Manhole 89 As-Builts_201710_Rev.pdf

395+00 396+00

397+00 398+00

X X X

X

XX

X

POTRERO CREEK

50'

SS

x

SSx SSx

SSx SSx

SSx

POTRERO CREEK

CROSSING

0'

CL UPRR (200' R.O.W.)

I-beam pea sho

1.

2.

3. Riprap installed around Manhole 89 for erosion protection.

4. Existing grades differ from what is shown.

5. Thirteen (13) piles with gravel backfill used for ring were cut down at grade level and below grade sections were abandoned in place.

See shoring drawings for locations, depths, and beam sizes. Typical pile spacing was 5'-3".

30" RCP

30" RCP

MH 89

As-Built (Constructed October 2017)

Abandoned Piles See Note 5

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10/19/2017

(PE allowed drilled hole backfill substitution from flowable fill to pea gravel during construction.)

3625 E. Ajo Way Tucson, Arizona 85713 Tel: 520.241.9520

September 6, 2017

Mr. Jesse Grinsteiner KE&G Construction Inc.

5100 S. Alvernon Tucson, Arizona 85706

GEOTECHNICAL ENGINEERING SERVICES Project No. 17112 IOI Potrero Creek Sewer Repair KE&G Job No. 170268 Potrero Creek Northeast of I-19 and Old Tucson Road Santa Cruz County, Arizona

As you requested, we have completed geotechnical engineering services for this project in accordance with our Proposal No. P17111 and KE&G Professional Service Agreement No. 170268-001. This letter report provides our opinions and recommendations.

Background and General Surface Conditions We understand that a wastewater manhole structure has apparently failed and is to be replaced. The manhole is within (along the toe of eastern bank) the Potrero Wash about 830 feet downstream (north) of the bridge on Old Tucson Road that spans the wash. The manhole serves to change the direction of the sewer transmission line which has an inside diameter of 30 inches and is made of reinforced concrete. An existing upstream line enters the manhole from the southeast, crossing below the wash. A downstream line exits the manhole to the north to the next manhole which is east of the wash.

The main wash channel generally has a trapezoidal cross-section with sloped banks but some areas of the banks have eroded to near-vertical (likely from undercutting). The wash bottom width is about 20± feet and the banks have a slope of about 1.5:1 to 2:1 (horizontal to vertical) and a height of about 5 feet above the bottom.

The left (western) overbank area continues to incline westerly but at a gradual, low gradient. The right overbank rises to a narrow terrace and then climbs steeply at nearly 1:1 about 18± feet to a railroad line (UPRR) that runs north-south. Just upstream of the manhole though, there is a stretch where the right bank is very shallow (just above the wash bed); along this length there is apparent steel-panel

Project No. 17112 Page 2 IOI Potrero Creek Sewer Repair September 6, 2017 cribbing that is supported by vertical piles. This cribbing appears to have been installed to help provide support to the slope behind or protect against erosion or both.

From the bridge, the wash runs northeasterly towards the railroad, gradually turning northward. From this point, to about 385± feet north to the manhole, the wash alignment is generally linear. From the manhole, the wash turns slightly north-northwest.

We understand that the current plan is to replace the manhole with a precast concrete vault. Additionally, short sections of the existing pipes entering and leaving the manhole location will be replaced. The new manhole vault is square and has inside dimensions of 5 ft. by 5 ft. by 5 ft. and a wall thickness of 8 inches. It has a 1-foot-thick base section and a 1-foot-thick top section; the base measures 7 feet by 7 feet. The vault detail sheet provided to me is attached to this report. Currently, it is desired to install the manhole such that the top of the vault (excluding a short riser) is near or slightly below the current bottom of wash elevation. This then puts the manhole bottom at 7.5 below the bottom of wash elevation.

Field Evaluation To obtain information on the subsurface soils and water level, we completed a hollow-stem auger boring to a depth of about 31.5 feet below the ground surface using a truck-mounted drilling rig. Jim Evanoff, P.E., viewed the site to obtain information on the general surface conditions observed and logged the drilling, sampling, and backfilling of the exploration.

