Appendix_C_-_2010_Geotechnical_Report.pdf

PRELIMINARY GEOTECHNICAL EVALUATION

JEMEZ RANGER STATION – SITE 1

SANTA FE NATIONAL FOREST, NEW MEXICO

CONTRACT NO. AG-8371-D-09-0179

PREPARED FOR:

USDA Forest Service

333 Broadway Road Southeast Albuquerque, New Mexico 87102

PREPARED BY:

Ninyo & Moore

Geotechnical and Environmental Sciences Consultants 3001 South 35th Street, Suite 6

Phoenix, Arizona 85034

February 5, 2010 Project No. 600587017

Preliminary Geotechnical Evaluation February 5, 2010 Jemez Ranger Station – Site 1 Project No. 600587017 Santa Fe National Forest, New Mexico

600587017R Site 1 i

TABLE OF CONTENTS

Page

1. INTRODUCTION

2. SCOPE OF SERVICES

3. SITE DESCRIPTION

4. PROPOSED CONSTRUCTION

5. FIELD EXPLORATION AND LABORATORY TESTING

6. GEOLOGY AND SUBSURFACE CONDITIONS

6.1. Geologic Setting

6.2. Subsurface Conditions

6.3. Asphalt Concrete

6.3.1. Fill

6.3.2. Alluvium

6.3.3. Bedrock

6.4. Groundwater

7. GEOLOGIC HAZARDS

7.1. Faulting

7.2. Landslides

7.3. Liquefaction

8. CONCLUSIONS

9. PRELIMINARY RECOMMENDATIONS

9.1. Earthwork and Excavations

9.2. Fill Placement and Compaction

9.3. Imported fill

9.4. Seismic Design Considerations

9.5. Foundations

9.6. Floor Slabs

9.7. Retaining Walls

9.8. Pavements

9.9. Gabions

9.9.1. Rock-fall Mitigation

9.10. Corrosion

9.11. Concrete

9.12. Site Drainage

9.13. Pre-Construction Conference

9.14. Construction Observation and Testing

10. LIMITATIONS

600587017R Site 1 ii

11. REFERENCES

Tables Table 1 – 2006 International Building Code Seismic Design Criteria Table 2 – Aggregate Base Gradation Table 3 – ACI Requirements for Concrete Exposed to Sulfate-Containing Soil

Figures Figure 1 – Site Location Map Figure 2 – Boring Location Map Figure 3 – Geologic Map Depicting Nearby Faults Figure 4 – Retaining Wall Drainage Guidelines

Appendices Appendix A – Boring Logs Appendix B – Laboratory Testing Appendix C – Preliminary Drainage Assessment Report (Wood Patel & Associates)

600587017R Site 1 1

1. INTRODUCTION

In accordance with our revised proposal dated October 27, 2009, and your authorization, we have performed a preliminary geotechnical evaluation for improvements to the existing Jemez

Ranger Station in the Santa Fe National Forest near Jemez Springs, New Mexico. The purpose of our evaluation was to assess the subsurface conditions at the site in order to formulate prelimi-nary geotechnical recommendations for the design and construction of the project. This report presents the results of our evaluation and our preliminary geotechnical conclusions and recom-mendations regarding the proposed construction.

2. SCOPE OF SERVICES

The scope of our services for the project generally included:

• Reviewing readily available aerial photographs and published geologic literature, including maps and reports pertaining to the project site and vicinity.

• Marking out the boring locations and notifying New Mexico One Call of the locations prior to drilling.

• Drilling, logging, and sampling seven small-diameter exploratory borings to depths ranging from approximately 6 to 15 feet below ground surface (bgs). The boring logs are presented in Appendix A.

• Performing laboratory tests on selected samples obtained from the borings to evaluate in-situ moisture content and dry density, gradation analysis, Atterberg limits, consolidation (re-sponse-to-wetting), and corrosivity characteristics (including pH, minimum electrical resistivity, soluble sulfates, and chlorides). The results of the laboratory testing are presented on the boring logs and/or Appendix B.

• Providing a preliminary hydrologic study performed by Wood Patel & Associates. The re-sults of this study are presented in Appendix C.

• Preparing this report presenting our findings, conclusions, and recommendations regarding the design and construction of the project.

Our scope of services did not include environmental consulting services such as hazardous waste sampling or analytical testing at the site. A detailed scope of services and estimated fee for such services can be provided upon request.

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3. SITE DESCRIPTION

The project site is situated adjacent to the east side of Highway 4 in the Santa Fe National Forest in New Mexico. The approximate location of the site is depicted on the Site Location Map (see

Figure 1). At the time of our evaluation, the project site generally consisted of an existing ranger station with several buildings, paved and unpaved parking areas, and a Ranger house. Several natural drainages converged and traversed adjacent to the site. Water collection channels to col-lect and divert water from the drainages away from the ranger station were observed. The Jemez

River was situated adjacent to the southwestern limits of the project site.

Buckling in the retaining walls adjacent to the river at the western limits of the site, as well as cracks in nearby buildings that extended from the foundation through the walls were observed during the site evaluation.

According to the Jemez Springs, New Mexico, 7.5-Minute United States Geological Survey

(USGS) Topographic Quadrangle Map (1976), the project site is situated at an elevation of ap-proximately 6,320 feet relative to mean sea level. The site is situated at the bottom of a steep slope that slopes from the east down to the west towards the Jemez River.

Three aerial photographs of the project site were reviewed for this project. A 1996 United States

Department of Agriculture (USDA), a 2005 USDA, and a 2006 Digital Globe aerial photograph depicted the site as being similar to its current condition, with several structures, a Ranger house, and paved and unpaved parking and access areas.

