Geotechnical Engineering Report

Transcription

1 Geotechnical Engineering Report Richardson Subdivision Apartments 37th Street and Grand Avenue Artesia, New Mexico September 13, 2011 Terracon Project No Prepared for: Development Design & Engineering, Inc. El Centro, California Prepared by: Terracon Consultants, Inc. Las Cruces, New Mexico

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3 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No TABLE OF CONTENTS Page EXECUTIVE SUMMARY... i 1.0 INTRODUCTION PROJECT INFORMATION Project Description Site Location and Description SUBSURFACE CONDITIONS Typical Subsurface Profile Groundwater RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION Geotechnical Considerations Earthwork Site Preparation Excavation Subgrade Preparation Fill Materials and Placement Compaction Requirements Grading and Drainage Corrosion Potential Foundation Recommendations Design Recommendations Construction Considerations Seismic Considerations Floor Slabs Design Recommendations Construction Considerations Pavements GENERAL COMMENTS...13 Exhibit No. Appendix A Field Exploration Site Location Map and Boring Location Plan... A-1 and A-2 Field Exploration Description... A-3 Boring Logs... A-4 thru A-11 General Notes... A-12 Unified Soil Classification System... A-13 Appendix B Laboratory Testing Laboratory Test Description... B-1 Laboratory Test Results... B-2 thru B-6 Reliable Responsive Convenient Innovative

4 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No EXECUTIVE SUMMARY This geotechnical executive summary should be used in conjunction with the entire report for design and/or construction purposes. It should be recognized that specific details were not included or fully developed in this section, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. The section titled General Comments should be read for an understanding of the report limitations. A geotechnical exploration has been performed for the Richardson Subdivision Apartments located near the northeast corner of 37th Street and Grand Avenue in Artesia, New Mexico. The proposed project will include a residential subdivision (approximately 3. acres) with a government controlled 80 unit multi-family apartment complex (10 structures with a community services building). Paved parking and drive areas are also associated with the project. Terracon s geotechnical scope of work included the advancement of eight (8) test borings to approximate depths ranging from 11-1/2 to 21-1/2 feet below existing site grades (bgs). Based on the information obtained from our subsurface exploration, the site is suitable for development of the proposed project. The following geotechnical considerations were identified: The site soils in the building areas generally consisted of compressible and expansive lean clay with varying amounts of sand from the surface to the total explored depths (11-1/2 to 21-1/2 feet bgs). Groundwater was not encountered in the test borings at the time of drilling. Due to the presence of compressible and expansive soils on the site, standard spread and continuous footings bearing on a minimum of 3 feet of engineered fill may be used for support of the structures. The majority of on-site clay soils do not appear suitable for use as engineered fill beneath foundations and floor slabs. However, on-site clay soils may be blended with imported granular soils to meet the engineered fill specification contained in this report. Standard spread and continuous foundations are used for support of the structures, construction of floor slabs on a minimum thickness of 3 feet of engineered fill composed of approved blended on-site or imported soils is considered acceptable for the project. Automobile parking areas 3 AC over 6 ABC over 10 Compacted Subgrade. 3 th Street 4-1/2 AC over 6 ABC over 10 Compacted Subgrade Earthwork on the project should be observed and evaluated by Terracon. The evaluation of earthwork should include observation and testing of engineered fill, subgrade preparation, foundation bearing soils, and other geotechnical conditions exposed during construction Reliable Responsive Convenient Innovative i

5 GEOTECHNICAL ENGINEERING REPORT RICHARDSON SUBDIVISION APARTMENTS NEC OF 37 TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO Terracon Project No September 13, INTRODUCTION This report presents the results of our geotechnical engineering services performed for the Richardson Subdivision Apartments located near the northeast corner of 37 th Street and Grand Avenue in Artesia, New Mexico. The proposed project will include a residential subdivision (approximately 3. acres) with a government controlled 80 unit multi-family apartment complex (10 structures with a community services building). Paved parking and drive areas are also associated with the project. Items addressed in this report are as follows: subsurface soil conditions groundwater conditions earthwork foundation design and construction seismic considerations floor slab design and construction pavements Our geotechnical engineering scope of work for this project included the advancement of eight test borings to depths ranging from approximately 11-1/2 to 21-1/2 feet below existing site grades. Logs of the borings along with a Site Location Map and Boring Location Plan (Exhibits A-1 and A- 2) are included in Appendix A of this report. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included in Appendix B of this report. Descriptions of the field exploration and laboratory testing are included in their respective appendices. 2.0 PROJECT INFORMATION 2.1 Project Description Site layout ITEM DESCRIPTION Refer to the Site Location Map and Boring Location Plan (Exhibits A-1 and A-2) Reliable Responsive Convenient Innovative 1

