HomeMy WebLinkAbout20110190.tiff •
�� HIGH PLAINS ENGINEERING & DESIGN, LLC
• 721 4th STREET,SUITE D, FORT LUPTON,CO 80621 • PHONE: (303)-857-9280 • FAX: (303)-857-9238
SUBSURFACE INVESTIGATION AND FOUNDATION
RECOMMENDATIONS
Prepared For:
Mr. Randall Anders
8443 US. Highway 85
Fort Lupton, CO 80621
Job Site Located At:
8443 U.S. Highway 85
• Weld County, CO
June 14, 2010
JOB # 10-2154
54'
Todd M. Schroeder P. 'g .';5' : •
•
•
2011-0190
• AGREEMENT OF PURPOSE AND DISCLAIMER:
The parties specifically agree and contract that the purpose of the provided
subsurface investigation is to test, analyze, and provide geotechnical
•
recommendations for the proposed building and/or residence. This report presents a
description of subsurface conditions encountered at the site, recommended
foundation system, and design and construction criteria influenced by the subsurface
conditions. The opinions and recommendations presented in this report are based on
the data generated during this field exploration, laboratory testing, and our
experience. A foundation design sealed by a Professional Engineer is required to
obtain a building permit but is not included in this report.
The parties specifically agree that High Plains Engineering & Design, LLC has not been
retained nor will they render an opinion concerning environmental issues, hazardous
waste or any other known and or unknown conditions that may be present on the job
site, since this is not our area of expertise.
LOCATION AND SITE CONDITIONS:
This report represents the results of the data obtained during the subsoil investigation
for the proposed one and one-half-story, single-family home at 8443 U.S. Highway 85,
Weld County, CO.
The proposed building site is presently a vacant lot. The site is reasonably level with
approximate slopes of 0.5% to the East. The lot appears to be well drained with no
• erosion evident.
The depths of foundation construction are anticipated to range from a MINIMUM of
four and one-half (41/2) feet to a MAXIMUM of seven (7) feet below grades, measured
from the highest elevation of the proposed excavation area, based on the grades
that existed at the time of this soil 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.
SUBSOIL CONDITIONS:
Three, four-inch-diameter holes were drilled to a depth of twenty-five feet at the
building site on May 24, 2010, as shown on the attached site map. Samples of the soil
were taken at two-foot intervals. These samples were analyzed in the field and
laboratory to determine the characteristics of the soil (per Unified Soil Classification
System) for identification and foundation design recommendations. In general, the
soil profiles in test-holes #1, #2 & #3 indicated Clay with Medium Plasticity (CL) to a
depth of 41/2 feet, underlain by Poorly Graded Sandy Silt (SP-SM) to a depth of 25 feet.
The Standard Penetration Test similar to ASTM D1586 showed 11 blows for 12-inch
penetration at a depth of 41/2 feet, and 7 blows for a 12-inch penetration at a depth of
9 feet. Please note that actual subsurface soil conditions may vary between samples
• and locations tested.
Job#10-2154 Page 2 of 9
One-dimensional swell/consolidation tests were not performed on selected samples to
evaluate the expansive, compressive and collapsing nature of the soils and/or
bedrock strata due to the amount of gravel in the soil. The soils in this report were
• classified using the American Society of Testing Materials (ASTM) procedures.
The geotechnical practice in State of Colorado utilizes a relative scale to evaluate
swelling (expansion) potentials. When a sample is wetted under a surcharge pressure
of 500 pounds per square foot (psf), the measured swell is classified as low, moderate,
high, or very high. The following table represents the relative classification criteria.
Please note that the measured swell is not the only criteria for slab-on-grade
recommendations and additional factors are considered by the engineer when
evaluating the risk for slab-on-grade construction.
TABLE 1
SLAB PERFORMANCE REPRESENTATIVE
RISK CATEGORY PERCENT SWELL
(500 PSF SURCHARGE)
LOW 0 TO<3
MODERATE 3 TO<5
HIGH 5 TO <8
VERY HIGH >8
Source: Colorado Association of Geotechnical Engineers, Guideline for Slab Performance
• Risk Evaluation and Residential Basement Floor System Recommendations (Denver
Metropolitan Area), 1996
GROUNDWATER:
Groundwater levels were recorded at the time of our field investigation; free water
was encountered at a depth of 12 feet. The groundwater can be expected to
fluctuate throughout the year depending on variations in precipitation, surface
drainage and irrigation on the site. The possible presence of shallow bedrock/dense
clays beneath the surface is favorable for the formation of "perched" groundwater.
