Earth Science + Technology

Geotechnical Engineering Services Report

Frederickson Market and Gas Station Frederickson, Washington

for Nisqually Board of Economic Development, LLC

July 15, 2016

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Geotechnical Engineering Services Report

Frederickson Market and Gas Station Frederickson, Washington

for Nisqually Board of Economic Development, LLC

July 15, 2016

 

1101 South Fawcett Avenue, Suite 200 Tacoma, Washington 98402 253.383.4940 

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Table of Contents

INTRODUCTION AND PROJECT UNDERSTANDING ................................................................................................. 1 

PURPOSE AND SCOPE OF SERVICES ..................................................................................................................... 1 

SITE CONDITIONS ..................................................................................................................................................... 2 

Project Location ................................................................................................................................................... 2 Vertical Datum ..................................................................................................................................................... 2 Geology and Groundwater Review ...................................................................................................................... 3 

Geology .......................................................................................................................................................... 3 Groundwater .................................................................................................................................................. 3 

Surface Conditions............................................................................................................................................... 3 Subsurface Conditions ........................................................................................................................................ 4 

Subsurface Explorations ............................................................................................................................... 4 Laboratory Test Results ................................................................................................................................ 4 Soil Conditions .............................................................................................................................................. 5 Groundwater Conditions ............................................................................................................................... 5 

EARTHQUAKE ENGINEERING .................................................................................................................................. 6 

Seismic Setting .................................................................................................................................................... 6 Seismic Design Factors ....................................................................................................................................... 6 Peak Ground Acceleration ................................................................................................................................... 6 Liquefaction Potential .......................................................................................................................................... 6 Lateral Spreading Potential ................................................................................................................................. 7 Surface Rupture Potential ................................................................................................................................... 7 

CONCLUSIONS AND RECOMMENDATIONS ............................................................................................................ 7 

Shallow Foundation Support ............................................................................................................................... 7 Minimum Footing Size .................................................................................................................................. 7 Allowable Soil Bearing Pressure and Bearing Surface Preparation ........................................................... 7 Lateral Load Resistance ............................................................................................................................... 7 Foundation Settlement ................................................................................................................................. 8 

Foundation Footing Drains .................................................................................................................................. 8 Slab-on-Grade Floors ........................................................................................................................................... 8 Buoyancy Considerations .................................................................................................................................... 9 Pavement Recommendations ............................................................................................................................. 9 

General .......................................................................................................................................................... 9 Light Duty Pavements - Asphalt Concrete (Automobiles Only) ................................................................... 9 

Earthwork ............................................................................................................................................................. 9 Stripping and Clearing .................................................................................................................................. 9 Excavation Considerations ........................................................................................................................ 10 Temporary Excavation Support and Dewatering ...................................................................................... 10 UST Excavation ........................................................................................................................................... 10 Subgrade Preparation ................................................................................................................................ 11 Erosion and Sedimentation Control .......................................................................................................... 11 

Structural Fill Materials .................................................................................................................................... 12 Minimum Gradation Requirements .......................................................................................................... 12 

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On-site Soil .................................................................................................................................................. 12 Imported Structural Fill .............................................................................................................................. 12 Pipe and UST Bedding ............................................................................................................................... 12 Capillary Break ........................................................................................................................................... 13 Trench and UST Backfill ............................................................................................................................. 13 Recycled Asphalt, Concrete, and Glass .................................................................................................... 13 

LIMITATIONS .......................................................................................................................................................... 13 

REFERENCES ........................................................................................................................................................ 13

LIST OF FIGURES

Figure 1. Vicinity Map Figure 2. Site Plan Figure 3. Key to Exploration Logs Figure 4. Log of Monitoring Well Figure 5. Sieve Analysis Results

APPENDIX

Appendix A. Report Limitations and Guidelines for Use

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INTRODUCTION AND PROJECT UNDERSTANDING

This report presents the results of our subsurface investigation, laboratory testing, and geotechnical recommendations for the proposed Market and Gas Station to be located at 17808 Canyon Road East, in Frederickson, Washington. The approximate location of the subject property is shown on the Vicinity Map, Figure 1. We have performed our services in general accordance with the agreement between the Nisqually Board of Economic Development and GeoEngineers, which was authorized on June 23, 2016.

Our project understanding is based on conversations with representatives of KMB Architects (project architect) and SCJ Alliance (project civil engineer), and review of the Civil Plan Set (5 sheets) prepared by SCJ Alliance dated July 13, 2016. The subject site is located on Pierce County Parcel No. 6026700040 comprising approximately 0.85 acres. We understand the site will be developed as a market and gas station. The market will be an approximately 5,300-square-foot single story building; finish floor will be at Elevation 390.80 feet (NAVD88). The gas station facilities will include six fueling islands covered by a free-standing canopy supported by columns and spread footings. We understand two, 10-foot diameter underground storage tanks (USTs) will be installed on site for fuel storage. The USTs require minimum bedding of 1 foot. Cover depth will be between 3 and 7 feet, so a total excavation depth between 14 and 18 feet below final grade is anticipated. Outside of the building area, the site will be surfaced with asphalt concrete pavement (ACP). The approximate locations of proposed improvements are shown on the Site Plan, Figure 2.

GeoEngineers completed a “Phase I Environmental Site Assessment” (Phase I ESA) dated March 24, 2016, for the property. We reviewed information collected as part our Phase I ESA near the project site, including a September 26, 2005 geotechnical report prepared by Zipper Zeman Associates and a May 21, 2012 supplemental soil and groundwater investigation prepared by the Riley Group. We reviewed logs of subsurface explorations provided in the referenced reports and performed additional explorations described below to develop our understanding of the existing site conditions.

This area of Frederickson is known to have seasonally shallow groundwater conditions that could impact the design of the USTs. Additionally, fluctuations in groundwater levels have been documented to change by as much as 25 feet in a single water year (October to September) in the Frederickson area.

PURPOSE AND SCOPE OF SERVICES

The purpose of our services is to evaluate soil and groundwater conditions as a basis for developing geotechnical design and construction recommendations. Our specific scope of services for this study includes the following:

1. Reviewing information provided by the design team, information contained within our in-house files, and readily available geologic maps.

2. Coordinating clearance of existing utilities. We contacted the “One-Call Underground Utility Locate Service” prior to beginning explorations in accordance with Washington state law.

3. Retaining a private utility locating service to check for underground utilities not identified by the One-Call service.

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4. Exploring subsurface conditions at the site by advancing one boring to an approximate depth of 41½ feet below existing grades. The boring was completed as a monitoring well with a flush monument.

5. Performing laboratory tests on selected soil samples obtained from the test pits. The laboratory testing program consisted of two sieve analysis tests.

6. Providing a discussion of the subsurface conditions encountered based on the results of our explorations, laboratory test results, and review.

7. Discussing seismic considerations, including seismic design criteria consistent with the 2015 International Building Code (IBC) and our opinion of the liquefaction potential of site soils.