The boring was advanced on the western bank about 18 feet south of the sewerline crossing the wash and entering the manhole and about 18 feet west of the wash bed. We used the Unified Soil Classification System to classify soils. The soil classification symbols appear on the exploration logs and are briefly described in the Attachment.

Project No. 17112 Page 3

Subsurface Conditions We encountered alluvial soil deposits from the ground surface to the full depth of exploration. The surface soils to a depth of about 5.5 feet below the ground surface (bgs) were loose to medium dense silty sands with gravel; the gravel occasionally occurring in thin layers. Below the surface soils were predominantly loose to medium dense sands. This primary deposit of fine to coarse sand with gravel showed apparent frequent interbedding of thin layers of fine to medium sand, silty sand/sandy silt, and fine silty sand.

The surface soils were slightly moist to the touch. At the time of our exploration, we encountered groundwater at a depth of 5.5 feet bgs. This elevation generally coincides with our estimate of the boring ground surface above the stream flow. The sampled soils were wet and appeared to be saturated. During drilling, water was added within the hollow-stem augers to equalize water head differential and help prevent soil from being flushed upward into the augers.

Figure 1 Aerial showing general surface conditions and locations. North is to top.

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September 6, 2017

The groundwater conditions at the time of our evaluation represent only the conditions at the time of exploration. Groundwater levels can and often do fluctuate for various reasons including variations in precipitation, evaporation, surface runoff, and regional withdrawal or recharge. The logs in the Appendix show details of the subsurface conditions encountered during the field evaluation.

Opinions and Recommendations

The wash, near the location of the manhole, changes direction from the north to the north-northwest. This curve creates higher velocities on the outer edge which probably laterally eroded the bank thus exposing the manhole. Once exposed to stream flow, it is likely that the manhole created more intense local scour that undermined its support resulting in downward rotation of the western side of the base. In observing the bank conditions behind the manhole, it is also possible that there could have been a shallow slope failure of the bank. Such a failure, if indeed it occurred, could have likely been coincident with a scour event.

Scour Considerations To obtain a reasonable understanding of the general scour potential of the wash near the manhole, we completed a rudimentary analysis. For the analysis, we used a spreadsheet available from the Pima County Regional Flood Control District. The spreadsheet is based on the methods and equations prescribed in the publication, Standards Manual for Drainage Design and Floodplain Management in Tucson, Arizona, December, 1989. We obtained our input hydraulic characteristics from FEMA’s 2011, Flood Insurance Study, Santa Cruz County, Arizona. The FEMA Flood Insurance Study (FIS) research contained a cross section that appears to be at or very near the manhole area. A printout of the spreadsheet is attached.

The analysis showed a general scour result of 4.4 ft. (below stream grade). Using a generally recommended factor of safety (FS) of 1.3 results in an estimated general scour of 5.7 feet, or about 6 feet. Therefore, at an expected bearing depth of 7.5 feet, the new vault base is below the calculated scour depth. The 30-inch pipe crossing the wash and entering the vault, however, will be mostly within the scour zone. To maintain the sewerline drainage profile, however, it seems there may not be any other practical choice but to accept this condition and the risk. The owner should, however, be made aware of this condition. Pipeline protective measures are possible, but then again, they may also be determined to be impractical (see also Buoyancy Considerations). In our opinion, positioning the vault top below the wash bed is appropriate as it helps avoid the greater scour depths associated with being a flow obstruction.

Project No. 17112 Page 5

September 6, 2017

Buoyancy Considerations Using the vault dimensions on the Jensen detail you provided, we have determined a displaced volume of about 246 cubic feet (cf). Multiplying this volume by the unit weight of water, 62.4 pounds per cubic foot (pcf), results in a buoyant force of 15,350 pounds. The detail states that the total weight is about 21,500 pounds. Because of potential scour, there could be little or no soil available for additional resistance to uplift. Therefore, using only the structure’s weight and buoyant force, the FS against uplift is .

