HomeMy WebLinkAboutENGINES & ENERGY CONVERSION LAB - BDR - BDR120006 - SUBMITTAL DOCUMENTS - ROUND 1 - RECOMMENDATION/REPORT4396 GREENFIELD DRIVE
WINDSOR, COLORADO 80550
(970) 545-3908 FAX (970) 663-0282
November 14, 2011
Colorado State University Research Foundation
601 South Howes Street – Room 410
Fort Collins, Colorado 80521
Attn: Mr. Stuart MacMillan
Re: Subsurface Exploration Report for Permeable Pavers - Addendum No. 2
Proposed 50,000 SF Multi-Tenant Office/Lab Addition and Pavement Areas
Colorado State University (CSU) – Engines and Energy Conservation Lab
430 North College Avenue
Fort Collins, Colorado
EEC Project No. 1112015
Mr. MacMillan:
Enclosed, herewith, are the results of the permeable paver subsurface exploration study completed
by Earth Engineering Consultants, Inc. (EEC) personnel for proposed site improvements to the
existing Colorado State University’s Engines and Energy Conservation Laboratory (EECL) facility
located at 430 North College Avenue in Fort Collins, Colorado. For this study two (2) soil profile
borings were drilled to approximate depths of 15-feet below existing site grades and a series of
three (3) shallow soil percolation borings were drilled to approximate depths of 3-feet below
existing site grades within an area planned for permeable pavers. This supplemental permeable
paver evaluation/study was completed in general accordance with our proposal dated October 21,
2011.
INTRODUCTION
Permeable Pavers are a paving alternative to more traditional types of hard surfacing materials,
where water is allowed to filter through the surface and into the underlying subsoils. Storm water
brings with it pollutants, chemicals, fertilizers, sediment and oils, impacting the quality of water
flowing into the various catchment areas. Permeable pavers permit rainwater to be absorbed by the
ground underneath, while still managing to provide a stable enough surface for vehicles. Permeable
Pavers preserve the quality of the water, and also increase the quantity of “good quality” water.
Permeable Pavers can be made from many different types of materials. The design team is
considering the use of permeable pavers as an alternative pavement method for portions of the CSU
EECL on-site pavement improvement areas for possible LEED credits. At this point, the type or
manufacturer of the permeable pavers has not yet been determined. The purpose of this study was
to evaluate the subsurface soils to assist the design team in determining if permeable pavers are
feasible for this project.
CDN #2627A-027
Earth Engineering Consultants, Inc.
CSU’s EECL – 430 North College Avenue
Permeable Paver Evaluation Report
November 14, 2011
EEC Project No. 1112015
Page 2
EXPLORATION AND TESTING PROCEDURES
The permeable paver/soil percolation related boring locations were established in the field by a
representative of Earth Engineering Consultants, Inc. (EEC) by pacing and estimating angles from
identifiable site features. The area evaluated currently is a poriton of the existing asphalt paved
parking lot which is identified as a “no-parking” zone, as shown on the enclosed site photographs.
The approximate boring locations are indicated on the attached boring location diagram. The
locations of the borings should be considerate accurate only to the degree implied by the methods
used to make the field measurements.
Due to the known presence of landfill debris and the possibility for asbestos containing materials
(ACM), an environmental assessment was conducted concurrently with our initial geotechnical
subsurface exploration in June of 2011, by Walsh Environmental Engineers and Scientists (Walsh).
As part of the environmental related concerns, the site is under a “Soil Characterization
Management Plan” (SCMP), and an environmental “soil-spotter” from National Inspection Services
(NIS), (the environmental consulting firm representing CSURF), was on-site during the
supplemental soil percolation exploration drilling operations.
The soil percolation borings were performed using a truck-mounted, CME-75 drill rig equipped
with a hydraulic head employed in drilling and sampling operations. The soil profile borings (P-1
and P-2), along with the shallow soil percolation borings (SP-1 through SP-3) were advanced using
4 and 6-inch diameter continuous flight augers respectively, and samples of the subsurface materials
encountered were obtained using split-barrel sampling procedures in general accordance with
ASTM Specifications D-1586. In the split barrel sampling procedure, a standard sampling spoon is
driven into the ground by means of a 140-pound hammer falling a distance of 30 inches. The
number of blows required to advance the sampler is recorded and is used to estimate the in-situ
relative density of cohesionless soils and, to a lesser degree of accuracy, the consistency of cohesive
soils. All samples obtained in the field were sealed and returned to the laboratory for further
examination, classification and testing. Moisture content tests were completed on each of the
recovered samples.