4. PROPOSED CONSTRUCTION

The project consists of the preliminary design for new structures at the existing Jemez Ranger station that will replace the existing facility. We understand that a typical Forest Service adminis-trative site generally contains the following: a 6,000 square foot office, a 3,600 square foot warehouse, a 900 square foot fire engine storage shed, a public parking lot, an employee parking lot for approximately 35 employees, and a gated and secured parking area for approximately 25

600587017R Site 1 3 government vehicles. At the time of our evaluation, the final design of the new Jemez Ranger

District facility was not yet finished.

5. FIELD EXPLORATION AND LABORATORY TESTING

On October 7, 2009, Ninyo & Moore conducted a subsurface evaluation at the site in order to evaluate the existing subsurface conditions and to collect soil samples for laboratory testing. Our evaluation consisted of the drilling, logging, and sampling of seven, small-diameter borings. The borings, denoted as B-1 through B-7, were advanced using a CME-75 truck-mounted drill rig equipped with hollow-stem augers. The location of the borings are depicted on the Boring Loca-tion Map (see Figure 2). The target depth of the borings was to be 15 feet bgs; however, auger refusal on cobbles and possible boulders was encountered in borings B-1 and B-2 at about 6 and

12 feet, respectively. Detailed descriptions of the soils encountered at each boring location are presented on the boring logs in Appendix A, Ninyo & Moore personnel logged the borings in general accordance with the Unified Soil Classi-fication System (USCS) and American Society for Testing and Materials (ASTM) D 2488 by observing cuttings and drive samples. Bulk and relatively undisturbed soil samples were col-lected at selected intervals. Relatively undisturbed ring samples were collected in the field, wrapped in plastic bags, and placed in moisture-tight containers, while the disturbed bulk sam-ples were placed in plastic bags to retain their moisture content.

The soil samples collected from our drilling activities were transported to the Ninyo & Moore laboratory in Phoenix, Arizona for geotechnical laboratory analysis. The analysis included in-situ moisture content and dry density, gradation analysis, Atterberg limits, consolidation (response-to-wetting), and corrosivity characteristics (including pH, minimum electrical resistivity, soluble sulfates, and chlorides). The results of the in-situ moisture content and dry density testing are presented on the boring logs in Appendix A. A description of each laboratory test method and the remainder of the test results are presented in Appendix B.

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6. GEOLOGY AND SUBSURFACE CONDITIONS

The geology and subsurface conditions at the site are described in the following sections.

6.1. Geologic Setting

The project site is located near the border of the western boundary of the Rio Grande Rift section of the Basin and Range physiographic province. This section is a north-south trend-ing zone that dissects New Mexico, and has caused deformation from extensional faulting in

Texas and Colorado. The northern limits of the Rio Grande rift are typified by westward-stepping, en echelon basins surrounded by volcanic mountains. Further south, the Rio

Grande Rift zone widens from extensional faulting (Keller and Cather, 1994).

The rift began forming approximately 36 million years ago in the early Tertiary period, when the Colorado Plateau began separating from the Central Highlands, resulting in a mid-continent separation and a subsiding inner valley. The extension resulted in steeply tilted margins to grabens (basins). Igneous intrusions moved into the extensional faults, resulting in volcanism along the rift boundaries. It has been estimated that as much as 15,000 feet of sediment has filled the alluvial basins within the rift. The Rio Grande River traverses along the Rio Grande Rift system (Keller and Cather, 1994).

Based on geologic maps of the area, the project site is situated on Holocene to Middle-

Pleistocene age (less than 10,000 years to 750,000 years) colluvial and alluvial deposits that generally consist of clay, silt, sand, gravel, and cobbles. The Madera and Abo Formations are underlying the colluvium at the site. These formations generally are composed of red siltstone, mudstone, sandstone, and white sandstone and limestone (Kelley, et. al, 2003).

6.2. Subsurface Conditions

Our knowledge of the subsurface conditions at the project site is based on our field explora-tion and laboratory testing, and our understanding of the general geology of the area. The following sections provide generalized descriptions of the materials encountered. More de-tailed descriptions are presented on the boring logs in Appendix A.

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6.3. Asphalt Concrete

Asphalt concrete (AC) was observed at the surface of each of B-1, B-2, B-6, and B-7, and was approximately 2 inches thick in our borings. Aggregate base was not observed underly-ing the AC in our borings.

6.3.1. Fill

Man-placed fill was encountered underlying the AC in the borings described above, and at the surface of borings B-3 through B-5. The fill ranged in thickness from approxi-mately 3 to 12 feet in our borings. The fill generally consisted of clayey sand and clayey gravel in our borings. Cobbles and possible boulders may be present in the fill.

6.3.2. Alluvium

Alluvium was encountered underlying the fill in each of our borings. The alluvium ex-tended to the remaining explored depth in our borings except in B-7, where alluvium extended to bedrock. The alluvium in our borings generally consisted of sandy clay, clayey sand, and clayey gravel. Cobbles and possible boulders were encountered in the alluvium.

6.3.3. Bedrock

Sandstone bedrock was encountered in boring B-7. The bedrock was described as a soft light brown to yellowish brown sandstone in our boring. This bedrock is described as a part of the Madera Formation.

6.4. Groundwater

Groundwater was not encountered in our borings. Based on nearby well data presented by the New Mexico State Engineer’s website, the regional depth to groundwater near the site has been measured to range from 12 to 30 feet bgs. Fluctuations in groundwater levels can change due to seasonal variations, the close proximity of the Jemez River, and runoff from

600587017R Site 1 6 the adjacent drainages. Nuisance water or seasonal perched groundwater might be encoun-tered in some excavations during construction depending on the seasonal conditions.

