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HomeMy WebLinkAbout- Consultant Review - 740 TURNPIKE STREET 10/22/2001 1 a M1 7 1 GEOTECHNICAL INVESTIGATION for 740 TURNPIKE STREET NORTH ANDOVER, MASSACHUSETTS October 22, 2001 GSI PROJECT NO. 201418 Prepared for: Scott Construction Company, Inc, Attn: Mr, Paul Westcott 12 Rogers Road Haverhill, Massachusetts 01835 C-7 GEOTECIINICAL SERVICES INC. -d Geotechnical Engineering A Environmental Studies A Materials Testing Construction Monitoring October 22, 2001 Scott Construction Company, Inc. Attn: Mr. Paul Westeott 12 Rogers Road Haverhill, Massachusetts 01835 re: GEOTECHNICAL INVESTIGATION 740 TURNPIKE STREET NORTH ANDOVER,MASSACHUSETTS GSI PROJECT NO. 201418 Dear Mr. Westcott: This reportpresents the results of a geotechnical investigation completed by Gcotechnical Services,Inc.(GSI) for the above-referenced project in North Andover,Massachusetts, Included are the findings of a subsurface exploration program performed by our office and an engineering evaluation of the subsurface conditions encountered. The evaluation concerns itself with the design and construction of foundations, pavement structures and associated earthwork activities required for the proposed building. This investigation was undertaken in accordance with your verbal authorization on October 17, 2001. The contents of this report are subject to the attached Limitations. The scope of set-vices performed by GSI to meet the above-stated objectives for geotechnical engineering services included the following: I Review of the,project plans sheets I through 9 prepared by Merrimack Engineering,Inc. dated June 22, 2001, revised September 5, 2001. 2. Coordination and observation of four(4) test borings at the locations illustrated on Figure 2. 3. Preparation of recommendations for spread footing foundation and slab-on-grade support of the proposed structures, including bearing capacities and settlement estimates. 4. Preparation of general recommendations for earthwork and foundation construction to be followed during the construction phase of this project. 5. Development of seismic design recommendations based on the subsurface conditions encountered. 6. Preparation of this geotechnical engineering report which summarizes our findings and recommendations. Services with respect to preparation of plans and specifications not referenced above, construction phase quality control, attendance at meetings and any other services not specifically outlined herein are not included in our current scope of services. A 12 Rogers Road, Haverhill, MA 01835 A 978/374/7744 A FAX 978/374/7799 'd .4 18 Cote Avenue, Goffstown, NH 03045 -A 603/624/2722 -A FAX 603/624/3733 -A i i i Geotechnical Investigation 740 Turnpike Street- North Andover, Massachusetts Page 2 GSI Project No.: 201418 SITE& PROJECT DESCRIPTION The project site is located at 740 Turnpike Street,also known as route 114,in North Andover,Massachusetts, A Site Locus Plan has been attached as Figure 2, The project site is comprised of a vacant lot currently under construction. Access to the site is by a gravel driveway directly off Turnpike Street. Site features include wetlands in the northern and western perimeters of the study site,stockpiled topsoil in the northeastern corner and western part of the site. A small storage shed was observed to the eastern side of the site. Silt fence has been installed around the outer limits of the project site. Vegetation within the study area was minimal due to the current earthwork, no topsoil was observed. A mix of coniferous and deciduous trees were observed along the perimeters of the project site. The study site is bounded by Turnpike Street(RTE. 114) and wetlands to the south,multi-story residential buildings to the east and northeast, Mosquito Brook flows along the north eastern boundary, General topography across the site is gently sloping downward in a northerly direction with overall relief oil the order of+5'. There was no standing water or bedrock outcroppings observed on the project site. Wetland areas, flagged by others,were observed north,west, and south of the development area. Based on our review of the USGS Topographic Map,the development portion of the site appears to situated atop a natural topographic divide between two wetland bodies. The northern portion appears non-contiguous and may ultimately feed the adjacent brook to the north. The southern wetiand appears contiguous with a larger wetland body to the south, but,has been isolated due to development in the region. The project includes of the construction of a new car wash facility, Additional site features include paved access roads,parking lots, and on-site detention areas for storm water. Lastly, the development of the site includes the filling of wetland areas and replication on-site. Based on our discussion and review of the provided plans the proposed building will be one and a half-story and constructed with concrete block and occupy a footprint on the order of 5,300 ft2• The finish floor elevation is proposed at 239.5 feet,which will require 3 to 5 feet of fill to achieve grade. No basement or lower level is currently proposed. For the purposes of this investigation typical building column loads are expected to range from 50 to 100 kips and continuous wall loads will range from 3,0 to 5.0 kips per lineal foot (klf). It is proposed to support the building on shallow spread footing foundations with a concrete slab-on-grade, SUBSURFACE EXPLORATION PROGRAM Subsurface Explorations-The subsurface exploration program for this project included the advancement of four test borings. The test borings, identified as B-1 through BA were completed to assess the type and relative density of the subsurface soils and provide samples for visual classification, The test borings were completed on October 19, 2001 by Con-Tec, Inc. using a Mobile B-47 drill rig under the oversight of a representative from GSI. The borings were advanced to depths ranging from 14 to 20 feet below existing surface grade using 2 3/4-inch inside diameter (I•D.) hollow-stern augers, Soil samples were obtained continuously through the previously identified fill and into the parent material and at 5 ft intervals thereafter with a 2-inch diameter split-spoon sampler. Standard Penetration Tests (SPTs) were performed at the sampling intervals in general