6 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No Structures ITEM Building construction Finished floor elevation Maximum loads Maximum allowable movement Maximum allowable differential movement Grading in building area Retaining walls Cut and fill slopes DESCRIPTION The proposed project will include a residential subdivision (approximately 3. acres) with a government controlled 80 unit multi-family apartment complex (10 structures with a community services building). The buildings will be single-story and two-story structures. Paved parking and roadway areas (portion of 3 th Street) are associated with the project. The buildings will consist of wood frame bearing on exterior and interior spot footings. The floor system is anticipated to be slab-ongrade. Existing Columns: 1 to 40 kips maximum (assumed) Walls: 2.0 klf maximum (assumed) Slabs: 10 psf max (assumed) 1 inch ½ inch over 40 feet for walls, ¾ inch over 40 feet for interior columns (assumed) Minimal cuts and fills are anticipated None None 2.2 Site Location and Description ITEM Location Existing site features Surrounding developments Current ground cover Existing topography DESCRIPTION Northeast of 37 th Street and Grand Avenue in Artesia, New Mexico Vacant lot. Evidence of previous development was not observed during the field exploration North: Single Family Residential East: Undeveloped West: 37 th Street South: Single Family Residential Subgrade soils sparsely vegetated with native grasses and mesquite bush. Construction debris piles were located throughout the site. Relatively flat Reliable Responsive Convenient Innovative 2

7 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No SUBSURFACE CONDITIONS 3.1 Typical Subsurface Profile Specific conditions encountered at the boring locations are indicated on the individual boring logs. Stratification boundaries on the boring logs represent the approximate location of changes in soil types; in-situ, the transition between materials may be gradual. Details for each of the borings can be found on the boring logs included in Appendix A of this report. Based on the results of the borings, subsurface conditions on the project site can be generalized as follows: Description Approximate Depth to Bottom of Stratum (feet) Stratum /2 to 21-1/2 Material Encountered Lean Clay with varying amounts of gravel, sand and carbonate cementation Consistency/Density Stiff to Hard Laboratory tests were conducted on selected soil samples and the test results are presented in Appendix B. The soil samples tested have a slight to significant tendency for hydrocompaction when elevated in moisture content. It is likely that some sample disturbance occurred due to the high blow counts and low moisture contents of tested samples. It is our opinion that the soils will exhibit low to moderate compression potential and low to moderate expansive potentials. 3.2 Groundwater Groundwater was not observed in the test borings at the time of field exploration. These observations represent groundwater conditions at the time of the field exploration and may not be indicative of other times, or at other locations. Groundwater conditions can change with varying seasonal and weather conditions, and other factors. 4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION 4.1 Geotechnical Considerations Due to the presence of compressible/expansive soils and based on the geotechnical engineering analyses, subsurface exploration and laboratory test results, Terracon recommends that the proposed structures be supported by standard spread and continuous footings bearing on a minimum thickness of 3 feet of engineered fill. Reliable Responsive Convenient Innovative 3

8 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No Low to moderate expansive soils are present on this site. This report provides recommendations to help mitigate the effects of soil shrinkage and expansion. However, even if these procedures are followed, some movement and (at least minor) cracking in the structures should be anticipated. The severity of cracking and other cosmetic damage such as uneven floor slabs will probably increase if any modification of the site results in excessive wetting or drying of the expansive soils. Eliminating the risk of movement and cosmetic distress may not be feasible, but it may be possible to further reduce the risk of movement if significantly more expensive measures are used during construction which may include additional engineered fill thicknesses and/or structural slabs. We would be pleased to discuss other construction alternatives with you upon request. Geotechnical engineering recommendations for foundation systems and other earth connected phases of the project are outlined below. The recommendations contained in this report are based upon the results of field and laboratory testing (which are presented in Appendices A and B), engineering analyses, and our current understanding of the proposed project. 4.2 Earthwork The following presents recommendations for site preparation, excavation, subgrade preparation and placement of engineered fills on the project. The recommendations presented for design and construction of earth supported elements including foundations and slabs are contingent upon following the recommendations outlined in this section. All grading for the structures should incorporate the limits of the proposed structures plus a minimum pad blow-up of five feet beyond proposed perimeter building walls (where applicable). Earthwork on the project should be observed and evaluated by Terracon. The evaluation of earthwork should include observation and testing of engineered fill, subgrade preparation, foundation bearing soils, and other geotechnical conditions exposed during the construction of the project Site Preparation Strip and remove existing vegetation, construction piles, surface debris and other deleterious materials from proposed building area. Exposed surfaces should be free of mounds and depressions which could prevent uniform compaction. Stripped materials consisting of vegetation and organic materials should be wasted from the site, or used to revegetate landscaped areas or exposed slopes after completion of grading operations. If it is necessary to dispose of organic materials on-site, they should be placed in non-structural areas, and in fill sections not exceeding feet in height. Reliable Responsive Convenient Innovative 4

