HomeMy WebLinkAboutMELDRUM/MYRTLE 4-PLEX - PDP - 13-01 - SUBMITTAL DOCUMENTS - ROUND 2 - GEOTECHNICAL (SOILS) REPORTCompaction Specifications For GW-GC & SW -SC Soils
On -site Soils or Approved Acceptable Deviation From
Imported Soils Minimum Compaction Optimum Moisture Content
(ASTM D698)
Beneath Interior Slabs
95%+
t3%
Beneath Garage and Exterior
95% +
t3%
Slabs
Backfill and Trenches in
90% +
f3%
Open Areas
Backfill and Trenches under
95% +
f3%
Structures, Slabs, etc.
Compaction Specifications For ML, CL, MH, & CH Soils
On -site Soils or Approved Minimum Compaction Acceptable Deviation From
Imported Soils (ASTM D698) Optimum Moisture Content
Beneath Interior Slabs*
93% - 98%
0% to +3%
Beneath Garage and Exterior
93%- 98%
0% to +3%
Slabs *
Backfill and Trenches in
90% +
0% to +3%
Open Areas
Backfill and Trenches under
95% - 98%
0% to +3%
Structures, Slabs, etc.
* MH and CH soils are not recommended in these areas
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conforming to the most recent procedures of ASTM D698 and AASHTO T99 (standard Proctor)
or ASTM D1557 and AASHTO T180 (modified Proctor), whichever applies. Copies of the
"Proctor Curves" will be furnished to the contractor. These test results shall be the basis of control
for the field moisture/density tests.
DENSITY TESTING
A 24-hour notice shall be given to the Soils Engineer or testing agency for scheduling compaction
tests. The density and moisture content of each layer of compacted fill will be determined by the
Soils Engineer, or qualified technician, in accordance with ASTM D2167 and D3017 (nuclear
method). Arty material found not to comply with the minimum specified density shall be reworked
and recompacted until the required density is obtained. Additional lifts shall not be placed until
each underlying lift has been approved. The results of all density tests will be furnished to both the
owner and the contractor by the soils engineer.
A minimum of one compaction test should be conducted for each twelve (12) inch of compacted
lift. Trenches should have a minimum of one test every three hundred (300) feet with a minimum
or two (2) tests per trench. Sub -excavations have a minimum of one test every twenty-five (25)
lineal feet of footing with a minimum of three (3) tests per pad.
TRENCH SAFETY
All excavations shall comply with current OSHA standards for the soil conditions encountered.
The Soils Engineer shall be consulted if there is a question regarding classification of the soils.
FMI
relatively horizontal. Test areas are recommended to determine the optimum lift thickness.
Thinner lifts may be necessary in order to achieve the required compaction. Each lift shall be
approved by the Engineer prior to placing each succeeding lift.
COMPACTION
When an acceptable uniform moisture content is obtained, each lift shall be compacted by a
method acceptable to the Soils Engineer to the densities and moisture contents specified in the
foregoing report or the attached table of this Appendix and as determined by the standard Proctor
test (procedures in ASTM D698). Compaction shall be performed by rolling or tamping with
approved tamping rollers, pneumatic -tired rollers, three -wheel power rollers, or other equipment
suited to the soil being compacted. If a sheepsfoot roller is used, it shall be provided with cleaner
bars attached in a manner which would prevent the accumulation of material between the tamper
feet. The roller should be so designed that the effective weight can be increased. If the required
compaction cannot be achieved with the equipment supplied, thinner "loose -lifts" and/or heavier
equipment are recommended.
MOISTURE -DENSITY DETERMINATION: STANDARD AND MODIFIED PROCTORS
Samples of representative materials to be used for fill shall be furnished by the contractor to the
Soils Engineer at least forty-eight (48) hours prior to compaction testing. Wetter samples will
require extra time for test results due to the required drying for sample preparation. The sample
is to be tested for determination of the maximum dry densities and optimum moisture contents
(Proctor test) for these materials. Tests for these determinations will be made using methods
A3
The subgrade surface of the area to be filled shall be thoroughly scarified to a minimum depth of
six (6) inches, moistened or dried as specified in the attached tables, and compacted in a manner
specified below for the subsequent layers of fill. Fill shall not be placed on frozen or muddy
ground.
