MTC Letter - Nubgaard LP SW Eval (19B337-02) LMrev MF edits

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January 7, 2020 Dusty Church Properties, LLC 2291 Douglas Rd Ferndale, WA 98225 c/c: Ali Taysi, Principal AVT Consulting, LLC 1708 F Street Bellingham, WA 98225 Subject: Stormwater Feasibility Evaluation Proposed Long Plat Development

2850 Nubgaard Road, Ferndale, Washington MTC Project No.: 19B337-02 Dear Mr. Taysi:

At your request, Materials Testing & Consulting, Inc. (MTC) has completed a targeted soil

characterization for stormwater design feasibility evaluation at the 28-acre site. Development will

require stormwater controls to be implemented per local municipal regulations for new construction. The

primary focus of this study was to perform field explorations in order to assess existing subsurface

conditions for stormwater design feasibility of on-site infiltration, and for laboratory-based determination

of design parameters if suitable infiltration conditions are encountered via visual assessment methods

(per 2014 DoE SWMMWW design criteria for stormwater pond improvements).

MTC understands the client intends to fully develop and subdivide the property, creating multiple lots

and associated exterior features along with construction of stormwater facilities to accommodate the new

proposed impervious surfaces. The site is currently undeveloped with reported historic agricultural use.

Onsite vegetation is primarily tall grass and mostly cleared of large vegetation except for the western

quarter, which remains moderately to heavily forested. For assessment of the site, subsurface

characterization was performed via backhoe test pits at sixteen locations distributed in a representative

pattern throughout the site.

MTC has performed this soil characterization for stormwater design in general accordance with site

characterization guidelines presented in the Washington Department of Ecology 2012 (2014 revision)

PattiPapetti

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PattiPapetti

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EXHIBIT 6

Nubgaard SW Evaluation, Ferndale, WA Materials Testing & Consulting, Inc. January 7, 2020 19B337-02

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Stormwater Management Manual for Western Washington (SMMWW). A summary of MTC’s findings,

interpretations, and recommendations are provided herein for use in final civil design, permitting, and

select construction planning for the proposed development.

Summary of Geologic Literature Review:

The Geologic map of Western Whatcom County, Washington (Easterbrook, D.J. 1976), published by the

U.S. Geological Survey), indicates that subsurface geology of the site is mapped as the unit Qb— Everson

Interstade Bellingham Glacial Drift. Glacial Drift is described as non-sorted, non-stratified assortment of

pebbly sandy silt and pebbly clay. These deposits are found mantling upland areas between flood plains

and below elevations of 600 feet.

The NCRS Web Soil Survey maps the study area as three similar units: Whatcom silt loam (8 to 15%

slopes), Whatcom-Labounty silt loam (0 to 8% slopes), and Whatcom-Labounty silt loam (0-15% slopes).

Whatcom-Labounty silt loam (0 to 8% slopes) covers about 60 % of the sites area. The other two units

span about 20% each and are mapped in the northwest and southwest quadrants. The depositional

landform for all three are hillslopes and the soils are derived from a parent material of volcanic ash and

loess over glaciomarine deposits. A typical soil profile consists of ashy silt loam to 16 inches, and loam

to 60 inches or greater. Depth to the seasonal high-water table is listed as 18 to 36 inches, and the soil is

broadly classified in Hydrologic Soil Group C/D. Capacity of the most limiting layer to transmit water

(Ksat) is moderately low to moderately high. Depth to restrictive conditions is listed as typically 80

inches or greater.

Existing Site Conditions:

The project location is a generally undeveloped, 28-acre lot with the exception of a small barn structure

located near the southeast corner. The property is moderately hilly and generally slopes to the south and

west. A small area in the northern central is raised, and in the southern area, topography runs primarily

to the west, becoming moderate in the southeast corner towards the tree line/stream buffer. Two small

wetland areas were flagged, and MTC was informed of an additional unflagged areas in the SW quadrant

by the onsite surveyors. Test Pit locations were then altered based on marked areas and these

discussions. The tree line was also flagged as a stream buffer and avoided.

Site Exploration and Assessment Methodology:

An MTC Project Geologist visited the site on November 14, 2019 to observe the excavation of sixteen

(16) test pits (TP) for soils characterization with respect to infiltration feasibility. MTC personnel

observed the excavation of test pits at sixteen locations selected on site based on discussions with the

client and design engineer for optimal coverage.