9 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No The site should be initially graded to create a relatively level surface to receive fill, and to provide for a relatively uniform thickness of fill beneath the proposed building structures. Although evidence of underground facilities such as septic tanks, cesspools, utilities and basements was not observed during the site reconnaissance, such features could be encountered during construction. If unexpected fills or underground facilities are encountered, such features should be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction Excavation It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment. On-site soils may pump or become unstable or unworkable at high water contents. Workability may be improved by scarifying and drying. Overexcavation of wet zones and replacement with granular materials may be necessary. Lightweight excavation equipment may be required to reduce subgrade pumping Subgrade Preparation A minimum of 3 feet of engineered fill is recommended below spread and continuous foundations and a minimum of 2 feet of engineered fill is recommended beyond the lateral extents of the foundations. The engineered fill should extend laterally an additional distance of 8 inches for each additional foot of excavation beyond the 3-foot minimum depth. Additionally, the engineered fill should extend horizontally a minimum distance of feet beyond the outside edge of the slab perimeter. The majority of clean on-site soils do not appear suitable for use as engineered fill at this site. Site soils (clays) that do not meet the engineered fill specifications can be blended with imported granular soils to achieve the recommended fill parameters provided in this report. Additional effort will be required by the earthwork contractor to moisture condition and blend the on-site clay soils with imported soils for use as engineered fill. Exposed areas which will receive fill, once properly cleared and benched where necessary, should be scarified to a minimum depth of ten inches, conditioned to near optimum moisture content, and compacted. Areas of loose or soft soils may be encountered at foundation bearing depth after excavation is completed for footings. When such conditions exist beneath planned footing areas, the subgrade soils should be surficially compacted prior to placement of the foundation system. If sufficient compaction can not be achieved in-place, the loose soils should be removed and replaced as engineered fill. For placement of engineered fill below Reliable Responsive Convenient Innovative

10 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No footings, the excavation should be widened laterally, at least eight inches for each foot of fill placed below footing base elevations. Subgrade soils beneath exterior slabs should be scarified, moisture conditioned and compacted to a minimum depth of 10 inches. The moisture content and compaction of subgrade soils should be maintained until slab or pavement construction Fill Materials and Placement All fill materials should be inorganic soils free of vegetation, debris, and fragments larger than six inches in size. Pea gravel or other similar non-cementitious, poorly-graded materials should not be used as fill or backfill without the prior approval of the geotechnical engineer. Approved imported materials or blended soils may be used as fill material for the following: general site grading exterior slab areas foundation areas foundation backfill pavement areas Imported or blended soils for use as fill material within proposed building areas should conform to low volume change materials as indicated in the following specifications: Percent Finer by Weight Gradation (ASTM C 136) 6" No. 4 Sieve No. 200 Sieve Liquid Limit... 3 (max) Plasticity Index... 1 (max) Maximum expansive potential (%)* *Measured on a sample compacted to approximately 9 percent of the ASTM D698 maximum dry density at about 3 percent below optimum water content. The sample is confined under a 100 psf surcharge and submerged/inundated. Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift. Fill lifts should not exceed ten inches loose thickness. Reliable Responsive Convenient Innovative 6

11 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No Compaction Requirements Recommended compaction and moisture content criteria for engineered fill materials are as follows: Material Type and Location Per the Modified Proctor Test (ASTM D 17) Minimum Compaction Requirement (%) Range of Moisture Contents for Compaction Minimum Maximum Approved on-site or imported fill soils: Beneath foundations: 9 0% +3% Beneath slabs: 9 0% +3% Beneath pavements: 9 0% +3% Miscellaneous backfill 90 0% +3% Grading and Drainage Positive drainage should be provided during construction and maintained throughout the life of the project. Infiltration of water into utility trenches or foundation excavations should be prevented during construction. Planters and other surface features which could retain water in areas adjacent to the buildings should be sealed or eliminated. In areas where sidewalks or paving do not immediately adjoin the structures, we recommend that protective slopes be provided with a minimum grade of approximately percent for at least 10 feet from perimeter walls. Backfill against footings, exterior walls, and in utility and sprinkler line trenches should be well compacted and free of all construction debris to reduce the possibility of moisture infiltration. Downspouts, roof drains or scuppers should discharge into splash blocks or extensions when the ground surface beneath such features is not protected by exterior slabs or paving. Sprinkler systems should not be installed within five feet of foundation walls. Landscaped irrigation adjacent to the foundation systems should be minimized or eliminated Corrosion Potential Soluble sulfate testing from the general area indicates that ASTM Type I Portland cement is suitable for all concrete on and below grade. However, the use of ASTM Type II Portland cement is recommended for additional sulfate resistance of construction concrete based on the published information. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. Reliable Responsive Convenient Innovative 7