7. GEOLOGIC HAZARDS

The following sections describe potential geologic hazards at the site, specifically faulting and landslides.

7.1. Faulting

The project site is situated on the western boundary of the Rio Grande Rift zone, a seismi-cally active zone with numerous Quaternary extensional (normal) faults on the west and east sides of the inter-continental rift. Based on our field reconnaissance, and aerial photograph review, there are no known Quaternary faults underlying the project site; however the Jemez

Fault Zone has been mapped adjacent to the project site. Figure 3 depicts the approximately location relative to the project site. The Jemez Fault zone is a north-northeast trending series of normal faults that dip to the east (Kelson, 1997).

7.2. Landslides

Based on our review of regional geologic maps, landsliding and ground creeping have been documented near this project site in colluvial and alluvial material; however, evidence of landsliding was not observed at the project site during our field evaluation.

7.3. Liquefaction

Based on the Standard Penetration Test (SPT) values at the site, the general lack of near sur-face water, and the low ground motion hazard (relatively low ground accelerations), the potential for liquefaction at the project site is not a design consideration.

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8. CONCLUSIONS

Based on the results of our subsurface evaluation, laboratory testing, and data analysis, it is our opinion that the proposed construction is feasible from a geotechnical standpoint, provided that the preliminary recommendations of this report are incorporated into the design and construction of the proposed project, as appropriate. Geotechnical considerations include the following:

• Excavation of the surface on-site soils can generally be accomplished with heavy-duty earthmoving equipment. Cobbles and possible boulders, as well as bedrock was encountered in our borings and may result in difficult excavation conditions and may slow the excavation rate.

• Grade raise fill or any new structures should not obstruct any natural springs in the area.

• Drainage systems should be constructed to divert water collected by natural drainages and springs, if any, away from new structures and paved surfaces.

• Foundations, slabs, and pavements should be founded on a zone of moisture conditioned and compacted engineered fill.

• Imported soils and soils generated from on-site excavation activities that exhibit a low plas-ticity and very low to low swell potential and have a low organic content (less than 4 percent) can generally be used for engineered fill.

• Groundwater was not observed in our borings. Based on well data collected from nearby wells, the approximate depth to groundwater has been estimated to be 12 to 30 feet bgs.

Nuisance water or seasonal perched groundwater might be encountered in some excavations during construction depending on the seasonal conditions.

• A fault has been documented and mapped adjacent to the project site.

• Mitigation for rock-fall and water erosion should be designed at the site.

• Corrosivity test results indicate that subgrade soils generally exhibit low corrosive potential to ferrous metals and the sulfate content of the soils present a negligible sulfate exposure to concrete.

If any of the assumptions in this report are incorrect or if additional relevant information be-comes available, Ninyo & Moore should be notified for additional recommendations.

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9. PRELIMINARY RECOMMENDATIONS

The following sections present our preliminary recommendations for this project. A more de-tailed geotechnical evaluation should be conducted for this project prior to construction.

9.1. Earthwork and Excavations

Vegetation, topsoil (including organic-containing soils) and debris from the clearing opera-tion should be removed from the site and disposed of at a legal dumpsite away from the construction area. Obstructions that extend below finish grade, if present, should be removed and the resulting holes filled with compacted soil. Demolition debris and obstructions that extend below finish grade, if present, should be removed from the site and disposed in a le-gal dumpsite.

The on-site geotechnical representative should carefully evaluate any areas of soft or wet soils revealed during the site preparation activities prior to placement of grade-raise fill or other construction. Drying, stabilization and/or overexcavation of some materials should be anticipated during construction.

Our evaluation of the excavation characteristics of the on-site materials is based on the re-sults of seven exploratory borings, our site observations, and our experience with similar materials. In our opinion, excavation of the surface on-site material can generally be accom-plished to the anticipated depths with heavy-duty earth-moving equipment in good operating condition. However, our borings indicated the presence of cobbles and possible boulders and bedrock, which will be more difficult to excavate and/or slow the rate of excavation depend-ing on the actual size of the material encountered during construction.

Earthwork activities undertaken during the cold weather season may be difficult and should be done by an experienced contractor. Frost penetration of the ground should be anticipated during the cold weather season in this area and frozen soil should addressed by the contrac-tor each day. Fill should not be placed on top of frozen soils. Any frozen soils should be removed prior to the placement of new engineered fill or other construction material. Frozen

600587017R Site 1 9 soil may be reused (provided it meets the selection criteria) once it has thawed completely.

In addition, compaction of the soils may be more difficult. The need for full-time inspection and documentation during construction is emphasized.

Due to nearby springs and shallow groundwater conditions, the grade at the site should not be raised to an elevation that will obstruct the outlet of a spring, nor should structures be constructed that will obstruct the outlet of a spring. Drainage systems should be constructed to divert water collected by natural drainages and springs, if any, away from structures and paved surfaces.

9.2. Fill Placement and Compaction

On-site and imported soils that exhibit relatively low plasticity indices and very low to low expansive potential are generally suitable for re-use as engineered fill. Relatively low plas-ticity indices are defined as a plasticity index (PI) (by the American Society for Testing and

Materials [ASTM] 4318) value of 20 or less. Very low to low expansive potential soils are defined as having an expansion index (by ASTM D 4829) of 50 or less. The Atterberg limits test performed on selected samples from our borings resulted in PI values ranging from 11 to

19, demonstrating low to moderate plasticity. As such, it is our opinion that many of the on-site soils are suitable for re-use as engineered fill during construction. Additional field sam-pling and laboratory testing may need to be conducted by the contractor should any unsuitable soils be encountered during construction.