Test pits were performed in a snaking grid pattern beginning in the northeast corner of the site with four


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rows of four performed in the open grassy area (See Below). MTC discussed test pit locations with

onsite surveyors and moved TP locations in order to avoid wetland areas. The western, forested quarter

of the property was avoided due to stream buffer markings.

TP-4 TP-3 TP-2 TP-1

TP-5 TP-6 TP-7 TP-8

TP-12 TP-11 TP-10 TP-9

TP-13 TP-14 TP-15 TP-16

Table 1 Relative Test Pit Locations

Test pits were completed to depths ranging between 5.0 and 9.1 feet BPG. All test pits contained

variable sand deposits extending as deep as 9.1 feet below existing grade before terminating on hard

conditions interpreted as restrictive glacial soils. MTC personnel monitored explorations, examined and

classified the soils encountered in accordance with the Unified Soil Classification System (USCS) and

ASTM D2487, and observed for indications of groundwater or water seepage. Test pits were backfilled

with existing soil tailings after exploration activities were completed.

Grab soil samples were collected from representative soil horizons and depths during test pit excavations,

as depicted on the attached logs. All samples were placed in plastic bags to limit moisture loss, labeled,

and transported to MTC’s laboratory for analysis and storage. Samples will be retained for a minimum

of 90 days from the date of collection. Due to the conditions encountered and discussions with the design

team, laboratory gradation analysis for infiltration rate determination was not performed at this time.

MTC can perform laboratory soil sample analyses for general soil characterization if deemed necessary

for final design at the request of the client.

A location and vicinity map is provided in Figure 1, Appendix A1. An aerial photo indicating the

approximate locations of MTC’s test locations can be seen in Figure 2, Appendix A2. Attached in

Appendix B are photos of the site conditions and explorations in progress. Exploration logs are presented

in Appendix C, with a USCS classification chart provided as Figure 3. Laboratory test results are

presented in Appendix D.

Subsurface Soil Conditions:

Subsurface soil conditions were observed and catalogued during test pit excavations. This section

summarizes our general understanding of site soil conditions gained from completing field explorations

and laboratory analyses. Soil profiles were very consistent among the three test locations. General soil

conditions encountered are summarized in Table 1 below.


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Table 1. Generalized Soil Stratigraphy

SOIL UNIT DEPTH (BPG - feet) DESCRIPTION

Topsoil (ML) 0.0 - 0.7/2.0 Dark Brown SANDY SILT. Topsoil was found in all TP locations from the surface up to 2’ BPG. Contained moderately heavy organics including tall grass with roots. DARK BROWN

Possible Fill (ML)

1.9 – 2.7 SANDY SILT. Found only in TP-4 and observed to be soft, very moist, and contain some organic content.. DARK BROWN. Variable contents and character.

Glacial Drift (ML, SM, SP)

0.7/2.7– 9.1+

Glacial Drift soils consisting of SILT, SANDY SILT, SILTY SAND, & SAND WITH SILT. Rare gravel up to cobble size. Very stiff to hard or dense with depth. Variable deposition with seepage observed within sandy lenses. Moist becoming very moist or wet with depth. LIGHT BROWN or GRAY with moderate to heavy mottling in upper 0.5’ - 2.0’ (weathered horizon).

Subsurface conditions throughout the site consistently found fine-grained glacial soils interpreted to be

glacial drift. This is generally consistent with the mapped soil of restrictive Bellingham drift. This drift

was somewhat variable in character, though was primarily fine-grained with some local sandy

interbedding. This unit was observed immediately below topsoil, except in TP-4 where potential local

fill was observed to overly it. The drift was free of organics & moderately to highly cemented with

depth, correlating with mapped regional glacial deposits. Glacial drift soils were observed to contain a

weathered rind of about 0.5 to 2.0 feet thick where strong orange mottling was observed as well as a

slight color alteration to gray.

All excavations terminated within hard or medium dense to dense glacial soil conditions interpreted to be

restrictive and assumed to continue with depth past the realm of concern for this study (based on our

knowledge of site vicinity geology and review of available regional data such as maps and well logs).

Surface and Subsurface Water Conditions:

MTC understands that three small wetland areas and a stream with associated buffers are located onsite.

The stream buffer and the eastern two wetland areas were flagged, and the third was described onsite by

3rd-party surveyors hired by the client (See Photo). No other major surface water features are present at

the site. Some ponding of surface water was observed in the vicinity of the mapped wetland areas, with

the majority observed in existing ruts from previous site use. Explorations were performed in the fall

with a moderate amount of recent rainfall and groundwater conditions are interpreted to be elevated

though not at a seasonal maximum. The closest major surface water feature to the project site is the


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Nooksack River, located approximately 1.8 miles to the southeast. Some small to moderate sized

detention ponds with other unnamed streams or ditches dot the developments surrounding the site.

