Attachment 6 - Geo Infiltration Testing - 2019-12-05 - FNL.pdf

4 4 1 2 S W C O R B E T T A V E N U E , P O R T L A N D , O R 9 7 2 3 9 5 0 3 . 2 4 8 . 1 9 3 9 M A I N 8 6 6 . 7 2 7 . 0 1 4 0 F A X P B S U S A . C O M

December 5, 2019

Mr. Bill Wilson William Wilson Architects 1010 SW 11th Avenue Portland, Oregon 97205

Regarding: Geotechnical Engineering Letter Report – Infiltration Testing White City VA Retention Pond Design 8495 Crater Lake Highway

White City, Oregon 97503 PBS Project 70995.002

Dear Mr. Wilson:

PBS Engineering and Environmental Inc. (PBS) is pleased to provide this letter summarizing the results of infiltration testing completed at the Veteran Affairs Department (VA) located in White City, Oregon.

PROJECT UNDERSTANDING

PBS understands that a new stormwater detention and treatment facility will be constructed at the northern end of the White City VA.

SCOPE OF WORK

Subsurface Exploration for Infiltration testing Subsurface conditions were explored by excavating two test pits, designated as TP-1 and TP-2, using a Deere 310J backhoe to depths of 10 feet below the existing ground surface (bgs). The test pits were logged, observed groundwater levels noted, and representative soil samples collected by a member of the PBS geotechnical engineering staff.

Field Infiltration Testing Two infiltration tests were completed, one in each test pit, at depths of approximately 5 feet bgs. The infiltration tests were performed in general accordance with the Rogue Valley Stormwater Quality Design Manual test procedures. A soil sample was collected immediately below the infiltration test depth in each test pit. The test pits were extended approximately 5 feet below the depth of the infiltration test.

Soils Testing Samples returned to our PBS laboratory were classified in general accordance with the Unified Soil Classification, Visual-Manual Procedure. Laboratory testing was not performed due to the degree of cementation that was observed throughout the subsurface materials.

Deliverable This geotechnical engineering letter report was prepared containing the results of our findings, including the following information:

• Field exploration logs and site plan showing approximate exploration locations

• Infiltration test results

White City VA Geotechnical Engineering Letter Report – Infiltration Testing

70995.002

• Groundwater considerations

SUBSURFACE CONDITIONS

Site Soils Two test pits were excavated to depths of 10 feet bgs on November 12, 2019, to perform field infiltration testing.

Both test pits were completed within the area of the proposed stormwater facilities (Figure 1).

PBS has summarized the subsurface units as follows:

Lean CLAY with SAND

(CL):

Hard, brown, lean clay with sand and trace gravel was encountered at the surface of both test pits to approximately 1 foot bgs. The clay exhibited medium plasticity and contained fine to medium sand and fine angular gravel in TP-1, which we have interpreted as fill. Rootlets were present to a depth of approximately 1 foot bgs.

Cemented SILT, SAND, and GRAVEL:

An approximately 6-inch-thick, iron-oxide cemented hardpan layer was encountered beneath the lean clay in both test pits. In TP-1, the hardpan consisted of a cemented gravel with sand and silt, and in TP-2 the hardpan consisted of a cemented silty sand.

GRAVEL with SILT and SAND (GW-SM) to SAND with SILT and

GRAVEL (SW-SM):

Very dense to dense, coarse-grained layers of sand and gravel were encountered within a matrix of silt and clay fines beneath the hardpan. These layers were also cemented and difficult to excavate. The sand and gravel were fine to coarse with rounded gravel clasts. Cobbles were encountered at approximately 7 feet bgs within this layer in TP-1.

Groundwater Static groundwater was not encountered at the time of our explorations to the depth explored. However, based on a review of regional groundwater logs provided by the Oregon Water Resources Department (OWRD), we anticipate that the static groundwater level may be present at a depth less than 20 feet bgs. Please note that groundwater levels can fluctuate during the year depending on climate, irrigation season, extended periods of precipitation, drought, and other factors.