In addition, suitable fill should not include organic material, clay lumps, construction debris, rock particles, and other non-soil fill materials larger than 6 inches in dimension. Unsuitable fill material should be disposed of off site or in non-structural areas.

Some of the soils encountered in our borings exhibited a potential for collapse upon inunda-tion with water. In addition, undocumented fill was encountered in some of our borings.

Accordingly, we recommend that the proposed building foundations and retaining walls, if any, be founded on a zone of moisture-conditioned and compacted engineered fill, that could

600587017R Site 1 10 range from 2 to 4 feet below the foundation bearing elevation, or to firm native material as observed by a representative of the geotechnical engineer, whichever is deeper. Fill should be placed in horizontal lifts no more than approximately 8 inches in loose thickness and compacted by appropriate mechanical methods, to 95 percent, or more, relative compaction, in accordance with ASTM D 1557 at a moisture content generally within 2 percent of its laboratory optimum moisture. The overexcavation should extend laterally 2 to 4 feet hori-zontally beyond the foundation footprint.

We recommend that at-grade slabs and pavements be supported on 1 to 2 feet of moisture-conditioned and compacted engineered fill. This improved zone can either be improved by overexcavation or scarification. The fill thickness should be measured from the bottom of the base material. The fill should be compacted by appropriate mechanical methods, to 95 percent relative compaction, in accordance with ASTM D 1557 at a moisture content gener-ally within 2 percent of its laboratory optimum moisture. The overexcavation below these areas should extend laterally 1 to 2, or more, horizontally beyond the slab/pavement foot-print. Fill soils supporting concrete slabs or structures should be maintained in a moist condition until overlying structures are constructed.

Following the overexcavation as described above, and prior to the placement of new fill, the resulting exposed surface should be carefully evaluated by the geotechnical consultant for the presence of soft, loose, wet, or frozen native alluvial soils or fill soils that were not re-moved as part of the overexcavation process. Based on this evaluation, additional remediation may be needed. This could include scarification or drying out of the exposed surface. This additional remediation, if needed, should be addressed by the geotechnical consultant during the earthwork operations. An earthwork (shrinkage) factor of 10 to 20 per-cent for the on-site soils is estimated.

Backfill material used in trench excavations should be moisture-conditioned to a moisture content generally above its optimum moisture content. Placed backfill should be mechani-cally compacted to a relative compaction of 95 percent of the laboratory dry density as

600587017R Site 1 11 evaluated by ASTM D 1557. Placed backfill under pavements should be compacted to a relative compaction of 100 percent of the laboratory dry density. The thickness for backfill will be dependent upon the type of compaction equipment utilized, but should generally be placed in lifts not exceeding 8 inches in loose thickness. Special care should be exercised to avoid damaging the pipe or other structures during the compaction of the backfill. In addi-tion, the underside (or haunches) of the buried pipe should be supported on bedding material that is compacted as described above. This may need to be performed with placement by hand or small-scale compaction equipment.

9.3. Imported fill

Imported fill, if utilized, should consist of granular material with a very low or low expan-sion potential. Import material in contact with ferrous metals should preferably have low corrosion potential (minimum resistivity more than 2,000 ohm-cm, chloride content less than 25 parts per million [ppm]). In lieu of this, corrosion protection techniques (e.g. ca-thodic protection, pipe wrapping, etc.), can be implemented. A corrosion specialist should be consulted for recommendations. Imported material in contact with concrete should have a soluble sulfate content of less than 0.1 percent. The geotechnical consultant should evaluate such materials and details of their placement prior to importation.

9.4. Seismic Design Considerations

Based on a Probabilistic Seismic Hazard Assessment for the conterminous United States, is-sued by the USGS (2002 data), the site is located in a zone where the peak ground accelerations having 10, 5, and 2 percent probability of being exceeded in 50 years are

0.07g, 0.10g, and 0.16g, respectively. These ground motion values are calculated for "firm rock" sites, which correspond to a shear-wave velocity of approximately 2,500 feet per sec-ond in approximately the top 100 feet bgs. Different soil or rock types may amplify or de-amplify these values. The proposed improvements should be designed in accordance with the requirements of governing jurisdictions and applicable building codes. Table 1 presents

600587017R Site 1 12 the seismic design parameters for the site in accordance with International Building Code

(IBC, 2006) guidelines and mapped spectral acceleration parameters (USGS, 2008).

Table 1 – 2006 International Building Code Seismic Design Criteria

Seismic Design Factors Value Site Class D Site Coefficient, Fa 1.5 Site Coefficient, Fv 2.3 Mapped Spectral Acceleration at 0.2-second Period, Ss 0.567 g Mapped Spectral Acceleration at 1.0-second Period, S1 0.284 g Spectral Acceleration at 0.2-second Period Adjusted for Site Class, SMS 0.378 g Spectral Acceleration at 1.0-second Period Adjusted for Site Class, SM1 0.190 g Design Spectral Response Acceleration at 0.2-second Period, SDS 0.378 g Design Spectral Response Acceleration at 1.0-second Period, SD1 0.190 g

9.5. Foundations

We recommend utilizing spread or continuous footings for this project. Spread or continuous footings should be supported at a depth of 24 to 36 inches below the adjacent grade on mois-ture-conditioned, recompacted material, as described in Section 9.1.2. Continuous footings should have a width of 16 or more inches, and isolated column footings should have a width of 24 or more inches. Column or continuous footings should be reinforced in accordance with the recommendations of the structural engineer. Footings may be designed using an al-lowable bearing capacity ranging from 2,000 to 3,000 psf for static conditions.