At the time of our explorations in the fall season, free water seepage was observed within ten out of the

sixteen test pit excavations. Seepage occurred at a depth of 2.2 to 9.0 feet and was generally observed to

occur within sandy lenses. The fine-grained, consolidated drift soils were typically moist. Moderate

oxidation staining was observed within the upper 0.5 to 2.0 feet of the glacial drift. Oxidation typically

indicates common wetting and drying cycles. The general lack of mottling at depth, as well as the

reduced moisture content observed, suggests that water perching on the glacial drift is common, and only

marginally penetrates the upper margin of the unit over the course of the wet season.

A pervasive groundwater table was not encountered. Cursory review of available well data from the

project vicinity indicates the regional water table resides at depths of about 230 feet, though one nearby

well was apparently within a perched system and reported static water levels at 5.3 feet BPG. Based on

the season of field work in the fall after relatively wet weather, the perched water occurrences observed

are expected to represent a seasonally elevated but not necessarily peak condition. MTC’s scope of

investigation did not include observation and determination of seasonal variations, conclusive

measurement or monitoring of groundwater elevations at the time of exploration, or determination of

regional groundwater levels past the restrictive depths explored.

Stormwater Design Feasibility Assessment:

Based on the results of our targeted site explorations and literature review, it is our opinion that on-site

infiltration for stormwater management within the project site is infeasible by conventional methods due

to native restrictive conditions with depth. Native subsurface conditions display a prevalent limiting

factor consisting of “hardpan” glacial drift soils with small interbeds of sandy material. No prevalent unit

of coarse-grained material was observed in project explorations. Depth to hardpan glacial drift soils

interpreted as a restrictive feature was observed to be as little as about 1.0 feet to as great as 2.7 feet BPG

maximum. Furthermore, mottling patterns in the upper 0.5 to 2.0 feet of the basal drift soil section,

corresponding with other signs of weathering alteration and local seepage along this contact, suggest

perched water and impeded soil saturation will occur commonly over the drift horizon throughout the

project site. This is consistent with our observation of ponding water at the surface of the site.

Because of the limiting factors of shallow glacial hardpan soils, lack of suitable native infiltrating soils

above the till horizon, and interpreted seasonal high perched water occurrences, the site does not appear

to display sufficient vertical separations or infiltrating soils amenable for traditional infiltration facility

use (e.g. in-ground beds, drainage trenches, or drywells). Limited separation systems such as shallow

bioretention cells or pervious pavements are also considered generally infeasible as a means of on-site

infiltration due to the lack of suitable native infiltrating soils above the till horizon and below topsoil.


6

Based on correspondence with the project civil engineer, we understand that if on-site infiltration is

infeasible, a stormwater detention pond is planned to accommodate the proposed site development.

Given that the site conditions are not conducive to infiltration, we recommend new stormwater sources

be routed to a detention facility on-site.

Detention Pond and Berm Construction:

The following recommendations are based on our understanding of the project at this time and address

general aspects of pond construction. This section is not intended to be an exhaustive review of all pond

considerations, and any design should be prescribed by the project retained civil engineer. MTC should

be given the opportunity to review final plans and design.

At a minimum, we recommend the detention pond berms should be constructed from low-permeability

fill consisting of compacted till material in accordance with specifications of the Washington Department

of Ecology SMMWW (Volume V, 2014 edition). Fill materials may consist of excavated native drift soils

if considered present to a quantity to serve the project, properly stockpiled and moisture-controlled, and

subject to sieve verification for suitability during the earthwork process. Alternatively, imported till soils

or clay soils can be substituted upon verification testing and approval by the project engineer and

geotechnical inspection firm.

We recommend berm construction be planned for relatively early in the earthwork process and prior to

final shaping of the basin interior. It is anticipated that fills will need to be applied to widths thicker than

planned bank slopes, to ensure adequate compaction with suitably-sized machinery and to allow for final

grading. Low-permeability till material should be compacted in 6-inch horizontal lifts up to planned

finish grade.


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Closing Remarks:

MTC may be contacted to review proposed site preparation plans and project specifications, to ensure

they are consistent with the intent of the observations and recommendations provided herein. In addition,

MTC can be contacted for construction phase testing, observation, and engineering consultation services

on an as-needed basis. Such services may include but are not limited to earthwork support consulting,

compaction testing of fills, subgrade bearing and general grading verifications, laboratory materials

analysis, and special inspections if required.