For the case of a unit length of 30-inch ID pipe with a wall thickness of 3 ½ inches, we determined a volume of 7.5 cf per linear foot. This results in a buoyant force of 466 pounds per linear foot. Published information for this dimension of reinforced concrete pipe gives the weight as 384 pounds per linear foot. Therefore, with the pipe empty and no soil resistance over it, the pipe will be buoyant. This condition will stress the pipe between its supports at the manhole and several feet beyond the opposing wash bank; you should have a Structural Engineer address this condition unless additional weighting measures are used. It may be, however, that others know or have determined, that it is unlikely for the pipe to be less than a certain amount filled. This internal weight together with the pipe deadweight could offset expected buoyant force.

Under most typical low-flow conditions, it would be expected to have about 2.5 feet of backfill overlying the pipe. At a submerged unit weight of 62 pcf, this results in an additional resistance of 155 pounds per linear foot. So under typical conditions the FS against uplift would be which is low. If it is determined that the risk associated with relying on a minimum pipe flow is too high, you may want to consider weight attachments or an embedded tension anchor. Another potential method could be partially backfilling (or collaring) the pipe with concrete; from about the haunch level to at least about 4 inches over the crown. This could also have the benefit of providing some scour protection.

Vault (Manhole) Support Considerations The net stress increase to supporting soil below the vault is expected to minimal.

Without any stress increase, bearing capacity is inconsequential and settlement should not occur provided the exposed soils are undisturbed. Additionally, as also suggested by subsurface mottling of the soils, the groundwater surface has undoubtedly fluctuated.

Historical drops in the groundwater level would have increased the effective pressures in the soils and pre-consolidated them, allowing increased pressures (although none is needed for this structure).

Project No. 17112 Page 6

September 6, 2017

Even though special preparations should not be necessary, as a practical matter, it will probably be demanding to excavate and set a precast element on wet subgrade soils such that there is relatively uniform support. Even with suitable dewatering, the exposed soils could displace and distort under foot or equipment traffic and we suspect that any significant drying time is undesirable. Final excavating to the base bearing elevation should be done cautiously so that a reasonably level undisturbed subgrade is provided. You may want to consider placing a thin (3-6 in.) low-slump concrete “mud mat” on the exposed surface, finished relatively level. Such a mat may also help reduce seepage.

If the subgrade soils become slightly disturbed, light compactive efforts could be possible. Because the soils will likely be at over-optimum moisture contents, compactive effort should be minimized. Significant disturbance may require measures such as using a geogrid or placing a base of coarse (between 3 and 8 inches) rock (using minimal compaction) into the subgrade.

Groundwater Control Excavations in the near future will encounter free groundwater. It will be necessary, therefore, to dewater the construction area prior to excavating. Methods could include cutoff walls, sheet piling, wellpoints, trenches and sumps or various combinations. The subsurface natural soils are sand mixtures that should have high permeability. A general estimate of permeability is 0.05 cm/sec or 0.098 feet/min. At this rate, each 1 sf area below the water table would yield 0.73 gal/min. We do not know if there is a local velocity head component to the current water level, but the wash parallels the general toe of the easterly-inclining foothills just to the east (see also Figure 1). Therefore, it’s possible that there is some total head differential, making seepage volumes higher. More complete information regarding flow quantities would require either flownet or finite element analyses which are not a part of the current services.

The dewatering method used should lower the local groundwater surface to at least 1 foot and preferably 2 feet, below the excavation bottom. Depending on the dewatering system, flow paths, and specific soil and groundwater conditions, hydraulic heave or a “quick” condition (because of seepage pressures) of the excavation bottom is possible.

Unshored or unbraced excavations should have slopes of 1.5 to 1 (horizontal to vertical) or less. Steeper slopes must be shored. Various shoring systems are possible;

their selection and design, however, is beyond the scope of our current evaluation. The design of a retaining system is dependent on the construction method, the sequence of

Project No. 17112 Page 7

September 6, 2017 operations, and adjacent construction. Measures should be taken to protect slopes from erosion and potential concentrated surface drainage. Traffic and surcharge loads should be at least 10 feet from the top of the excavation unless shoring design includes the additional stress. All excavations shall be completed in accordance with the most recent OSHA requirements.