8. Providing recommendations for design and construction of shallow spread footings for the market building and fuel canopy. We discuss allowable bearing capacity and increase for seismic and wind loads, estimates of settlement for assumed loading conditions, lateral resistance values for foundations including passive pressures and coefficient of friction between the foundation and bearing surfaces, and foundation bearing surface preparation.

9. Providing recommendations for building slab subgrade preparation and modulus values for slab design.

10. Providing recommendations for conventional ACP design. We provide recommended thickness for surface wearing course, base course, subbase (as needed) for the soil conditions observed and assumed traffic conditions.

11. Providing recommendations for site preparation and earthwork. We discuss clearing and stripping, suitability of on-site soils for use as structural fill including constraints for wet weather construction, specifications for imported soil for use as structural fill, and fill placement and compaction requirements.

12. Providing recommendations for temporary cut slopes and a discussion of the potential for buoyant conditions, which should be considered in design of the USTs.

SITE CONDITIONS

Project Location

The project site is located at 17808 Canyon Road East approximately 600 feet south of the intersection with 176th Street East. The approximate location of the site is shown on Figure 1. The site is located in Township 19N, Range 3E, Section 36 (Willamette Meridian). Access to the site is gained through the entrance on Canyon Road East.

Vertical Datum

In this report we reference vertical elevation to the North American Vertical Datum of 1988 (NAVD88). Elevations provided from other sources may use another vertical datum for referencing elevations. When possible the reference datum is identified and converted to an approximate elevation relative to NAVD88. At the project location the National Geodetic Vertical Datum of 1929 (NGVD29) is approximately 3.5 feet lower than NAVD88.

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Geology and Groundwater Review

We reviewed the Aerial Geology of Central Pierce County, Washington (Walters and Kimmel 1968) to gain an understanding of the regional soil conditions. The Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed and Vicinity, Pierce County, Washington (Savoca, et al. 2010) was reviewed for regional groundwater conditions. We also reviewed information collected as part our Phase I ESA at the project site, including a September 26, 2005 geotechnical report prepared by Zipper Zeeman Associates and a May 21, 2012 supplemental soil and groundwater investigation prepared by the Riley Group.

Geology

The soils mapped in the project vicinity (Walters and Kimmel 1968) are predominantly Steilacoom gravel (Qs), which is a recessional outwash deposit and typically consists of gravel, cobbles and sand with some silt. Subsurface explorations provided in the reviewed reports indicate soils consisting of medium dense to very dense sand and gravel typical for the Frederickson area.

Groundwater

The site is located near the confluence of two “dry” channels; geographic/geologic features referred to as the Kirby Channel and the Clover-Chambers Channel, which are a remnant of the Vashon Glaciation. These channels exert influence on the flow of surface water and groundwater. The groundwater levels in this area vary seasonally with precipitation and also in response to prolonged wetter or drier than average weather cycles that can occur over a period of several years.

Based on our research and experience at nearby project sites, we estimate a typical seasonal high groundwater is near Elevation 371 feet in the vicinity of the project site. Annual (water-year) fluctuations between high and low are typically on the order of 5 to 10 feet. During extreme years the annual groundwater fluctuation can be on the order of 15 to 25 feet and can result in groundwater levels well above the estimated typical seasonal high.

Surface Conditions

We evaluated surface conditions during our site visit on June 13, 2016 to the mark the exploration location and also while on site to perform our exploration on June 30, 2016. The approximately triangular-shaped project site is located southwest of the intersection of 176th Street and Canyon Road East in an area that has been partially developed. Canyon Road East bounds the site to the east; private roads bound the site to the north and southwest. The approximately 0.85-acre site measures about 250 feet on the east side and about 260 feet on the north side.

Existing development in the site vicinity includes paved roads and utility stubs to the individual parcels. Based on our review of the Existing Conditions map prepared by SCJ Alliance, site grades are approximately level. The ground surface slopes gently down to the west at about 2 percent or less from about Elevation 393 feet near Canyon Road East to about Elevation 388 feet at the northwest corner of the site.

The existing surface consists of gravel, sand and cobbles, which could be native soil or reworked native soil. Vegetation is sparse consisting of grass clumps and weeds.

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Subsurface Conditions

Subsurface conditions at the site were explored by advancing one boring on June 30, 2016. The boring was completed as a monitoring well. The approximate location of monitoring well MW-1 is shown on Figure 2.

Our review of the explorations provided in the referenced reports included 11 test pits and six monitoring wells. The test pits were completed in September 2005 and the monitoring wells were completed in April 2012. We understand the project site has been recently regraded; however, the lateral extent and depth of earthwork is unknown. Accordingly, the information provided on the reviewed logs may not represent current shallow subsurface conditions.

Four of the test pits were performed within the project site and extended to depths between 10 and 13 feet. The interpreted soil conditions presented on the logs consist of about 4 feet of loose silty sand overlying medium dense to very dense gravel, sand, and sand with silt, extending to the depth explored.

The six monitoring wells were located about 100 to 180 feet northwest of the project site. The monitoring wells extended to depths of about 25 to 30 feet. Air knife is indicated as the drilling method, accordingly soil densities are not provided. The interpreted soil conditions presented on the logs consists of gravel, gravel with silt, silty gravel, sand, and silty sand. One of the monitoring wells logs indicates peat and silt in the upper 3 feet, and clay between depths of about 15 and 30 feet. Depth to groundwater is noted on the logs at depths between about 18 and 23 feet in April 2012.

Subsurface Explorations

The boring was advanced using truck mounted drilling equipment and operator subcontracted to GeoEngineers. The boring was advanced to a depth of about 41 ½ feet below the existing ground surface (bgs) to approximately Elevation 349.5 feet. The boring was completed as a monitoring well with a screen interval from about Elevation 351 feet to 371 feet.

Our field representative obtained samples, classified the soils, and maintained a detailed log of the boring. Soil samples were obtained from the boring using Standard Penetration Test (SPT) methods. The SPT is a 1.4-inch inside diameter sampler driven into the soil using a 140-pound hammer free falling a distance of 30 inches. The number of blows required to drive the sampler the last 12 inches or other indicated distance is recorded on the log as the blow count. Sample attempts were made at approximately 5-foot depth intervals. The samples were retained in sealed plastic bags. The soils were classified visually in general accordance with the system described in Figure 3, which includes a key to the exploration log. A summary log of the monitoring well MW-1 is included as Figure 4.

The location of the monitoring well was determined by pacing from existing site features such as edge of pavement and fire hydrants shown on the topographic survey provided by SCJ Alliance (Plan Sheet EX-01), dated July 13, 2016. The surface elevation presented on the log was estimated by interpolating between topographic contour lines provided on the plan sheet. The location and elevation of the exploration should be considered approximate.

Laboratory Test Results

Soil samples were obtained during drilling and transported to GeoEngineers laboratory. Representative soil samples were selected for laboratory tests to evaluate the pertinent geotechnical engineering characteristics of the site soils and to confirm our field classification.