12 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No Foundation Recommendations The building structures can be supported by spread footings bearing on engineered fill. Design recommendations for foundations for the proposed structures and related structural elements are presented in the following paragraphs Design Recommendations Foundation Type Structures Bearing Material DESCRIPTION Allowable Bearing Pressure Minimum Embedment Depth Below Finished Grade Total Estimated Movement Estimated Differential Movement VALUE Spread and Continuous Footings The proposed project will include a residential subdivision (approximately 3. acres) with a government controlled 80 unit multi-family apartment complex (10 structures with a community services building). The buildings will be single-story and twostory structures. Minimum 3-foot thickness of engineered fill for support of spread footings and continuous footings. 2,000 psf 18 inches 1 inch ½ inch in 40 feet under walls Finished grade is defined as the lowest adjacent grade within five feet of the foundation for perimeter (or exterior) footings and finished floor level for interior footings. The allowable foundation bearing pressures apply to dead loads plus design live load conditions. The design bearing pressure may be increased by one-third when considering total loads that include wind or seismic conditions. The weight of the foundation concrete below grade may be neglected in dead load computations. Exterior footings should be placed a minimum of 18 inches below finished grade to provide confinement for the bearing soils. Finished grade is the lowest adjacent grade for perimeter footings and floor level for interior footings. Footings should be proportioned to reduce differential foundation movement. Proportioning on the basis of equal total movement is recommended; however, proportioning to relative constant dead-load pressure will also reduce differential movement between adjacent footings. Additional foundation movements could occur if water from any source infiltrates the foundation soils; therefore, proper drainage must be provided in the final design and during construction. Reliable Responsive Convenient Innovative 8

13 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No Footings, foundations, and masonry walls should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement. The use of joints at openings or other discontinuities in masonry walls is recommended. Foundation excavations and engineered fill placement should be observed by the geotechnical engineer. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required Construction Considerations A minimum of three feet of engineered fill is recommended below all footings. The subgrade soils should be removed to a minimum depth of 36 inches and a minimum of 24 inches horizontally beyond the edge of footings. The engineered fill should extend laterally an additional distance of 8 inches for each additional foot of excavation beyond the 36-inch minimum depth. The soils should be replaced with approved engineered fill, conditioned to near optimum moisture content and compacted. 4.4 Seismic Considerations We have provided seismic design parameters according to the 2009 International Building Code (IBC) for design and construction of the proposed structure. Selected site ground motion parameters for the project have been determined in general accordance with the IBC. The values provided are based on the subsurface exploration presented herein and the USGS software for use in interpolating values. CONTERMINOUS 48 STATES-2003 NEHRP SEISMIC DESIGN PROVISIONS LATITUDE: LONGITUDE: Spectral Response Accelerations SMs and SM1 SMs = FaSs and SM1 = FvS1 Period (sec) Site Class D - Fa = 1.6, Fv = 2.4 Sa (g) (SMs, Site Class D) (SM1, Site Class D) Period (sec) SDs = 2/3 x SMs and SD1 = 2/3 x SM1 Site Class D - Fa = 1.6,Fv = 2.4 Sa (g) (SDs, Site Class D) (SD1, Site Class D) Reliable Responsive Convenient Innovative 9

14 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No Floor Slabs 4..1 Design Recommendations DESCRIPTION Interior floor system Floor slab support Modulus of subgrade reaction Slab-on-grade concrete. VALUE 3 feet of engineered fill soils placed and compacted in accordance with Earthwork section of this report. 100 pounds per square inch per inch (psi/in) Construction of floor slabs compacted fills composed of approved soils is considered acceptable for the project. In areas of exposed concrete, control joints should be saw cut into the slab after concrete placement in accordance with ACI Design Manual, Section 302.1R (tooled control joints are not recommended). Additionally, dowels should be placed at the location of proposed construction joints. To control the width of cracking (should it occur) continuous slab reinforcement should be considered in exposed concrete slabs. Positive separations and/or isolation joints should be provided between slabs and all foundations, columns or utility lines to allow independent movement. Interior trench backfill placed beneath slabs should be compacted in accordance with recommendations outlined in the Earthwork section of this report. Other design and construction considerations, as outlined in the ACI Design Manual, Section 302.1R are recommended Construction Considerations A minimum of 3 feet of engineered fill is recommended below slabs-on-grade. The engineered fill should extend horizontally a minimum distance of feet beyond the outside edge of perimeter footings. Some differential movement of a slab-on-grade floor system is possible should the subgrade soils become elevated in moisture content. Such movements are anticipated to be within general tolerance for normal slab-on-grade construction. To reduce potential slab movements, the subgrade soils should be prepared as outlined in the Earthwork section of this report. 4.6 Pavements Design of parking and drive pavements for the project has been based on the procedures outlined in the 1990 Flexible Pavement Design California Design Procedures. Assumed traffic criteria used for pavement thickness design includes single 18-kip equivalent standard axle loads (ESAL's) of 36,000 for planned auto parking areas. A Traffic Index (TI) of.0 for auto areas was calculated. Actual design traffic loading should be verified. Reevaluation of Reliable Responsive Convenient Innovative 10

