountered in borrow areas.
CITY OF FORT COLLINS C-2
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
The Contractor may be required to add moisture to the excavation materials in the bor-
row area if, in the opinion of the Geotechnical Engineer, it is not possible to obtain uni-
form moisture content by adding water on the fill surface. The Contractor may be re-
quired to rake or disk the fill soils to provide uniform moisture content through the soils.
The application of water to embankment materials shall be made with any type of water-
ing equipment approved by the Geotechnical Engineer, which will give the desired re-
sults. Water jets from the spreader shall not be directed at the embankment with such
force that fill materials are washed out.
Should too much water be added to any part of the fill, such that the material is too wet
to permit the desired compaction from being obtained, rolling and all work on that section
of the fill shall be delayed until the material has been allowed to dry to the required mois-
ture content. The Contractor will be permitted to rework wet material in an approved
manner to hasten its drying.
8. COMPACTION OF FILL AREAS
Selected fill material shall be placed and mixed in evenly spread layers. After each fill
layer has been placed, it shall be uniformly compacted to not less than the specified per-
centage of maximum dry density. Fill materials shall be placed such that the thickness of
loose material does not exceed 8 inches and the compacted lift thickness does not ex-
ceed 6 inches. Fill placed under foundations, exterior flatwork and pavements should be
compacted to a minimum of 95 percent of maximum standard Proctor dry density (ASTM
D698).
Compaction, as specified above, shall be obtained by the use of sheepsfoot rollers, mul-
tiple-wheel pneumatic-tired rollers, or other equipment approved by the Engineer. Com-
paction shall be accomplished while the fill material is at the specified moisture content.
Compaction of each layer shall be continuous over the entire area. Compaction equip-
ment shall make sufficient trips to ensure that the required dry density is obtained.
9. COMPACTION OF SLOPES
Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equip-
ment. Compaction operations shall be continued until slopes are stable, but not too
dense for planting, and there is no appreciable amount of loose soil on the slopes. Com-
paction of slopes may be done progressively in increments of three to five feet (3' to 5')
in height or after the fill is brought to its total height. Permanent fill slopes shall not ex-
ceed 3:1 (horizontal to vertical).
10. DENSITY TESTS
Field density tests shall be made by the Geotechnical Engineer at locations and depths
of his choosing. Where sheepsfoot rollers are used, the soil may be disturbed to a depth
of several inches. Density tests shall be taken in compacted material below the disturbed
surface. When density tests indicate that the dry density or moisture content of any layer
of fill or portion thereof is below that required, the particular layer or portion shall be re-
worked until the required dry density or moisture content has been achieved.
CITY OF FORT COLLINS C-3
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
11. SEASONAL LIMITS
No fill material shall be placed, spread, or rolled while it is frozen, thawing, or during un-
favorable weather conditions. When work is interrupted by heavy precipitation, fill opera-
tions shall not be resumed until the Geotechnical Engineer indicates that the moisture
content and dry density of previously placed materials are as specified.
12. NOTICE REGARDING START OF GRADING
The contractor shall submit notification to the Geotechnical Engineer and Owner advis-
ing them of the start of grading operations at least three (3) days in advance of the start-
ing date. Notification shall also be submitted at least 3 days in advance of any resump-
tion dates when grading operations have been stopped for any reason other than ad-
verse weather conditions.
13. REPORTING OF FIELD DENSITY TESTS
Density tests performed by the Geotechnical Engineer, as specified under "Density
Tests" above, shall be submitted progressively to the Owner. Dry density, moisture con-
tent and percent compaction shall be reported for each test taken.
|
|
|
|
CITY OF FORT COLLINS
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
APPENDIX D
PAVEMENT CONSTRUCTION RECOMMENDATIONS
CITY OF FORT COLLINS D-1
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
PAVEMENT MATERIALS AND CONSTRUCTION
Aggregate Base Course (ABC)
1. A Class 5 or 6 Colorado Department of Transportation (CDOT) specified ABC should be
used. A reclaimed concrete pavement (RCP) alternative which meets the Class 5 or 6
designation and design R-value/strength coefficient is also acceptable. Blending of recy-
cled products with ABC may be considered.