Mr. Taysi, we trust this report presents the information you require. If you have questions, please do not

hesitate to call.

Respectfully Submitted;

Mike Furman, G.I.T. Luke Preston McCann, L.G. Project Geologist Senior Licensed Geologist Attached: Limitations and Use of this Report Appendix A1. Location and Vicinity Map

Appendix A2. Aerial Photo with Test Locations Appendix B. Photos of Site Exploration Appendix C. Exploration Logs Appendix D. Laboratory Results

1-7-2020


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Limitations and Use of This Report Recommendations contained in this report are based on our understanding of the proposed development

and construction activities, our field observations and explorations, and our laboratory test results. It is

possible that soil and groundwater conditions could vary and differ between or beyond the points

explored. If soil or groundwater conditions are encountered during construction that vary or differ from

those described herein, we should be notified immediately in order to review and provide supplemental

recommendations. If the scope of the proposed construction, including the proposed loads or structural

locations, changes from that described in this report, we should be notified to review and provide

supplemental recommendations.

We have prepared this report in substantial accordance with the generally accepted geotechnical

engineering practice as it exists in the site area at the time of our study. No warranty, expressed or

implied, is made. The recommendations provided in this report are based on the assumption that an

adequate program of tests and observations will be conducted by MTC during the construction phase in

order to evaluate compliance with our recommendations.

This report may be used only by the Client and their design consultants and only for the purposes stated

within a reasonable time from its issuance, but in no event later than 18 months from the date of the

report. It is the Client's responsibility to ensure that the Designer, Contractor, Subcontractors, etc. are

made aware of this report in its entirety. Note that if another firm assumes Geotechnical Engineer of

Record responsibilities they need to review this report and either concur with the findings, conclusions,

and recommendations or provide alternate findings, conclusions and recommendation under the guidance

of a professional engineer registered in the State of Washington.

Land or facility use, on- and off-site conditions, regulations, or other factors may change over time, and

additional work may be required. Based on the intended use of the report, MTC may recommend that

additional work be performed and that an updated report be issued. Non-compliance with any of these

requirements by the Client or anyone else will release MTC from any liability resulting from the use of

this report. The Client, the design consultants, and any unauthorized party, agree to defend, indemnify,

and hold harmless MTC from any claim or liability associated with such unauthorized use or non-

compliance. We recommend that MTC be given the opportunity to review the final project plans and

specifications to evaluate if our recommendations have been properly interpreted. We assume no

responsibility for misinterpretation of our recommendations.

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.


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Appendix A1. Location and Vicinity Map

Materials Testing & Consulting, Inc. 777 Chrysler Drive

Burlington, WA 98226

Regional and Site Vicinity Nubgaard SW Evaluation

2850 Nubgaard Road Anacortes, WA

FIGURE

1

Maps Source: Google Imagery 2019

Project Location

Project Vicinity


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Appendix A2. Aerial Photo with Test Locations



Site Plan with Test Locations Nubgaard SW Evaluation

2850 Nubgaard Road Anacortes, WA

FIGURE

2

Map Source: Google Maps Dated: January 2020 Overlay by MTC: MF Scale and locations are approximate * Not for Construction *

TP-4 TP-1 TP-2 TP-3

TP-5

TP-6

Test Pit Location (Typical)

TP-7

TP-8

TP-9

TP-10 TP-11 TP-12

TP-13

TP-14 TP-15 TP-16

300 0

SCALE (FEET) 1 inch ~300 feet


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Appendix B. Photos of Site Exploration

Photo A: Overview of site interior looking south from the central-northern area of the site.

Photo B: TP-1 in progress at northeast corner of the site, looking east.


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Photo C: Subsurface conditions at TP-2. Note shallow sandy silt to silty sand deposits overlying a primarily fine-grained unit with seepage and stabilized water observed at 8 feet BPG.

Photo D: Photo provided by onsite surveyors (hired by client) denoting approximate wetland areas. The southwestern area was not flagged during field work.