accordance with ASTM-D1586. G S I p 3 f E Geotechnical Investigation 740 Turnpike Street- North Andover, Massachusetts Page 3 GSI Project No.: 201418 Materials encountered during the exploration program were visually classified in the field by a representative from GSI in general accordance with the Burmister classification system. Field descriptions, penetration resistance,the observed depth to groundwater,and other pertinent observations are noted on the soil boring logs in Appendix B, The exploration locations were determined in the field by taping from previously staked building corners and are considered accurate to the degree implied by the survey method used. The elevations were determined by interpolating from the Grading Plan(Sheet 4)prepared by Merrimack Engineering, Inc. The location of each exploration is illustrated on Figure 2 of this report, SUBSURFACE CONDITIONS The subsurface explorations were advanced beneath the proposed construction areas to define the nature and character of the underlying soil, groundwater, and bedrock. Descriptions of the subsurface conditions underlying the proposed construction area are as follows: Fill -The area had been stripped of existing topsoil prior to advancement of our test borings. As such, the borings were advanced through one to three feet of previously placed fill. It should be noted that locally deeper fills may be uncovered during construction, The fill varies in composition from a fine to coarse SAND, little Gravel, trace to little Silt, to a fine SAND, some Silt, trace Gravel with trace organic matter observed. SPT values ranged from 8 to 50+blows per foot. Subsoil - Underlying the fill a remnant subsoil strata typically comprised of an orange, fine to medium SAND, little to some Silt, trace Gravel, trace organic matter was observed. The thickness of the subsoil ranged from 6-inches to one foot. Though not observed in the test borings,the possibility exists that remnant topsoil may be present. Glacial Till-Underlying the fill and remnant subsoil was encountered a medium-dense to very dense deposit of glacial till. Glacial till is a non-sorted, non-stratified natural deposit of sand, silt, gravel, and boulders, mixed in various proportions and deposited directly by the glaciers in a non-aqueous depositional environment, The glacial till varies in composition from a fine to medium SAND,little Silt, little Gravel,to a SILT,some fine Sand, trace Gravel. SPT values ranged from 19 to 50+blows per foot. Refusal-Refusal conditions were encountered in all test borings at depths ranging from 14 to 20 feet below surface grade. Auger refusal is defined as the inability of the hollow stern augers to advance despite increasing torque and downward pressure applied by the drill rig. Auger refusal may be caused by nested cobbles, very dense soils, boulders, obstructions, or bedrock. Split spoon refusal is defined as either 100 blows or more required to drive the split spoon sampler 12 inches with a 140 lb. hammer falling 30 inches; 50 blows for less than 6 inches of advancement;or 10 blows with no discernable,vertical movement of the split spoon sampler. Based on the salient conditions observed at the site and observations made during the test borings the shallow refusals are probably a result of very dense glacial till or bedrock. I i Geotechnical Investigation 740 Turnpike Street - North Andover, Massachusetts Page 4 GSI Project No.: 201418 j' Groundwater - Groundwater was encountered at deptlis ranging from 4 to 7 feet below surface grade. Groundwater conditions were observed during advancement of the test borings, while sampling and immediately upon completion and should be anticipated to vary in response to equilibration time, rainfall, snowmelt, seasonal fluctuations, site development and other factors not present during the time that the explorations were performed. Given the general topography of the surrounding area, relative depth to groundwater encountered within the explorations,and general project site topography, it is anticipated that groundwater flow and surface runoff will be in a northerly direction. FOUNDATION DESIGN CONSIDERATIONS Recommended Foundation System - The native glacial till is considered suitable for support of the proposed building on a spread footing foundation with a concrete slab-on-grade. The previously placed fill is considered unsuitable for direct or indirect support of spread footings or concrete slab-on-grade, As such, it is GSI's recommendation thatpreviously placed fill,remnant subsoil,and other unsuitable material should be excavated from within the building footprint and exterior footing zone of influence. The footing zone of influence is defined as the area encompassed by a IH:IV splay originating 1 foot from the bottom edge of the footing and projecting downward and outward (Figure 3), Structural fill should consist of compacted stiuchiral fill. Bearing Capacity & Settlement Evaluation - Based on our explorations and foundation design recommendations the footings will bear atop the compacted structural fill. Provided the subgrade is prepared as outlined hereon below GSI recommends the footings be proportioned for a net allowable bearing capacity of 2.0 tsf, The foregoing allowable bearing pressure for soil is predicated by footing geometry and depth below grade. With regards to footing geometry, the minimum footing width of column and strip footings should be 4 ft and 2 ft respectively. The minimum depth for bearing is 18 inches below basement finish grade. Based oil the net allowable bearing pressure for footings placed on prepared subgrades, total footing settlement is not expected to exceed I inch with differential settlement between adjacent columns being less than 3/4 inch. The majority of the settlement is expected to occur during construction and long term settlements are anticipated to be negligible, Seismic Design Parameters -The subsurface conditions were reviewed with respect to criteria set forth in Article 1805.3,"LIQUEFACTION"and Table 1612.4.1,"SITE COEFFICIENT"of the Massachusetts State Building Code 6`'edition(MSBC). An evaluation with respect to"Liquefaction"of the site in the event of a significant seismic disturbance was performed. In accordance with the MSBC,the standard resistance for various sampling depths was compared to the depth to the groundwater table in accordance with