MOISTURE CONTROL
The fill material, while being compacted, shall as nearly as practical contain the amount of
moisture as required in the attached table of this Appendix. The moisture shall be uniform
throughout the fill. In the event that water must be added to the soils or that the soils must be dried
to meet the specifications, the soils must be thoroughly pulverized, mixed, blended and cured prior
to placement. The effort required for optimum compaction will be minimized by keeping stockpile
soils near Optimum Moisture Contents. When moisture is added to dry, clayey soils, a curing
period of several days may be needed to allow uniform absorption of the water into the soil.
Freezing temperatures and/or inclement weather conditions may impede moisture control and
compaction operations.
PLACEMENT OF FILL MATERIALS
Distribution of material in the fill shall be such as to preclude the formation of lenses of material
differing from the surrounding material. The materials shall be delivered and spread on the fill or
prepared surface in such a manner as will result in a level, uniformly compacted fill. Prior to
compacting, each layer shall have a maximum "loose -lift" height of twelve (12) inches (or as
dictated by the compaction equipment and/or soil conditions) and its upper surface shall be
A2
L 1
APPENDIX A
Suggested Specifications for Placement of Compacted Earth Fills and/or Backfills.
Note: This is intended to be used as a guideline for this project by the owner or owner's representative. Municipal codes. special construction
requirements or other controlling factors may require modifications to these suggested specifications. Supervision and control ofthe fill operations
is not within the scope of this investigation. This is not a claim that Scott, Cox & Associates is the Soils Engineer for the fill and compaction
operations.
GENERAL
Supervision and control of the overlot and structural fill and backfill shall be under the direction
of the Soils Engineer for the project. The soils engineer shall approve all earth materials prior to
their use, the methods of placing, and the degree of compaction obtained. A letter of approval
from the Soils Engineer will be required prior to the owner's final acceptance of the filling
operations.
MATERIALS
The soils used for compacted fill beneath interior floor slabs and backfill around foundation walls
should be relatively impervious and non -swelling for the depth specified in the soils report. No
material with a maximum dimension of six (6) inches or greater shall be used for fill. All fill
materials shall be subject to the approval of the Soils Engineer prior to placement.
SUBGRADE PREPARATION
All topsoil, vegetation, frozen materials, old structures or other unsuitable materials, shall be
removed to a depth satisfactory to the Soils Engineer before beginning preparation of the subgrade.
Al
Table 2
Summary of Swell/Consolidation Tests
Project No.: 2388-09-01-01
rfu clue) al nawLua
Natural Moisture
(%)
nlvuLul� wVld%—.
Natural Dry
Density
(PCF)
Unconfined
Compression
(PSF)
Loading
(PSF)
Settlement
(Dry)
(%)
Settlement
(Saturated)
(%)
Swell
(%)
TH-I (3a 2'
94.4
8500
100
0.1
1.3
Clayey silt,
13.3
500
0.6
moist, hard,
1000
0.1
brown
1.4% Swell
2000
L5
upon the
4000
4.8
addition of
water
TH-2 @ 7'
95.2
>9000
100
0.0
0.7
Gravelly, very
9.5
500
0.7
clayey sand,
1000
2.5
s1. moist,
0.7% Swell
2000
6.4
dense, brown
upon the
4000
9.8
addition of
water
Page I of I
Summary of Test Results
Proiect No. 2388-09-01-01
Unconfined
Standard
Boring
Moisture
Dry
% passing
Liquid
Plasticity
Compressive
Penetration
Soil
No.
Depth, ft
Content, %
Density, pcf
No.10/200
Limit, %
Index
Strength, psf`
Test
Description
TH-1
2-3
13.3
94.4
8500
Clayey silt
3-4
12.9
>9000
6/12
Silty Clay
7-8
13.3
>9000
15/12
Silty Clay
15-16
15.8
60
27/12
Clayey sand
TH-2
2-3
11.7
>9000
12/12
Very silty clay
7-8
9.5
95.2
>9000
Clayey sand
8-9
9.5
>9000
19/12
Clayey sand
20-21
5.3
50/7
Sand with gravel
Calibrated hand -penetrometer
SCOTT, COX & ASSOCIATES, INC. Table 1
m
TP-1
TN-2
I.
I
0 FT. d
m L 0 FT.