We recommend that the bottom of the basement or crawlspace excavations be
maintained at least 4 feet above the free groundwater level.
The ground water levels recorded represent the free, static water levels after
equalization of hydrostatic pressures in the test-hole borings. It is possible that the
groundwater levels recorded in the test-hole borings may not be present at those
levels in the foundation 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, and analysis, would be necessary
to determine these factors.
•
Job#10-2154 Page 3 of 9
FOUNDATION RECOMMENDATIONS:
• The Poorly Graded Sandy Silt (SP-SM) material has a bearing strength of 1250 pounds
per square foot (psf) and an equivalent liquid pressure of 30 pcf. We recommend the
use of a continuous spread footing, due to the low expansion-consolidation potential
of the analyzed soils. The foundation must be constructed at the location in which soils
investigation was performed.
The depth of excavation for the foundation shall reach a MINIMUM of four and one-half
(41/2) feet, and a MAXIMUM of seven (7) feet, measured from the highest elevation of
the proposed excavation area, based on the grades that existed at the time of the soil
investigation.
An open-hole observation is required at this site, which is not billed with this soil
investigation. The purpose of the open-hole observation is to confirm that proper
foundation excavation depths have been reached, or to determine whether any
significant variation from this report exists and whether the soils report and/or
foundation design will require modification. The open-hole observation must be
performed immediately after the excavation, and prior to backfilling or placing the
footings. Failure to obtain the recommendations from the open-hole observation, prior
to placement of foundation elements, renders this report and its recommendations null
and void.
• All loose and disturbed soil shall be removed before placing of the concrete for the
foundation. The bottom of the foundation shall be a minimum of 30" below final
grade (or that required by local jurisdiction; whichever is greater) for frost protection.
Soil settlement resulting from the assumed structural loads is estimated to be one inch
or less. Soil expansion at this site may be up to one inch in some areas. No foundation
wall is to exceed twenty-five feet in length without utilizing buttresses or counterforts
unless otherwise designed by the foundation engineer.
Engineered steel reinforcements shall be required in the footings and foundation walls.
This will give walls or footing beams the strength to span or bridge over any loose or
soft pockets of soil that may develop during construction.
Owners shall be made aware of all contents of this report, and the fact that water
accumulation around foundation elements is the primary cause of distressed
foundations.
•
Job#10-2154 Page 4 of 9
FOUNDATION DRAIN:
• The external drainage system should be lined with a 10 mil plastic liner, which will
contain a 4-inch diameter perforated drainpipe (rigid perforated PVC pipe is
recommended) encased in a minimum of 8-inches deep by 12-inches of clean, 34-inch
to 11/2-inch river rock. The drain should extend around the lower level of the footing
perimeter with the invert at the high end of the drain being placed a minimum of four-
inches below the bottom of the footing. The drain should be run to a non-perforated
sump pit with a lift pump and high water alarm, or provide a free flow gravity outlet to
the surface at a minimum slope of 1/8 inch per foot to facilitate efficient removal of
water, (1/4 inch per foot is desired). The river rock should be placed a minimum of 8
inches over the pipe for the full width of the trench. The top of the gravel should be
covered with Geotextile filter fabric or equivalent, to minimize clogging of the river
rock and perforated pipe by backfill material.
Note: The foundation drain may be omitted by the design-engineer upon completion
of the open-hole observation performed by a member of this office.
To help prevent secondary damage that could be caused by slab movement, the
following construction techniques are additional recommendations for the foundation
construction.