2. Bases should have a minimum Hveem stabilometer value of 72, or greater. ABC, RAP,
RCP, or blended materials must be moisture stable. The change in R-value from 300-psi
to 100-psi exudation pressure should be 12 points or less.
3. ABC or RCP bases should be placed in thin lifts not to exceed 6 inches and moisture
treated to near optimum moisture content. Bases should be moisture treated to near op-
timum moisture content, and compacted to at least 95 percent of standard Proctor maxi-
mum dry density (ASTM D 698, AASHTO T 99).
4. Placement and compaction of ABC or RCP should be observed and tested by a repre-
sentative of our firm. Placement should not commence until the underlying subgrade is
properly prepared and tested.
Hot Mix Asphalt (HMA)
1. HMA should be composed of a mixture of aggregate, filler, hydrated lime, and asphalt
cement. Some mixes may require polymer modified asphalt cement or make use of up to
20 percent reclaimed asphalt pavement (RAP). A job mix design is recommended and
periodic checks on the job site should be made to verify compliance with specifications.
2. HMA should be relatively impermeable to moisture and should be designed with crushed
aggregates that have a minimum of 80 percent of the aggregate retained on the No. 4
sieve with two mechanically fractured faces.
3. Gradations that approach the maximum density line (within 5 percent between the No. 4
and 50 sieves) should be avoided. A gradation with a nominal maximum size of 1 or 2
inches developed on the fine side of the maximum density line should be used.
4. Total void content, voids in the mineral aggregate (VMA) and voids filled should be con-
sidered in the selection of the optimum asphalt cement content. The optimum asphalt
content should be selected at a total air void content of approximately 4 percent. The
mixture should have a minimum VMA of 14 percent and between 65 percent and 80 per-
cent of voids filled.
5. Asphalt cement should meet the requirements of the Superpave Performance Graded
(PG) Binders. The minimum performing asphalt cement should conform to the require-
ments of the governing agency.
6. Hydrated lime should be added at the rate of 1 percent by dry weight of the aggregate
and should be included in the amount passing the No. 200 sieve. Hydrated lime for ag-
gregate pretreatment should conform to the requirements of ASTM C 207, Type N.
CITY OF FORT COLLINS D-2
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
7. Paving should be performed on properly prepared, unfrozen surfaces that are free of wa-
ter, snow, and ice. Paving should only be performed when both air and surface tempera-
tures equal, or exceed, the temperatures specified in Table 401-3 of the 2006 Colorado
Department of Transportation Standard Specifications for Road and Bridge Construction.
8. HMA should not be placed at a temperature lower than 245oF for mixes containing PG
64-22 asphalt, and 290oF for mixes containing polymer-modified asphalt. The breakdown
compaction should be completed before the HMA temperature drops 20oF.
9. Wearing surface course shall be Grading S or SX for residential roadway classifications
and Grading S for collector, arterial, industrial, and commercial roadway classifications.
10. The minimum/maximum lift thicknesses for Grade SX shall be 1½ inches/2½ inches. The
minimum/maximum lift thicknesses for Grade S shall be 2 inches/3½ inches. The mini-
mum/maximum lift thicknesses for Grade SG shall be 3 inches/5 inches.
11. Joints should be staggered. No joints should be placed within wheel paths.
12. HMA should be compacted to between 92 and 96 percent of Maximum Theoretical Den-
sity. The surface shall be sealed with a finish roller prior to the mix cooling to 185oF.
13. Placement and compaction of HMA should be observed and tested by a representative
of our firm. Placement should not commence until approval of the proof rolling as dis-
cussed in the Subgrade Preparation section of this report. Sub base, base course or ini-
tial pavement course shall be placed within 48 hours of approval of the proof rolling. If
the Contractor fails to place the sub base, base course or initial pavement course within
48 hours or the condition of the subgrade changes due to weather or other conditions,
proof rolling and correction shall be performed again.
Portland Cement Concrete (PCC)
1. Portland cement concrete should consist of Class P of the 2021 CDOT - Standard Spec-
ifications for Road and Bridge Construction specifications for normal placement. PCC
should have a minimum compressive strength of 4,500 psi at 28 days and a minimum
modulus of rupture (flexural strength) of 650 psi. Job mix designs are recommended and
periodic checks on the job site should be made to verify compliance with specifications.