,
m=
m
r
p
E
12/12
r
r
6/12
i
5 FT.
5 FT.
i
15/12
19/12
10 FT.
10 FT.
i
15 FT.
15 FT.
271/12
® CLAY: ei. silty, el. sandy, moist, dark brown
777
20 FT.
20 FT.
-
�orahol�
collapse • 2m
50/1
7 '
SILT: clayey, el. Bandy, el. moist to moist,
firm to hard, brown
ElSAND:
clayey, silty, el. gravelly, el. moist to
brown
moist, mod densa,
25 FT.
25 FT.
SAND: coares, gravelly, el. clayey, elity,
very moist, very dense brown
30 FT.
30 FT.
Drilled 3/9/01 f
3/213/01
-2- Groundwater 0 drilling
All soil
and/or rock contacts
shown are approximate. s Groundwater on 3/12 and
4/2
LOCATION:
LOCI OF
CLIENT:
" SCOTT, COX
t ASSOCIATES, INC.
Lot 8/`J(o
Narrisons Add.
BOI��NC�CJ Loveland, Colorado
Rocky Mountain
GM
Fort Collins, Colorado
PROJECT NO. 2388-09-01-01 FIG;URE NO. 3
LEGEND OF 5*T0' i5OL_ 5
Fill materials
Gravel
Sand
Silt
Clay
Weathered bedrock
51ltstone
Claystone
Sandstone
Limestone
Igneous 4 Metamorphic
rocks
Shelby sample
6/
VA Standard
Penetra t ion
Test sample s
6/2
/California sample`
,,I-
Groundwa ter
level
Denotes caving
of the boring
at that level
Symbols may be
combined to • 6/12 indicates that 6 blows
represent mixtures. of a 1400 hammer fa IIing 30'
was required to penetrate 12'
3COTT, COX t ASSOCIATES, MC.
Loveland, Colorado
Figure No. 2
r-rujcc,� 4-K. -,cam I -u.
ORTH
NTS
West Myrtle Street
"600 S.
Meldrum
Q)
L
VI
L
-
rV
L
0
"604 S.
Meldrum
TH-1
IV,
TH-2
BORING LOCATION 1" 1AP
Lot 8, Block 9(0, Harrisons Addition SCOTT, COX t ASSOCIATES, INC.
Fort Collins, Colorado dL�b Loveland, Colorado
FIGURE NO. I
contractor and owner should discuss and understand the risks of construction at this site,
and should agree on what level of risks and measures are acceptable.
We recommend that construction be observed by a qualified soils technician trained and
experienced in the field to take advantage of opportunities to recognize undetected conditions
which might affect the performance of the foundation systems. It is recommended that a copy or
summary of this report be provided to any new or future owners of this property. A copy of A
Guide to Swelling Soils for Colorado Homebuyers and Homeowners, Colorado Geological
Survey Special Publication 43 should also be provided to any new or future owners of the
property. The CGS publication states "It is essential that the homeowner understands how to
check and maintain all of the different systems that were designed to protect a house against
swelling soil damage". (This applies to not only homes but other structures as well.)
16
or if any part of this report is used more than one year from the date of the report, additional testing
and evaluation by the geotechnical engineer may be required to validate or modify our
recommendations. It is the Contractor's and/or Owner's responsibility to inform the
Engineer of any changes of the scope of this project as described in this report. No individual,
other than the client, should use this report for its intended purpose without first consulting with
the geotechnical engineer.
The test holes drilled were spaced to obtain a reasonably accurate picture of subsurface conditions
for design purposes. Due to the limited number of borings and samples, variations in the
subsurface conditions often exist which may not be observable given the scope of this
investigation. These variations are sometimes sufficient to necessitate modifications in design.
The open hole inspection should be conducted and is the geotechnical engineer's last chance to
determine if any subsurface conditions observed substantiate changes in these recommendations.
Additional testing and evaluation may be necessary pending the outcome of the open hole
inspection.
The methodology used to establish recommendations for construction on soils is not an exact
science. Engineering judgement and experience, in addition to laboratory and field analyses, are
used to make these recommendations. Therefore, the recommendations and solutions made in this
report cannot be considered risk -free and are not a guarantee of the performance of the structures.
The recommendations included in this report are our best estimates of the measures that are
necessary to help ensure that the proposed structures perform in a satisfactory manner. The
ILI
Sprinkling systems should not be installed within ten (10) feet of the structure, and spray from
sprinklers should not fall within five (5) feet of the foundation. Gutters and downspouts are
recommended and should be arranged to carry drainage from the roof at least five (5) feet beyond
the foundation walls.
SLOPE CONSIDERATIONS - The scope of this report does not include a slope stability analysis.
At a minimum, the structure placed adjacent to slopes of 3h:1 v (33.3%), or more, should have the
setbacks from the toe of the slope as described in Section 1806.5 of the UBC 1997 Volume 2 if
a slope stability analysis is not to be conducted.