• SLAB ON GRADE CONSTRUCTION:
1. When and where slabs-on-grade are chosen and the owners are willing to
accept the risks associated with slab movement, the following
recommendations are to be followed:
a. Slabs should be constructed as "free floating". Positive separations and/or
isolation joints should be provided between slabs and all foundation walls,
bearing members (columns), plumbing and utility lines. Isolation may be
achieved with '/2 inch expansion material or by sleeving. Vertical movement of
the slabs should not be restricted.
b. Eliminate plumbing under slabs where feasible. Where such plumbing is
unavoidable, it should be thoroughly pressure tested during construction.
c. Concrete slabs constructed below grade shall be placed on natural,
undisturbed soil or structural granular fill placed at +/- 2 percent of optimum
moisture and compacted to 98% of Standard Proctor Density ASTM D698. A
vapor retarder is required per IRC R506.2.3 except use 15-mil minimum thickness,
located per ACI guidelines and installed per ASTM specifications. Floor slabs
and footings should not be constructed on frozen subgrade. Slabs should be
reinforced with rebar or wire mesh to help control crack separation.
•
Job#10-2154 Page 5 of 9
2. Provide frequent scoring of the slabs in square dimensions (non- rectangular) to
provide joints for controlled cracking of the slab. Control joints should be placed
at distances equal to 24 to 30 times the slab thickness and the depth of sawed
• control joints should be 1/4 of the slab thickness. Joints should be sawed as soon
as the concrete will withstand the energy of sawing without raveling the edges
of the joint. For most concrete mixtures, sawing should be completed within 6 to
18 hours after pouring, but never more than 24 hours. Install a good quality
sealant (pliable/non-hardening) in these joints to prevent surface discharges of
liquid from penetrating slab sub-grades.
3. The soils that will support the concrete slabs should be kept moist during
construction by occasional sprinkling of water. The soils should be moistened to
+/- 2 % optimum moisture within 48 hours of pouring the slabs. This procedure will
help maintain the moisture content of the underlying soil. **Heavy watering or
pooling of any kind next to the foundation or within the backfilled area is not
recommended.**
4. A minimum void or clear space of 3 inches should be provided at or near the
bottom of all non-bearing partitions. In finished room areas, all drywall and
paneling should be stopped approximately 3 inches above the top of the slab.
This will allow some space for upward movement of the slab before pressures
are applied to the wall and upper levels of the structure. The builder should
provide a 1/2 inch space at the bottom of all doorjambs to allow for limited
movement of the floor slab. The owner is hereby notified that it is their
•
responsibility to maintain these void spaces.
5. If a forced air heating system is used and the furnace is located on the slab, we
recommend provision of a collapsible connection between the furnace and the
ductwork. In the event a hot water heating system is used, the piping should not
be placed beneath the concrete slab.
BACKFILL AND SURFACE DRAINAGE:
The foundation and retaining walls must be well cured and well braced prior to
backfilling.
Any soil disturbed adjacent to bearing foundation components are to be re-
compacted to a minimum of 85% Standard Proctor Density (ASTM D698). Backfill that
bears concrete slabs shall be compacted to 95% Standard Proctor Density (ASTM
D698). Mechanical compaction methods shall be utilized, (water-flooding techniques
are strictly prohibited). See Compaction Section for more information regarding
compaction requirements and techniques.
Job#10-2154 Page 6 of 9
•
Proper drainage away from the foundation walls shall be provided. The owners are
advised to immediately fill any settled areas to eliminate water accumulation near the
foundation. A minimum slope of 12 inches in the first 10 feet from the perimeter of the
• building is recommended. Roof downspouts and sill cocks should discharge into long
concrete splash blocks (5 feet long min.) or into gutter extensions to deposit runoff
water beyond the limits of the backfill soil near the foundation walls. Plastic
membranes should not be used to cover the ground surface immediately surrounding
the structure; geotextile fabric should be utilized for weed control. Any drainage
water from uphill shall be diverted around the structure.
Sprinkling systems should not be installed or direct water to be within 10 feet of the
foundation. The owner/builder is also advised that irrigation lines can leak and/or
break, resulting in release of excessive amounts of water near the foundation. This can
cause damage to slabs and foundation walls. WATER ACCUMULATION AROUND
FOUNDATION ELEMENTS IS THE MAIN CAUSE OF DISTRESSED FOUNDATIONS.