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Sieve analyses were performed on selected samples in general accordance with ASTM International (ASTM) Test Method D 6913. This test method covers the quantitative determination of the distribution of particle sizes in soils. Typically, the distribution of particle sizes larger than 75 micrometers (m) is determined by sieving. The results of the tests were used to verify field soil classifications. Figure 5 presents the results of the sieve analyses.

Soil Conditions

At the exploration location we encountered materials we interpret as natural glacial outwash (Steilacoom gravel) deposits. The outwash was observed to the depth explored and consisted of sand with gravel, and gravel with sand. Cobbles were present throughout the deposit at varying frequency. The soils were observed in a dense to very dense condition.

Groundwater Conditions

Groundwater was encountered at the time of drilling at a depth of about 20 feet bgs. Subsequent measurements were collected on July 5 and July 12, 2016. A summary of the collected groundwater elevation data is presented in Table 1, below.

TABLE 1. MEASURED GROUNDWATER ELEVATIONS

Date Top of Casing Elevation1,2

(feet) Depth to Water

(feet) Groundwater Elevation1

(feet)

July 5, 2016 391 18.9 372.1

July 12, 2016 391 19.5 371.5

Notes: 1 All elevations presented relative to NAVD88 2 Top of Casing elevation estimated from topographic contours presented on site plan prepared by SCJ Alliance, July 13, 2016.

Based on our experience in Frederickson, this water year produced exceptionally high seasonal groundwater peak conditions. We reviewed data for the current water year (October 2015 to September 2016) which we obtained from nearby wells located southwest of the project site. This data indicates that the seasonal peak occurred in March 2016. Between March 2016 and July 5, 2016 the groundwater level at the nearby wells had dropped on the order of 12 feet. Accordingly, we infer that the groundwater level at the project site in March 2016 could have been at approximately Elevation 384 feet when the extreme seasonal peak level occurred.

As discussed above, we estimate a typical seasonal peak groundwater level is near Elevation 371 feet at the subject site. Above normal rainfall or consecutive years of above normal rainfall can lead to a seasonal high groundwater level that is well above a typical season as indicated by this year’s data. For the purposes of design, we recommend using a groundwater level at about Elevation 384 feet.

We anticipate groundwater levels will fluctuate throughout the year based on seasonal precipitation, generally being lowest in the fall (September through October) and highest in the spring (February through May). Perched groundwater can occur at elevations above the regional groundwater levels where less permeable materials underlie more permeable materials.

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EARTHQUAKE ENGINEERING

Seismic Setting

The site is located in western Washington, which is seismically active. Seismicity in this region is attributed primarily to the interaction between the Pacific, Juan de Fuca and North American tectonic plates. As the Juan de Fuca plate is subducted beneath the North American plate at the Cascadia Subduction Zone (CSZ) intercrustal (between plates) and intracrustal (within a plate) earthquakes are produced.

Ongoing research by geologists regarding large magnitude CSZ-related intercrustal earthquake activity along the Washington and Oregon coasts suggest as many as five large magnitude earthquakes (magnitude 8 to 9) have occurred along the CSZ in the last 1,500 years at intervals between about 250 and 450 years, the most recent of which occurred about 300 years ago.

Hundreds of smaller intracrustal earthquakes have been recorded in western Washington. Four of the most recent earthquakes were: (1) in 1946, a magnitude 7.2 earthquake occurred in the Vancouver Island, British Columbia area; (2) in 1949, a magnitude 7.1 earthquake occurred in the Olympia area; (3) in 1965, a magnitude 6.5 earthquake occurred between Seattle and Tacoma; and (4) on February 28, 2001, a magnitude 6.8 occurred in Nisqually near Olympia.

Seismic Design Factors

Based on subsurface conditions encountered in our exploration and our understanding of the geologic conditions in the project vicinity, the site may be characterized as Class C in accordance with the 2015 IBC Design Manual. Seismic design parameters are provided in Table 2, below.

TABLE 2. 2015 IBC SEISMIC DESIGN VALUES

Site Coefficient Site Factor MCE1 Spectral Response Design Spectral Response

Ss = 1.249g Fa = 1.000 SMS = 1.249g SDS = 0.832g

S1 = 0.483g Fv = 1.317 SM1 = 0.636g SD1 = 0.424g

Note: 1 MCE = Maximum Considered Earthquake

Peak Ground Acceleration

The peak ground acceleration (PGA) is used in seismic analyses such as liquefaction, lateral spreading, and seismic slope stability as well as assessing seismic surcharge loads for retaining walls. Based on our understanding of site conditions, we recommend using a PGA of 0.510g as determined in accordance with Section 11.8.3 of American Society of Civil Engineers (ASCE) Standard 7-10.

Liquefaction Potential

Liquefaction refers to a condition where vibration or shaking of the ground, usually from earthquake forces, results in development of excess pore pressures in loose, saturated soils and subsequent loss of strength in the deposit of soil so affected. In general, soils that are susceptible to liquefaction include loose to medium dense sands to silty sands that are below the water table. The Liquefaction Susceptibility Map of Thurston County (Palmer, et al. 2004) indicates the site soils have a “very low to low” liquefaction potential. The conditions observed in our explorations include dense to very dense gravel and sand. Accordingly, based on observations and experience, it is our opinion that the potential for liquefaction at this site is low.

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Lateral Spreading Potential

Lateral spreading related to seismic activity typically involves lateral displacement of large, surficial blocks of non-liquefied soil when a layer of underlying soil loses strength during seismic shaking. Lateral spreading usually develops in areas where sloping ground or large grade changes (including retaining walls) are present. Based on our understanding of the soil and groundwater conditions and current site topography, it is our opinion that the risk of lateral spreading is low.

Surface Rupture Potential

According to the Washington Department of Geology and Earth Sciences map Faults and Earthquakes in Washington State (Czajkowski and Bowman 2014), no faults are located within 3 miles of the project site. Based on this, it is our opinion that the risk for seismic surface rupture at the site is low.

CONCLUSIONS AND RECOMMENDATIONS

Based on our review and observations during the field exploration program it is our opinion that the site soils are suitable for shallow foundation support of the proposed structures. Our exploration was performed at a discrete location; composition, consistency, and density of soil at other locations could vary from those described in this report.

Shallow Foundation Support

Minimum Footing Size

Perimeter wall footings should be at least 16 inches wide and interior isolated spread footings should be at least 24 inches wide. We recommend that exterior footings for structures be founded at least 18 inches below lowest adjacent grade (note: the design frost depth for the Puget Sound area is 12 inches). Interior footings should be founded at least 12 inches below top of slab or adjacent finished grade. Design of the building foundations should comply with the 2015 IBC.