Dewatering by collection trenches and sumps may be possible but it often isn’t (or it’s impractical) when lowering the water level more than several feet in granular soils.

If it is attempted, it will probably be necessary to draw water down in stages. Because of the necessary dewatering depths, this method would likely require some type of shoring support for the sump because safe unsupported slopes would cover a significant area.

Lateral Earth Pressures For soils above any free water surface, with level backfill and no surcharge loads, the recommended ultimate equivalent fluid pressures (EFP) for unrestrained elements and coefficients of base friction are presented below.

Active State

Natural undisturbed soil .......................................... 33 psf/ft

Granular soil backfill................................................ 30 psf/ft

Passive State

Natural undisturbed soil .......................................... 380 psf/ft Granular soil backfill................................................ 525 psf/ft

Coefficient of Base Friction ..................... 0.45*

* Reduce to 0.40 if used in conjunction with passive pressure.

For soils above any free water surface, with level backfill and no surcharge loads, the recommended ultimate equivalent fluid pressures (EFP) for restrained elements are below.

At-Rest State

Natural undisturbed soil .......................................... 51 psf/ft

Granular soil backfill................................................ 48 psf/ft

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September 6, 2017

For soils below any free water surface, with level backfill and no surcharge loads, the recommended ultimate equivalent fluid pressures (EFP) for unrestrained elements and coefficients of base friction are presented below. Hydrostatic water pressure must be added to the values below.

Active State

Natural undisturbed soil .......................................... 21 psf/ft

Granular soil backfill................................................ 20 psf/ft

Passive State

Natural undisturbed soil .......................................... 186 psf/ft Granular soil backfill................................................ 231 psf/ft

Coefficient of Base Friction ..................... 0.45*

* Reduce to 0.40 if used in conjunction with passive pressure.

For soils below above any free water surface, with level backfill and no surcharge loads, the recommended ultimate equivalent fluid pressures (EFP) for restrained elements are below. Hydrostatic water pressure must be added to the values below.

At-Rest State

Natural undisturbed soil .......................................... 31 psf/ft

Granular soil backfill................................................ 31 psf/ft

The earth pressures and base friction presented are ultimate values and a factor of safety should be applied for design. Factors of safety of 1.5 to 2 are typical.

Significant movement, approximately 1 to 2 % of the element’s height for granular soil, is necessary to mobilize full passive resistance. Granular soils with significant clay or silt content could require 3 to 4 % movement.

As noted above, passive pressure development will require substantial movement into the soil to fully mobilize. Selection of a safety factor should therefore be done judiciously. Passive pressure and base friction can be combined, but passive pressure contribution should be discounted unless there is adequate movement. If the element can be considered too stiff or is substantially embedded to prevent appropriate deflection, we recommend that at-rest earth pressures be used for design.

Other Considerations We understand that it is probably apparent, but it would be preferable to begin this work when surface flow within the wash recedes. If this cannot be accommodated, then it will be necessary divert the flow. Such diversions can be done in a number of

Project No. 17112 Page 9

September 6, 2017 ways. Industrial-size sandbags faced with heavy gauge plastic sheeting has been used;

Jersey barriers, or similar, could be used. Such elements could be used as a dam with pumps that convey the water through bypass pipes discharging downstream. Cutting a new temporary channel may also be a possibility. Additionally, you should create a protocol for monitoring upstream weather conditions to help prevent a flash flood incident that could harm personnel and equipment.

The area should be dewatered prior to removing the existing facilities to help avoid disruption of the underlying subgrade. The existing manhole structure should be slowly separated from the subgrade to reduce suction effects that could disturb the subgrade.