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Appendix C. Exploration Logs



USCS Soil Classification Chart Nubgaard SW Evaluation

2850 Nubgaard Road Ferndale, WA

FIGURE

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MATERIALS TESTING & CONSULTINGBurlington, WA

Geotechnical Services

MTC Job # 19B337-02

Ferndale, WA2850 Nubgaard Road

Nubgaard LP SW Evaluation

Log of Test Pit TP-1

Date Started : 11/14/19

Date Completed : 11/14/19

Sampling Method : Grab Samples

Location : 100'S 200'W of NE corner (See Map)

Logged By : Mike Furman

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DESCRIPTION

SANDY SILT, dark brown, moist, soft, prevalent organics (grass/roots). Topsoil

SILTY SAND, light brown, very moist, loose, very fine-grained sand with about 40% fines.

SANDY SILT, gray, moist, stiff to very stiff, fine-grained sand with orange mottling observed in the upper 1 foot.

Blocky texture observed in spoils.

SILT with sand clay and gravel, gray, moist, hard. Gravel is 0.5" dia and subrounded.


T.D. @ 6.0' at planned depthNo seepage or free water observed.

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MTC Job # 19B337-02







Location : 200'W of TP-1 (See Map)


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SILTY SAND, light brown, moist, loose, medium & fine-grained sand with orange mottling.

SANDY SILT, light brown, moist, stiff to very stiff.

SILT with sand and gravel some clay, gray, moist, hard. Gravel is 0.5" dia and subrounded.


Becomes very moist at 6' BPG.

Light seepage observed between 6.5 to 9.1 feet BPG.

T.D. @ 9.1' at planned depthStabilized water observed at 8' BPG.

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MTC Job # 19B337-02









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SANDY SILT, light brown, moist, stiff to very stiff with orange mottling throughout.

SILT with sand gravel and clay, gray, moist, hard. Gravel is 0.5" dia and subrounded with orange mottling observed in the upper 4 inches.


Very hard digging reported by operator

T.D. @ 6.5' at planned depthNo free water seepage observed.

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MTC Job # 19B337-02







Location : 200'W of TP-3, 100' S of Fence (See Map)


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SANDY SILT, dark brown to brown, very moist, soft. Potentially reworked native

Thickness ranges from 2' at south to 3' at north

SANDY SILT with gravel and clay, gray, moist, stiff becoming hard with depth. Gravel is 0.5" dia and subrounded with orange mottling observed in the upper 12 inches.


Very hard digging reported by operator

Atterberg Results

Liquid Limit = 42

Plasticity Index = 23

T.D. @ 8.1' at planned depthNo free water seepage observed.

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MTC Job # 19B337-02







Location : 200' S TP-4 (See Map)


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3" diameter root observed

SILTY SAND with some gravel, light brown to gray, moist to very moist, medium dense becoming dense with depth. Gravel is 1/4" with very fine-grained sand and orange mottling throughout.


Silt lens 4" thick observed at about 3.3' BPG.

Light seepage observed on north side at 4' BPG.

SANDY SILT with clay, gray, moist, stiff becoming hard with depth. Fines content about 50-60%.


T.D. @ 7.0' at planned depthSeepage observed at 4' BPG.

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MTC Job # 19B337-02







Location : 200' S TP-3, 200'E TP-5 (See Map)


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SANDY SILT, light brown, moist, soft.Subsoil

SANDY SILT with some gravel, light brown to gray, moist, stiff becoming hard with depth. Gravel is 1/2" with fine-grained sand and orange mottling throughout the upper two feet.


Slight decrease in sand content at 4 feet BPG.

T.D. @ 8.1' at planned depthSeepage observed at 4' BPG.

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MTC Job # 19B337-02









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SILTY SAND, light brown, moist, medium dense.

Texture becoming blocky with depth.

Seepage observed at 3.5' BPG.

SANDY SILT with some gravel, gray, moist, stiff becoming very stiff with depth.


T.D. @ 6.1' at planned depthSeepage observed at 3.5' BPG.

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MTC Job # 19B337-02









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ML

ML

GR

AP

HIC

DESCRIPTION



Seepage observed at 2.2 feet BPG.

SANDY SILT with clay, light brown to gray, moist, stiff becoming very stiff with depth. Orange mottling observed in the upper 1 foot. Sand is very fine-grained.


Atterberg Results

Liquid Limit = 39


T.D. @ 8.0' at planned depthSeepage observed at 2.2' BPG.

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MTC Job # 19B337-02







Location : 150' S TP-8 (See Map)


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SANDY SILT, light brown, moist, medium stiff. Orange mottling observed throughout.

Seepage observed at 2.0 feet BPG.

SANDY SILT with clay, dark brown to brown, very moist, soft. Moderatly heavy organics observed throughout.