Allowable Soil Bearing Pressure and Bearing Surface Preparation

We anticipate that dense to very dense gravel or sand will underlie the proposed shallow foundations. If oversized particles or deleterious materials are encountered, they should be removed. For design, it is our opinion an allowable soil bearing pressure of 3,500 pounds per square foot (psf) may be used for footings founded as recommended. The allowable bearing pressure may be increased by one-third to account for short-term live loads such as induced by wind or seismic forces.

We recommend that a representative of GeoEngineers observe foundation excavations before placing structural fill or concrete in order to confirm that bearing surfaces have been adequately prepared. Unsuitable bearing materials must be recompacted or removed and replaced with compacted structural fill as recommended by the geotechnical engineer.

Lateral Load Resistance

Lateral loads can be resisted by a combination of friction between the footing and the supporting soil, and by the passive lateral resistance of the soil surrounding the embedded portions of the footings. A coefficient of friction between concrete and structural fill or natural soil of 0.4 and a passive lateral resistance corresponding to an equivalent fluid density of 350 pounds per cubic foot (pcf) may be used for design. The

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friction coefficient and passive lateral resistance are allowable values and include a factor of safety of about 1.5.

The passive earth pressure and friction components may be combined provided that the passive component does not exceed two-thirds of the total resistance. The passive earth pressure value is based on the assumptions that the adjacent grade is level and that groundwater remains below the base of the footing throughout the year. The top foot of soil must be neglected when calculating passive lateral earth pressure unless the area adjacent to the foundation is covered with ACP or a slab-on-grade.

If soil adjacent to footings is disturbed during construction, the disturbed soil must be placed and recompacted as structural fill; otherwise the lateral passive resistance value will be reduced.

Foundation Settlement

We anticipate the structural loads for the proposed market building and canopy structure will not exceed about 50 kips for isolated spread footings or 5 kips per foot for continuous footings. Based on the anticipated loading conditions, we estimate that the post-construction settlement of footings founded on undisturbed natural soil or compacted structural fill will be less than 1 inch. Differential settlement between comparably loaded isolated spread footings or along a 25-foot section of continuous wall footing should be less than ½ inch. We expect most of the footing settlements will occur as loads are applied.

Immediately prior to placing concrete, any debris or loose soil in the footing excavation must be removed. Debris or loose soils not removed from the footing excavations could result in increased settlement.

Foundation Footing Drains

Based on our observations and laboratory testing, the existing natural soils consist of relatively free-draining material. As such, it is our opinion that foundation footing drains are not needed as a measure to maintain the allowable bearing pressure provided above.

Slab-on-Grade Floors

In our opinion, a modulus of subgrade reaction of 300 pounds per cubic inch (pci) can be used for designing the building floor slab provided that the subgrade consists of undisturbed natural soil or compacted structural fill and has been prepared in accordance with the “Site Development and Earthwork” section of this report. We recommend that slab-on-grade floors be founded on a minimum of 1 foot of compacted structural fill subbase placed below the capillary break material. The structural fill subbase may be omitted provided a proof roll indicates the subgrade is in a firm and unyielding condition.

In areas where a proof roll indicates existing soils are loose, wet, or disturbed, we recommend overexcavating the slab area by a minimum of 1 foot, then compacting the exposed soil to at least 95 percent of the maximum dry density (MDD) per ASTM International (ASTM) D 1557 in accordance with the “Earthwork” section of this report, prior to placing structural fill to establish subgrades.

We recommend that slab-on-grade floors be underlain by a 4-inch thick capillary break layer. If water vapor migration through the slabs is a concern, an appropriate vapor barrier, such as 10-mil plastic sheeting, should be used to reduce the upward migration of moisture through the slab. This will be desirable where the slabs will be surfaced with tile or will be carpeted. It may also be prudent to apply a sealer to the slab to further retard the migration of moisture through the floor.

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Buoyancy Considerations

We understand two 10-foot diameter USTs will be installed on site for fuel storage. The USTs will require an excavation depth between 14 and 18 feet below final grade. Based on our review of the grading plan, final grade near the UST location will be approximately Elevation 391 feet. Accordingly, the UST excavation will extend to between approximately Elevation 373 to 377 feet. Because this is below the estimated extreme seasonal peak groundwater level, we recommend that buoyancy of the USTs be considered during design.

Pavement Recommendations

General

Below we provide geotechnical design recommendations for light-duty ACP. The pavement section described below must be supported on a subgrade that comprises existing soil in a firm and unyielding condition. The existing soil may be left in place as subbase provided that a proof-roll confirms the material is in a firm and unyielding condition. Loose or pumping areas identified during a proof-roll must be overexcavated a minimum of 12 inches and replaced with compacted structural fill.

Long-term performance of all pavements is influenced significantly by drainage conditions beneath the pavement sections. It is important that surface water be diverted away from and prevented from accumulating adjacent to or beneath pavement sections.

Light Duty Pavements - Asphalt Concrete (Automobiles Only)

■ Surfacing: 2 inches of hot mix asphalt (HMA), Class 1/2 inch, PG 58-22.

■ Base: 4 inches of crushed surfacing base course.

■ Subbase: Proof compacted existing soil or 12 inches of select granular fill (as needed).

■ Subgrade: Recompacted existing soil.

The recommended pavement sections may not be adequate for heavy construction traffic conditions such as loads imposed by concrete transit mixers, dump trucks or crane loads. Additional pavement thickness may be necessary to prevent pavement damage during construction and/or repair of damaged pavements should be anticipated.

Asphalt treated base (ATB) may be used to replace crushed rock base course to protect the working surface if construction is planned during the wet season. We recommend 2½ inches of ATB be substituted for the 4 inches of crushed rock base course.

Earthwork

Stripping and Clearing

Because of the limited vegetation currently present at the site, we anticipate stripping depths will be on the order of 1 or 2 inches. After completion of clearing activities, the site can be rough graded. Areas of loose, soft, or pumping soils observed during striping, clearing and rough grading should be identified. Repair options will be dependent on the end use, i.e., pavement or slab subgrades, or foundation bearing.

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Excavation Considerations

We anticipate that the soils encountered in the explorations can be excavated with conventional excavation equipment, such as large excavators and/or dozers. Cobbles were observed in our exploration and also noted on the logs of explorations we reviewed. Although not observed in our exploration, boulders could be present in the natural soils; accordingly, the contractor should be prepared to remove boulders if encountered.

Temporary Excavation Support and Dewatering

Excavations deeper than 4 feet should be shored or laid back at a stable slope if workers are required to enter. Shoring and temporary slope inclinations must conform to the provisions of Title 296 Washington Administrative Code (WAC), Part N, “Excavation, Trenching and Shoring.” Regardless of the soil type encountered in the excavation, shoring, trench boxes or sloped sidewalls will be required under Washington Industrial Safety and Health Act (WISHA). The contract documents should specify that the contractor is responsible for selecting excavation and dewatering methods, monitoring the excavations for safety and providing shoring, as required, to protect personnel and structures.