Again, excavations shall be properly sloped or shored sufficiently to resist earth pressures and hydrostatic pressures. This is expected to be complicated by the need to expose and accommodate two pipelines meeting at about 90 degree angles at the manhole. The wash bank east of the manhole is not very high above the wash bed elevation, but sections could slough and a shallow slope failure could occur; slopes in the immediate area should be flattened as a precaution. Protective excavation enclosures should be sized to provide adequate working space.

The installed manhole vault and pipes should be backfilled with suitable granular soils. The site soils, on the basis of our exploration, appear to be suitable for use as backfill. In our opinion, compacting the backfill by jetting is acceptable. We expect that removal of shoring will probably result in some flow of soils into the excavation; removal should be done cautiously. Backfilling and removing shoring should progress together. After backfilling and acceptance, dewatering could be stopped.

If sump pumps are used, consider using a gravel or gravel/fabric filter on the excavation slopes to protect the pump from particles. In some cases, a perforated 55-gallon drum, lined with a fabric filter, has been used to enclose the pump.

After installation, the wash banks should be restored and, particularly because the area is at the perimeter of a bend, protected. There are many restorative measures that could be undertaken, including recompaction and/or riprap, proprietary armoring, and various vegetal or biotechnical methods.

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September 6, 2017

Closure Information contained in this report relative to site dewatering is intended only for conceptual design purposes and should not be construed as providing all information necessary for dewatering.

The services we performed for this project include professional opinions and judgments based on the data collected. We performed our professional services using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable geotechnical engineers practicing in southern Arizona. We do not intend to provide recommendations that prevent all undesirable effects resulting from structural movements. We intend to provide reasonable solutions to help control effects the soil may have on the structures. We make no other warranty, expressed or implied.

We prepared the report as an aid for the design of the project. This report is not a bidding document and any contractors reviewing it must draw their own conclusions regarding site conditions and specific construction techniques to be used on this project.

Our services did not include any environmental assessment or investigation for the presence or absence of hazardous or toxic materials in the soil, groundwater, or air, on or below or around, this site. All conditions documented or observed are strictly for the information of our client. If environmental information is required, we recommend that an environmental assessment be completed which addresses these concerns.

We based our recommendations on the assumption the soil and groundwater conditions across the site are similar to those encountered at the exploration locations.

The extent and nature of subsurface soil and groundwater variations may not be evident until construction. If conditions encountered during construction appear to differ from those described in this report, we should be consulted to assess the impact and provide supplemental recommendations. Our evaluation and report does not include the effects, if any, of underlying geologic hazards or regional groundwater withdrawal and we express no opinion regarding their effects on surface movement.

Project No. 17112 Page 11

We thank you for selecting us as your Geotechnical Consultant and look forward to being a member of your team on the remainder of this project. If you have any questions about this report, or require additional consultation, please call us.

Sincerely, James W. Evanoff Jr., P.E.

Principal/Owner

Copies: Addressee (1) Email

Project No. 17112

ATTACHMENTS

Soil Classification

Exploration Log Notes

Exploration Log

FIS Data

Scour Spreadsheet

Jensen Product Schematic

SOIL CLASSIFICATION

MAJOR DIVISIONS

USCS

GROUP

TYPICAL DESCRIPTION

COARSE-

GRAINED

SOILS

More than 50% of sample is larger than the No. 200 sieve

GRAVEL

More than 50% is larger than the

No. 4 sieve

CLEAN GRAVEL

no to little fines (material passing No. 200 sieve)

GW Well-graded gravel, gravel/sand mixtures, little to no fines

GP Poorly-graded gravel, gravel/sand mixtures, little to no fines

GRAVEL WITH FINES

GM Silty gravel, gravel/silt/sand mixtures

GC Clayey gravel, gravel/clay/sand mixtures

SAND

More than 50% is smaller than the

No. 4 sieve

CLEAN SAND

no to little fines (material passing No. 200 sieve)