15 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No the recommended pavement sections may be necessary if the actual traffic varies from the assumed criteria outlined above. Recommended alternatives for flexible and rigid pavements are as follows: Traffic Area Parking and Drive Areas Alternative Recommended Pavement Section Thickness (inches) Asphalt Concrete Surface Portland Cement Concrete Aggregate Base Course A B Total New pavement thicknesses for 3 th Street developed for the project have been based on the procedures outlined in the Infrastructure Design Directive IDD by the New Mexico Department of Transportation (NMDOT). Estimated traffic criteria used for pavement thickness design of each residential roadway includes single 18-kip equivalent standard axle loads (ESAL's) of 10,000. Actual design traffic loading should be verified. Reevaluation of the recommended pavement sections may be necessary if the actual traffic varies from the assumed criteria outlined above. Based upon AASHTO criteria, New Mexico is located within Climatic Region V of the United States. This region is characterized as being dry, with freeze-thaw cycling. For design purposes, these conditions typically result in saturated or near-saturated subgrade soil moisture conditions for approximately 4 percent of the annual moisture variation cycle. For flexible pavement design of the roadway alignment, a terminal serviceability index of 2.0 was utilized along with an inherent reliability of 8 percent. Using the correlated design R-value (10), appropriate EAL/day, environmental criteria and other factors, the structural numbers (SN) of the pavement sections were determined on the basis of the 1993 AASHTO design equation. Recommended alternatives for flexible pavements are as follows: Traffic Area Alternative Recommended Pavement Section Thickness (inches) Asphalt Concrete Surface Portland Cement Concrete Aggregate Base Course Total 3 th Street A 4-1/ /2 B Reliable Responsive Convenient Innovative 11

16 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No Each alternative should be investigated with respect to current material availability and economic conditions. Rigid concrete pavement, a minimum of 6 inches in thickness, is recommended at the location of dumpsters where trash trucks will park and load or areas of anticipated heavy vehicle loads. Minimizing subgrade saturation is an important factor in maintaining subgrade strength and stability. Some distress of pavements is possible due to the clay subgrade soils. Water allowed to pond on or adjacent to pavements could saturate the subgrade and cause premature pavement deterioration. The pavement should be sloped to provide rapid surface drainage, and positive surface drainage should be maintained away from the edge of the paved areas. Design alternatives which could reduce the risk of subgrade saturation and improve long-term pavement performance include crowning the pavement subgrades to drain toward the edges, rather than to the center of the pavement areas; and installing surface drains next to any areas where surface water could pond. Properly designed and constructed subsurface drainage will reduce the time subgrade soils are saturated and can also improve subgrade strength and performance. Periodic maintenance extends the service life of the pavement and should include crack sealing, surface sealing and patching of any deteriorated areas. Also, thicker pavement sections could be used to reduce the required maintenance and extend the service life of the pavement. If asphaltic concrete is used for this project, we recommend that reinforced concrete pads be provided in front of and beneath trash receptacles or other areas anticipated to support heavy vehicle traffic loads. The dumpster trucks should be parked on the rigid concrete pavement when the trash receptacles are lifted. The concrete pads at and adjacent to the trash enclosure should be a minimum of 6 inches thick and properly reinforced. The performance of all pavements can be enhanced by minimizing excess moisture which can reach the subgrade soils. The following recommendations should be considered at minimum: site grading at a minimum 2 percent grade away from the pavements. the subgrade and the pavement surface have a minimum 1/4 inch per foot slope to promote proper surface drainage. consider appropriate edge drainage and pavement underdrain systems. install pavement drainage surrounding areas anticipated for frequent wetting (e.g., garden centers, wash racks). install joint sealant and seal cracks immediately. compaction of any utility trenches for landscaped areas to the same criteria as the pavement subgrade. Reliable Responsive Convenient Innovative 12

17 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No seal all landscaped areas in or adjacent to pavements to minimize or prevent moisture migration to subgrade soils. place compacted, low permeability backfill against the exterior side of curb and gutter. place curb, gutter and/or sidewalk directly on subgrade soils without the use of base course materials..0 GENERAL COMMENTS Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide observation and testing services during grading, excavation, foundation construction and other earth-related construction phases of the project. The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing. Reliable Responsive Convenient Innovative 13