COMPACTION:
Placing Fill: No brush, sod, frozen material, perishable material, unsuitable material, or
stones of four inches or greater in maximum dimension shall be placed in the fill. The
distribution of the material on the fill shall be such as to avoid the formation of layers of
materials differing substantially in characteristics from the surrounding materials. The
materials are to be delivered to the backfill surface at a uniform rate, and in such
• quantity as to permit a satisfactory construction procedure. Unnecessary
concentration of backfill machinery travel tending to cause ruts and other hollows
more than six inches in depth, are to be re-graded and compacted. After dumping of
fill material on the backfill surface, the material is to be spread by approved methods
in approximately 6 inches compacted thickness.
Moisture Control: The material in each layer shall be compacted by rolling and shall
contain the optimum moisture required for maximum compaction, as nearly
practicable and as determined by the soils engineer. The moisture content shall be
uniform throughout all layers. If in the opinion of the soils engineer it is not possible to
obtain moisture content by adding water on the fill surface, the contractor may be
required to add the necessary moisture to backfill material in the borrow area.
Compaction: When the moisture condition and content of each spread layer is
satisfactory, it shall be compacted by a method approved by the soils engineer to
95% ASTM D698 (Standard Proctor Density) for slab areas, and 98% ASTM D698 for
footing and/or pad areas. A Standard Proctor test is to be performed for each typical
fill material and frequent tests of the density of the fill must be taken.
In general, to compact cohesion-less free-draining materials, the above guidelines
also apply.
Job#10-2154 Page 7 of 9
When compacting cohesion-less free-draining materials such as gravel and sand, the
materials shall be deposited in layers and compacted by treads of a crawler type
tractor, surface of internal vibrators, pneumatic or smooth rollers, power or hand
• tampers, or by any other means approved by the soils engineer. The thickness of the
horizontal layers after compaction is not to exceed 6 inches compacted thickness if
compaction is performed by tractor treads, surface vibrators or similar equipment, or
not more than penetrating length of the vibrator head if compaction is performed by
internal vibrators. When the moisture content and condition of each spread layer is
satisfactory, it shall be compacted by a method approved by the soils engineer to
95% ASTM D1557 (Modified Proctor Density) for slab areas, and 98% ASTM D1557 for
footing and/or pad areas.
RADON:
Most counties in Colorado have average radon levels (measured in home) above the
U.S. EPA recommended "action level" of 4 picocuries per liter of air (pCi/1). Results of
a 1987-1988 EPA-supported radon study for Colorado indicated that granite rocks, in
particular, generally have elevated levels of uranium. These rocks have the potential
of producing higher than average levels of radon gas in the home. Increasing
ventilation of basements and crawl spaces and sealing of joints can mitigate build-ups
of radon gas. This mitigation is best implemented during the design and construction
phases of residences.
The U.S. EPA {www.epa.gov/iaq/radon} is a good source for additional radon
• information.
CONSTRUCTION DETAILS - GENERAL COMMENTS:
In any soil investigation, it is necessary to assume that the subsurface soil conditions do
not vary greatly from the conditions encountered in the field and laboratory testing.
The accompanying design is presented using best professional judgment based on the
limits of the extent of testing commissioned by the client. Our experience has been
that at times, soil conditions do change and variations do occur. These may become
first apparent at the time of excavation for the foundation system.
**If soils conditions are encountered which appear different from the test borings as
presented in this report, it is required that this office be called to make an observation
of the open excavation prior to placing the footings. The cost of this observation is not
part of this report.**
This project should be constructed by a qualified contractor with experience in similar
projects. The owner/builder is advised to observe and document the construction
process to ensure the construction is performed in accordance with the design
drawings and technical specifications. The foundation and retaining walls must be
well cured and well braced prior to backfilling.
•
Job#10-2154 Page 8 of 9
•
This report does not address general hillside stability, landslide potential, and/or other
natural hazards. Several areas in the Colorado Front Range have known geologic
hazards associated with them. We recommend that readers of this report educate
• themselves further as to the existence of geologic hazards on or around their specific
property of interest. The Colorado Geologic Survey {www.geosurvey.state.co.us or
303-866-2611) is a good source for publications (maps, reports, etc.) dealing with
specific geologic issues and/or issues related to specific geographic areas.
DISCLAIMER:
We do not guarantee the performance of the project in any respect, but only that our
engineering work and judgments rendered meet the standard care of our profession.
The presence of underground workings (e.g. coal mines) and subsidence potential
from any workings was not part of this investigation. The owner should contact the
State and County agencies to determine if mining has been conducted in the area
and if any precautions are recommended.