Article 1805.3, GSI has determined that the site is not susceptible to liquefaction based on the relative density of the subsurface soils and the depth to groundwater. For calculation of the lateral seismic forces on the structure, the site subsurface soils should be considered a soil type S,. For such soil type, the recommended site coefficient (S) for seismic design is 1.0. In accordance with Article 1612.2.2 "SEISMIC GROUND ACCELERATION MAPS," the effective peak acceleration coefficient Ag and the effective peak velocity-related acceleration Av shall be taken as 0.12g throughout Massachusetts for the purpose of seismic design in accordance with 780 CMR. G f i i I' Geotechnical Investigation 740 Turnpike Street- North Andover, Massachusetts Page 5 GSI Project No.: 201418 Frost Protection-In accordance with MSBC exterior footings should be protected from frost at a minimum depth for the locality in which the structure is located. Based on local code and building practice,the exterior footing should be protected with at least 4 feet of earthen embedment. Interior footings should be placed at least 18 inches below finish floor grade provided the interior area is to be heated,otherwise a minimum 4 feet of earthen cover is required. If foundation construction is to occur during cold weather, the foundation elements should be protected against frost. Concrete Slab-on-Grade - A concrete slab-on-grade is deemed suitable for the proposed building. Our recommendations are based on the provisions for floor slab design outlined in ACI 302.1. Based on the retrieved samples from the subsurface exploration program,the subgrades have been classified as a medium support soil. GSI recommends that a minimum 6-inch layer of Slab Base Course Soil,meeting the gradation requirements indicated on Table 1 be utilized above a subgrade prepared as indicated hereon. The slab base course provides uniform support for the slab and provides improved drainage of water from beneath the slab. The slab base course soil should be compacted to at least 95 percent relative compaction as determined by the Modified Proctor Test(ASTM D 1557). Based upon the foregoing floor slab base preparation,a modulus of subbase reaction(Ks) of 250 pounds per cubic inch (pei) may be used for design. Slab-on-Grade Danrpprooflng Recommendations - GSI recommends that a subslab vapor retarder be ! placed beneath the proposed slab-on-grade. The recommended retarder should be a minimum, 8-mil polyethylene with joints lapped a minimum of 12 inches. As recommended in ACI 360R-92,Design ofslabs on Grade, paragraph 9.8, the vapor retarder should not be placed in direct contact with the slab-on-grade. The retarder should be placed atop a properly prepared subgradc beneath the floor slab base course material, This will allow excess bleed water to pass out the bottom of the slab, allowing faster finishing and prevent slab curling. LATERAL EARTH PRESSURE RECOMMENDATIONS Based on our understanding of the project site work will require retaining walls to achieve final grades, Retaining wall must be designed to resist"active"earth pressure conditions. The active condition exists when the top of the wall is free to deflect, reducing the lateral earth pressure. It is recommended lateral earth pressures be computed using an equivalent fluid weight equal to Ky. Assuming a free-draining backfill meeting the gradation requirements for structural fill an equivalent fluid weight of 40 pef(active)should be used for design. Lateral pressures exerted from surcharge pressures such as traffic located within a distance equal to 1.5 times the height of the wall, should be applied using elastic theory. An earth pressure coefficient of 0.3 for the active may be used. Lateral loads imposed from seismic ground acceleration may be computed as 0.045yH2, Assuming a unit weight of 125 pcf,this translates to 6Hz, The lateral seismic load should be applied as an inverted triangle over the height of the wall. For sliding stability analyses, GSI recommends that a static friction coefficient of .55 be used for the foundation/soil interface. The retaining backfill should be a free-draining soil meeting the specifications outlined in Table I for structural fill. The free-draining soil will obviate any hydrostatic pressures. A subdrainage system consisting of a perforated 6-inch polyethylene pipe surrounded by a minimum 2-foot wide "chimney drain" of free-draining structural fill should be placed behind the noted walls. The pipe should be enveloped within 6-inches of 3/8 to 3/4 inch crushed stone wrapped with a non-woven geotextile. The subdrains should discharge by gravity to the nearest available manhole or catch basin. Our recommended lateral earth pressure diagram is contained on Figure 4, NG I Geotechnical Investlgation 740 Turnpike Street- North Andover, Massachusetts Page 6 GSI Project No.: 201418 EARTHWORK CONSTRUCTION CONSIDERATIONS i Foundation and Floor Slab Subgrade Preparation - Prior to foundation construction, all traces of I: previously placed fill,remnant subsoil/topsoil, and other unsuitable materials should be removed from the entire building footprint and within the footing zone of influence as previously discussed. Footings should bear directly upon undisturbed glacial till subgrades or compacted structural fill. P ' After removing the unsuitable soils, the exposed foundation and floor slab subgrade soils should be proofrolled prior to foundation construction to densify disturbed soils resulting from the excavation and to preload the subgrade, Recommended proofrolling should include 4 coverages with a 2-ton double-drum vibratory roller or 8 coverages with a '/a ton vibratory plate compactor. During the proofrolling process the subgrade should be observed by a qualified engineer to identify areas exhibiting weaving or excessive reaction. It may be necessary to remove such loose and unstable soils and replace with a free draining granular fill or crushed stone, at the direction of the Engineer. Proofrolling near the groundwater table or upon soils that become saturated due to precipitation may be detrimental to the competency of the foundation subgrade, Under these circumstances, proafiol]iing is not recommended,however,strict monitoring of excavation effort is required to ensure minimal disturbance is imparted. Structural fill Recommendations - Structural fill