GEOTECHNICAL LIMITATIONS
The data presented herein were collected to help develop designs and cost estimates for this
project. Professional judgments and estimates on design alternatives and criteria are presented in
this report. These are based on evaluation of technical information gathered, our understanding
of the characteristics of the structure proposed, and our experience with subsurface conditions in
this area. We do not guarantee the performance of the project in any respect, but only that our
engineering work and judgments rendered meet the standard of care of our profession.
This investigation was conducted for a unique set of project specifications. In the event that the
scope of the project has changed from those described in this report such as, the building
orientation, location, size, types and depths/elevations of construction, risk acceptance, usage, etc.
14
COMPACTION- Suggested recommendations pertaining to compaction of the soils are included
in Appendix A of this report. Municipal codes, special construction requirements or other
controlling factors may require modifications to those recommendations.
LANDSCAPING AND DRAINAGE- Every precaution should be taken to prevent wetting of the
subsoils and percolation of water down along the foundation elements. Controlling the drainage
will lessen the chances of water related damage. Finished grade should be sloped away from the
structure on all sides to give positive drainage. A minimum of twelve (12) inches fall in the first
ten (10) feet (10%) is recommended. Where asphalt or concrete adjoins the foundation walls, the
slope can be reduced to four (4) inches fall in ten (10) feet (3.3%). Any cracks or joints shall be
sealed and maintained so that surface waters cannot penetrate the surface. If the concrete or
asphalt extends no further than five (5) feet from the foundation, the remaining slope away from
the foundation should be ten percent (10%) as described above. Positive drainage away from the
foundation should be maintained throughout the life of the structure. In the event that the backfill
settles, the original grade must be restored so that the site drains effectively.
Planted areas are not recommended around the perimeter of the foundations. However, if the
owners are willing to accept the risks of foundation and slab movement, low water -use (xeriscape)
plant varieties could be used. An impervious horizontal membrane, such as polyethylene, should
not be used next to the foundation wall. We recommend the use of a landscape fabric which will
allow normal evaporation, in lieu of a plastic membrane. All plants located next to the foundation
should be hand -watered using only the minimum amount of water.
13
discharge area should be protected from damage due to animal activity, vegetation and traffic. The
discharge area should be placed so that it does not interfere with adjacent properties.
EARTHWORK
SITE PREPARATION- Recommendations pertaining to site grading are included below and in
Appendix A of this report. We recommend the topsoil below building, filled and paved areas be
stripped and stockpiled for reuse in planted areas. The upper six (6) inches of the subgrade below
paved and filled areas should be scarified and recompacted within plus or minus two percent
(+2%) of optimum moisture to at least ninety-five percent (95%) of standard Proctor density
ASTM D-698-78 (See Appendix A of this report). Underground water -lines, sewer -lines and
perimeter drains should be bedded with at least twelve (12) inches of granular material over the
pipe. The water and sewer bedding should not be used within ten (10) feet of the foundation to
minimize the transfer any groundwater which may enter the bedding to the foundation. The
foundation and retaining walls should be well -cured and well braced prior to backfilling.
FILL MATERIALS- In our opinion, most of the on -site soils encountered could be used as backfill
against foundation walls and utility trenches provided the recommendations for compaction,
moisture control and testing are followed. If imported backfill materials are used next to the
foundation walls, they should be relatively impervious and non -expansive. Past experience has
shown that severe damage could occur to the foundation walls if excessively expansive material
is placed for backfill and allowed to become wet. The soils should be well pulverized and the
proper moisture blended prior to placement for compaction. Refer to Appendix A of this report
for recommended moisture contents.
12
foundation walls, below -grade floor levels should be constructed with a perimeter drainage system.
The type of drain, i.e. interior, exterior or both, should be determined at the time of the excavation
inspection.
The drainage system should contain a four (4) inch diameter perforated drain pipe encased in a
minimum of twelve (12) inches of clean, 3/4 inch minus gravel. The drain pipe should extend
around the lower level perimeter with the invert at the high end of the drain being placed a
minimum of four (4) inches below the bottom of the footing. The drain should be run to a non -
perforated sump pit or to daylight well away from the foundation at a minimum slope of inch
per foot to facilitate efficient removal of water. The gravel should be placed a minimum of eight
(8) inches over the pipe for the full width of the trench. For exterior perimeter drains, the entire
system should be covered with geotextile fabric to minimize clogging of the gravel by backfill
material. For underslab drains, lateral drains should be installed in addition to the perimeter drain,
at a maximum spacing of ten (10) feet on center.