18 APPENDIX A FIELD EXPLORATION

19 37 th STREET PROJECT LOCATION GRAND AVENUE Source: USGS 7. Minute Topographic Map Artesia, New Mexico 198 N DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES. Project Mngr: Drawn By: Checked By: Approved By: DC JM MEW MEW Project No Scale Not to scale File No. Site Vicinity Date: 08/30/ Hickory Loop, Suite 10 Las Cruces, New Mexico Fax: SITE LOCATION MAP RICHARDSON APARTMENTS 37 TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO FIG No. A-1

20 B-2 B-3 B-8 B-7 B-1 B-4 B- B-6 37 TH STREET GRAND AVENUE Source: Development Design & Engineering N Approximate Boring Location DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES. Project Mngr: Drawn By: Checked By: Approved By: DC JM MEW MEW Project No Scale Not to Scale File No. Boring Location Date: 08/30/ Hickory Loop, Suite 10 Las Cruces, New Mexico Fax: BORING LOCATION PLAN RICHARDSON APARTMENTS 37 TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO FIG No. A-2

21 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No Field Exploration Description A total of eight (8) test borings were drilled at the site on August 16, The borings were drilled to depths of about 11-1/2 and 21-1/2 feet below the ground surface at the approximate locations shown on the attached Site Location Map and Boring Location Plan, Exhibit A-1 and A-2, respectively. The test borings were located as follows: Borings Location Depth (feet) B-1 thru B-8 Building Footprints 11-1/2 to 21-1/2 The test borings were advanced with a truck-mounted CME-7 drill rig utilizing 8-inch diameter hollow-stem augers. The borings were located in the field using aerial photos, on-site property corner stakes and using the proposed site plan. The accuracy of boring locations should only be assumed to the level implied by the method used. Lithologic logs of each boring were recorded by the field geologist during the drilling operations. At selected intervals, samples of the subsurface materials were taken by driving split-spoon or ring-barrel samplers. Bulk samples of subsurface materials were also obtained. Penetration resistance measurements were obtained by driving the split-spoon and ringbarrel samplers into the subsurface materials with a 140-pound automatic hammer falling 30 inches. The penetration resistance value is a useful index in estimating the consistency or relative density of materials encountered. A CME automatic SPT hammer was used to advance the split-barrel sampler in the borings performed on this site. The effect of the automatic hammer's efficiency has been considered in the interpretation and analysis of the subsurface information for this report. Groundwater conditions were evaluated in the borings at the time of site exploration. Reliable Responsive Convenient Innovative Exhibit A-3

22 IENT DEVELOPMENT DESIGN & ENGINEERING SITE 37TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO LOG OF BORING NO. B-1 PROJECT RICHARDSON APARTMENTS SAMPLES Page 1 of 1 TESTS GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. SPT - N BLOWS \ ft. WATER CONTENT, % DRY DENSITY LEAN AY WITH SAND; Brown, very stiff, dry, trace gravel. Carbonate indurated. 1 2 RB = 77.7% LL=31 PI=13 10 Trace gravel Stiff BOREHOLE_ GPJ TERRACON.GDT 9/13/ Hard, gravelly. Boring terminated at feet. No free water encountered at time of drilling. The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft (4") BORING STARTED BORING COMPLETED RIG CME- FOREMAN DC APPROVED MEW JOB # 68110

23 IENT DEVELOPMENT DESIGN & ENGINEERING SITE 37TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO LOG OF BORING NO. B-2 PROJECT RICHARDSON APARTMENTS SAMPLES Page 1 of 1 TESTS GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. SPT - N BLOWS \ ft. WATER CONTENT, % DRY DENSITY LEAN AY; Light brown, stiff, carbonate indurated White to light brown, hard Brown to light brown, very stiff Boring terminated at 11. feet. No free water encountered at time of drilling. BOREHOLE_ GPJ TERRACON.GDT 9/13/11 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft BORING STARTED BORING COMPLETED RIG CME- FOREMAN DC APPROVED MEW JOB # 68110

24 IENT DEVELOPMENT DESIGN & ENGINEERING SITE 37TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO LOG OF BORING NO. B-3 PROJECT RICHARDSON APARTMENTS SAMPLES Page 1 of 1 TESTS GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. SPT - N BLOWS \ ft. WATER CONTENT, % DRY DENSITY LEAN AY; Light brown, stiff, carbonate indurated Light brown to white, dry Very stiff Brown to white BOREHOLE_ GPJ TERRACON.GDT 9/13/ Boring terminated at 21. feet. No free water encountered at time of drilling. The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft BORING STARTED BORING COMPLETED RIG CME- FOREMAN DC APPROVED MEW JOB # 68110