to be used below the building for foundation support should conform to the gradation requirements given in Table 1. The specified gradation is based on consideration of the recommended allowable bearing pressure and estimated settlement of a spread footing foundation as presented in the Foundation Considerations Section. Structural fill should be placed in maximum loose lifts of 8-inches and be compacted to 95 percent of maximum dry density as determined by the modified proctor test(ASTM-D 1557). The loose lift thickness may be increased to 12-inches if a minimum 8-ton vibratory roller is used for soil compaction. The adequacy of the compaction efforts should be verified by field density testing. Based on a review of the retrieved samples excavated on-site material is not anticipated to meet structural fill specifications. Material which does not meet the gradation requirements of Table 1 may,however,be re-used as ordinary fill beneath proposed pavement areas or within landscape areas. Foundation Subgrade Protection-It is essential that foundation subgrades be protected to ensure bearing competency. Particular areas of concern include the subgrades for foundation elements,pavement areas and utility trenches. Excavation methods,construction traffic,moisture,precipitation, and groundwater control are activities or events which may damage subgrades. It should also be noted that the native glacial till deposit is inherently vulnerable to disturbance when exposed to wet conditions. This vulnerability is due to the high percentage of fines (i.e, silt and clay) within the deposit. The contractor should be aware of this vulnerability and should take the necessary precautionary measures required to prevent disturbance. Some precautionary measures may include diversion of storm water run-off from the construction area,reducing construction traffic and activities once the subgrade is properly prepared, and maintaining an effective de- watering program. Should the subgrade exhibit weaving or instability due to disturbance,the area should be over-excavated to a more competent bearing soil and replaced with compacted structural fill or crushed stone. It is recommended that a geoteclnnical engineer from GSI inspect all bearing subgrades throughout construction. i i 0 f p1 E E Geotechnical Investigation 740 Turnpike Street- North Andover, Massachusetts Page 7 GSI Project No.: 201418 Construction Dewatering - Based on the depth to groundwater, temporary groundwater control may be required during foundation construction. In addition, GSI recommends the contractor be prepared to divert surface water as necessary and to removed any stormwater which may have ponded within the excavation limits. It is anticipated that construction dewatering may be accomplished with localized filtered sumps and pumps, It has been GSI's experience that a lift of crushed stone at footing grade would facilitate dewatering during construction and provide a dry/stable subgrade during construction. Temporary Excavations - Deep excavations (greater than 5 ft) are not anticipated to be required for foundation construction, however, they may be required for utility installation. It is envisioned that such excavations may be accomplished with slope laybacks, For stable excavation designs,the on-site glacial till soil and fill should be considered Type B and Type C soils, respectively in accordance with Occupational Safety and Health Administration (OSHA) regulations (29 CFR Part 1926). The maximum temporary slopes for Soil Type B soils is 1H:1V and for Type C is 1.51-1:IV, provided the groundwater is lowered below the bottom of the excavation and the height of the cut is a maximum 20 feet. The foregoing slope requirement does not consider surcharge loads(stockpiled soils,equipment,materials) which may be situated at the crest of the slope and vibration loads (blasting, soil compaction). It should be noted that these slope requirements are minimums required by OSHA regulations and that any excavation which exceeds the minimum requirements nmstbe designed by a registered professional engineer. Furthermore, it must be stressed the contractor is ultimately responsible for stability of temporary slopes associated with construction activities. Construction Monitoring -It is recommended that GSI be retained to review construction procedures for conformance with contract requirements, documents and design concepts, We trust that the contents of this report meets with your satisfaction. Should you have any questions or need any additional information,please do not hesitate to contact our office. Very truly yours, GEOTECHNICAL SERVICES,INC Richard E. Bushnell,P.E. Harr . Wetherbee, P.E. Project Engineer Principal Engineer Enclosures gsitecmech/ 1040lurnpikcsirrarpt 1 i 1 i I i i i i i APPENDIX A LIMITATIONS G s I I 740 TURNPIKE STREET, i NORTH ANDOVER, MASSACHUSETTS GSI Project No, 201418. RECOMMENDED SOIL GRADATION SPECIFI'CA DONS TABLE.1 Soil Type(Percent passing by weight) Sieve Size Slab Base Soil Structural Fill 5" --- 100 4" 100 --- #4 40-70 40-75 #40 25-45 .. #200 10 max 0-12 NOTES: Ordinary fill used for landscape areas may be any soil material that is relatively free from organic matter, debris, frost, stones larger than 213 the maximum lift thickness, or other deleterious materials. The specification for Structural Fill may be modified based on the availability of on-site materials and the compaction specifications. Materials proposed for use as Structural fill which do not meet the above gradation specification shall be subject to stringent compaction control testing. Solis possessing silt/clay contents greater than 15% are prone to frost and are moisture susceptible. r 71°07'0.00" 7 °06'0,00"VY 11 Mt AF P. r ({G 1J f' 1. tf.- ti `ti ii �• i r / d ff .. s { :�� ,' ' Q R ��'�-*�y.% "r-y 4, l (bly����,i I1I/,/.. r •.��. .�+•' +�_� �},� /4)/." �� 'J� l,�'R�11..1��,.�y.-.. � -c'�/•��� •��'�7. ._�<.1„,.�,.y\ «- � �` � ���fr, Ill �• � t��t �•,• 4• '` '.,! //7S 111 .�"'_', �`�r... _ � 11 } I Z 4 r � r �\.,�.� ''•� ••''•f .� �•\� ' .�. _ ; • `♦� ��4':.,,t ..(1 ice', �.i� - �,�i t�/1 i} ai,�� 1ti)C•.�`, Z , ? � 1 Q o 111r�• ��- �. Ca .1 /� 2� a / .