Seepage observed at 3 feet BPG.

SANDY SILT with clay, gray, wet, medium sitff.

Semi-blocky texture observed in spoils.

T.D. @ 5.0' at planned depthSeepage observed at 2' & 3' BPG.

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MTC Job # 19B337-02







Location : 50' S TP-9, 200'W TP-9 (See Map)


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SILTY SAND, light brown, wet, loose. Orange mottling observed throughout.

SILT WITH SAND clay and gravel, gray, moist, very stiff becoming hard with depth.


Very hard digging reported at 6 feet BPG.

T.D. @ 8.2' at planned depthNo freewater seepage observed.

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MTC Job # 19B337-02









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SANDY SILT with clay, gray, moist, very stiff becoming hard with depth. Trace orange mottling observed in the upper 8 inches.


Atterberg Results

Liquid Limit = 37


T.D. @ 6.0' at planned depthNo freewater seepage observed.

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MTC Job # 19B337-02









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GR

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DESCRIPTION


SANDY SILT, light brown, moist, stiff. Orange mottling observed throughout.

Seepage observed at 3.5 feet BPG from a sand lens.

SILT with sand and gravel, gray, moist, stiff to very stiff.


SANDY SILT, gray, very moist, very stiff. Seepage observed at 5 feet BPG within a sandy lens.


SAND WITH SILT, gray, wet, dense.


T.D. @ 9.1' at planned depthSeepage observed at 3.5', 5' & 9' BPG.

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MTC Job # 19B337-02







Location : 275' S TP-12, (See Map)


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SILT WITH SAND, brown, very moist, soft with orange mottling throughout.

SAND WITH SILT, light brown, moist, medium dense. Orange mottling observed throughout.

SANDY SILT with gravel, light brown becoming gray with depth, very moist, stiff to very stiff.

Trace seepage observed at 4 feet BPG around a root


2 foot diameter angular rock observed at 5 feet BPG.

T.D. @ 6.0' at planned depthTrace seepage observed at 4' BPG.

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MTC Job # 19B337-02







Location : 200' S TP-11, 200' E of TP-13, (See Map)


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SANDY SILT with clay and gravel, light brown becoming gray with depth, moist, stiff to very stiff. Gravel up to 3" dia with orange mottling observed in upper 1.5 feet.


Atterberg Results

Liquid Limit = 29


T.D. @ 8.2' at planned depthNo free water seepage was observed.

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MTC Job # 19B337-02









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DESCRIPTION


SANDY SILT with clay and gravel, light brown, very moist, soft. Orange mottling observed throughout.

SILTY SAND with gravel, light brown, very moist, medium dense. Orange mottling observed throughout.



SILT WITH SAND and gravel, gray, moist, hard.


T.D. @ 6.3' at planned depthSeepage observed at 4 feet BPG.

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MTC Job # 19B337-02







Location : 190'W of TP-15, 145'E of barn (See Map)


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DESCRIPTION


SANDY SILT, light brown to gray, very moist, stiff to very stiff. Orange mottling observed in upper 2 feet.

1 foot dia rock observed at 3' BPG.

Clay content observed to increase at 4 feet BPG.


SILTY SAND with gravel, brown, very moist, medium dense.


SANDY SILT with gravel, gray, moist, hard.


T.D. @ 8.0' at planned depthSeepage was observed at 6' BPG.

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Nubgaard Road SW Evaluation Materials Testing & Consulting, Inc. January 6, 2020 19B337-02

30

Appendix D. Laboratory Test Results Laboratory tests were conducted on several representative soil samples to better identify the soil

classification of the units encountered and to evaluate the material's general physical properties and

engineering characteristics. A brief description of the tests performed for this study is provided below.

The results of laboratory tests performed on specific samples are provided at the appropriate sample

depths on the individual exploration logs. However, it is important to note that these test results may not

accurately represent in situ soil conditions. All of our recommendations are based on our interpretation

of these test results and their use in guiding our engineering judgment. MTC cannot be responsible for

the interpretation of these data by others.

Soil samples for this project will be retained for a period of 3 months following completion of this report,

unless we are otherwise directed in writing.

SOIL CLASSIFICATION

Soil samples were visually examined in the field by our representative at the time they were obtained.

They were subsequently packaged and returned to our laboratory where they were reexamined and the

original description checked and verified or modified. With the help of information obtained from the

other classification tests, described below, the samples were described in general accordance with ASTM

Standard D2487. The resulting descriptions are provided at the appropriate locations on the individual

exploration logs, located in Appendix C, and are qualitative only.