The sump pit should be a minimum of eighteen (18) inches in diameter by three (3) feet deep and
should be surrounded by at least six (6) inches of clean gravel similar to that provided around the
drain. In the event that free water is observed in the sump, a pump designed to discharge all flow
from the sump for a minimum of five (5) feet beyond the backfill zone should be installed.
Drains which are to discharge downslope by means of gravity (daylighted) should either be
connected to a sump pit or have a cleanout installed to facilitate monitoring and maintenance. The
3. Eliminate underslab plumbing where feasible. Where such plumbing is unavoid-
able, it should be pressure tested during construction to minimize leaks which
would result in wetting of the subsoils.
4. Divide slabs -on -grade into panels by use of control joints. We recommend joints
be placed no more than twelve (12) feet on center in each direction. Control joints
should also be located at potential weak areas such as the corners of driveway
slabs. The depth of the control joints should be one -quarter (1/4) of the slab
thickness.
5. Slabs should be underlain with a four (4) inch layer, or more, of clean gravel to
help distribute floor loads and to provide a capillary break should moisture collect
beneath the slab. No particles smaller than 3/8" should be permitted in the gravel.
Other methods of moisture proofing may be required by the floor covering
manufacturer.
6. All exterior slabs should be constructed using a more durable sulfate -resistant
concrete containing Type I/II cement and with higher air contents and lower water -
cement ratios.
7. Slabs should be reinforced with wire mesh or equivalent to help control crack
separation.
8. To avoid settlement and distortion of exterior slabs due to improper compaction,
we recommend that concrete slabs that must span the backfill be supported by the
foundation walls. This is conventionally done by use of a brick ledge or haunch.
Exterior slabs should not be doweled to the foundation wall. The slab should
be reinforced as necessary for the span involved.
9. Slab -on -grade areas should not be finished for at least two (2) years (preferably
three (3) years) from the issuance of the Certificate of Occupancy to allow for
initial movement.
10. Refer to ACI 301.R for additional recommendations for design and construction
of floor slabs.
BELOW -GRADE FLOORS AND SUBDRAINS
The ambient groundwater table at the site is not expected to rise to a level which would affect full
basement level construction unless a source of water not presently contributing becomes available.
Due to the potential for groundwater fluctuations and to alleviate hydrostatic pressures behind the
H
is low or high. In some cases, the amount of movement may be considered to be intolerable. Slabs
placed on the native, unaltered silts and/or sands may experience slight heaving and cracking, but,
in our opinion, should not be excessive.
Where floor movement and/or cracking cannot be tolerated by the owner, we recommend that
structural floors be constructed in place of slabs -on -grade. Structural wood floors are typically
constructed eighteen (18) inches or more above the natural soils, creating a zone of separation
(crawl -space) between the floor and the soil. This allows the soil to expand and contract
independently of the floor and any interior fixtures. Structural concrete and structural steel floors
require less :than the eighteen (18) inch void space required for wood floors. Another alternative
which can reduce the amount of movement and cracking of interior and exterior slabs would be
to remove at least two (2) feet of the soil under the slab and replace with moisture and density
controlled on -site or imported soil. Refer to Appendix A of this report for compaction, testing
guidelines. All fill shall be tested, inspected and approved by the Engineer.
Where slabs -on -grade are chosen and the owners are willing to accept the risks associated with
slab movement, the following recommendations should be followed:
Slabs should be constructed to be "free floating". The slabs should be isolated
from all structural components and utilities which penetrate the slab. Isolation may
be achieved with % inch isolation material or by sleeving.
2. A one and one-half (1'/z) inch void should be constructed under all partition walls
located over slabs. The void should be monitored periodically by the owner for the
life of the structure. The void should be immediately re-established if the voids are
within one-half ('/2) inch of closing.
9
LATERAL PRESSURES- Lateral earth pressures are affected by wetting of the backfill soils,
backfill compaction densities, type and slope of backfill materials, allowable wall movements and
surcharge loading. Hydrostatic pressures could also be imposed from water collecting behind the
foundation walls. Additional lateral forces may be imposed from the equipment used during
backfilling operations. All of these factors shall be taken into account when calculating the
backfill pressures and designing the foundation walls. We recommend a perimeter drain system
as outlined in the BASEMENTS AND. SUBDRAINS section of this report to minimize the
accumulation of water behind foundation walls. A minimum equivalent fluid density of 40 pcf
should be used for normally compacted, on -site soils when designing the foundation walls and/or
retaining structures. The design lateral earth pressure reported may need to be revised pending the
outcome of the open hole inspection.