• \ �\ fr (VVVVjyffff� , IIIYYY111 \ !1\ \\\ \1 (f ~� r i> 45 It ZM. E } h u . , „ P 92 71°07'0.00" 71°06'0.00" Name: LAWR NCE Location: 042°39'66.6" N 071°06'58.0" W Date: 10/22/2001 Caption: 740 Turnpike Street I. Scale: 1 inch equals 2000 feet GSI Project No. 201418 Figure 1 -LOCUS Copyright(C)1997,Maptech,Inc. i Proposed Building 8-4 B-1 B-3 LEGEND B-� Boring Location and Numbering NOTES, 1, Base Plan was re-drawn from a Proposed Site Layout Plan prepared by Merrimack Engineering, Inc, dated Sept 5, 2001, 2, Vest borings were located by taping from the staked building corners and should loe considered accurate to the degree Implied Joy the survey method used. 3. Test borings were drilled by Con-Tec, Inc, on October 19, 2001 under the observatlon of GSI G GEOTECHNICAL SERVICES INC. SUBSURFACE EXPLORATION S 18 COTE AVENUE, UNIT i 1, caFFsTowH, NH a3�l45 LOCATION PLAN r TEL (603) 6242722 FAX, (603) 624--3733 740 TURNPIKE STREET Drawn By: reb Date: October 2001 Figure Checked By: hkw Scale: 1 20' N o . NORTH ANDOVER, MASSACHUSETTS Pile laMe:74 "t ' Project No.: 201413 PROPOSED CONCRETE SLAB—ON—GRADE PROPOSED FOUNDATION SYSTEM P081t,Ive drainage from foundation -------------- FLOOR SLAB BASE COURSE compact to 95% ORDINARY OR STRUCTURAL FILL RACKFILL of maximum dry density t In accordance with project plans compact to 95% of ASTM D-1557 FOOTING ZONE STRUCTURAL FILL OF INFLUENCE, compact to 95% of maximum dry density 1 as determined by ASTM D-1557 1 Fill to be placed In the dry upon a competent subgrade -TERT SUBGR""7 COMPETENT SUBGRADE r'OMpL FOOTING ZONE OF INFLUENCE G GEOTECHNICAL SERVICES INC. S 18 COTE AVENUE, UNIT #11, GOFFSTOWN, NH 03045 TEL. (603) 6242722 FAX. (603) 624-3733 740 TURNPIKE STREET Drawn By: reb Date: Oct 2001 Figure Chocked BY: hkw Scale. NTS -- No . NORTH ANDOVER, MASSACHUSETTS 3 File Name: Project No.: 201418 I r 5 H Surcharge = q _ 0.3 q --- PCF 2 (RE56LTA1� H k404 LEVEL. 9ACKFlLL 3 l2/3}H`75 PSF =� • PASSIVE ACTIVE *SURCHARGE SEISMIC EARTH PRESSURE PRESSURE + PRESSURE + PRESSURE EARTH PRESSURE DIAGRAM FOR RETAINING WALL NOTE: *POINT AND LINE LOADS SHOULD BE APPLIED USING ELASTIC THEORY G LATERAL EARTH PRESSURE DIAGRAM GEOTECHNICAL SERVICES INC. s 18 COTE AVENUE, UNIT i11, GOFFSTOWN, NH 03045 TEL. (603) 6242722 FAX, (603) 624-3733 740 TURNPIKE STREET Drawn By: reb Date: Oct 2001 Figure Checked By: hkw Scale: NITS �T NORTH ANDOVER MASSACHUSETTS � � �� �v Q • 4 File Name: Project No.: 201418 1 4 LIMITATIONS ' Explorations I. The analyses,recommendations and designs submitted in this report are based in part upon the data obtained from preliminary subsurface explorations. The nature and extent of variations between these explorations may not become evident until construction. If variations then appear evident, it will be necessary to re-evaluate the recommendations of this report. 2, The generalized soil profile described in the text is intended to convey trends in subsurface conditions. The boundaries between strata are approximate and idealized and have been developed by interpretation of widely spaced explorations and samples;actual soil transitions areprobably more gradual, For specific information, refer to the individual exploration logs. 3. Water level readings have been made in the test pits and/or test borings under conditions stated on the logs, These data have been reviewed and interpretations have been made in the text of this report. However, it must be noted that fluctuations in the level of the groundwater may occur due to variations in rainfall,temperature,and other factors differing from the time the measurements were made. Review 4, It is recommended that this firm be given the opportunity to review final design drawings and specifications to evaluate the appropriate implementation of the recommendations provided herein, 5. In the event that any changes in the nature,design,or location of the proposed areas are planned,the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of the report modified or verified in writing by Geotechnical Services, Inc. Construction 6, It is recommended that this firm be retained to provide geotechnical engineering services during the earthwork phases of the work. This is to observe compliance with the design concepts, specifications, and recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior to the start of construction. Use of Report 7. This report has been prepared for the exclusive use of Scott Consti ction Company, Inc. in accordance with generally accepted soil and foundation engineering practices. No other warranty, expressed or implied, is made. 8. This report has been prepared for this project by Geotechnical Services, Inc. This report was completed for preliminary design purposes and may be limited in its scope to complete an accurate bid. Contractors wishing a copy of the report may secure it with the understanding that its scope is limited to evaluation considerations only, I I i i f o: APPENDIX B TEST BORING LOGS s I i PRO,'MCT: 740 Turnpike Street BORING NO: B^1 LOCATION: North Andover, MA TEST BORI I�G :LOG BBEET: 1 OF 1 PROJECT NO.: 201418 START: October 19, 2001 FINISH: October 19, 2001 BORING CONTRACTOR; Con^Tec GEOTECHNICAL SERVICES, INC. PREPARED BY: P. Archambault FOREMAN: Walter Hoeckele 18 Cote Avenue CHECKED BY: R. Bushnell, P.E. RIG: Mobil B-47 ELEVATION: 236'± Goffstown, NH 03045 CORE GROUNDWATER OBSERVATIONS Q FIELD TESTING EL}UIPMENT AUGER CASING SAMPLER BAR DATE 10-15-01( ) p LABORATORY TYPE HSA SS DEPTH FT 4.8' TESTING SIZE ID (IN) 2 1\4 2.0 CASING AT (FT) 15' © btONLTORTNG HAMMER WT (LB) 140 BIT TIME (HR) Upon Completion HAMMER FALL (IN) 30 WELL INSTALLED ❑ NO GROUNDWATER ENCOUNTERED ❑ LIQUID INTRODUCED DURING DRILLING D E SOIL AND ROCK CLASSIFICATION—DESCRIPTION P SAMPLE DATA T BURMISTER SYSTEM (SOIL) H U.S. CORPS OF ENGINEERS SYSTEM (ROCK) SAMPLE DBPT9 RECOVERY 3PT NUMBER (ft) (IN) (awHs/ 0 S-1 0-2 10 18-13 Dark brain,medium dense,f-c SAND,little Gravel,trace-little Silt,trace organics(PILL) 1 10-5 2 8-2 24 6 2-3 Dark brown,loose,f-in SAND,]tide-some Silt,trace Gravel,trace organics 3 5-12 ----------------------------------------------------------------------------------------------------------------------------- ------ 4 S-3A 4-5 11 8-8 Orange Brown,ured(um dense,fist(')SAND,little Silt,trace Gravel(Aeronaut Subsoil) - - - ---------------------------------- 5 S-3B 5.6 10 11-15 Bzownlgray, medium dense,i m SAIJD,some-littlo Silt,trace liMla Gravel(CT ACIAL TI[I) 6 7 8 9 to S4 10.12 14 10-32 Olive Brawn,very deitsc,f-m(`)SAND,some Silt,little Gravel 11 23-30/3" 12 13 Auger RefiFsal at 13.7' 14 15 16 17 18 19 20 21 22 23 24 25 2G SAMPLE IDENTIFICATION COHESIVE SOILS (Blows par ft.) GRANULAR SOILS (Blows Par ft.) PROPORTIONS USED COHESIVE SOIL TBRY•',AD D to 2: Very Soft 0 to 4: Very Loose trace (D-10%f 1/4 = Clayey Silt S SPLIT SPOON 2 to 4: Soft 4 to 10: Loose little (10-207.) 