SW Well-graded sand, sand/gravel mixtures, little to no fines

SP Poorly-graded sand, sand/gravel mixtures, little to no fines

SAND WITH FINES

SM Silty sand, sand/silt/gravel mixtures

SC Clayey sand, sand/clay/gravel mixtures

FINE-

GRAINED

SOILS

More than 50% of sample is smaller than the No. 200 sieve

SILT AND CLAY

Liquid limit less than 50

INORGANIC

ML

Silt and very fine sand, silty or clayey fine sand, or clayey silt

CL Lean clay, gravelly clay, sandy clay, silty clay, low to medium plasticity

ORGANIC OL Low plasticity organic silt and silty clay

SILT AND CLAY

Liquid limit 50 or more

INORGANIC

MH Silt, micaceous or diatomaceous fine sand or silt, elastic silt

CH Fat clay, high plasticity clay, sandy fat clay, gravelly fat clay

ORGANIC OH Organic clay, organic silt, of medium to high plasticity

HIGHLY ORGANIC SOILS PT Peat, muck, humus, and other fibrous highly organic soils

NOTES

Adapted from the Unified Soil Classification System (USCS), ASTM D 2487 & D 2488. Soil descriptions are based on the visual-manual procedures of ASTM D 2488 unless noted otherwise.

Dual symbols (group symbols separated by a hyphen) are used for soils with between 5 and 12 percent fines or when the liquid limit and plasticity index values plot within the CL-ML area of the plasticity chart.

Examples: SP-SM, CL-ML.

Borderline symbols (group symbols separated by a forward slash) indicate that the soil may be in one of two possible groups. Examples: SC/CL, CL/CH, GP/SP, CH/MH.

SOIL CLASSIFICATION

IOI Potrero Creek Sewer Repair Northeast of I-19 & Old Tucson Road

Santa Cruz County, Arizona

Figure A-1

Project No. 17112 September 5, 2017

Particle Size 12 in. 3 in. 3/4 in. No. 4* No. 10* No. 40* No. 200*

Boulders1 Cobbles1 Gravel Sand Fines Coarse Fine Coarse Medium Fine Silt/Clay

Cobbles and boulders are not considered part of the soil’s primary classification. References to the amount or percentage are based on volume rather than weight. Furthermore, unless open excavations have been completed, their presence is inferred and estimated based on drilling/sampling observations, viewing of nearby exposed cuts and local experience.

U.S. Standard Sieve designation

Consistency of Cohesive Soils Relative Density of Cohesionless Soils

Clay and Silt Penetration Resistance, N Sand and Gravel Penetration Resistance, N

Very Soft < 2 Very Loose 0 - 4

Soft 2 - 4 Loose 5 - 10

Firm 5 - 8 Medium Dense 11 - 30

Stiff 9 - 15 Dense 31 - 50

Very Stiff 16 - 30 Very Dense > 50

Hard > 30

Plasticity of Fine-Grained Soils Description of Moisture Condition Plasticity Index Term Dry Dry to touch, dusty

0 Non-plastic Slightly Moist Moisture below optimum 1 - 10 Low Plasticity Moist Moisture near optimum

11 - 25 Medium Plasticity Very Moist Moisture over optimum > 25 High Plasticity Wet Visible free water

SOIL CLASSIFICATION

IOI Potrero Creek Sewer Repair Northeast of I-19 & Old Tucson Road

Santa Cruz County, Arizona

Figure A-2

Project No. 17112 September 5, 2017

EXPLORATION LOG NOTES

Northeast of I-19 & Old Tucson Road

Santa Cruz County, Arizona

Figure A-3

Project No. 17112 September 5, 2017

The number shown in Boring refers to the approximate location of the same number shown on the Site

Plan as positioned in the field by pacing from property lines and/or existing features.