Total and differential settlement of up to about 1 inch and 1/2 inch, respectively, may occur.

Distortions of about 1 inch (vertical) over 20 feet (horizontal) are possible.

Foundations bearing on moisture-conditioned recompacted material and subject to lateral loadings may be designed using an ultimate coefficient of friction of 0.35 (total frictional re-sistance equals the coefficient of friction multiplied by the dead load). A passive resistance value of 250 to 350 psf of depth can be used. The lateral resistance can be taken as the sum of the frictional resistance and passive resistance, provided that the passive resistance does

600587017R Site 1 13 not exceed one-half of the total ultimate resistance. The passive resistance may be increased by one-third when considering loads of short duration such as wind or seismic forces. The foundations should preferably be proportioned such that the resultant force from all loads, including lateral loadings falls within the kern (i.e., middle one-third of the footing base).

9.6. Floor Slabs

The design of the floor slabs is the responsibility of the structural engineer. However, from a geotechnical standpoint, we recommend that the floor slab have a thickness of 4 to 6 inches and be reinforced and jointing with steel as designed by a structural engineer. Placement of the reinforcement in the slab is vital for satisfactory performance. The slabs should be un-derlain by 4 to 6 inches of moist sand and/or gravel. The need for a moisture-retarding and/or vapor retarding system should be considered by the structural engineer or architect based on the moisture sensitivity of the anticipated flooring.

The floor slab should either be constructed so that it “floats” independent of the foundations or be designed to be structurally connected to the foundations. Based on the relatively low expansion potential of the on-site soils, and conversation with local county inspectors,, a post-tension slab-foundation system is needed for this project. Soils underlying the slabs should be moisture-conditioned and compacted in accordance with the recommendations contained in Section 9.2. Joints should be constructed at intervals designed by the structural engineer to help reduce random cracking of the slab.

9.7. Retaining Walls

Retaining wall foundations, if any, should be founded in the manner described in Sec-tion 9.2. Retaining walls that are not restrained from movement at the top and have a level backfill behind the wall may be designed using an “active” equivalent fluid unit weight of

35 pounds per cubic foot (pcf). This value assumes compaction within about 5 feet of the wall will be accomplished with relatively light compaction equipment, and that very low to low expansive backfill will be placed behind the wall. This value also assumes that the re-

600587017R Site 1 14 taining walls will have a height less than 12 feet. Retaining walls should also be designed to resist a horizontal earth pressure of 0.30q. The value for “q” represents the vertical surcharge pressure induced by adjacent light loads, slab, or traffic loads plus any adjacent footing loads.

The “at-rest” earth pressure against walls that are restrained at the top or braced so that they cannot yield, and with level backfill, may be taken as equivalent to the pressure exerted by a fluid weighing 55 pcf. Restrained retaining walls should also be designed to resist a horizon-tal earth pressure of 0.5q. The value for “q” represents the vertical surcharge pressure induced by adjacent light loads, slab, or traffic loads plus any adjacent footing loads.

For “passive” resistance to lateral loads, we recommend that an equivalent fluid weight of

250 to 350 pcf be used up to a value of 3,000 psf. This value assumes that the ground is horizontal for a distance of 10 feet or more behind the wall or three times the height generat-ing the passive pressure, whichever is more. We recommend that the upper 12 inches of soil not protected by pavement or a concrete slab be neglected when calculating passive resis-tance. For frictional resistance to lateral loads, we recommend that a coefficient of friction of

0.35 be used between soil and concrete. If passive and frictional resistances are to be used in combination, we recommend that the passive resistance be limited to one-half of the total ul-timate resistance. The passive resistance values may be increased by one-third when considering loads of short duration, such as wind or seismic forces.

Measures should be taken so that moisture does not build up behind retaining walls. Retain-ing walls should be provided with a drain, as shown on Figure 3. Back drainage measures should include free-draining backfill material and perforated drainpipes or weepholes. In lieu of the wrapped open-graded gravel, a geocomposite drainage mat attached to the wall and discharging into the drain pipe or weep holes may be considered. Drainpipes should out-let away from structures, and retaining walls should be waterproofed in accordance with the recommendations of the project civil engineer or architect. To reduce the potential for water-and sulfate/salt-related damage to the retaining walls, particular care should be taken in the

600587017R Site 1 15 selection of the appropriate type of waterproofing material to be utilized and in the applica-tion of this material.

9.8. Pavements

For the paved areas, we understand that both asphalt concrete (AC) and Portland cement concrete (PCC) sections may be considered. The design parameters for these pavement sec-tions should include a 20-year design life, equivalent single axle loads (ESAL) of 18 kips, and an assumed traffic load of 100,000 ESALs. The pavement sections given below are as-sumed to bear on imported or on-site soils with an average soil R-value of 20 or more.

PCC pavements are recommended for areas that will experience regular truck traffic, load-ing dock areas, main ingress and egress areas, and in areas where vehicles will be turning or loading (e.g., adjacent to trash dumpsters). PCC in heavy traffic areas should have a thick-ness of 8 to 10 inches, with edges thickened to 10 to 12 inches. In parking areas not subject to truck traffic, the concrete pavement thickness can be reduced to 6 to 8 inches, with edges thickened to 8 to 10 inches.

Concrete pavements should have longitudinal and transverse joints that meet the applicable requirements of Sandoval County. Concrete pavements should be underlain by 4 to 6 inches or more of aggregate base (AB) that meets Federal Lands Highway Standard Specifications for Construction of Roads and Bridges (FLH). The AB described in the pavement sections below should meet Section 703 of the FLH specifications requirements, as shown in Table 2.