2. Portland cement should be Type II “low alkali” and should conform to ASTM C 150.
3. Portland cement concrete should not be placed when the subgrade or air temperature is
below 40°F.
4. Concrete should not be placed during warm weather if the mixed concrete has a temper-
ature of 90°F, or higher.
5. Mixed concrete temperature placed during cold weather should have a temperature be-
tween 50°F and 90°F.
CITY OF FORT COLLINS D-3
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
6. Free water should not be finished into the concrete surface. Atomizing nozzle pressure
sprayers for applying finishing compounds are recommended whenever the concrete
surface becomes difficult to finish.
7. Curing of the Portland cement concrete should be accomplished by the use of a curing
compound. The curing compound should be applied in accordance with manufacturer
recommendations.
8. Curing procedures should be implemented, as necessary, to protect the pavement
against moisture loss, rapid temperature change, freezing, and mechanical injury.
9. Construction joints, including longitudinal joints and transverse joints, should be formed
during construction, or sawed after the concrete has begun to set, but prior to uncon-
trolled cracking.
10. All joints should be properly sealed using a rod back-up and approved epoxy sealant.
11. Traffic should not be allowed on the pavement until it has properly cured and achieved at
least 80 percent of the design strength, with saw joints already cut.
12. Placement of Portland cement concrete should be observed and tested by a representa-
tive of our firm. Placement should not commence until the subgrade is properly prepared
and tested.
CITY OF FORT COLLINS
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
APPENDIX E
PAVEMENT MAINTENANCE PROGRAM
CITY OF FORT COLLINS E-1
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
MAINTENANCE RECOMMENDATIONS FOR FLEXIBLE PAVEMENTS
A primary cause for deterioration of pavements is oxidative aging resulting in brittle pave-
ments. Tire loads from traffic are necessary to "work" or knead the asphalt concrete to keep it
flexible and rejuvenated. Preventive maintenance treatments will typically preserve the original or
existing pavement by providing a protective seal or rejuvenating the asphalt binder to extend
pavement life.
1. Annual Preventive Maintenance
a. Visual pavement evaluations should be performed each spring or fall.
b. Reports documenting the progress of distress should be kept current to provide
information on effective times to apply preventive maintenance treatments.
c. Crack sealing should be performed annually as new cracks appear.
2. 3 to 5 Year Preventive Maintenance
a. The owner should budget for a preventive treatment at approximate intervals of 3
to 5 years to reduce oxidative embrittlement problems.
b. Typical preventive maintenance treatments include chip seals, fog seals, slurry
seals and crack sealing.
3. 5 to 10 Year Corrective Maintenance
a. Corrective maintenance may be necessary, as dictated by the pavement condition,
to correct rutting, cracking, and structurally failed areas.
b. Corrective maintenance may include full depth patching, milling and overlays.
c. In order for the pavement to provide a 20-year service life, at least one major cor-
rective overlay should be expected.
CITY OF FORT COLLINS E-2
SOUTHEAST COMMUNITY CENTER
CTLT PROJECT NO. FC11498.000-125-R1
MAINTENANCE RECOMMENDATIONS FOR RIGID PAVEMENTS
High traffic volumes create pavement rutting and smooth polished surfaces. Preventive
maintenance treatments will typically preserve the original or existing pavement by providing a
protective seal and improving skid resistance through a new wearing course.
1. Annual Preventive Maintenance
a. Visual pavement evaluations should be performed each spring or fall.
b. Reports documenting the progress of distress should be kept current to provide
information of effective times to apply preventive maintenance.
c. Crack sealing should be performed annually as new cracks appear.
2. 4 to 8 Year Preventive Maintenance
a. The owner should budget for a preventive treatment at approximate intervals of 4
to 8 years to reduce joint deterioration.
b. Typical preventive maintenance for rigid pavements includes patching, crack seal-
ing and joint cleaning and sealing.
c. Where joint sealants are missing or distressed, resealing is mandatory.
3. 15 to 20 Year Corrective Maintenance
a. Corrective maintenance for rigid pavements includes patching and slab replace-
ment to correct subgrade failures, edge damage, and material failure.
b. Asphalt concrete overlays may be required at 15 to 20 year intervals to improve
the structural capacity of the pavement.