As part of the testing program, all samples were examined in the laboratory by an engineer and
classified in accordance with the attached General Notes and the Unified Soil Classification System,
based on the soil’s texture and plasticity. The estimated group symbol for the Unified Soil
Classification System is indicated on the boring logs and a brief description of that classification
system is included with this report.
CDN #2627A-027
Earth Engineering Consultants, Inc.
CSU’s EECL – 430 North College Avenue
Permeable Paver Evaluation Report
November 14, 2011
EEC Project No. 1112015
Page 3
SUBSURFACE CONDITIONS
An EEC field engineer was on site during the supplemental drilling operations to evaluate the
subsurface conditions encountered and to direct the drilling activities. Field logs prepared by EEC’s
site personnel were based on visual and tactual observation of auger cuttings and disturbed samples.
A “soil-spotter” from NIS was also on-site during the subsurface exploration activities as required
per the site-specific SCMP. The boring logs included with this report may contain modifications to
the field logs based on results of laboratory testing and engineering evaluation. Based on results of
the field boring and laboratory testing, subsurface conditions can be generalized as follows.
At the surface of each permeable paver related soil boring, the existing pavement section generally
consisted of approximately 2 to 2-1/2-inches of asphaltic concrete pavement underlain by
approximately 6-inches of existing aggregate base course. In summary, the subsurface materials
encountered beneath the surficial layers in the two (2) soil profile borings and each of the three (3)
shallow soil percolation borings consisted of existing fill material and landfill debris, which
extended to the depths explored, approximately 3 to 15-feet below existing site grades. Based on
visual observations, it appeared the upper approximate 3-feet of material generally consisted of silty
sand with gravel and/or clayey sand with gravel and intermittent cobbles. Below a depth of about
3-feet, the fill material generally consisted of clayey sand with gravel with intermittent evidence of
landfill debris, which extended to the depths explored.
In our previous subsurface exploration, (please refer to our report dated June 14, 2011), the native
sand, gravel and intermittent cobble zone was encountered at depths of about 17 to 18-feet below
site grades. Within a few of the split-spoon samples obtained at the 4, 9, and 14-foot intervals, and
periodic auger cuttings, slight evidence of landfill debris consisting of cinders, wood, and
construction debris were noted; other materials may be present and variations in depth may exist
across the site.
The stratification boundaries indicated on the boring logs represent the approximate locations of
changes in soil; in-situ, the transition of materials may be gradual and indistinct.
WATER LEVEL OBSERVATIONS
Groundwater was not encountered in either of the soil profile borings drilled to maximum depths of
15-feet below site grades, or the shallow soil percolation borings, drilled to 3-feet below site grades.
As requested, due to the environmental concerns, the two (2) soil profile borings were backfilled
with bentonite upon completion of the drilling operations, and the three (3) shallow soil percolation
CDN #2627A-027
Earth Engineering Consultants, Inc.
CSU’s EECL – 430 North College Avenue
Permeable Paver Evaluation Report
November 14, 2011
EEC Project No. 1112015
Page 4
boreholes were also backfilled with bentonite the following day after performing the field
percolation testing; therefore stabilized/subsequent groundwater measurements were not obtained.
During our initial exploration conducted in June of 2011, groundwater was measured at depths of
approximately 17 to 18-feet below site grades.
Fluctuations in groundwater levels can occur over time depending on variations in hydrologic
conditions and other conditions not apparent at the time of this report. In addition, zones of perched
and/or trapped may be encountered at times throughout the year in more permeable areas within the
subgrade materials. The location and amount of perched water can also vary over time depending
on variations in hydrologic conditions and other conditions not apparent at the time of this report.
ANALYSIS AND RECOMMENDATIONS
Pavement Design Considerations – Permeable Pavers
We understand design concepts for a permeable paver pavement section is currently being discussed
for the site to achieve LEED credits and to reduce the amount of storm water runoff to detention
areas. The following provides general design considerations for use with permeable pavers. The
subgrade preparation recommendations provided in EEC’s “Surface Exploration Report” dated June
14, 2011, for conventional parking areas will need to be revised if a permeable paver pavement
alternative is selected for the site.