In general, temporary cut slopes should be inclined no steeper than about 1½H:1V (horizontal:vertical) in the fill and medium dense natural soils, and no steeper than 1H:1V in the dense to very dense natural glacial soils. These guidelines assume that all surface loads are kept at a minimum distance of at least one-half the depth of the cut away from the top of the slope and that significant seepage is not present on the slope face. Flatter cut slopes will be necessary where significant seepage occurs. Some sloughing and raveling of the cut slopes should be expected. Temporary covering with heavy plastic sheeting should be used to protect these slopes during periods of wet weather.

Based on our explorations and understanding of proposed grading plans, we do not expect groundwater will have a significant impact on general site grading earthwork. However, some perched groundwater could be encountered depending on the time of year of construction. We anticipate that groundwater handling needs will be lower during the late summer and early fall months. We anticipate that shallow perched groundwater can typically be handled adequately with sumps, pumps, and/or diversion ditches, as necessary. Ultimately, we recommend that the contractor performing the work be made responsible for controlling and collecting groundwater encountered.

UST Excavation

In addition to the earthwork recommendations provided above, the following recommendations are provided for the UST excavation. Because of the depth of the excavation and the tendency for the sand and gravel soils to ravel, we recommend excavation slopes be inclined no steeper than about 1½H:1V. Surcharge loads must be excluded from the area at the top of the excavation slope a horizontal distance equal to the height of the slope. Surface water flow must be directed away from top of slopes.

If site constraints are not conducive to sloped excavation techniques, we recommend temporary shoring be considered.

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Subgrade Preparation

General

Prior to placing structural fill or structural concrete elements, all subgrade areas should be proofrolled or probed by hand to identify any soft, loose, or pumping soils. Proofrolling can be completed using a piece of heavy tire-mounted equipment such as a loaded dump truck. If loose or pumping soils are observed, the unsuitable subgrade soils must be overexcavated and replaced with compacted structural fill. After completing the proofrolling, the subgrade areas should be compacted to a firm and unyielding condition.

Some of the soils encountered in our explorations contain enough fines (material passing the U.S. Standard No. 200 sieve) to be susceptible to disturbance from construction traffic during extended periods of wet weather. The wet weather season in western Washington generally begins in October and continues through May; however, periods of wet weather can occur during any month of the year.

A representative of GeoEngineers should observe the subgrade preparation operations to help determine the depth of removal of loose or pumping soils (if encountered), and to evaluate if subgrade disturbance or progressive deterioration is occurring. Subgrade disturbance or deterioration could occur if the subgrade becomes wet. If the subgrade deteriorates due to saturation and disturbance from wheeled equipment, the soil will need to be moisture conditioned (dried out) and recompacted, or replaced with imported structural fill prior to placement of base course materials and building slab areas.

Erosion and Sedimentation Control

In our opinion, the erosion potential of the on-site soils is moderate. Construction activities including stripping and grading will expose soils to the erosional effects of wind and water. The amount and potential impacts of erosion are partly related to the time of year that construction occurs. Wet weather construction will increase erosion and sedimentation potential.

Potential sources or causes of erosion and sedimentation depend upon construction methods used, slope length and gradient, amount of soil exposed and/or disturbed, soil type, construction sequencing and weather. Implementing an erosion and sedimentation control plan will reduce the project impact on erosion-prone areas. The erosion and sedimentation control measures should be designed, installed and maintained in accordance with Pierce County requirements. The plan should incorporate basic planning principles including:

■ Scheduling grading and construction to reduce soil exposure.

■ Retaining existing asphalt whenever feasible.

■ Revegetating or mulching denuded areas.

■ Directing runoff away from denuded areas.

■ Reducing the length and steepness of slopes with exposed soils.

■ Decreasing runoff velocities.

■ Preparing drainage paths and outlets to handle concentrated or increased runoff.

■ Confining sediment to the project site.

■ Inspecting and maintaining control measures frequently.

July 15, 2016| Page 12 File No. 0277-030-03

In addition, we recommend that all disturbed areas be finish graded and paved or seeded as soon as practicable to reduce the risk of erosion. Some sloughing and raveling of slopes with exposed or disturbed soil should be expected. Temporary erosion protection should be used and maintained in areas with exposed or disturbed soils to help reduce erosion and reduce transport of sediment to adjacent areas and receiving waters. Erosion and sedimentation control measures may be implemented by using a combination of interceptor swales, straw bale barriers, silt fences and straw mulch for temporary erosion protection of exposed soils.

Permanent erosion protection should be provided by paving or landscape planting. Until the permanent erosion protection is established and the site is stabilized, site monitoring should be performed by qualified personnel to evaluate the effectiveness of the erosion control measures and to repair and/or modify them as appropriate. Provisions for modifications to the erosion control system based on monitoring observations should be included in the erosion and sedimentation control plan.

Structural Fill Materials

Minimum Gradation Requirements

All soil material placed in building and pavement areas or used to backfill the UST excavation or utility trenches is classified as structural fill for the purpose of this report. Structural fill should be free of debris, organic material and rock fragments larger than 6 inches. The suitability of material for use as structural fill will depend on the gradation and moisture content of the soil. As the amount of fines (material passing the U.S. No. 200 sieve) increases, soil becomes increasingly more sensitive to small changes in moisture content and adequate compaction becomes more difficult or impossible to achieve.

On-site Soil

Based on our observations and review, it is our opinion that most of the existing soils at the locations explored can be considered suitable for reuse as structural fill. On-site materials used as structural fill should be free of roots, other deleterious materials, and particles larger than 6 inches in diameter. If encountered, the oversized material will need to be removed prior to reuse as structural fill.

Imported Structural Fill

We recommend that structural fill placed during dry weather consist of imported “Gravel Borrow” such as described by the Washington State Department of Transportation (WSDOT) Section 9-03.14(1) Standard Specifications. We recommend that structural fill placed during wet weather, or in areas where groundwater seepage is encountered, consist of material of approximately the same quality as “Gravel Backfill for Walls,” as described in Section 9-03.12(2) of the WSDOT Standard Specifications.

Pipe and UST Bedding

We recommend trench backfill placed as bedding for utility pipes and the USTs consist of material of approximately the same quality as “Gravel Backfill for Pipe Zone Bedding,” as described in Section 9-03.12(3) of the WSDOT Standard Specifications. The pipe or UST manufacturer and local jurisdictions may have additional requirements that must be followed.

July 15, 2016| Page 13 File No. 0277-030-03

Capillary Break

Capillary break material should consist of a well-graded sand and gravel or crushed rock with a maximum particle size of ¾ inch and less than 5 percent fines, such as “AASHTO Grading No 7” as described in Section 9-03.1(4)C of the WSDOT Standard Specifications. We recommend GeoEngineers review contractor submittals for alternate capillary break materials.