The number shown in Blow Counts per 6" refers to the number of blows of a 140-pound hammer free-falling 30 inches, to advance the sampler. H in Sample Type is a bulk hand sample from the auger cuttings. R in Sample is a sample obtained by driving a 3-inch-outside-diameter sampler lined with

2.42-inch-inside-diameter brass or stainless steel rings. Refusal to penetration for the ring sampler is considered more than 50 blows per foot or fraction thereof. N in Sample is a sample obtained by driving a 2.0-inch-outside-diameter, 1-3/8-inch-inside-diameter, split-spoon sampler. This sampler is used to perform the Standard Penetration Test (SPT) ASTM D1586. Refusal to penetration is considered to be one of the following items: 1. A total of 50 blows has been applied during any one of the three 6-inch increments; 2. A total of 100 blows has been applied; 3. There is no observed advance of the sampler during application of 10 successive blows of the hammer. The cumulative number of blows for the final

12 inches of advancement is the Standard Penetration Resistance (N-Value).

USCS Code refers to the soil type as defined by the Unified Soil Classification System. The soils descriptions are based on visual-manual procedures (ASTM D2488) unless noted otherwise and, where appropriate, classifications were modified by visual examination of samples in the laboratory and by appropriate test. All explorations were backfilled with the excavated soils.

The boring logs are intended for use in conjunction with the purposes of our services defined in the report. Boring log data should not be construed as part of the construction plans or as defining construction conditions.

Boring logs depict our interpretations of subsurface conditions at the locations and date(s) shown.

Variations in subsurface conditions and soil characteristics between borings should be expected.

Groundwater levels may fluctuate due to seasonal variations and other factors. The stratification lines shown on the logs represent our interpretation of the approximate change in soil types based on observations of sampling or drilling action, nearby cut exposure, or previous experience. The actual transitions may vary and may occur gradually.

In general, terms and symbols on the boring logs conform with "Standard Definitions of Terms and

Symbols Relating to Soil and Rock Mechanics" (ASTM D653).

U

SC

S Pa tte rn

BORING

D ep th , f t.

Sa m pl e

Bl ow

C ou nt s

Pe r 6 in

U

SC

S G ro up

Interpretive Description

D ry

D en si ty pc f

M oi st ur e, Hammer Type:

Drilling Company: Project No.

Method: Date:

Equipment: Location:

Logged by:

17112Geomechanics Southwest Inc.

HSA 3 1/4 in. ID, 8 in. OD

CME 75

Automatic

August 23, 2017 See Site Plan J. Evanoff

SILTY SAND, with gravel, brown, medium dense, slightly moist

SAND, with gravel, loose, brown, fine to coarse, wet, free groundwater encountered

No sample recovery

Profile appears to be frequently interbedded with thin (6-8 inches) layers of fine sand, or fine to medium sand, or silty sand/sandy silt

12': becomes gray, suspect that blowcounts are not representative of actual relative density medium dense, mottled brown/gray fine silty sand containing two 1/2-inch charcoal-like inclusions, color becomes gray

No sample recovery

After auger withdrawal, hole initially caved at 7 feet and then at

5.5 feet. Hole backfilled with cement grout to surface

3-4-5

3-4-5

29-45-65

4-6-8

1-1-14

15-15-8

4-4-6

12-11-11

SM

SP/SWN

N

N

N

N

N

N

N

Bottom of Exploration at 31.5 ft.

Free water encountered at 5.5 ft

3500 3500

3510 3510

3520 3520

3530 3530

3540 3540

3550 3550

3560 3560

3570 3570

7800 8100 8400 8700 9000 9300 9600 9900 10200 10500 10800 11100 11400 11700

EL

EV

AT

IO

N

IN

F

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T (N

AV

D

STREAM DISTANCE IN FEET ABOVE MOUTH

FE

DE

RA

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GE

NC

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AN

AG

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EN

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AG

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C Y

S A

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RP

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PR

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114P

Q R S T U V W X

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R oa d B r id ge Ol d

Tu cs on H ig hw ay B rid ge

LEGEND

0.2% ANNUAL CHANCE FLOOD

1% ANNUAL CHANCE FLOOD

2% ANNUAL CHANCE FLOOD

10% ANNUAL CHANCE FLOOD

STREAM BED

CROSS SECTION LOCATION

Description

CALCULATED INDIVIDUAL SCOUR COMPENENTS INPUT HYDRAULIC CHARACTERISTICS OF CONVEYANCE CALCULATED CHARACTERISTICS