FLOOR SYSTEMS AND SLABS -ON -GRADE
The samples of the soils encountered at the site exhibited low swell potential as moisture contents
are increased. Strata may be present which could exhibit higher and lower swelling than detected
during this investigation. Floor slabs placed on or near potentially swelling soils are expected to
heave and crack to some degree. Most of the movement will be differential or uneven. It is
impossible, with the current state of technology, to predict with certainty how much slab
movement will actually occur. From an engineering perspective, slab movements on the order of
h inch or so would be considered low, whereas 1'/Z inches or more would be considered moderate
to high. Ultimately, though, it should be the owner who determines whether''/2 inch of slab heave
3. All footings and pads should bear on similar strata.
4. We recommend the performance of an excavation inspection to make a final
determination of foundation type and validate these recommendations. A test
pit should be excavated at least three (3) feet deeper than the foundation elevations
to expose the supporting soils for the inspection. The test pit shall be excavated at
least five (5) feet away from any footing or pad locations. The test pits shall be
filled and well compacted after all observations have been made.
5. Refer to the FLOOR SYSTEMSAND SLABS -ON -GRADE section of this report for
recommendations for below -grade floor systems and slabs -on -grade.
6. To prevent over -drying, over -moistening or deterioration of the exposed soils prior
to placement of the footings, the excavation should not be left open for an extended
period of time. In the event that the excavation is left open for more than one week
after the open hole inspection, or if rain, snow melt or groundwater has accumu-
lated in the excavation, the engineer shall be notified for a re -inspection to
determine the condition of the supporting materials and make recommendations for
remediation accordingly.
7. Footings or pads shall not be constructed on frozen ground, topsoil, unapproved
fills or other deleterious materials. Loose soil shall be removed from the footing
forms prior to placing concrete.
8. Footing and pads shall not be placed on sloped surfaces unless provisions for
dowels or keyways are designed to accommodate these conditions.
The assignment offoundation types and these recommendations.should not be considered absolute.
Due to the inherent variability ofsoil conditions at any given site, the type offoundation is subject
to change if conditions encountered in the actual excavation are inconsistent with the findings of
this report. We recommend the completed excavation be observed by a member of our technical
staff to identify the groundwater level and to verify that the actual soil conditions are consistent
with those encountered during this investigation.
irl
FOUNDATION RECOMMENDATIONS
SPREAD FOOTINGS- Based on conditions observed in the field, laboratory tests and the
anticipated bearing loads, we feel that the structure could be supported by a continuous spread
footing and isolated pad foundation. The footings should be placed on the undisturbed native silts
and or sands, and should be kept at least three (3) feet above the groundwater. The footings should
be designed fora maximum allowable bearing pressure of 1500 pounds per square foot (dead load
plus live load) with a minimum dead load of 500 pounds per square foot.
If isolated areas of unacceptable soils, fill or trash are exposed during final footing excavation,
these areas.. should be removed down to acceptable soils prior to placement of the footings.
Footings can then be placed directly on the acceptable soil, or the excavation can be backfilled up
to the desired footing bearing elevation with select, approved fill. The fill should extend a
minimum 1'/2 times the footing width beyond the edges of the footings. Fill beneath the pads
should extend a minimum of two (2) feet beyond the edges of the pads. All fill should be placed,
compacted, tested and approved in accordance with the recommendations contained in the Section
"Site Grading and Utilities", and Appendix A of this report.
The following recommendations should be followed in the design of the foundation system:
All footings and pads should bear below frost depth. Frost depth in this area is
considered to be thirty (30) inches.
2. Foundation walls should be reinforced with rebar to span an unsupported length of
ten (10) feet. Rebar should be run continuously around comers and should be
properly spliced. Foundations should be designed by a Registered Engineer for the
conditions described in this report.
G
SAND - Sands with slight to moderate amounts of clay and slight to moderate amounts of gravel
were encountered below the upper silts to the termination of the borings. The clay content
lessened while the gravel content increased with depth. The sands appear to be slightly moist to
moist, medium dense to very dense and brown in color. The sands exhibit moderate bearing
capacities and low swell potential as detected in our tests.
Due to the often variable nature ofsoil deposits, it is impossible to fully characterize the strength
and swelling properties of these materials at all depths at any given site. Strata may exist at the
site which possess higher or lower swell potentials than these tests indicate.