To assess the feasibility for use of permeable pavers on site, EEC personnel conducted preliminary
infiltration characteristics by running “soil percolation” characteristics, similar to that used for
developing design criteria for an on-site sewage disposal system. The subsoils analyzed within the
proposed permeable paver pavement section on site, (i.e., the general vicinity of soil profile borings
P-1 and P-2), consisted of a granular silty sand with gravel and intermittent cobble fill zone to
depths of about 3-feet below site grades with the presence of intermittent landfill debris/materials
below. The landfill debris/materials extended to the maximum depths of exploration,
approximately 15-feet. The upper granular fill materials exhibited soil percolation characteristics
on the order of about 5 to 15 minutes per inch, which correlates to about 4 to 12-inches per hour.
According to various pervious/permeable paving documents, “as a general rule, soils with a
percolation rate of ½ to 1 inch/hour are suitable for subgrade under pervious/permeable pavements.”
Although not specifically encountered/observed during our subsurface exploration phase, clay soils
and/or other impermeable layers, which may exist at other locations, can hinder the performance of
pervious/permeable pavements and may need to be modified to allow proper retention and
percolation of precipitation. Design concepts to consider for accommodating the presence of
CDN #2627A-027
CDN #2627A-027
DRILLING AND EXPLORATION
DRILLING & SAMPLING SYMBOLS:
SS: Split Spoon - 13/8" I.D., 2" O.D., unless otherwise noted PS: Piston Sample
ST: Thin-Walled Tube - 2" O.D., unless otherwise noted WS: Wash Sample
R: Ring Barrel Sampler - 2.42" I.D., 3" O.D. unless otherwise noted
PA: Power Auger FT: Fish Tail Bit
HA: Hand Auger RB: Rock Bit
DB: Diamond Bit = 4", N, B BS: Bulk Sample
AS: Auger Sample PM: Pressure Meter
HS: Hollow Stem Auger WB: Wash Bore
Standard "N" Penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2-inch O.D. split spoon, except where noted.
WATER LEVEL MEASUREMENT SYMBOLS:
WL : Water Level WS : While Sampling
WCI: Wet Cave in WD : While Drilling
DCI: Dry Cave in BCR: Before Casing Removal
AB : After Boring ACR: After Casting Removal
Water levels indicated on the boring logs are the levels measured in the borings at the time indicated. In pervious soils, the indicated
levels may reflect the location of ground water. In low permeability soils, the accurate determination of ground water levels is not
possible with only short term observations.
DESCRIPTIVE SOIL CLASSIFICATION
Soil Classification is based on the Unified Soil Classification
system and the ASTM Designations D-2488. Coarse Grained
Soils have move than 50% of their dry weight retained on a #200
sieve; they are described as: boulders, cobbles, gravel or sand.
Fine Grained Soils have less than 50% of their dry weight
retained on a #200 sieve; they are described as : clays, if they
are plastic, and silts if they are slightly plastic or non-plastic.
Major constituents may be added as modifiers and minor
constituents may be added according to the relative proportions
based on grain size. In addition to gradation, coarse grained
soils are defined on the basis of their relative in-place density
and fine grained soils on the basis of their consistency.
Example: Lean clay with sand, trace gravel, stiff (CL); silty
sand, trace gravel, medium dense (SM).
CONSISTENCY OF FINE-GRAINED SOILS
Unconfined Compressive
Strength, Qu, psf Consistency
< 500 Very Soft
500 - 1,000 Soft
1,001 - 2,000 Medium
2,001 - 4,000 Stiff
4,001 - 8,000 Very Stiff
8,001 - 16,000 Very Hard
RELATIVE DENSITY OF COARSE-GRAINED SOILS:
N-Blows/ft Relative Density
0-3 Very Loose
4-9 Loose
10-29 Medium Dense
30-49 Dense
50-80 Very Dense
80 + Extremely Dense
PHYSICAL PROPERTIES OF BEDROCK
DEGREE OF WEATHERING:
Slight Slight decomposition of parent material on
joints. May be color change.
Moderate Some decomposition and color change
throughout.
High Rock highly decomposed, may be extremely
broken.