INFILTRATION TESTING

PBS completed two open-hole, falling-head infiltration tests in test pits TP-1 and TP-2 at a depth of approximately 5 feet bgs. The infiltration tests were conducted within an approximately 2-foot by 2-foot depression approximately 1-foot deep that was excavated at the bottom of the test pit. After a period of saturation, the height of the water column in the excavation was then measured initially and at regular, timed intervals. No measurable drop of the water levels was observed in either of the infiltration tests.

Table 1. Infiltration Test Results

Test Location Depth (feet bgs) Field Measured Infiltration Rate (in/hr)

Recommended Hydrologic Soil Group*

TP-1 5 0 D

TP-2 5 0 D

*The recommended hydrologic soil group classification is based upon infiltration rates and soil classification.

Soil types can vary significantly over relatively short distances. The infiltration rates noted above are representative of one discrete location and depth. Installation of infiltration systems within the layer the field rate was measured is considered critical to proper performance of the systems.

The United States Department of Agriculture (USDA) categorizes soils in four hydrologic soil groups, A through D, and are designated mainly by particle size and hydraulic conductivity. Table 2 below shows general characteristics of each group as they are identified by the USDA.

Table 2. USDA Hydrologic Soil Group Parameters (USDA, 2009)

Soil Properties Hydrologic Soil Group A B C D

Saturated Hydraulic Conductivity (k) (inches/hour) k>5.67 1.42<k<5.67 0.14<k<1.42 k<0.14

LIMITATIONS

This report has been prepared for the exclusive use of the addressee, and their architects and engineers, for aiding in the design and construction of the proposed development and is not to be relied upon by other parties. It is not to be photographed, photocopied, or similarly reproduced, in total or in part, without express written consent of the client and PBS. It is the addressee's responsibility to provide this report to the appropriate design professionals, building officials, and contractors to ensure correct implementation of the recommendations.

The opinions, comments, and conclusions presented in this report are based upon information derived from our literature review, field explorations, and engineering analyses. It is possible that soil, rock, or groundwater conditions could vary between or beyond the points explored. If soil, rock, or groundwater conditions are encountered during construction that differ from those described herein, the client is responsible for ensuring that PBS is notified immediately so that we may reevaluate the recommendations of this report.

Unanticipated fill, soil and rock conditions, and seasonal soil moisture and groundwater variations are commonly encountered and cannot be fully determined by merely taking soil samples or completing explorations such test pits. Such variations may result in changes to our recommendations and may require additional funds for expenses to attain a properly constructed project; therefore, we recommend a contingency fund to accommodate such potential extra costs.

The scope of work for this subsurface exploration and geotechnical report did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous substances in the soil, surface water, or groundwater at this site.

If there is a substantial lapse of time between the submission of this report and the start of work at the site, if conditions have changed due to natural causes or construction operations at or adjacent to the site, or if the basic project scheme is significantly modified from that assumed, this report should be reviewed to determine the applicability of the conclusions and recommendations presented herein. Land use, site conditions (both on and off site), or other factors may change over time and could materially affect our findings; therefore, this report should not be relied upon after three years from its issue, or in the event that the site conditions change.

ADDITIONAL SERVICES

Future development plans and construction specifications should be reviewed by PBS for conformance with the geotechnical recommendations for site development. Additionally, geotechnical-related aspects of construction, such as footing, slab, and pavement subgrades, underpinning of existing structures, shoring installation, and preparation of structural fill and backfill, should be observed by a representative of PBS.

CLOSING

We trust this letter meets your current needs. Please contact Ryan White at 503.539.5028 or Ryan.White@pbsusa.com with any questions or comments.