GRAIN-SIZE DISTRIBUTION

Grain-size distribution analyses were conducted in general accordance with ASTM Standard D422 on

representative soil samples to determine the grain-size distribution of the on-site soil. The information

gained from these analyses allows us to provide a description and classification of the in-place materials.

In turn, this information helps us to understand engineering properties of the soil and thus how the in-

place materials will react to conditions such as heavy seepage, traffic action, loading, potential

liquefaction, and so forth. The results are presented in this Appendix.


31

Project:Project #:

Client: Sample ColorSource:

Sample #:

#1 #2 #3 #4 #5 #6

Weight of Wet Soils + Pan: 34.72 33.78 37.01

Weight of Dry Soils + Pan: 28.74 29.36 31.49

Weight of Pan: 14.73 19.44 19.56

Weight of Dry Soils: 14.01 9.92 11.93 Liquid Limit @ 25 Blows: 42.1 %

Weight of Moisture: 5.98 4.42 5.52 Plastic Limit: 19.3 %% Moisture: 42.7 % 44.6 % 46.3 % Plasticity Index, IP: 22.8 %

Number of Blows: 23 19 13

#1 #2 #3 #4 #5 #6

Weight of Wet Soils + Pan: 35.72 35.57

Weight of Dry Soils + Pan: 34.55 34.38

Weight of Pan: 28.51 28.22

Weight of Dry Soils: 6.04 6.16

Weight of Moisture: 1.17 1.19% Moisture: 19.4 % 19.3 %

Copyright Spears Eng ineering & Technical Services PS, 19 96 -9 8

13-Dec-19TP-4 @ 8.0'AVT Consulting, LLC

A. Eifrig

11-Dec-19M. Furman

ASTM D4318 - Liquid Limit, Plastic Limit and Plasticity Index of Soils

Nubgaard Long Plat Stormwate Unified Soils Classification System, ASTM D-2487Date Received:

B19-1205

Liquid Limit Determination

Sampled By:Date Tested:

Tested By:

Plastic Limit Determination

All results app ly only to actual lo cations and materials tes ted . As a mutual p ro tect ion to clients , the p ub lic and ourselves , all rep orts are sub mitted as the co nfid ential p rop erty o f clients , and autho rizat io n fo r p ub licatio n o f s tatements , co nclus ions o r extracts from o r regard ing o ur rep orts is reserved p end ing o ur writ ten ap proval.

19B337-02 CL, Sandy Lean Clay

brown

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

10 100

% M

ois

ture

Number of Blows, "N"

Liquid Limit

0.0 %

10.0 %

20.0 %

30.0 %

40.0 %

50.0 %

60.0 %

70.0 %

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%

Pla

sti

cit

y In

de

x

Liquid Limit

Plasticity Chart

MH or OH

ML or OLCL‐ML



Lab Sample: TP-4 @ 8.0’ Nubgaard SW Evaluation


FIGURE

4


32

Project:Project #:


Sample #:

#1 #2 #3 #4 #5 #6



Weight of Pan: 14.91 19.36 19.32


Weight of Moisture: 5.83 5.80 6.01 Plastic Limit: 17.8 %

% Moisture: 38.8 % 40.3 % 41.4 % Plasticity Index, IP: 21.0 %


#1 #2 #3 #4 #5 #6





Weight of Moisture: 1.04 1.12

% Moisture: 17.9 % 17.6 %

Cop yright Sp ears Eng ineering & Technical Services PS, 199 6-9 8


A. Eifrig

11-Dec-19M. Furman



B19-1206



Tested By:


All results ap p ly only to actual lo cat ions and materials tes ted . As a mutual p ro tect ion to clients , the p ub lic and ourselves , all rep orts are sub mitted as the confidential p ro perty o f clients , and autho rizat io n fo r pub licat ion o f s tatements , conclus io ns o r extracts from o r reg ard ing o ur rep orts is reserved p end ing our writ ten ap pro val.


brown

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

10 100

% M

ois

ture


Liquid Limit

0.0 %

10.0 %

20.0 %

30.0 %

40.0 %

50.0 %

60.0 %

70.0 %

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%

Pla

sti

cit

y In

de

x

Liquid Limit

Plasticity Chart

MH or OH

ML or OLCL‐ML



Lab Sample: TP-8 @ 7.9’ Nubgaard SW Evaluation


FIGURE

5


33

Project:Project #:


Sample #:

#1 #2 #3 #4 #5 #6



Weight of Pan: 14.91 14.61 19.78





#1 #2 #3 #4 #5 #6






% Moisture: 18.0 % 19.2 %

Co pyright Sp ears Eng ineering & Technical Services PS, 199 6 -98


A. Eifrig

11-Dec-19M. Furman



B19-1207



Tested By:


All results ap p ly only to actual locat ions and materials tes ted . As a mutual p ro tect ion to clients , the p ub lic and ourselves , all repo rts are sub mitted as the confidential p rop erty o f clients , and autho rizat io n fo r p ub licat io n o f s tatements , conclus io ns o r extracts fro m or regard ing o ur rep orts is reserved pend ing our writ ten app ro val.


brown

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

10 100

% M

ois

ture


Liquid Limit

0.0 %

10.0 %

20.0 %

30.0 %

40.0 %

50.0 %

60.0 %

70.0 %

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%

Pla

sti

cit

y In

de

x

Liquid Limit

Plasticity Chart

MH or OH

ML or OLCL‐ML



Lab Sample: TP-11 @ 6’ Nubgaard SW Evaluation


FIGURE

6


34

Project:Project #:


Sample #:

#1 #2 #3 #4 #5 #6



Weight of Pan: 19.62 14.87 19.52





#1 #2 #3 #4 #5 #6






% Moisture: 15.8 % 15.7 %

Co pyright Sp ears Eng ineering & Technical Services PS, 199 6 -98


A. Eifrig

11-Dec-19M. Furman



B19-1208



Tested By:


All results ap p ly only to actual locat ions and materials tes ted . As a mutual p ro tect ion to clients , the p ub lic and ourselves , all repo rts are sub mitted as the confidential p rop erty o f clients , and autho rizat io n fo r p ub licat io n o f s tatements , conclus io ns o r extracts fro m or regard ing o ur rep orts is reserved pend ing our writ ten app ro val.

19B337-02 SC-SM, Silty, Clayey Sand

brown

0%

5%

10%

15%

20%

25%

30%

35%

10 100

% M

ois

ture


Liquid Limit

0.0 %

10.0 %

20.0 %

30.0 %

40.0 %

50.0 %

60.0 %

70.0 %

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%

Pla

sti

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y In

de

x

Liquid Limit

Plasticity Chart

MH or OH

ML or OLCL‐ML



Lab Sample: TP-14 @ 8’ Nubgaard SW Evaluation


FIGURE

7


35

Project: Nubgaard Long Plat Stormwater Evaluation Client:Project #: 19B337-02

Date Received: December 11, 2019 Sampled by:Date Tested: December 12, 2019 Tested by:

Sample # Location Tare Before Wash + Tare After Wash + Tare Amount of Loss % -#200B19-1205 TP-4 @ 8.0' 720.3 1089.0 837.7 251.3 68.2%B19-1206 TP-8 @ 7.9' 739.7 1217.3 908.4 308.9 64.7%B19-1207 TP-11 @ 6.0' 760.1 1113.5 905.7 207.8 58.8%B19-1208 TP-14 @ 8.0' 723.9 1229.8 1015.2 214.6 42.4%

0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!0.0 #DIV/0!

Reviewed by:

Meghan Blodgett-Carrillo

Corporate ~ 777 Chrysler Drive • Burlington, WA 98233 • Phone (360) 755-1990 • Fax (360) 755-1980

Regional Offices: Olympia ~ 360.534.9777 Bellingham ~ 360.647.6111 Silverdale ~ 360.698.6787 Tukwila ~ 206.241.1974

Visit our website: www.mtc-inc.net

All results ap p ly o nly to actual locat ions and materials tes ted . As a mutual p ro tect ion to clients , the pub lic and ourselves , all repo rts are submit ted as the confid ent ial p rop erty o f clients , and autho rizat ion fo r p ub licatio n o f s tatements , co nclus ions o r extracts from o r reg ard ing o ur rep orts is reserved pend ing o ur writ ten app ro val.

Materials Testing & Consulting, Inc. Geotechnical Engineering • Special Inspection • Materials Testing • Environmental Consulting

Amount of Materials Finer Than #200 Sieve - ASTM C-117, ASTM D-1140 & AASHTO T-11

AVT Consulting, LLC.

M. FurmanA. Eifrig



Lab Sample: #200 Wash Nubgaard SW Evaluation


FIGURE

8

MTC Letter - Nubgaard LP SW Eval (19B337-02) LMrev MF edits

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