Trench and UST Backfill

During dry weather conditions, we recommend that backfill placed in utility trenches or in the UST excavation meet the requirements of “Gravel Borrow” as described in Section 9-03.14(1) of the WSDOT Standard Specifications, unless suitable on-site soils can be used. We recommend that backfill placed during wet weather conditions consist of material of approximately the same quality as “Gravel Backfill for Walls,” as described in Section 9-03.12(2) of the WSDOT Standard Specifications.

Recycled Asphalt, Concrete, and Glass

Crushed ACP and Portland cement concrete (PCC) may be considered for use as structural fill provided it meets the gradation criteria described above for its intended use and that the material can be compacted to a uniformly firm and unyielding condition. Crushed asphalt has the potential to creep under large and sustained loads. Accordingly, we recommend that crushed/recycled asphalt not be used under foundation elements. In addition, recycled concrete and asphalt should not be used where free-draining materials are needed. Recycled glass may be considered for use as capillary break material or pipe bedding; local jurisdiction and manufacturer’s requirements should be reviewed. In general, we recommend “Recycled Materials” conform to Section 9-03.21 of the WSDOT Standard Specifications. We further recommend that recycled material submittals be reviewed by the project civil or geotechnical engineer.

LIMITATIONS

We have prepared this report for the exclusive use of the Nisqually Board of Economic Development and their authorized agents for the Frederickson Market and Gas Station located at 17808 Canyon Road East, Frederickson, Washington.

Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. No warranty or other conditions, express or implied, should be understood.

Please refer to Appendix A “Report Limitations and Guidelines for Use” for additional information pertaining to use of this report.

REFERENCES

Czajkowski, Jessica L., and Bowman, Jeffery D., “Faults and Earthquakes in Washington State,” 2014. Washington Department of Geology and Earth Sciences, Open File Report 2014-05. (http://wa-dnr.s3.amazonaws.com/publications/ger_ofr2014-05_fault_earthquake_map.pdf).

International Code Council. 2015 “2015 International Building Code.”

July 15, 2016| Page 14 File No. 0277-030-03

Jones, M., Jones, J., and Olsen, T., 2000. Groundwater Flooding in Glacial Terrain of Southwest Puget Sound, Washington, USGS Fact Sheet 111-00.

National Oceanic and Atmospheric Administration (NOAA) Orthometric Height Conversion between NAVD88 and NGVD29 (http://www.ngs.noaa.gov/cgi-bin/VERTCON/vert_con.prl).

Palmer, Stephen P., Magsino, Sammantha l., Bilderback, Eric L., Poelstra, James L., Folger, Derek S., and Niggemann, Rebecca A. “Liquefaction Susceptibility and Site Class Maps of Washington State, By County, Map 34A—Thurston County Liquefaction Susceptibility, Sheet 67 of 78.” 2004. Washington Division of Geology and Earth Resources, Open File Report, 2004-20.

The Riley Group, Inc., May 21, 2012. “Supplemental Soil and Groundwater Investigation, Frederickson Property, 17721 and 17725 52nd Avenue Court East, Frederickson, Washington.”

Savoca, M.E., Welch, W.B., Johnson, K.H., Lane, R.C., Clothier, B.G., and Fasser, E.T., 2010, “Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed and Vicinity, Pierce County, Washington.” U.S. Geological Survey Scientific Investigations Report 2010-5055, 46 p.

U.S. Seismic Design Maps, United States Geological Survey - Earthquake Hazards Program, (http://earthquake.usgs.gov/hazards/designmaps/grdmotion.php).

Walters, K.L. and Kimmel, G.E., 1968, Areal Geology of Central Pierce County, Washington, in Ground-water Occurrence and Stratigraphy of Unconsolidated Deposits, Central Pierce County, Washington, Plate 1, (http://www.ecy.wa.gov/programs/eap/wsb/wsb_Geology-and-Groundwater.html#p22).

Washington State Department of Transportation, 2012, “Standard Specifications for Road, Bridge and Municipal Construction.”

Zipper Zeeman Associates, Inc., September 26, 2005. “Draft, Subsurface Exploration and Geotechnical Engineering Evaluation, Proposed Retail Development, 176th Street East and Canyon Road, Frederickson, Pierce County, Washington.”

µ

SITE

Vicinity Map

Figure 1

Frederickson Market and Gas Station Frederickson, Washington

2,000 2,0000Feet

Data Source: Mapbox Open Street Map, 2015

Notes:1. The locations of all features shown are approximate.2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.

Projection: NAD 1983 UTM Zone 10N

P:\0\

0277

030\

GIS\M

XDs\

0277

0300

3_F0

1_VM

.mxd

Date

Expo

rted:

07/1

1/16

by c

chelf

MW-1

Proposed Store

Cany

on R

oad

East

Proposed Fuel Canopy

Proposed USTs

Figure 2

Frederickson Market and Gas StationFrederickson, Washington

Site Plan

W E

N

S

Legend

Notes:1. The locations of all features shown are approximate.2. This drawing is for information purposes. It is intended to

assist in showing features discussed in an attacheddocument. GeoEngineers, Inc. cannot guarantee the accuracyand content of electronic files. The master file is stored byGeoEngineers, Inc. and will serve as the official record of thiscommunication

Data Source:Base drawing provided by SCJ Alliance dated 07/11/16.

Vertical Datum: MLLW (NAVD 88).

Projection: NAD83 Washington State Planes, South Zone, US Foot.

Monitoring well and approximate location

Proposed contour

Existing contour

P:\0

\027

7030

\CAD

\03\

Geo

tech

\027

7030

03_F

02_S

ite P

lan.

dwg

TAB:

F2 D

ate

Expo

rted:

07/

13/1

6 - 1

4:08

by

syi

Feet

030 30

MW-1

AC

Cement ConcreteCC

Asphalt Concrete

No Visible SheenSlight SheenModerate SheenHeavy SheenNot Tested

NSSSMSHSNT

ADDITIONAL MATERIAL SYMBOLS

Measured groundwater level inexploration, well, or piezometer

Measured free product in well orpiezometer

Graphic Log Contact

Groundwater Contact

Material Description Contact

Laboratory / Field Tests

Sheen Classification

Sampler Symbol Descriptions

NOTE: The reader must refer to the discussion in the report text and the logs of explorations for a proper understanding of subsurfaceconditions. Descriptions on the logs apply only at the specific exploration locations and at the time the explorations were made; they arenot warranted to be representative of subsurface conditions at other locations or times.