HARDNESS AND DEGREE OF CEMENTATION:
CDN #2627A-027
CSU EEC – PERMEABLE PAVER FIELD EXPLORATION
430 NORTH COLLEGE AVENUE – FORT COLLINS, COLORADO
EEC PROJECT NO. 1112015
NOVEMBER 2011
CDN #2627A-027
CDN #2627A-027
CDN #2627A-027
DATE:
RIG TYPE: CME 75
FOREMAN: DAR
AUGER TYPE: 4-1/4" Inside Dia. HSA
SPT HAMMER: MANUAL
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/6 IN) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
EXISTING HMA PAVEMENT: Approx. 2 - 2-1/2" _ _
EXISTING ABC: Approx. 6 to 8" 1
FILL MATERIAL: Silty Sand with Gravel and/or _ _
Clayey Sand with Gravel and Cobbles 2
_ _
3
LANDFILL DEBRIS encountered below 3.0' _ _
loose unconsolidated material, evidence of 4
wood, cinders, and miscellaneous _ _ 3
construction/landfill debris encountered 5 2 2000 18.1
within CLAYEY SAND with GRAVEL fill material _ _ 4
6
_ _
7
_ _
8
_ _
9
_ _ 4
*Evidence of FILL MATERIAL at 9-feet SS 10 6 -- 31.3
cinders were noted within the SS Sample @ 9-feet _ _ 8
11
_ _
12
_ _
13
_ _
14
_ _ 3
*Evidence of wood debris at 14-feet 15 2 -- 33.5
_ _ 3
BOTTOM OF PROFILE BORING @ 15.5' 16
_ _
17
_ _
18
_ _
19
_ _
20
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants
SS
DATE:
RIG TYPE: CME 75
FOREMAN: DAR
AUGER TYPE: 4-1/4" Inside Dia. HSA
SPT HAMMER: MANUAL
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/6 IN) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
EXISTING HMA PAVEMENT: Approx. 2 - 2-1/2" _ _
EXISTING ABC: Approx. 6 to 8" 1
FILL MATERIAL: Silty Sand with Gravel and/or _ _
Clayey Sand with Gravel and Cobbles 2
_ _
3
LANDFILL DEBRIS encountered below 3.0' _ _
loose unconsolidated material, evidence of 4
wood, cinders, and miscellaneous _ _ 3
construction/landfill debris encountered 5 7 -- 22.5
within CLAYEY SAND with GRAVEL fill material _ _ 11
6
_ _
7
_ _
8
_ _
9
_ _ 2
*Evidence of loose FILL MATERIAL @ 9' SS 10 1 -- 52.5
cinders were noted within the SS Sample @ 9-feet _ _ 2
organics present indicating high moisture contents 11
_ _
12
_ _
13
_ _
14
_ _ 3
*Evidence of wood debris at 14-feet 15 2 -- 28.1
_ _ 6
BOTTOM OF PROFILE BORING @ 15.5' 16
_ _
17
_ _
18
_ _
19
_ _
20
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants
COLORADO STATE UNIVERSITY (CSU) - ENGINES AND ENERGY CONSERVATION LAB (EECL)
430 NORTH COLLEGE AVENUE - FORT COLLINS, COLORADO
PROJECT NO: 1112015 NOVEMBER 2011
LOG OF PROFILE BORING P-2
SHEET 1 OF 1 WATER DEPTH
START DATE 11/9/2011 WHILE DRILLING N/A to 15'
FINISH DATE 11/9/2011 AFTER DRILLING Not Reported
APPROX. SURFACE ELEV Not Reported 24 HOUR Backfilled
SS
A-LIMITS SWELL
A-LIMITS SWELL
APPROX. SURFACE ELEV Not Reported 24 HOUR Backfilled
FINISH DATE 11/9/2011 AFTER DRILLING Not Reported
SHEET 1 OF 1 WATER DEPTH
START DATE 11/9/2011 WHILE DRILLING N/A to 15'
LOG OF PROFILE BORING P-1
430 NORTH COLLEGE AVENUE - FORT COLLINS, COLORADO
COLORADO STATE UNIVERSITY (CSU) - ENGINES AND ENERGY CONSERVATION LAB (EECL)
PROJECT NO: 1112015 NOVEMBER 2011
Limestone and Dolomite:
Hard Difficult to scratch with knife.
Moderately Can be scratched easily with knife.
Hard Cannot be scratched with fingernail.
Soft Can be scratched with fingernail.
Shale, Siltstone and Claystone:
Hard Can be scratched easily with knife, cannot be
scratched with fingernail.
Moderately Can be scratched with fingernail.
Hard
Soft Can be easily dented but not molded with
fingers.
Sandstone and Conglomerate:
Well Capable of scratching a knife blade.
Cemented
Cemented Can be scratched with knife.
Poorly Can be broken apart easily with fingers.
Cemented
CDN #2627A-027