THE PARTIES SPECIFICALLY AGREE THAT HIGH PLAINS ENGINEERING 8( DESIGN, LLC. HAS
NOT BEEN RETAINED NOR WILL THEY RENDER AN OPINION CONCERNING ANY
ENVIRONMENTAL ISSUES, HAZARDOUS WASTE OR ANY OTHER KNOWN OR UNKNOWN
CONDITIONS THAT MAY BE PRESENT ON SITE.
DUE TO CHANGING TECHNOLOGY, BUILDING CODES AND CITY/COUNTY REQUIREMENTS,
THIS SOIL REPORT MUST BE USED WITHIN ONE YEAR OF THE DATE ON THE FRONT OF THE
REPORT OR MUST BE REVISED.
•
Job#10-2154 Page 9 of 9
0
• 1
2 CLAY WITH MEDIUM PLASTICITY(CL)
3
4
Blowcounts I I/12
5
/ 6
/ 7
/ 8
blowcounts 7/12 9
10
/ 11
• WATER TABLE v / 12
/ 13 POORLY GRADED SANDY SILT(SP-SM)
14
15
/ 16
•/ 17
18
19
/ 20
/ 21
/ 22
/ 23
/ 24
25
• SOIL PROFILE
1---- 1' HIGH PLAINS ENGINEERING & DESIGN, LLC
721 4th STREET, SUITE D, FORT LUPTON, CO 80621 PHONE - (303> 857-9280 FAX - (303) 857-9238
• 12% -
10% ,
8% ,
6% . .._ .
4% - .y-- , ---
2% -
O%O _-,
-2% I ♦. I I , • .
-4% . , *,
-6% r .
-8% ' ,
-10% , - ,
100 500 1000 2000 3000 10000
GRAPH OF FOUR FOOT DEPTH
Z X SOIL TYPE
101E N DEPTH L.L. P L. 4 F'.. EXPANSION CON5OUDATION
1
I I 4' ncn-plasl.c TOO MUCH GRAVEL FOR TEST POORLY GRADED SANDY SILT(SP-5M)
O -
12%
10% , . . _ ___
8% 4,
4% - ,
2% - , # - - '
0% • • - T— I
-2% ► _. -_
-4% ' ' '
-6% - 1
-8% . .__ ,
-10% - - - ,
T
100 500 1000 2000 3000 10000
GRAPH OF NINE FOOT DEPTH
Z % SOIL TYPE
HOLE# DEPTH L.L. '1. P.I EXPANSION CONSOLIDATION
I 9 non-plastic TOO MUGS GRAVEL FOR TEST POORLY GRADED SANDY SILT(SP-5M)
• JOB NO: 10.2 1 54 J05 LOCATION:
DATE. 06/14/1O 8443 U.5.HIGHWAY 85
DRAWN• Jason WELD COUNTY,CO
CHECKED:
•
•
n HIGH PLAINS ENGINEERING & DESIGN, LLC
721 4TH STREET, SUITE D, FORT LUPTON, CO 80621 PHONE (303) 857-9280 FAX (303) 857-9238
•
WELL SLOPED-17'PER
10FT,MIN.
BRACE WALLS,TOP& -
BOTTOM PRIOR TO
BACKFILLING - �-
-DAMP PROOFING
FOUNDATION WALL '
�- BACKFILL
AREA 7
•
SLAB LEVEL GEOTEXTILE
7
FILTER FABRIC 10 MIL PLASTIC LINER GLUED TO WALL
GRADE OR EQUIVALEN//T WITH FIBERED ROOFING ADHESIVE OR
I EQUIVALENT AND EXTEND ALONG
BOTTOM OF EXCAVATION TO
$9,
o.�.•_.. 6 INCHES ABOVE BOTTOM
CONCRETE FOOTER • • j•'�•�" iA OF PIPE ALONG EXTERIOR
$�`'�''`+ OF EXCAVATION
45
DEPTH OF HIGH POINT/ I
4"MINIMUM BELOW
FOUNDATION TO BOTTOM
OF PERFORATED DRAIN
PIPE AND SLOPEDY"PER 12"MINIMUM DEPTH OF
FOOT TO DRAIN OR 3/4 TO 1-1/2"CLEAN RIVER ROCK
DAYLIGHT DO NOT CUT OR DISTURB SOIL
AT AN ANGLE GREATER THAN
45.ADJACENT TO FOUNDATION 4"DIA.PERFORATED PLASTIC PIPE
'RIGID PERFORATED PVC PIPE
IS PREFERRED'
DETAILS OF PERIPHERAL DRAIN SYSTEM (OUTSIDE)
THE DRAIN SHOULD BE RUN TO A NON-PERFORATED SUMP PIT WITH A LIFT PUMP
AND A HIGH WATER ALARM OR PROVIDE A FREE GRAVITY OUTLET TO THE SURFACE,
• AT A MINIMUM SLOPE OF 1/8" PER FOOT.