GRAPH

Topsoil/Forest Duff/Sod

Crushed Rock/Quarry Spalls

FIGURE 3

2.4-inch I.D. split barrel

SYMBOLS TYPICAL

KEY TO EXPLORATION LOGS

CR

DESCRIPTIONSLETTER

TSGC

PT

OH

CH

MH

OL

GM

GP

GW

DESCRIPTIONSTYPICAL

LETTER

(APPRECIABLE AMOUNTOF FINES)

MAJOR DIVISIONS

POORLY-GRADED SANDS,GRAVELLY SAND

PEAT, HUMUS, SWAMP SOILSWITH HIGH ORGANICCONTENTS

CLEAN SANDS

GRAVELS WITHFINES

CLEANGRAVELS

HIGHLY ORGANIC SOILS

SILTSAND

CLAYS

SILTSAND

CLAYS

SANDAND

SANDYSOILS

GRAVELAND

GRAVELLYSOILS

(LITTLE OR NO FINES)

FINEGRAINED

SOILS

COARSEGRAINED

SOILS

SW

MORE THAN 50%OF COARSEFRACTION

RETAINED ON NO.4 SIEVE

CL

WELL-GRADED SANDS,GRAVELLY SANDS

SILTY GRAVELS, GRAVEL - SAND- SILT MIXTURES

LIQUID LIMITGREATER THAN 50

SILTY SANDS, SAND - SILTMIXTURES

(APPRECIABLE AMOUNTOF FINES)

SOIL CLASSIFICATION CHART

LIQUID LIMITLESS THAN 50

SANDS WITHFINES

SP(LITTLE OR NO FINES)

ML

SC

SM

NOTE: Multiple symbols are used to indicate borderline or dual soil classifications

MORE THAN 50%OF COARSEFRACTION

PASSING NO. 4SIEVE

CLAYEY GRAVELS, GRAVEL -SAND - CLAY MIXTURES

CLAYEY SANDS, SAND - CLAYMIXTURES

INORGANIC SILTS, ROCKFLOUR, CLAYEY SILTS WITHSLIGHT PLASTICITY

ORGANIC SILTS AND ORGANICSILTY CLAYS OF LOWPLASTICITY

INORGANIC SILTS, MICACEOUSOR DIATOMACEOUS SILTYSOILS

ORGANIC CLAYS AND SILTS OFMEDIUM TO HIGH PLASTICITY

INORGANIC CLAYS OF HIGHPLASTICITY

MORE THAN 50%PASSING NO. 200

SIEVE

MORE THAN 50%RETAINED ON NO.

200 SIEVE

WELL-GRADED GRAVELS,GRAVEL - SAND MIXTURES

POORLY-GRADED GRAVELS,GRAVEL - SAND MIXTURES

INORGANIC CLAYS OF LOW TOMEDIUM PLASTICITY, GRAVELLYCLAYS, SANDY CLAYS, SILTYCLAYS, LEAN CLAYS

GRAPH

SYMBOLS

Standard Penetration Test (SPT)

Shelby tube

Piston

Direct-Push

Bulk or grab

Continuous Coring

Distinct contact between soil strata

Approximate contact between soilstrata

Contact between geologic units

Contact between soil of the samegeologic unit

%F%GALCACPCSDSHAMCMDOCPMPIPPPPMSATXUCVS

Percent finesPercent gravelAtterberg limitsChemical analysisLaboratory compaction testConsolidation testDirect shearHydrometer analysisMoisture contentMoisture content and dry densityOrganic contentPermeability or hydraulic conductivityPlasticity indexPocket penetrometerParts per millionSieve analysisTriaxial compressionUnconfined compressionVane shear

Blowcount is recorded for driven samplers as the numberof blows required to advance sampler 12 inches (ordistance noted). See exploration log for hammer weightand drop.

A "P" indicates sampler pushed using the weight of thedrill rig.

A "WOH" indicates sampler pushed using the weight ofthe hammer.

Rev. 02/16

2

6

5

10

18

14

17

6

50/6"

50

50/6"

50/6"

66

40

50/6"

50/6"

Brown silty fine to coarse gravel with sand,occasional cobbles (dense, moist)

Gray fine to coarse gravel with silt and sand,cobbles (very dense, moist)

Grayish brown fine to coarse gravel, sand,cobbles, trace silt (very dense, moist)

Grayish brown silty fine to coarse gravel withsand (very dense, wet)

Brown fine to coarse sand with silt and gravel(very dense, wet)

Gray fine to coarse sand with gravel, trace silt(dense, wet)

Grades to very dense

Grayish brown fine to coarse gravel with sandand trace silt (very dense, wet)

GM

GP-GM

GP

GM

SW-SM

SP

GP

1

2

3

4

5SA

6SA

7

8

3.0

18.0

20.0

40.0

41.5

Concrete surfaceseal

Bentonite backfill

2-inch Schedule40 PVC wellcasing

10-20 Silica sandbackfill

2-inch Schedule40 PVC screen,0.01-inch slotwidth

PVC end cap10-20 Silica sandbackfill

11

15

9

5

Logged ByEWHDrilled

Date Measured

DrillingMethod6/30/2017 6/30/2016

HorizontalDatum

Vertical Datum

A 6 (in) well was installed on 6/30/2016 to a depth of 40(ft).

7/5/2016Easting (X)Northing (Y)

DrillingEquipment

41.5

Top of CasingElevation (ft) 391.00

Start EndChecked By

18.9

Truck Mounted B-59

Elevation (ft)

Groundwater

Driller

Depth toWater (ft)

JQSTotalDepth (ft)

Hollow Stem Auger

Notes:

HammerData

Surface Elevation (ft)

Autohammer140 (lbs) / 30 (in) Drop

Holocene Drilling, Inc.

372.2

391NAVD88

1177915.316647463.8234

WA State Plane,SouthNAD83 (feet)

Flush mount

Note: See Figure 3 for explanation of symbols.

FIELD DATA

Dep

th (

feet

)

0

5

10

15

20

25

30

35

40

Inte

rval

Ele

vatio

n (f

eet)

390

385

380

375

370

365

360

355

350

Co

llect

ed S

amp

le

Rec

over

ed (

in)

Blo

ws/

foot

Gra

phic

Log MATERIAL

DESCRIPTION

Gro

upC

lass

ifica

tion

Wat

er L

evel

Sam

ple

Nam

eT

estin

g

WELL LOG

Moi

stur

eC

onte

nt (

%)

Fin

esC

onte

nt (

%)

Log of Monitoring Well MW-1Frederickson Market and Gas Station

Frederickson, Washington

0277-030-03

Project:

Project Location:

Project Number:Figure 4

Sheet 1 of 1Tac

oma:

Dat

e:7/

15/1

6 P

ath:

P:\0

\027

7030

\03\

GIN

T\0

2770

3003

.GP

J D

BT

empl

ate/

LibT

empl

ate:

GE

OE

NG

INE

ER

S_D

F_S

TD

_US

.GD

T/G

EI8

_GE

OT

EC

H_W

ELL

_%F

0

10

20

30

40

50

60

70

80

90

100

0.0010.010.11101001000

PER

CEN

T PA

SSIN

G B

Y W

EIG

HT

GRAIN SIZE IN MILLIMETERS

U.S. STANDARD SIEVE SIZE

SANDSILT OR CLAYCOBBLES

GRAVEL

COARSE MEDIUM FINECOARSE FINE

Exploration Number

Depth(feet) USCS Soil Classification

MW-1MW-1

2530

Well-graded sand with silt (SW-SM)Poorly-graded sand (SP)

SymbolMoisture

(%)1115

3/8”3” 1.5” #4 #10 #20 #40 #60 #1003/4”

Figure 5

Sieve Analysis Results

Frederickson Market and G

as StationFrederickson, W

ashington

0277-030-03 Date Exported: 07/5/16

Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they wereperformed, and should not be interpreted as representative of any other samples obtained at other times, depths or locations, or generated by separate operations or processes.