25 IENT DEVELOPMENT DESIGN & ENGINEERING SITE 37TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO LOG OF BORING NO. B-4 PROJECT RICHARDSON APARTMENTS SAMPLES Page 1 of 1 TESTS GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. SPT - N BLOWS \ ft. WATER CONTENT, % DRY DENSITY LEAN AY; Brown to light brown, stiff, carbonate indurated Very stiff, dry = 8.6% LL=31 PI= Boring terminated at 11. feet. No free water encountered at time of drilling. BOREHOLE_ GPJ TERRACON.GDT 9/13/11 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft BORING STARTED BORING COMPLETED RIG CME- FOREMAN DC APPROVED MEW JOB # 68110

26 IENT DEVELOPMENT DESIGN & ENGINEERING SITE 37TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO LOG OF BORING NO. B- PROJECT RICHARDSON APARTMENTS SAMPLES Page 1 of 1 TESTS GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. SPT - N BLOWS \ ft. WATER CONTENT, % DRY DENSITY LEAN AY; Light brown, stiff, carbonate indurated Very stiff,trace gravel Hard BOREHOLE_ GPJ TERRACON.GDT 9/13/ Gravelly. Boring terminated at 20. feet. No free water encountered at time of drilling. The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft (6") BORING STARTED BORING COMPLETED RIG CME- FOREMAN DC APPROVED MEW JOB # 68110

27 IENT DEVELOPMENT DESIGN & ENGINEERING SITE 37TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO LOG OF BORING NO. B-6 PROJECT RICHARDSON APARTMENTS SAMPLES Page 1 of 1 TESTS GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. SPT - N BLOWS \ ft. WATER CONTENT, % DRY DENSITY LEAN AY; Light brown, stiff, dry. Very stiff, carbonate indurated = 84.6% LL=30 PI= Boring terminated at 11. feet. No free water encountered at time of drilling. BOREHOLE_ GPJ TERRACON.GDT 9/13/11 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft BORING STARTED BORING COMPLETED RIG CME- FOREMAN DC APPROVED MEW JOB # 68110

28 IENT DEVELOPMENT DESIGN & ENGINEERING SITE 37TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO LOG OF BORING NO. B-7 PROJECT RICHARDSON APARTMENTS SAMPLES Page 1 of 1 TESTS GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. SPT - N BLOWS \ ft. WATER CONTENT, % DRY DENSITY LEAN AY; Light brown, very stiff, dry, carbonate indurated Dark brown to white, dry. 2 RB Hard, brown BOREHOLE_ GPJ TERRACON.GDT 9/13/ Gravelly. Boring terminated at feet. No free water encountered at time of drilling. The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft (4") BORING STARTED BORING COMPLETED RIG CME- FOREMAN DC APPROVED MEW JOB # 68110

29 IENT DEVELOPMENT DESIGN & ENGINEERING SITE 37TH STREET AND GRAND AVENUE ARTESIA, NEW MEXICO LOG OF BORING NO. B-8 PROJECT RICHARDSON APARTMENTS SAMPLES Page 1 of 1 TESTS GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. SPT - N BLOWS \ ft. WATER CONTENT, % DRY DENSITY LEAN AY; Light brown, very stiff, carbonate indurated Brown to red-brown Boring terminated at 11. feet. No free water encountered at time of drilling. BOREHOLE_ GPJ TERRACON.GDT 9/13/11 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft BORING STARTED BORING COMPLETED RIG CME- FOREMAN DC APPROVED MEW JOB # 68110

30 GENERAL NOTES DRILLING & SAMPLING SYMBOLS: : Split Spoon /8" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger ST: Thin-Walled Tube - 2" O.D., unless otherwise noted PA: Power Auger RS: Ring Sampler " I.D., 3" O.D., unless otherwise noted HA: Hand Auger DB: Diamond Bit Coring - 4", N, B RB: Rock Bit BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary The number of blows required to advance a standard 2-inch O.D. split-spoon sampler () the last 12 inches of the total 18-inch penetration with a 140-pound hammer falling 30 inches is considered the Standard Penetration or N-value. For 3 O.D. ring samplers (RS) the penetration value is reported as the number of blows required to advance the sampler 12 inches using a 140-pound hammer falling 30 inches, reported as blows per foot, and is not considered equivalent to the Standard Penetration or N-value. WATER LEVEL MEASUREMENT SYMBOLS: : Water Level WS: While Sampling N/E: Not Encountered WCI: Wet Cave in WD: While Drilling DCI: Dry Cave in BCR: Before Casing Removal AB: After Boring ACR: After Casing Removal Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater. In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations. DESCRIPTIVE SOIL AIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have more than 0% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 0% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency. CONSISTENCY OF FINE-GRAINED SOILS RELATIVE DENSITY OF COARSE-GRAINED SOILS Unconfined Compressive Strength, Qu, psf Standard Penetration or N-value () Blows/Ft. Consistency Standard Penetration or N-value () Blows/Ft. Ring Sampler (RS) Blows/Ft. Relative Density < Very Soft Very Loose 00 1, Soft Loose 1,000 2, Medium Stiff Medium Dense 2,000 4, Stiff Dense 4,000 8, Very Stiff > 0 > 99 Very Dense 8,000+ > 30 Hard RELATIVE PROPORTIONS OF SAND AND GRAVEL Descriptive Term(s) of other constituents Percent of Dry Weight GRAIN SIZE TERMINOLOGY Major Component of Sample Particle Size Trace < 1 Boulders Over 12 in. (300mm) With 1 29 Cobbles 12 in. to 3 in. (300mm to 7 mm) Modifier > 30 Gravel 3 in. to #4 sieve (7mm to 4.7 mm) RELATIVE PROPORTIONS OF FINES Descriptive Term(s) of other constituents Trace With Modifiers Percent of Dry Weight < 12 > 12 Sand Silt or Clay #4 to #200 sieve (4.7mm to 0.07mm) Passing #200 Sieve (0.07mm) PLASTICITY DESCRIPTION Term Plasticity Index Non-plastic Low Medium High > 30