Table 2 – Aggregate Base Gradation

Percent Passing by Mass Designated Sieve (AASHTO T 27 and T11) Grading Designation Sieve Size

D (Base) E (Base) 2 inch

1-1/2 inch 1 inch 100

3/4 inch 86-100 100 1/2 inch 3/8 inch 51-82 62-90

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Table 2 – Aggregate Base Gradation

Percent Passing by Mass Designated Sieve (AASHTO T 27 and T11) Grading Designation Sieve Size

D (Base) E (Base) No. 4 36-64 36-74

No. 40 12-26 12-26 No. 200 4-7 4-7

Max Liquid Limit 25

The minimal reinforcement for the concrete pavement areas should be No. 4 reinforcing bars placed 18 inches on-center (each way) in the middle one-third of slab height. The structural engineer may decide that additional reinforcement is needed. Concrete pavement should in-clude control joints with spacing as deemed appropriate by the structural engineer.

An AC pavement section consisting of 3 to 5 inches, or more, of plant-mix asphalt (per FLH

Section 400) over 6 to 8 inches, or more, of graded AB can be considered in the standard duty parking areas. For heavier traveled areas of the parking lot, an AC pavement section consisting of 3 to 5 inches, or more of plant-mix asphalt over 9 to 11 inches, or more, of graded AB can be utilized.

For both the PCC and AC pavements given above, we recommend the underlying subgrade soils be prepared as described in Section 9.2 of this report. AB material should be compacted to a relative compaction of 100 percent of the maximum dry density, as evaluated by

AASHTO T99, at a moisture content within approximately 2 percent of optimum.

9.9. Gabions

Gabion baskets may be used for erosion protection for the areas near drainages and the river.

Gabion baskets are constructed of special, galvanized wires, which form a grid that contains cobbles or rip/rap. The manufacturer should be contacted to evaluate if the wires are appro-priate for the chemical content of the soil and water in the wash.

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Gabion baskets should be placed as erosion control at no steeper than a 1.5 H to 1 V slope, and should be underlain by a filter fabric placed on top of compacted earth embankments.

Gabion baskets can be stacked to form retaining walls, and if slopes steeper than 1.5 to 1 are desired, analysis for their use as a retaining wall should be considered.

For scour protection, a “Reno-Mat” gabion mattress could be placed along the bottom of the channel (or buried at a shallow depth). The gabion mattress would be hinged to the gabion baskets. The length and thickness of the gabion mattress should be specified by the designer, and may need to be longer than the scour depth.

9.9.1. Rock-fall Mitigation

A rock-fall barrier wall may be used to protect parking areas and structures near the toe of the slope. These walls should be founded in the manner as described in Section 9.5.

These walls should be designed to mitigate cobbles and boulders that are transferred down slope towards the structures.

As an alternative to rock fall mitigation, a rock collection ditch may be constructed be-tween the toe of the slope and the structures to be protected. A rock-fall evaluation should be conducted for further recommendations regarding the geometry of the ditch

(e.g. side slopes, width, and depth).

9.10. Corrosion

The corrosion potential of the on-site materials was analyzed to evaluate its potential effect on the underground utilities and structures. Corrosion potential was evaluated using the re-sults of laboratory testing obtained during our subsurface evaluation.

Laboratory testing on the samples tested consisted of pH, minimum electrical resistivity, and chloride and soluble sulfate contents. The results of the corrosivity tests are presented in Ap-pendix B.

600587017R Site 1 18

The soil pH value of the sample tested was 7.6, which is considered to represent an alkaline environment. The electrical resistivity value measured in the laboratory was 2,326 ohm-cm, which is not considered to be a corrosive environment to ferrous metals. The chloride con-tent of the sample tested was 13 parts per million (ppm), which also does not indicate a potentially corrosive environment to ferrous metals. The soluble sulfate content of the soil sample was measured to be 0.002 percent by weight, which represents a negligible sulfate exposure for concrete.

The results of the laboratory testing indicate that the on-site materials generally are not cor-rosive to ferrous metals; nevertheless we recommend special consideration be given to the use of heavy gauge, corrosion protected steel pipe, or pipe wrapping. To minimize corrosion of buried metallic utilities, we recommend that topsoil, organic soils, existing fill soils, and mixtures of sand and clay not be placed adjacent to buried metallic utilities. We suggest a clean sand or gravel be placed around buried metal piping. Also, buried utilities of different metallic construction should be electrically isolated from each other to minimize galvanic corrosion problems and new piping should be electrically isolated from old piping so that the old metal will not increase the corrosion rate of the new metal. A corrosion specialist should be consulted for further recommendations.

9.11. Concrete

Laboratory chemical tests performed on selected samples of on-site soils indicated a sulfate content of 0.002 percent by weight. Based on the following American Concrete Institute

(ACI) table, the on-site soils should be considered to have a negligible sulfate exposure to concrete.

600587017R Site 1 19

Table 3 – ACI Requirements for Concrete Exposed to Sulfate-Containing Soil f’c, Normal-Weight and Lightweight

Aggregate Con-crete, psi

Sulfate Exposure

Water- Soluble Sulfate

(SO4) in Soil, Percentage by Weight

Cement Type

Water- Cementitious Materials

Ratio, by Weight, Normal-Weight

Aggregate Concrete1 x 0.00689 for MPa Negligible 0.00 - 0.10 -- -- --

Moderate2 0.10 - 0.20 II, IP(MS), IS (MS) 0.50 or less 4,000 or more

Severe 0.20 - 2.00 V 0.45 or less 4,500 or more

Very severe Over 2.00 V plus pozzolan3 0.45 or less 4,500 or more

1 A lower water-cementitious materials ratio or higher strength may be needed for low permeability or for protection against corrosion of embedded items or freezing and thawing (ACI Table 4.2.2).