Sincerely, Shaun Cordes, RG, CEG Project Engineering Geologist

Ryan White, PE, GE Principal/Geotechnical Engineering Group Manager

Attachments: Figure 1 Site Plan Table A-1 Terminology Used to Describe Soil

Table A-2 Key to Test Pit and Boring Log Symbols Figures A1–A2 Logs for Test Pits TP-1 and TP-2

SC:RW:rg

6/30/2020 Exp. 7/1/2020

TP-2

TP-1

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DAT E: DEC 2019 ∙ PROJECT: 70995.002

FIGURE

SITE PLAN

WHIT E CIT Y VA RET ENT ION

POND DESIGN

WHIT E CIT Y, OREGON

0 250 500125 Feet 1 inch = 250 feet

EXPLANATION

T P-1 - Test pit nam e and approxim ate location w ith infiltration test

Notes: Goog le Earth im ag ery

Salem

Eugene

Medford

Portland

Site

Hwy 62

Table A-1

Terminology Used to Describe Soil

Soil Descriptions

Soils exist in mixtures with varying proportions of components. The predominant soil, i.e., greater than 50 percent based on total dry weight, is the primary soil type and is capitalized in our log descriptions (SAND, GRAVEL, SILT, or CLAY). Smaller percentages of other constituents in the soil mixture are indicated by use of modifier words in general accordance with the

ASTM D2488-06 Visual-Manual Procedure. “General Accordance” means that certain local and common descriptive practices may have been followed. In accordance with ASTM D2488-06, group symbols (such as GP or CH) are applied on the portion of soil passing the 3-inch (75mm) sieve based on visual examination. The following describes the use of soil names and modifying terms used to describe fine- and coarse-grained soils.

Fine-Grained Soils (50% or greater fines passing 0.075 mm, No. 200 sieve)

The primary soil type, i.e., SILT or CLAY is designated through visual-manual procedures to evaluate soil toughness, dilatency, dry strength, and plasticity. The following outlines the terminology used to describe fine-grained soils, and varies from ASTM

D2488 terminology in the use of some common terms.

Primary soil NAME, Symbols, and Adjectives Plasticity

Description

Plasticity

Index (PI)

SILT (ML & MH) CLAY (CL & CH) ORGANIC SOIL (OL & OH)

SILT Organic SILT Non-plastic 0 – 3

SILT Organic SILT Low plasticity 4 – 10

SILT/Elastic SILT Lean CLAY Organic SILT/ Organic CLAY Medium Plasticity 10 – 20

Elastic SILT Lean/Fat CLAY Organic CLAY High Plasticity 20 – 40

Elastic SILT Fat CLAY Organic CLAY Very Plastic >40

Modifying terms describing secondary constituents, estimated to 5 percent increments, are applied as follows:

Description % Composition

With Sand % Sand ≥ % Gravel 15% to 25% plus No. 200

With Gravel % Sand < % Gravel

Sandy % Sand ≥ % Gravel ≤30% to 50% plus No. 200

Gravelly

% Sand < % Gravel

Borderline Symbols, for example CH/MH, are used when soils are not distinctly in one category or when variable soil units contain more than one soil type. Dual Symbols, for example CL-ML, are used when two symbols are required in accordance with ASTM D2488.

Soil Consistency terms are applied to fine-grained, plastic soils (i.e., PI > 7). Descriptive terms are based on direct measure or correlation to the Standard Penetration Test N-value as determined by ASTM D1586-84, as follows. SILT soils with low to non-plastic behavior (i.e., PI < 7) may be classified using relative density.

Consistency

Term SPT N-value

Unconfined Compressive Strength tsf kPa

Very soft Less than 2 Less than 0.25 Less than 24

Soft 2 – 4 0.25 – 0.5 24 – 48

Medium stiff 5 – 8 0.5 – 1.0 48 – 96

Stiff 9 – 15 1.0 – 2.0 96 – 192

Very stiff 16 – 30 2.0 – 4.0 192 – 383

Hard Over 30 Over 4.0 Over 383

SAMPLING DESCRIPTIONS

Table A-2

Key To Test Pit and Boring Log Symbols S P T D ri ve

S am p le r

S ta n d ar d P e n e tr at io n T e st

A

T M

D

S h e lb y T u b e P u sh

S am p le

T M

D

S p e ci al iz e d D ri ve

S am p le rs

(D e ta ils N o te d o n L o g s)

S p e ci al iz e d D ri ll o r

P u sh am p le r (D e ta ils N o te d o n

Lo g s)