GROUNDWATER- Groundwater levels were recorded immediately after and twenty-four hours
after completion of the drilling operation. At the time of our field investigation, free groundwater
was encountered in the test borings at a depth of twenty (20) feet. The groundwater table can be
expected to fluctuate throughout the year depending on variations in precipitation, surface
irrigation, and runoff on the site.
The groundwater levels recorded represent the free, static water levels after equalization of
hydrostatic pressures in the borings. This means that the groundwater levels recorded in the
borings may not be present at those levels in the excavations. Flow rates, seepage paths.
hydrostatic pressures, seasonal groundwater fluctuations, water quality and other factors were
not determined in this investigation. A program, which may include special well construction, test
procedures, long-term monitoring program and analysis, would be necessary to determine these
factors.
5
further change in volume is recorded. The confining load is then incrementally increased until the
specimen is compressed to its original volume. Results of those tests are presented at the end of
this report.
A calibrated hand penetrometer was used to estimate the approximate unconfined compressive
strength of selected samples. The calibrated hand penetrometer has been correlated with
unconfined compression tests and provides a better estimate of soil consistency than visual
examination alone.
SUBSURFACE CONDITIONS
In summary, clayey silts were encountered over silty gravelly sands to the depths explored. Free
groundwater was encountered the borings. Refer to the attached boring logs, swell/consolidation
table and summary of tests.
CLAY - Clay with slight amounts of sand and silt was encountered the surface to one (1) foot in
Test Hole No. 1. The clay appears to be moist and brown in color. The clays appear to exhibit low
bearing capacities with a low swell potential.
SILT- Silts with moderate amounts of clay and slight amounts of sand were encountered in the
upper four (4) to twelve (12) feet. The silts appear to be slightly moist to moist, firm to hard and
brown in color. The silts exhibit low bearing capacities with a low swell potential as detected in
our tests.
4
An index of relative density and consistency was obtained in general accordance with the
procedures of the standard penetration test, ASTM Standard Test D-1586. The penetration test
result listed on the log is the number of blows required to drive the two (2) inch diameter split -
spoon sampler twelve (12) inches (or as shown) into undisturbed soil by a one hundred forty (140)
pound hammer dropped thirty (30) inches.
Undisturbed samples for use in the laboratory were collected using three (3) inch O.D. thin wall
samplers (Shelby) in general accordance with sections of ASTM D-1587. In this procedure, a
seamless steel tube with a beveled cutting edge is pushed hydraulically into the ground to obtain
a relatively undisturbed sample of cohesive or moderately cohesive soil. A two and one-half (2'/z)
inch O.D. California Barrel Sampler was also used to collect partially disturbed samples. All
samples were sealed in the field and preserved at natural moisture content prior to testing.
LABORATORY TESTING PROCEDURES
The recovered samples were tested in the laboratory to measure their dry unit weights, natural
water contents, and for classification purposes. Selected samples were tested to determine strength
and stability characteristics such as swelling, compressibility, collapse and shear strength.
One dimensional swell/consolidation tests were performed on selected samples to evaluate the
expansive, compressive and collapsing nature of the soils and/or bedrock strata. In the
swell/consolidation test, a trimmed specimen is placed in a one-dimensional confinement ring and
a vertical load of 100psf and/or 500 psf is applied. The sample is allowed to air-dry for the 100
psf tests. The sample is then inundated with water and allowed to swell or consolidate until no
N
lot is anticipated to be removed prior to construction. No water features or rock outcrops were
observed on the site.
FIELD INVESTIGATION
The field investigation was conducted on March 12 and April 2, 2001. The field investigation
consisted of drilling, logging and sampling two (2) borings at selected locations across the site, as
indicated on the Boring Location Map. The borings were drilled to depths ranging from twenty
one (21) to twenty-five (25) feet using a truck -mounted continuous flight auger drilling rig.
The boring locations were established by Scott, Cox & Associates, Inc. personnel based on a site
plan provided by Rocky Mountain CM. Distances from the referenced features are approximate
and were made by pacing. Angles for locating the borings were estimated. The boring locations
and elevations should be considered accurate only to the degree implied by the methods used to
make those measurements.
Logs of the boring operations were compiled by a representative of our firm as the borings were
advanced. The graphical logs of the borings are presented in Figure No. 3. Soil sampling was
concentrated at approximate foundation -influence elevations. The approximate location of soil
and rock contacts, free groundwater levels, samples and standard penetration tests are shown on
each boring log. The transition between different strata can be, and often is, gradual. The
descriptions of the soil and/or bedrock strata are based, primarily, on visual and tactual methods
which are subject to interpretation pending other methods, classification systems and/or tests.