2 Seawater.

3 Pozzolan that has been evaluated by test or service record to improve sulfate resistance when used in concrete containing Type V cement.

Notwithstanding the sulfate test results and due to the limited number of chemical tests per-formed, as well as our experience with similar soil conditions, we recommend the use of

Type II cement for construction of concrete structures at this site. Due to potential uncertain-ties as to the use of reclaimed irrigation water, or topsoil that may contain higher sulfate contents, pozzolan, or admixtures designed to increase sulfate resistance may be considered.

The concrete should have a water-cementitious materials ratio no more than 0.50 by weight for normal weight aggregate concrete. The structural engineer should ultimately select the concrete design strength based on the project specific loading conditions. Higher strength concrete may be selected for increased durability and resistance to slab curling and shrink-age cracking. For this project, air entrainment should be considered for exposed concrete.

In order to reduce the potential for shrinkage cracks in the concrete during curing, we rec-ommend that for slabs-on-grade, the concrete be placed with a slump in accordance with

Table 5.2.1 of Section 302.1R of “Guidelines for Floor and Slab Construction,” or Table 2.2

600587017R Site 1 20 of Section 332R in “Guidelines for Residential Cast-in-Place Concrete Construction.” If a higher slump is needed for screeding and leveling, a superplasticizer is recommended to achieve the higher slump without changing the recommended water to cement ratio. The slump should be checked periodically at the site prior to concrete placement. We also rec-ommend that crack control joints be provided in slabs in accordance with the recommendations of the structural engineer to reduce the potential for distress due to minor soil movement and concrete shrinkage. We further recommend that concrete cover over rein-forcing steel for slabs on grade and foundations be in accordance with IBC 1907.7.1. The structural engineer should be consulted for additional concrete specifications.

9.12. Site Drainage

A preliminary drainage assessment of the project site was performed by Wood Patel & Asso-ciates. This study consists of a preliminary study of the hydraulic and hydrologic conditions at the site and is presented in Appendix C.

Surface drainage should be provided to divert water away from the building and off of paved surfaces. Surface water should not be permitted to drain toward the structures or to pond ad-jacent to footings or on pavement areas. Roof gutters should be installed on structures.

Downspouts should discharge to drainage systems away from structures, pavements, and flatwork. Drainage systems should be constructed to divert water collected by natural drain-ages and springs, if any, away from structures and paved surfaces. Positive drainage for this project is defined as a slope of 2 or more percent for a distance of 5 or more feet away from the structures. Soil improvements below the new grade slabs and pavement sections should be sloped toward the edges of these areas.

9.13. Pre-Construction Conference

We recommend that a pre-construction conference be held. Representatives of the owner, the civil engineer, the geotechnical consultant, and the contractor should be in attendance to dis-

600587017R Site 1 21 cuss the project plans and schedule. Our office should be notified if the project description included herein is incorrect, or if the project characteristics are significantly changed.

9.14. Construction Observation and Testing

During construction operations, we recommend that a qualified geotechnical consultant per-form observation and testing services for the project. These services should be performed to evaluate exposed subgrade conditions, including the extent and depth of overexcavation, to evaluate the suitability of proposed borrow materials for use as fill and to observe placement and test compaction of fill soils. If another geotechnical consultant is selected to perform ob-servation and testing services for the project, we request that the selected consultant provide a letter to the owner, with a copy to Ninyo & Moore, indicating that they fully understand our recommendations and that they are in full agreement with the recommendations con-tained in this report. Qualified subcontractors utilizing appropriate techniques and construction materials should perform construction of the proposed improvements.

10. LIMITATIONS

The field evaluation, laboratory testing, and geotechnical analyses presented in this geotechnical report have been conducted in general accordance with current practice and the standard of care exercised by geotechnical consultants performing similar tasks in the project area. No warranty, expressed or implied, is made regarding the conclusions, recommendations, and opinions pre-sented in this report. There is no evaluation detailed enough to reveal every subsurface condition.

Variations may exist and conditions not observed or described in this report may be encountered during construction. Uncertainties relative to subsurface conditions can be reduced through addi-tional subsurface exploration. Additional subsurface evaluation will be performed upon request.

Please also note that our evaluation was limited to assessment of the geotechnical aspects of the project, and did not include evaluation of structural issues, environmental concerns, or the pres-ence of hazardous materials.

600587017R Site 1 22

This document is intended to be used only in its entirety. No portion of the document, by itself, is designed to completely represent any aspect of the project described herein. Ninyo & Moore should be contacted if the reader requires additional information or has questions regarding the content, interpretations presented, or completeness of this document.

This report is intended for design purposes only. It does not provide sufficient data to prepare an accurate bid by contractors. It is suggested that the bidders and their geotechnical consultant per-form an independent evaluation of the subsurface conditions in the project areas. The independent evaluations may include, but not be limited to, review of other geotechnical reports prepared for the adjacent areas, site reconnaissance, and additional exploration and laboratory testing.

Our conclusions, recommendations, and opinions are based on an analysis of the observed site conditions. If geotechnical conditions different from those described in this report are encoun-tered, our office should be notified and additional recommendations, if warranted, will be provided upon request. It should be understood that the conditions of a site could change with time as a result of natural processes or the activities of man at the subject site or nearby sites. In addition, changes to the applicable laws, regulations, codes, and standards of practice may occur due to government action or the broadening of knowledge. The findings of this report may, there-fore, be invalidated over time, in part or in whole, by changes over which Ninyo & Moore has no control.