1/8 = Silt & Clay U UNDISTURBED 4 to 8: Medium Stiff 1D to 311: Medium Dense same (2D-35%) 1/16 = Clay & Silt OR OPEN END ROD 8 to 15: Stiff go to 50: Dense and (35-90%) 1/32 - Silty Clay C ROCK CORE 15 to 30; Very Stiff Over SO: Very Dense 1/64 = Clay Over 30: Hard Standard Penetration Test (SPT) = 140e hammer falling 3011, Blows are per b" taken with an 1611 long x 2" T.D. split spaon 7ampler in accordance with ASTM D 1666, unless otherwise noted. REMARKS: The stratification lines represent the approximate boundary between soil types and the transition may be gradual. hater level readings have been made in the test borings at times and under conditions stated on the test boring lugs. Fluctuations in the level of the groundwater may occur due to other factors than those present at the time measurements were made. NOTES: i PROJECT: 7 No Turnpike Street TEST 'BORING .LQG 9BEETG N0: OF-2 LOCATION: North Andover, MA PROJECT No.: 201418 START: October 11, 2U01 FINISH: October 19, 2001 BORING CONTRACTOR: Con-Tec GEOTECHNICAL SERVICES, INC. PREPARED BY: P- Archambault FOREMAN: Walter Hoeckele CHECKED BY: R. Bushnell, P.C. 18 Cote Avenue RIG: Mobil B-47 ELEVATION: 235 ± Goffstown, NH 03045 CORE GROUNDWATER OBSERVATIONS ❑ FIELD TESTING EQUIPMENT AUGER CASING SAMPLER BAR DATE 10-19-01 ❑ LABORATORY TYPE HSA SS DEPTH (FT) 6.6' TESTIN(I SIZE ID (IN) 2 1\4 2.0 CASING AT (FT) is, ❑ MONITORING HAHMER WT (LB) 140 BIT TIME (HR) Upon Completion WELL INSTALLED HAMMER FALL (IN) 30 ❑ NO GROUNDWATER ENCOUNTERED i 13 LIQUID INTRODUCED DURING DRILLING D E SOIL AND ROCK CLASSIFICATION-DESCRIPTION P SAMPLE DATA BURMISTER SYSTEM (SOIL) H U.S. CORPS OF ENGINEERS SYSTEM (ROCK) SAMPLE DEPTH RECOVERY SPT NUMBER (ft) (IN) (BLOWS/ 5 TH.► 0 8-1 0.2 13 4-6 Brown medion dense, -in AND,some Silt,trace Gravel,tntce erg dcs(PILL) 1 18-28 2 S-2 24 10 32-52 Dark Brown/Black,very dense,Gm SAND,little-some Silt,little Gravel,trace orpnlcs 3 23-28 -- - — — ----------------------------- ------------------ 4 S-3 4-6 3 11-12 Brorvn dense,f-m(')SAND,little-soma Silt,trace Ciray.1(6 onio Odor,remaaant Subsoil) S 21-26 - - - - - - -------------- 6 S4 6-8 12 12-21 Grey,dense,Aid-)SAND,little Silt,little Gravel(GLACIAL TILL) 7 18-19 8 9 10 S-5 10-12 18 9-12 CTey,medium dense,f m(+)SAND,some Silt,]title Gravel 11 17-21 12 13 14 15 S-6 15-17 15 15-20 Grey/Green,very dense,&tn(')SAND and-some Silt,little Gravel 16 5015" 17 Auger Refusal at 17.5' 18 19 20 21 22 23 24 25 26 SAMPLE IDENTIFICATION COHESIVE SOILS (Blows per ft.) GRANULAR SOILS (Blows per ft.) PROPORTIONS USED COHESIVE SOIL THREAD 0 to 2: Very Soft 0 to 41 Vary Loose trace (0-IM 1/4 - Clayey Silt S SPLIT SPOON 2 to 4: Soft 4 to 10: Loose little (10-20%) 1/6 - Silt & Clay U UNDISTURBED 4 to 8: Medium Stiff 10 to 30: Medium Dense some (20-35%) 1/16 = Clay s Silt OR OPEN END ROD 8 to IS: Stiff 30 to 50: Dense and (35-50%) 1/32 = Silty Clay C ROCK CORE 15 to 30: Very Stiff Over 50: Very Dense 1/64 = Clay Over 30: Hard Standard Penetration Test (SPT) - 140+ hammer falling 3011, Blows are per 611 taken with an 18" long x 2" I.D. split spoon sampler in accordance with ASTH D 1566, unless otherwise noted. REMARKS: The stratification lines represent the approximate boundary between soil types and the transition may be gradual. Uater level readings have been made in the test borings at times and under conditions stated on the test boring logs. Fluctuations In the level of the groundwater may occur due to other factors than those present at the time measurements were made. NOTES: a PROJECT: 740 Turnpike Street WRENG NO- B 3 LOCATION: North Andover, MA TEST BORING LOG SHEET: 1 Of 1 PROJECT NO.: 201418 START: October 14, 2901 FINISH: October 19, 2001 BORING CONTRACTOR: Con-Tec GEOTECHNICAL SERVICES, INC. PREPARED BY: P- Archambawlt FOREMAN: halter Hoeckele 18 Cote AvenUo CHECKED BY: R. Bushnell, P.E. , RIG: Mobil B-47 + ULEVATION: 236 _ Goffstown, NH 03045 CORE GROUNDWATER OBSERVATION'S 0 FIELD TESTING EQUIPMENT AUGER CASING SAMPLER BAR DATE 1K1-19-n1 © LABORATORY TYPE HSA SS DEPTH (FT) TESTING SIZE I➢ (IN) 2 1\4 2.0 CASING AT (FT) (] MONITORING HAMMER WT (LB) 140 BIT TIME (HR) Upon Completion WE HA1*MR FALL (IN) 30 X NO GROUNDWATER ENCOUNTERED I'L INSTALLED '.. Q LIQUID INTRODUCED DURING DRILLING D E SOIL AND ROCK CLASSIFICATION-DESCRIPTION P SAMPLE DATA T BURMISTER SYSTEM (SOIL) H U.S. CORPS OF ENGINEERS SYSTEM (ROCK) SAMPLE DEPTH RECOVERY 8PT NUMBER (ft) (IN) (BwHs/ 0 S-1 0.2 12 8-8 Brown,medium dense,f-rn SAND,little Silt,trace Gravel,trace organic(FILL) 1 13-25i2" 2 S-2A 2-3 7 9-10 Brown,meditun dense,t')SAND,some Silt,little Gravel,trace organics --------------- --------- - ------------------------------------------ 3 S-213 3.4 10 19 18 CneylOrange Brown dense,f-sun SAND,some Silt(Remnant Subsoil) _ 4 S-3 4-6 15 8-10 C mo/Bra - — - - y wv,orediunr dense,f-ru SAND,L(tIe-soma Silt(GLACIAL TILL) 5 11.12 6 7 9 10 S-4 10.12 18 7.8 Gray,medium dense,f-m SAND and-same Silt,trace-little Gravel 11 11-12 12 13 14 15 8-5 15.17 3 10-50/3" Grey,very dense,f SAND,sonic-and Silt,some Gravel 16 17 18 19 20 S-6 20-22 2 5012" Gmy/Blue,very dense,SILT,some f&nd,trace Gravel 21 22 Standard Refusal©20' 23 24 25 26 SAIVLE IDENTIFICATION COHESIVE SOILS (Blows per ft.) GRANULAR SOILS (Blows per ft.) PROPORTIONS USED COHESIVE SOIL THREAD 0 to 2: Vary Soft 0 to 4: Very Loose trace (0-10%) 1/4 = Clayey Silt S SPLIT SPOON 2 to 4: Soft 4 to 10: Loose little (10-20%) 1/6 = Silt & Clay U UNDISTURBED 4 to 8: Medium Stiff 10 to 30= Medium Dense some (20-35%) 1/16 - Clay & Silt OR OPEN END ROD 8 to 15: Stiff 30 to 50: Dense and (35-50%) 1/32 = Silty Clay C ROCK CORE 15 to 30: Very Stiff Over 50: Very Dense 1/b4 = clay Over 30: Hard Standard penetration Test (SAT) = 140# hammer falling 3011, Blows are per 6" taken with an 18" long x 2" T.D. split spoon sampler in accordance with ASTM D 1566, unless otherwise noted. REMARKS: The stratification lines represent the approximate boundary between soil types and the transition may be gradual. Water level readings have been made in the test borings at times and