31 Coarse Grained Soils More than 0% retained on No. 200 sieve UNIFIED SOIL AIFICATION SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Group Symbol Soil Classification Group Name B Gravels Clean Gravels Cu 4 and 1 Cc 3 E GW Well-graded gravel F More than 0% of coarse Less than % fines C fraction retained on Cu < 4 and/or 1 > Cc > 3 E GP Poorly graded gravel F No. 4 sieve Gravels with Fines More Fines classify as ML or MH GM Silty gravel F,G, H than 12% fines C Fines classify as or CH GC Clayey gravel F,G,H Sands 0% or more of coarse fraction passes No. 4 sieve Clean Sands Cu 6 and 1 Cc 3 E SW Well-graded sand I Less than % fines D Cu < 6 and/or 1 > Cc > 3 E SP Poorly graded sand I Sands with Fines Fines classify as ML or MH SM Silty sand G,H,I More than 12% fines D Fines Classify as or CH SC Clayey sand G,H,I Fine-Grained Soils 0% or more passes the No. 200 sieve Silts and Clays Liquid limit less than 0 Silts and Clays Liquid limit 0 or more inorganic organic PI > 7 and plots on or above A line J Lean clay K,L,M PI < 4 or plots below A line J ML Silt K,L,M Liquid limit - oven dried Liquid limit - not dried < 0.7 OL Organic clay K,L,M,N Organic silt K,L,M,O inorganic PI plots on or above A line CH Fat clay K,L,M organic PI plots below A line MH Elastic Silt K,L,M Liquid limit - oven dried Liquid limit - not dried < 0.7 OH Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat Organic clay K,L,M,P Organic silt K,L,M,Q A Based on the material passing the 3-in. (7-mm) sieve B If field sample contained cobbles or boulders, or both, add with cobbles or boulders, or both to group name. C Gravels with to 12% fines require dual symbols: GW-GM well-graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay. D Sands with to 12% fines require dual symbols: SW-SM well-graded sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay 2 E (D30) Cu = D 60 /D 10 Cc = D10 x D60 F If soil contains 1% sand, add with sand to group name. G If fines classify as -ML, use dual symbol GC-GM, or SC-SM. H If fines are organic, add with organic fines to group name. I If soil contains 1% gravel, add with gravel to group name. J If Atterberg limits plot in shaded area, soil is a -ML, silty clay. K If soil contains 1 to 29% plus No. 200, add with sand or with gravel, whichever is predominant. L If soil contains 30% plus No. 200 predominantly sand, add sandy to group name. M If soil contains 30% plus No. 200, predominantly gravel, add gravelly to group name. N PI 4 and plots on or above A line. O PI < 4 or plots below A line. P PI plots on or above A line. Q PI plots below A line. Form 111 6/98

32 APPENDIX B LABORATORY TESTING

33 Geotechnical Engineering Report Richardson Subdivision Apartments Artesia, New Mexico September 13, 2011 Terracon Project No Laboratory Testing Samples retrieved during the field exploration were taken to the laboratory for further observation by the project geotechnical engineer and were classified in accordance with the Unified Soil Classification System (USCS) described in Appendix A. At that time, the field descriptions were confirmed or modified as necessary and an applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials. Laboratory tests were conducted on selected soil samples and the test results are presented in this appendix. The laboratory test results were used for the geotechnical engineering analyses, and the development of foundation and earthwork recommendations. Laboratory tests were performed in general accordance with the applicable ASTM, local or other accepted standards. Selected soil samples obtained from the site were tested for the following engineering properties: Consolidation In-situ Water Content Sieve Analysis In-situ Dry Density Atterberg Limits Reliable Responsive Convenient Innovative Exhibit B-1