G ra b S am p le

R o ck

C o ri n g I n te rv al

S cr e

(W at e r o r

A ir S a m p lin

W at e r

Le ve l D u ri

D ri lli n g /E xc av at io n W at e r

Le ve l A ft ri lli n g /E xc av at io

LOG GRAPHICS

PP Pocket Penetrometer HYD Hydrometer Gradation

TOR Torvane SIEV Sieve Gradation

DCP DS Direct Shear

ATT Atterberg Limits DD Dry Density

PL Plasticity Limit CBR California Bearing Ratio

LL Liquid Limit RES Resilient Modulus

PI Plasticity Index VS Vane Shear

P200 Percent Passing US Standard No. 200 Sieve bgs Below ground surface

OC Organic Content MSL Mean Sea Level

CON Consolidation HCL Hydrochloric Acid

UC Unconfined Compressive Strength

Details of soil and rock classification systems are available on request. Rev. 02/2017

Dynamic Cone Penetrometer

Geotechnical Testing Acronym Explanations

Lithology Boundary:

separates distinct units

(i.e., Fill, Alluvium, Bedrock) at approximate depths inciated

Sampler

Type

Sample

Recovery Sample

Interval

Instrumentation Detail Sampling Symbols Soil and Rock

Well Pipe

Piezometer

Piezometer

Ground Surface

Well Cap

Bottom of Hole

S o il o r R o ck

T y p e s

Well Seal

Well Screen

Soil-type or Material-type

Change Boundary: separates soil and material changes within the same lithographic unit at approximate depth indicated

Table A-1

Terminology Used to Describe Soil

Soil Descriptions

Coarse - Grained Soils (less than 50% fines)

Coarse-grained soil descriptions, i.e., SAND or GRAVEL, are based on the portion of materials passing a 3-inch (75mm) sieve.

Coarse-grained soil group symbols are applied in accordance with ASTM D2488-06 based on the degree of grading, or distribution of grain sizes of the soil. For example, well-graded sand containing a wide range of grain sizes is designated SW;

poorly graded gravel, GP, contains high percentages of only certain grain sizes. Terms applied to grain sizes follow.

Material NAME Particle Diameter

Inches Millimeters

SAND (SW or SP) 0.003 – 0.19 0.075 – 4.8

GRAVEL (GW or GP) 0.19 – 3 4.8 – 75

Additional Constituents:

Cobble 3 – 12 75 – 300

Boulder 12 – 120 300 – 3050

The primary soil type is capitalized, and the fines content in the soil are described as indicated by the following examples.

Percentages are based on estimating amounts of fines, sand, and gravel to the nearest 5 percent. Other soil mixtures will have similar descriptive names.

Example: Coarse-Grained Soil Descriptions with Fines

>5% to < 15% fines (Dual Symbols) ≥15% to < 50% fines

Well graded GRAVEL with silt: GW-GM Silty GRAVEL: GM

Poorly graded SAND with clay: SP-SC Silty SAND: SM

Additional descriptive terminology applied to coarse-grained soils follow.

Example: Coarse-Grained Soil Descriptions with Other Coarse-Grained Constituents

Coarse-Grained Soil Containing Secondary Constituents

With sand or with gravel ≥ 15% sand or gravel

With cobbles; with boulders Any amount of cobbles or boulders.

Cobble and boulder deposits may include a description of the matrix soils, as defined above.

Relative Density terms are applied to granular, non-plastic soils based on direct measure or correlation to the Standard

Penetration Test N-value as determined by ASTM D1586-84.

Relative Density Term SPT N-value

Very loose 0 – 4

Loose 5 – 10

Medium dense 11 – 30

Dense 31 – 50

Very dense > 50

0.0

1.0

1.5

4.5

10.0

Infiltration testing completed at 5 feet bgs

PP = >4.5 tsfPP

Hard, brown, lean CLAY (CL) with sand and roots; medium to high plasticity; fine to medium sand; moist

Olive brown, well-graded GRAVEL (GW-GM) with silt and sand; non-plastic;

fine to coarse sand; fine to coarse, subrounded gravel; iron staining; moderate cementation; moist Olive brown to brown, well-graded SAND (SW-SM) with silt and gravel; non-plastic;

fine to coarse sand; fine to coarse, rounded gravel; weak cementation; moist

Olive brown, well-graded GRAVEL (GW-GM) with silt and sand; non-plastic;

fine to coarse sand; fine to coarse, rounded gravel; moist cobbles at 7 feet bgs

Final depth 10.0 feet bgs; test pit backfilled with excavated material to existing ground surface. Groundwater not encountered at time of exploration.

