RFP_602 Galena_Exhibit D_Geotechnical Study.pdf

240 Annie Road P.O. Drawer 1887

Silverthorne, CO 80498 phone: (970) 468-1989 fax: (970) 468-5891 email: kasummit@kumarusa.com www.kumarusa.com

Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs and Summit County, Colorado

July 26, 2023

The NHP Foundation

Attn: Lauren Avioli

1090 Vermont Avenue, NW, Suite 400

Washington, D.C. 20005

LAvioli@nhpfoundation.org Project No. 23-6-172

Subject: Preliminary Geotechnical Engineering Study, Proposed Workforce Housing, 602

Galena Street, Frisco, Colorado

Dear Lauren:

As requested, Kumar & Associates performed a preliminary geotechnical engineering study for the subject project. The project site is shown on Fig. 1. The purpose of the study was to develop preliminary recommendations for project design, planning and permitting. The study was conducted in accordance with our proposal for geotechnical engineering services, dated

July 13, 2023, Proposal P6-23-205R.

Proposed Construction: Review of preliminary plans indicate the project consists of the construction of a multi-family workforce residential building on the 0.54-acre subject site, as shown on Fig. 1. The new residential building will be a four-level, wood-frame structure, with a slab-on-grade or structural floor over crawlspace lower level. Grading for the project is anticipated to be relatively minor and structural loads are anticipated to be relatively light to moderate and typical of the proposed construction. Subsurface conditions, findings, and preliminary recommendations are provided below.

Field Observations: Three exploratory pits were observed by Kumar & Associates on July 12, 2023 on the subject site, as shown on Fig. 1. The pits were excavated with a tracked mini-excavator, contracted by the Client. Samples of the subsoils obtained during the field exploration were tested in the laboratory to determine their classification and other engineering characteristics. The results of the field exploration and laboratory testing were analyzed to develop preliminary recommendations for foundation types, depths and allowable pressures for the proposed structures foundations. This report summarizes the data obtained during this http://www.kumarusa.com/ mailto:LAvioli@nhpfoundation.org JSoifer Pen

JSoifer Callout 3 occupied levels + Roof

Kumar & Associates, Inc.

study and presents our conclusions, preliminary design recommendations and other geotechnical engineering considerations based on the proposed construction and the subsoil conditions encountered.

Below about 12-inches of existing fill in Pit 1, and about 6 to 12-inches of topsoil in Pits 2 & 3, the natural subsoils encountered in the pits consisted of medium dense, well graded gravel

(GW) with sand, cobbles and small boulders, to the full depth of exploration of 8 feet.

Groundwater was not encountered in Pits 1 and 2, but was encountered in Pit 3 at a depth of 6 feet at the time of excavation. The pits were backfilled after sampling. Groundwater in Pit 3, excavated in a landscape area and near roof drainage for the existing structure, could have resulted from perched water from landscape watering and building drainage from recent storm events. Groundwater depths can vary seasonally and groundwater could be encountered in foundation and utility excavations at the time of construction.

Recommendations: Considering the subsurface conditions encountered in the exploratory pits, our professional experience in the project vicinity, and the nature of the proposed construction, the natural granular soils should be suitable for support of the proposed structure on shallow spread footings, with allowable bearing pressures in the range of 2,500 to 3,000 pounds per square foot (psf). Based on experience, we expect movement of footings designed and constructed as discussed in this section will be about 1 inch or less. Footings should bear a minimum of 40 inches below adjacent exterior grade for frost protection, in accordance with local building code requirements.

Topsoil, building and utility remnants, asphalt pavement, existing fill, and other deleterious material should be removed from development areas, including foundation, floor slab and new pavement areas, and replaced with properly compacted new structural fill to re-establish bearing or slab elevations, if needed.

The on-site natural granular soils, and properly compacted new structural fill (if needed), are suitable to support lightly loaded slab-on-grade construction, exterior concrete and pavement.

To reduce the effects of some differential movement, floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement.

A detailed, design-level geotechnical engineering study should be completed once building locations and plans are finalized.

Kumar & Associates, Inc.

The recommendations submitted in this preliminary study are based on the field exploration for the subject project and our professional experience, and are intended for preliminary design, planning and permitting purposes. The recommendations presented in the design-level geotechnical engineering study report for the subject project should be relied upon for final design and construction. The recommendations presented in this letter are intended to meet the standard of care practiced for similar studies in the project area at the time of this letter.

Please call if we can be of further assistance.

Respectfully submitted, KUMAR & ASSOCIATES, INC.

James A. Parker, P.E., P.G.

Attachments: Figure 1 – Location of Exploratory Pits Figure 2 – Exploratory Pit Logs Figure 3 – Legend and Notes Figure 4 – Gradation Test Results Table 1 – Summary of Laboratory Test Results

Pit 3

Pit 2

Pit 1

Proposed Building

602 Galena Street

Kumar and Associates

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LOCATION OF EXPLORATORY PITS

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PIT 1

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DEPTH-FEET

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DEPTH-FEET

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PIT 2

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PIT 3

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WC=2.7 +4=52 -200=3

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WC=4.6 -200=4

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WC=4.3 -200=3

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WC=8.1 -200=4

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LOGS OF EXPLORATORY PITS

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DISTURBED BULK SAMPLE.