2
SCOPE
The following report presents the results of our geotechnical investigation for Lot 8, Block 96 of
the Harrisons Addition Subdivision, Fort Collins, Colorado. The building is anticipated to be of
typical wood frame construction. Full basement construction with a cast -in -place concrete
foundation is anticipated for this structure. The depths of foundation construction are anticipated
to range from two (2) to eight (8) feet below grades which existed at the time of this investigation.
It is anticipated that final grades may be adjusted to accommodate drainage and construction
depths. It is recommended that we review the final grading plan to determine if any revisions to
the recommendations presented in this report are necessary.
The purpose of this investigation was to identify subsurface conditions and obtain the test data
necessary to provide recommendations for design and construction of foundations, below -grade
floor systems and slabs -on -grade. The conclusions and recommendations presented in this report
are based upon the acquired field and laboratory data and on previous experience with subsurface
conditions in this area.
SITE DESCRIPTION
The site is located in Fort Collins at the intersection of South Meldrum Street and West Myrtle
Street. At the time of our investigation, the site consisted of two lots, 600 and 604 Meldrum
Street. The planned structure is anticipated to be located on the eastern half of both lots. The site
is generally covered with leave and twig material and is relatively flat. Each lot had an existing
residence which is planned to remain following construction. A garage type outbuilding on each
t
TABLE OF CONTENTS
SCOPE.................................................................... 1
SITEDESCRIPTION........................................................ 1
FIELD INVESTIGATION.................................................... 2
LABORATORY TESTING PROCEDURES ..................................... 3
SUBSURFACE CONDITIONS ................................................ 4
FOUNDATION RECOMMENDATIONS ...... :................................. 6
FLOOR SYSTEMS AND SLABS -ON -GRADE ................................... 8
BELOW -GRADE FLOORS AND SUBDRAINS.................................. 10
EARTHWORK............................................................ 12
GEOTECHNICAL LIMITATIONS ............................................ 14
APPENDIXA............................................................. Al
LIST OF FIGURES
BORING LOCATION MAP ............................................. Figure I
LEGEND OF SYMBOLS ............................................... Figure 2
LOG OF BORINGS .................................................... Figure 3
SUMMARY OF TEST RESULTS ......................................... Table 1
SWELL/CONSOLIDATION TEST RESULTS ............................... Table 2
G:\Geotechnica1\Reports\Rocky Mtn CM\U88.09-01-01\Lot 8_96 Harrison Addition.wpd
"SCOTT, COX & ASSOCIATES, INC. consulting engineers
May 2, 2001
Project No.: 2388-09-01-01
Rocky Mountain CM
P.O. Box 9555
Fort Collins, CO 80525
Gentlemen:
The enclosed report presents the results of a geotechnical investigation for Lot 8, Block 96 of the
Harrisons Addition Subdivision (600 and 604 Meldrum), Fort Collins, Colorado. This report
contains the results of our investigation and recommendations concerning design and construction
of the foundation, ground -level floor systems and slabs -on -grade.
In summary, clayey silts and silty sands were encountered to the depths explored. Although the
soils appear to be suitable for supportof the proposed home, care will be needed in both the design
and construction of the building to minimize the potential for foundation and floor slab movement.
We appreciate the opportunity to be of service to you on this project. If you have any questions,
please feel free to call.
SCOTT, COX & ASSOCIATES, INC.
Respe ly.
.B." Lea better, III, P.E.,
Chief Geotechnical Engineer
RE
G L.
Approved by: - v:L
M. Edwaz lassgow, P.E. '%;,USIONAL�
G:\Geotechnical\Reports\Rocky Mtn CM\2388-09-01-01\Lot 8_96 Harrison Addition.wpd
5110 Granite Street, Suite D • Loveland, Colorado 80538 • (970) 663-0138 • Fax: (970) 663-1660
Serving Colorado with offices in • Boulder • Longmont 0 Loveland
GEOTECHNICAL INVESTIGATION
FOR LOT 8, BLOCK 96,
HARRISONS ADDITION SUBDIVISION
(600 And 604 Meldrum),
FORT COLLINS, COLORADO
Prepared for:
Rocky Mountain CM
P.O. Box 9555
Fort Collins, CO 80525
ORZ
May 2, 2001
Project No.: 2388-09-01-01
Prepared By
SCOTT, COX & ASSOCIATES, INC.
5110 Granite Street, Suite D
Loveland, Colorado 80538