under, conditions stated on the test boring logs. Fluctuations in the level of the groundwater may occur due to other factors than those present at the time measurements were mada. NOTES: I PROJECT: 740 Turnpike Street BORING NO: 0-•4 LOCATION: North Andover, NA TEST -BORING LOG ` . Sun: 1 Of 1 PROJECT NO.: 201418 START: October 19, 2001 FINISH: October, 14, 2001 BORING CONTRACTOR: Con-Tec GEOTECHNICAL SERVICES, INC. PREPARED Bx: P. Archambault '... FOREMAN: Walter Hoeckele 18 Cote Avenue CHECKED BY: R. Bushnell, P.E. RIG: Mobil B-47 Goffstown, NH030A5 ELEVATION: 23S'± CORE GROUNDWATER OBSERVATIONS ❑ FIELD TESTING EQUIPMENT AUGER CASING SAMPLER BAR DATE 10-19-01 ❑ LABORATORY TYPE HSA SS DEPTH {FT} 7.0" TESTING SiZ£ ID (IN) 2 1\4 2.0 CASING AT (FT) 15' ❑ MONITORING HAMMER WT (LB) 14U BIT TIME (HR) Open Completion WELL INSTALLED HAMMER FALL (IN) 30 ❑ NO GROUNDWATER ENCOUNTERED ❑ LIQUID INTRODUCED DURING DRILLING D E SOIL AND ROCK CLASSIFICATION-DESCRIPTION P SAMPLE DATA T BURMISTER SYSTEM (SOIL) H U.S. CORPS OF ENGINEERS SYSTEM (ROCK) SAMPLE DEPTH RECOVERY SPT NUMBER (ft) (IN) (alAw3/ 0 S-1 0-2 13 7-22 Brown,very dense,Pin SAND,little Silt,little Gravel(FILL) 1 30-31 — — — — — --— — — ----------------—-------------------------------------2 S-2 24 10 11-12 Orasga BrownlGroy,medinrrr dense,SILT and£Sand,trace Gravel trace organics(Remnant Subsoil) 3 14-14 _. ---------------—------------------------------------------ ---------- 4 8.3 4-6 18 5-13 Brown dcosv,f--mt3 SAND,soma Silt,trace Gravel(C,i ACL4L TII L) 5 17-23 6 7 8 9 10 8-4 10-12 19 11-18 Gray,very dense,BAND and-some Silt,little Gravel 11 32-30 12 13 14 15 8-5 15-17 15 21-31 1 Green/Brown,very dense,i{+)SAND and-some Silt,little Gravel 16 33-35 17 18 19 8.6 19-21 0 25/0" Zero Recovery 20 Standard Rotival at 19' 21 22 23 24 25 26 SAMPLE IDENTIFICATION COHESIVE SOILS (Blows per ft.) GRANULAR SOILS (Blows per ft.) PROPORTIONS USED COHESIVE SOIL THREAD 0 to 2: Very Soft 0 to 4: Very Loose trace (0-10Z) 1/4 3 Clayey Silt S SPLIT SPOON 2 to 4: Soft 4 to 10: Loose little (1U-20%) 1/8 - Silt 8 Clay U UNDISTURBED 4 to 8: Medium Stiff 10 to 30: Medium Dense some (20-35/.) 1/16 = Clay 8 Silt OR OPEN END ROD 8 to 15: Stiff 30 to SO: Dense and (35-50%) 1/32 - Silty clay C ROCK CORE 15 to 30: Very Stiff Over 50: Very Dense 1/64 = Clay Over 30: Hard Standard Penetration Test (SPT) = 1400 hammer falling 30", Blows are per 6" taken with an lb" long x 2" I.D. split spoon sampler in accordance with ASTN D 1586, unless otherwise noted. REMARKS: The stratification lines represent the approximate boundary between soil types and the transition may be gradual. (dater level readings have been made in the test borings at times and under conditions stated on the test boring logs. Fluctuations in the level of the groundwater may occur due to other factors than those present at the time measurements were made. NOTES: l f € i IMPOPIRRI. About. Aeotechnicoi Enuineepinu Be opt r r rr • , r r, r r r r • , r r r r r Jui I • f0110 Wing information is-provided tohelp you manage your Geotechnical Services Are Performed top • elevation, configuration, location, orientation, or Specific PuPposes, Persons, and Ppojects weight of the proposed structure, Geotechnical engineers structure their services to meet the spe- composition of the design team, or cific needs of their clients. A geotechnical engineering study con- r' project ownership, ducted for a civil engineer may not fulfill the needs of a construc- As a general rule, always inform your geotechnical engineer tion contractor or even another civil engineer. Because each geot- of project changes---even minor ones—and request an ethnical engineering study is unique, each geotechnical engi- neering report is unique, prepared solely for the client. No one accept responsibility or liability for problems that occur except you should rely on your geotechnical engineering report because their reports do not consider developments of which without first conferring with the geotechnical engineer who pre they were not reformed. pared it. And no one—not even you—should apply the report for any purpose or project except the one originally contemplated. SuhsuPface Conditions Can Change A Geotechnical Engineeping Repopt Is Based on A geotechnical engineering report is based on conditions that existed at the time the study was performed. Do not rely on a A Unique Set of Ppojeet-Specific Factors geotechnical engineering report whose adequacy may have Geotechnical engineers consider a number of unique, project-spe- been affected by: the passage of time; by man-made events, cifc factors when establishing the scope of a study.Typical factors such as construction on or adjacent to the site; or by natural include: the client's goals, objectives, and risk management pref- events, such as floods, earthquakes, or groundwater fluctua- erences; the general nature,of the structure involved, its size, and tions. Always contact the geotechnical engineer before apply- configuration; the location of the structure on the site; and other ing the report to determine if It is still reliable. A minor amount planned or existing site improvements, such as access roads, of additional testing or analysis could prevent major problems, parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates other Most Geotechnical Findings Are wise, do not rely on a geotechnical engineering report that was: e not prepared for you, Professional Opinions e not prepared for your project, Site exploration identifies subsurface conditions only at those • not prepared for the specific site explored, or points where subsurface tests are conducted or samples are • completed before important project changes were made, taken. Geotechnical engineers review field and laboratory data and then apply their professional judgment to render an opinion Typical changes that can erode the reliability of an existing about subsurface conditions throughout the site. Actual sub- geotechnical engineering, report include those that affect: surface conditions may differ—sometimes significantly--from e the function of the proposed structure, as when those indicated in your report. Retaining the geotechnical engi- it's changed from a parking neer who developed our report to provide construction obser- I g p g garage to an office p Y P building, or from a light industrial plant to a vation is the most