APPROX. TEST PIT TP-1 LOCATION:

(See Site Plan)

0 50 100

MOISTURE

CONTENT %

STATIC

PENETROMETER

DYNAMIC CONE

PENETROMETER

COMMENTS

Lat: 43.444809 Long: -122.840027

T

E S

T P

IT

L

O G

P E

R P

A G

E

5.

2_ T

P 1-

2_

.G

P J

P B

S _D

A T

A T

M P

L_ G

E O

.G

T

P

R

IN

T D

A T

E

/2

1/

:R P

G

G R

A P

H

IC

LO

G

TEST PIT TP-1

PBS PROJECT NUMBER:

70995.002

DEPTH

FEET

FIGURE A1LOGGED BY: D. Eibert

COMPLETED: 11/12/19

WHITE CITY, OREGON

Lines representing the interface between soil/rock units of differing description are approximate only, inferred where between samples, and may indicate gradual transition.

EXCAVATION METHOD: Deere Backhoe with 24" Bucket EXCAVATED BY: Taylor Site Development Inc.

T E

S T

IN

G

D E

P T

H

S A

M P

LE

T

Y

M P

LE

ID

WHITE CITY VA RETENTION POND

MATERIAL DESCRIPTION

Surface Conditions: Soil and Roots

S -1

S -2

S -3

0 50 100 0.0

2.0

4.0

6.0

8.0

10.0

12.0

0.0

1.0

1.5

2.5

3.5

10.0

Infiltration testing completed at 5 feet bgs

Difficult digging from 7 to 10 feet bgs

PP = >4.5 tsfPP

Hard, brown, lean CLAY (CL) with sand and roots; medium plasticity; fine to medium sand; moist

Orange, silty SAND (SM); non-plastic; fine to medium sand; iron staining; moderate cementation; moist Olive brown, silty SAND (SM) with gravel;

non-plastic; fine to coarse sand; fine to coarse, rounded gravel; moderate cementation; moist Brown, silty SAND (SM); non-plastic; fine sand; moist

Brown, well-graded GRAVEL (GW-GM) with silt and sand; non-plastic; fine to coarse sand; fine to coarse, rounded gravel; moist

Final depth 10.0 feet bgs; test pit backfilled with excavated material to existing ground surface. Groundwater not encountered at time of exploration.

APPROX. TEST PIT TP-2 LOCATION:

(See Site Plan)

0 50 100

MOISTURE

CONTENT %

STATIC

PENETROMETER

DYNAMIC CONE

PENETROMETER

COMMENTS

Lat: 42.444768 Long: -122.839255

T

E S

T P

IT

L

O G

P E

R P

A G

5.

2_ T

P 1-

2_

.G

P J

P B

S _D

A T

A T

M P

L_ G

E O

.G

T

R

IN

T D

A T

E

/2

1/

:R P

G

G R

A P

H

IC

LO

G

TEST PIT TP-2

PBS PROJECT NUMBER:

70995.002

DEPTH

FEET

FIGURE A2LOGGED BY: D. Eibert

COMPLETED: 11/12/19

WHITE CITY, OREGON

Lines representing the interface between soil/rock units of differing description are approximate only, inferred where between samples, and may indicate gradual transition.

EXCAVATION METHOD: Deere Backhoe with 24" Bucket EXCAVATED BY: Taylor Site Development Inc.

T E

S T

IN

G

D E

P T

H

S A

M P

LE

T

Y

M P

LE

ID

WHITE CITY VA RETENTION POND

MATERIAL DESCRIPTION

Surface Conditions: Soil and Roots

S -1

S -2

S -3

0 50 100 0.0

2.0

4.0

6.0

8.0

10.0

12.0