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%%U NOTES

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1. THE EXPLORATORY PITS WERE EXCAVATED WITH A BACKHOE ON JULY 19, 2023. THE EXPLORATORY PITS WERE EXCAVATED WITH A BACKHOE ON JULY 19, 2023. 2. THE LOCATIONS OF THE EXPLORATORY PITS WERE MEASURED APPROXIMATELY BY PACING FROM THE LOCATIONS OF THE EXPLORATORY PITS WERE MEASURED APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE PLAN PROVIDED. 3. THE ELEVATIONS OF THE EXPLORATORY PITS WERE NOT MEASURED AND THE LOGS OF THE THE ELEVATIONS OF THE EXPLORATORY PITS WERE NOT MEASURED AND THE LOGS OF THE EXPLORATORY PITS ARE PLOTTED TO DEPTH. 4. THE EXPLORATORY PIT LOCATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE THE EXPLORATORY PIT LOCATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY PIT LOGS REPRESENT THE THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY PIT LOGS REPRESENT THE APPROXIMATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER LEVELS SHOWN ON THE LOGS WERE MEASURED AT THE TIME AND UNDER GROUNDWATER LEVELS SHOWN ON THE LOGS WERE MEASURED AT THE TIME AND UNDER CONDITIONS INDICATED. FLUCTUATIONS IN THE WATER LEVEL MAY OCCUR WITH TIME. 7. LABORATORY TEST RESULTS: LABORATORY TEST RESULTS: WC = WATER CONTENT (%) (ASTM D 2216); = WATER CONTENT (%) (ASTM D 2216); WATER CONTENT (%) (ASTM D 2216); +4 = PERCENTAGE RETAINED ON NO. 4 SIEVE (ASTM D 422); = PERCENTAGE RETAINED ON NO. 4 SIEVE (ASTM D 422); PERCENTAGE RETAINED ON NO. 4 SIEVE (ASTM D 422); -200 = PERCENTAGE PASSING NO. 200 SIEVE (ASTM D 1140).= PERCENTAGE PASSING NO. 200 SIEVE (ASTM D 1140).PERCENTAGE PASSING NO. 200 SIEVE (ASTM D 1140).

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TOPSOIL; SILTY SAND AND GRAVEL WITH ORGANICS, MOIST, BROWN.

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FILL: SILTY SAND AND GRAVEL WITH ORGANICS, MOIST, BROWN.

AutoCAD SHX Text WELL GRADED GRAVEL WITH SAND (GW); WITH COBBLES AND SMALL BOULDERS, MEDIUM DENSE, MOIST TO WET, BROWN.

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DEPTH TO WATER LEVEL ENCOUNTERED AT THE TIME OF EXCAVATION.

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LEGEND AND NOTES

These test results apply only to the

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AutoCAD SHX Text testing report shall not be reproduced, AutoCAD SHX Text except in full, without the written

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AutoCAD SHX Text Sieve analysis testing is performed in

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CLAY TO SILT

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SAND

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DIAMETER OF PARTICLES IN MILLIMETERS

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HYDROMETER ANALYSIS

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SIEVE ANALYSIS

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TIME READINGS

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U.S. STANDARD SERIES

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CLEAR SQUARE OPENINGS

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60MIN

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19MIN

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4MIN

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24 HRS

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45 MIN

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7 HRS

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15 MIN

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GRAVEL

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COBBLES

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FINE

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COARSE

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PERCENT RETAINED

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PERCENT PASSING

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MEDIUM

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FINE

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COARSE

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SILT AND CLAY %

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LIQUID LIMIT

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GRAVEL %

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SAMPLE OF:

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FROM:

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PLASTICITY INDEX

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SAND %

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GRADATION TEST RESULTS

23-6-172

JOB NO: 23-6-172

PROPOSED WORKFORCE HOUSING - 602 GALENA TABLE 1

NATURAL NATURAL HVEEM WATER SOIL OR

MOISTURE DRY UNIT SILT & LIQUID PLASTIC SUR- STABILOMETER SOLUBLE BEDROCK

PIT DEPTH CONTENT WEIGHT GRAVEL SAND CLAY LIMIT INDEX SWELL CHARGE (R-VALUE) SULFATES DESCRIPTION

(#) (feet) (%) (pcf) (%) (%) (%) (%) (%) (%) (psf) (%)

1 2 2.7 52 45 3 WELL GRADED GRAVEL WITH SAND

2 2 4.6 4 WELL GRADED GRAVEL WITH SAND

6 4.3 3 WELL GRADED GRAVEL WITH SAND

3 2 8.1 4 WELL GRADED GRAVEL WITH SAND

JOB NAME:

SUMMARY OF LABORATORY TEST RESULTS

SAMPLE

LOCATION

GRADATION ATTERBERG LIMITS SWELL-COMPRESSION