The grain size analysis results were obtained in general accordance with ASTM D 6913.

#200

APPENDIX A Report Limitations and Guidelines for Use

July 15, 2016| Page A-1 File No. 0277-030-03

APPENDIX A REPORT LIMITATIONS AND GUIDELINES FOR USE1

This appendix provides information to help you manage your risks with respect to the use of this report.

Read These Provisions Closely

It is important to recognize that the geoscience practices (geotechnical engineering, geology and environmental science) rely on professional judgment and opinion to a greater extent than other engineering and natural science disciplines, where more precise and/or readily observable data may exist. To help clients better understand how this difference pertains to our services, GeoEngineers includes the following explanatory “limitations” provisions in its reports. Please confer with GeoEngineers if you need to know more how these “Report Limitations and Guidelines for Use” apply to your project or site.

Geotechnical Services Are Performed for Specific Purposes, Persons and Projects

This report has been prepared for Nisqually Board of Economic Development, LLC for the project(s) specifically identified in the report. The information contained herein is not applicable to other sites or projects. GeoEngineers structures its services to meet the specific needs of its clients. No party other than the party to whom this report is addressed may rely on the product of our services unless we agree to such reliance in advance and in writing. Within the limitations of the agreed scope of services for the Project, and its schedule and budget, our services have been executed in accordance with our Agreement with Nisqually Board of Economic Development, LLC dated June 23, 2016, and generally accepted geotechnical practices in this area at the time this report was prepared. We do not authorize, and will not be responsible for, the use of this report for any purposes or projects other than those identified in the report.

A Geotechnical Engineering or Geologic Report is Based on a Unique Set of Project-Specific Factors

This report has been prepared for the proposed Frederickson Market and Gas Station to be located at 17808 Canyon Road East, in Frederickson, Washington. GeoEngineers considered a number of unique, project-specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, it is important not to rely on this report if it was:

■ not prepared for you,

■ not prepared for your project,

■ not prepared for the specific site explored, or

■ completed before important project changes were made.

 

                                                            

1 Developed based on material provided by ASFE, Professional Firms Practicing in the Geosciences; www.asfe.org.

July 15, 2016| Page A-2 File No. 0277-030-03

For example, changes that can affect the applicability of this report include those that affect:

■ the function of the proposed structure;

■ elevation, configuration, location, orientation or weight of the proposed structure;

■ composition of the design team; or

■ project ownership.

If changes occur after the date of this report, GeoEngineers cannot be responsible for any consequences of such changes in relation to this report unless we have been given the opportunity to review our interpretations and recommendations. Based on that review, we can provide written modifications or confirmation, as appropriate.

Subsurface Conditions Can Change

This geotechnical or geologic report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by man-made events such as construction on or adjacent to the site, new information or technology that becomes available subsequent to the report date, or by natural events such as floods, earthquakes, slope instability or groundwater fluctuations. If more than a few months have passed since issuance of our report or work product, or if any of the described events may have occurred, please contact GeoEngineers before applying this report for its intended purpose so that we may evaluate whether changed conditions affect the continued reliability or applicability of our conclusions and recommendations.

Topsoil

For the purposes of this report, we consider topsoil to consist of generally fine-grained soil with an appreciable amount of organic matter based on visual examination, and to be unsuitable for direct support of the proposed improvements. However, the organic content and other mineralogical and gradational characteristics used to evaluate the suitability of soil for use in landscaping and agricultural purposes was not determined, nor considered in our analyses. Therefore, the information and recommendations in this report, and our logs and descriptions should not be used as a basis for estimating the volume of topsoil available for such purposes.

Geotechnical and Geologic Findings Are Professional Opinions

Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies the specific subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and laboratory data and then applied its professional judgment to render an informed opinion about subsurface conditions at other locations. Actual subsurface conditions may differ, sometimes significantly, from the opinions presented in this report. Our report, conclusions and interpretations are not a warranty of the actual subsurface conditions.

 

July 15, 2016| Page A-3 File No. 0277-030-03

Geotechnical Engineering Report Recommendations Are Not Final

The construction recommendations included in this report are preliminary and should not be considered final. GeoEngineers’ recommendations can be finalized only by observing actual subsurface conditions revealed during construction. GeoEngineers cannot assume responsibility or liability for the recommendations in this report if we do not perform construction observation.

We recommend that you allow sufficient monitoring, testing and consultation during construction by GeoEngineers to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes if the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork activities are completed in accordance with our recommendations. Retaining GeoEngineers for construction observation for this project is the most effective means of managing the risks associated with unanticipated conditions.

A Geotechnical Engineering or Geologic Report Could Be Subject to Misinterpretation

Misinterpretation of this report by members of the design team or by contractors can result in costly problems. GeoEngineers can help reduce the risks of misinterpretation by conferring with appropriate members of the design team after submitting the report, reviewing pertinent elements of the design team’s plans and specifications, participating in pre-bid and preconstruction conferences, and providing construction observation.

Do Not Redraw the Exploration Logs

Geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. The logs included in a geotechnical engineering or geologic report should never be redrawn for inclusion in architectural or other design drawings. Photographic or electronic reproduction is acceptable, but separating logs from the report can create a risk of misinterpretation.

Give Contractors a Complete Report and Guidance

To help reduce the risk of problems associated with unanticipated subsurface conditions, GeoEngineers recommends giving contractors the complete geotechnical engineering or geologic report, including these “Report Limitations and Guidelines for Use.” When providing the report, you should preface it with a clearly written letter of transmittal that:

■ advises contractors that the report was not prepared for purposes of bid development and that its accuracy is limited; and

■ encourages contractors to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of information they need or prefer.

Contractors Are Responsible for Site Safety on Their Own Construction Projects

Our geotechnical recommendations are not intended to direct the contractor’s procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to on-site personnel and adjacent properties.

July 15, 2016| Page A-4 File No. 0277-030-03

Biological Pollutants

GeoEngineers’ Scope of Work specifically excludes the investigation, detection, prevention or assessment of the presence of Biological Pollutants. Accordingly, this report does not include any interpretations, recommendations, findings or conclusions regarding the detecting, assessing, preventing or abating of Biological Pollutants, and no conclusions or inferences should be drawn regarding Biological Pollutants as they may relate to this project. The term “Biological Pollutants” includes, but is not limited to, molds, fungi, spores, bacteria and viruses, and/or any of their byproducts.

A Client that desires these specialized services is advised to obtain them from a consultant who offers services in this specialized field.