•
/ \-
1-Th- HIGH PLAINS ENGINEERING & DESIGN, LLC
721 4TH STREET, SUITE D, FORT LUPTON, CO 80621 PHONE (303) 857-9280 FAX (303) 857-9238
DRILL 3/8" DIA HOLE IN TOP 2" X 4" STUD WALL
BASE PLATE AND USE 60-PENNY SECURED FROM ABOVE
NAILS AT 3'-0" O.C. TO STABILIZE BY METAL STRAPS OR NAILING
FRAME WALL. DRIVE LARGE NAIL 1/2" DRYWALL ATTACHED
INTO LOWER BASE PLATE TO STUDS, ONLY
WALL BASEBOARD NAILED
TO BASE PLATE ONLY (�/ 3" SPACE TO ALLOW FOR INDEPENDENT
• N I MOVEMENT OF THE FLOOR SLAB
N
N
1 I
4 CONCRETE SLAB FLOOR
1/2" X 1" NAILING STRIP
TO HOLD BASEBOARD 2' X 4" MFG. TREATED BASE PLATE
IN PLACE SECURED WITH 3" CONCRETE NAILS
OR RAMSET STUDS
FLOATING WALL FRAMING DETAIL
NON-BEARING WALL ON CONCRETE FLOOR
NOTE: Provide void space at the top of the wall framing
when rigid wall coverings are to be installed,
i.e. tile showers
-,:-.X.N/N-rTh
HIGH PLAINS ENGINEERING & DESIGN, LLC
1 4TH STREET, SUITE D, FORT LUPTON, CO 80621 PHONE (303) 857-9280 FAX (303) 857-9238
FOUNDATION GRADING DETAIL
1I 5' MIN.
TV�
KY,r
8" MIN
SLAB-ON-GRADE
• -- ..._.._.._.-_._ -GRADE
DECORATIVE GRAVEL
OR STONE AREA
STEEL STAKES
FOUNDATION WALL
GEOTEXTILE FABRIC - METAL OR WOOD EDGE
W/ I/2" SPACE AT
BOTTOM TO ALLOW FOR
THE RELEASE OF WATER
NOTE
I . PROVIDE A MINIMUM SLOPE OF 1 2" IN THE
FIRST 1O'-O" FROM FOUNDATION ( I O%)
2. DOWNSPOUTS AND EXTENSIONS SHOULD
EXTEND BEYOND THE GRAVEL OR STONE AREA
S 3 . HARDSCAPING NEXT TO FOUNDATION SHOULD
SLOPE AWAY AT 2% SLOPE
•
•
5ITE N/ Ar
• 8443 U.S. highway 85
Weld County, C •
uo'
76'
00o 16'
000 F
000
9 '
EXISTING a
SHOP EXISTING
SHOP
5 EXISTING -<
HOUSE QD
® CI1
59' ACCESS
1111 -�
0., PP7'
x
EXISTING
PRODUCE-STAN x
X
X
LEGEND
All locations shown above are based on speciFic information
o Percolation Test Hole furnished by others or estimates made in the field by High
Plains Engineering & Design personnel. The locations, distances,
•X-Percolation Profile Hole directions, etc. are not the result of a property survey but
are approximations and are not warranted to be exact. It is
A—Soil Profile Hole the owner/builder's responsibility to define property -
boundaries and ensure all onsite improvements are located
X X-Fence within the platted site and out of inappropriate easements.
All distances are to be verified prior to excavation.
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