This report is intended exclusively for use by the client. Any use or reuse of the findings, conclu-sions, and/or recommendations of this report by parties other than the client is undertaken at said parties’ sole risk.

600587017R Site 1 23

11. REFERENCES

American Concrete Institute, 1991a, Guidelines for Concrete Floor and Slab Construction (ACI 302.1R).

American Concrete Institute, 1991b, Guidelines for Residential Cast-in-Place Concrete Con-struction (ACI 332R).

American Society for Testing and Materials (ASTM), 2009 Annual Book of ASTM Standards.

Federal Lands Highway Standard Specifications for Construction of Roads and bridges on Fed-eral Highway Projects, FP-03.

International Code Council, 2006, International Building Code.

Keller, G.R., and Cather, S.M., 1994, Basins of the Rio Grande rift: Structure, stratigraphy, and tectonic setting: Geological society of America special Paper 291, 304 pp.

Kelson, K.I., and Personius, S.F., compilers, 1997, Fault number 2029a, Jemez-San Ysidro fault, Jemez section, in Quaternary fault and fold database of the United States: U.S. Geologi-cal Survey website, http://earthquakes.usgs.gov/regional/qfaults, accessed 11/25/2009

03:43 PM.

New Mexico Bureau of Geology and Mineral Resources, 2003, Preliminary Geologic Map of the Jemez Springs 7.5 Minute Quadrangle, Sandoval County, New Mexico. Open File Report

OF-GM 73.

New Mexico Office of the State Engineer, 2009, WATERS database, World Wide Web, http://www.ose.state.nm.us/waters_db_index.html

Ninyo & Moore, In-house proprietary information.

United States Geological Survey, 1976, Jemez Springs, 7.5 Minute Series (Topographic): Scale 1" = 2,000'.

United States Geological Survey, 2002, National Seismic Hazard Mapping Project, World Wide Web, http://geohazards.cr.usgs.gov/eq.

SITE LOCATION MAP

FIGURE

1DATE:

2/10 file no: 0587vmap1209a

PROJECT NO:

600587017

Ap p ro x i ma te Sca l e :

1 i n ch = 30 0 0 f e e t

Source: US Geological Survey 7.5-minute topographic map, Jemez Springs, New Mexico, 1970, rev. 1976.

APPROXIMATE

SITE LOCATION

N

SANTA FE NATIONAL FOREST, NEW MEXICO

JEMEZ RANGER STATION SITE 1

Source: Map supplied from Wood / Patel, 2009.

Ap p ro x i ma te Sca l e :

1 i n ch = 80 f e e t fil e n o b lm a

BORING LOCATION MAP

FIGURE

2DATE:

12/09

N

PROJECT NO:

600587017 SANTA FE NATIONAL FOREST, NEW MEXICO

JEMEZ RANGER STATION SITE 1

LEGEND

Approximate Boring LocationB-7

B-6

B-5

B-4

B-3

B-1B-2

B-7

Source: Preliminary map of the Jemez Springs 7.5 minute quadrangle, Sandoval County, New Mexico, 2003.

fil e n o g e o a

GEOLOGIC MAP DEPICTING NEARBY FAULTS

FIGURE

3DATE:

2/10

PROJECT NO:

600587017 SANTA FE NATIONAL FOREST, NEW MEXICO

JEMEZ RANGER STATION SITE 1

POTENTIAL UNDERLYING

FAULTS

JEMEZ FAULT ZONE

N

APPROXIMATE

SITE LOCATION

NOT TO SCALE

file no: 0587rwd1209a

RETAINING WALL

DRAINAGE GUIDELINES

FIGURE

SOIL BACKFILL COMPACTED

PER REPORT

OUTLET

4-INCH-DIAMETER PERFORATED

SCHEDULE 40 PVC PIPE OR EQUIVALENT

INSTALLED WITH PERFORATIONS DOWN;

1% GRADIENT OR MORE TO A SUITABLE

3/4-INCH OPEN-GRADED GRAVEL WRAPPED

IN AN APPROVED GEOFABRIC.

3 INCHES

WALL FOOTING

FINISHED GRADE

RETAINING WALL

12 INCHES

V A

R

IE

S

12 INCHES

6 INCHES OR MORE

GEOFABRIC

PROJECT NO:

600587017

DATE:

2/10

SANTA FE NATIONAL FOREST, NEW MEXICO

JEMEZ RANGER STATION SITE 1

NOTE: IN LIEU OF THE WRAPPED OPEN-GRADED

GRAVEL, A GEOCOMPOSITE DRAINAGE MAT

ATTACHED TO THE WALL AND DISCHARGING

INTO THE DRAIN PIPE OR WEEP HOLES MAY

BE CONSIDERED.

NOT TO SCALE

NOT FOR CONSTRUCTION

600587017R Site 1

APPENDIX A

BORING LOGS

Field Procedure for the Collection of Disturbed Samples Disturbed soil samples were obtained in the field using the following methods.

Bulk Samples Bulk samples of representative earth materials were obtained from the exploratory borings.

The samples were bagged and transported to the laboratory for testing.

The Standard Penetration Test Spoon Disturbed drive samples of earth materials were obtained by means of a Standard Penetra-tion Test spoon sampler. The sampler is composed of a split barrel with an external diameter of 2 inches and an unlined internal diameter of 1-3/8 inches. The spoon was driven up to 18 inches into the ground with a 140-pound hammer free-falling from a height of 30 inches in general accordance with ASTM D 1586.