effective method of managing the risks asso- i refrigerated warehouse, ciated with unanticipated conditions. E A RepoPt's Recommendations Are Not Final report's accuracy is limited; encourage them to confer with the I Do not overrely on the construction recommendations included geotechnical engineer who prepared the report (a modest fee i in your report. Those recommendations are not final, because may be required) and/or to conduct additional study to obtain geotechnical engineers develop them principally from judgment the specific types of information they need or prefer. A prebid e and opinion. Geotechnical engineers can finalize their recom- conference can also be valuable, Be sure contractors have suffr- I mendations only by observing actual subsurface conditions cient time to perform additional study. Only then might you be in revealed during construction. The geotechnical engineer who a position to give contractors the best information available to developed your report cannot assume responsibility or liability for you, while requiring them to at least share some of the financial the report's recommendations if that engineer does not perform responsibilities stemming from unanticipated conditions. construction observation. Read Responsibility Provisions Closely A Geotechnical Engineering Report is Subject Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than To Misinterpretation other engineering disciplines. This lack of understanding has Other design team members' misinterpretation of geotechnical created unrealistic expectations that have led to disappoint engineering reports has resulted in costly problems. Lower ments, claims, and disputes. To help reduce such risks, geot- that risk by having your geotechnical engineer confer with echnical engineers commonly include a variety of explanatory appropriate members of the design team after submitting the provisions in their reports. Sometimes labeled "limitations", report. Also retain your geotechnical engineer to review perti- many of these provisions indicate where geotechnical engi- nent elements of the design team's plans and specifications, neers responsibilities begin and end, to help others recognize Contractors can also misinterpret a geotechnical engineering their own responsibilities and risks. Read these provisions report. Reduce that risk by having your geotechnical engineer closely. Ask questions. Your geotechnical engineer should participate in prebid and preconstruction conferences, and by respond fully and frankly. providing construction observation. Gecenvironmental Concerns Are Not Covered Do Not Redraw the Engineer's logs The equipment, techniques, and personnel used to perform a Geotechnical engineers prepare final boring and testing logs geoenvironmental study differ significantly from those used to based upon their interpretation of field logs and laboratory perform a geotechnical study. For that reason, a geotechnical data. To prevent errors or omissions, the logs included in a engineering report does not usually relate any geoenvironmen- geotechnical engineering report should never be redrawn for tat findings, conclusions, or recommendations; e.g., about the inclusion in architectural or other design drawings, Only photo- likelihood of encountering underground storage tanks or regu- graphic or electronic reproduction is acceptable, but recognize lated contaminants. unanticipated environmental problems have that separating logs from the report can elevate risk. led to numerous project failures. If you have not yet obtained your own geoenvironmental information, ask your geotechnical Give Contractors a Complete consultant for risk management guidance, Do not rely on an Report and Guidance environmental report prepared for someone else, Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface condi- REIN on Your Geotechnical EngineeP top tions by limiting what they provide for bid preparation. To help Additional Assistance prevent costly problems,give contractors the complete geotech- Membership in ASFE exposes geotechnical engineers to a wide nical engineering report, but preface it with a clearly written let- array of risk management techniques that can be of genuine ben- ter of transmittal, In that letter,advise contractors that the report efit for everyone involved with a construction project. Confer with was not prepared for purposes of bid development and that the your ASFE-member geotechnical engineer for more information. PROFESSIONAL A F FIRMS PRACTICING IN THE GEOSCIENCES 8811 Colesviile Road Suite G106 Silver Spring, MID 20910 Telephone: 301-565-2733 Facsimile: 301-589-2017 email: info@asfe.org www.asfe.org Copyright 1998 by ASFE, Inc.Unless ASFE grants wo ten permission to do so,duplication of this document by any means whatsoever is expressly prohibited. Reuse or the wording in this document,in whole or 3n part, also is expressly prohibited,and may be done only with the express permission of ASFE or for purposes of review or scholarly research. IIGER06 3,bM pE APPENDIX C ASFE GEOTECHNICAL ENGINEERING REPORT INFORMATION N C-0 s i E TMM Cal ED ifleeping Repop MIME=, opt ■ � 1. r ► 1 ` ► AIN 0 • elevation, configuration structure.orientation, or Geoiechnl .01 $eeviceS Are Performed f :weight of the propose OSeS, Persons, and Projects • composition of the design team, or eeific PuriA • project ownership. ;,technical engineers structure their services to meet the con-engineering study our eotechnical engineer cific needs of their clients.A g As a general rule, always inform y g _ acted far a civil engineer may not fulfill the needs of a construe minor another civil engineer. Because each gent- of project changes mvact. Geotechnical engineers cannotnd t an onon contractor or even is unique, each geotechnical engi- assessment of their p echnicai engineering study for problems that occur repo is unique, prepared accept responsibility or liability veering rep re urge solely for the client. lV a one axcept you should rely on your ge ,technical engineering P because their reports do not consider developments of which without first conferring with the geotechnical engineer who pre• they were not Informed. pared it. And no one—not even you—should apply the report for a purpose n project except the one originally contemplated. Snbsurfaca Conditions Can Change Y q geotechnical engineering report is based on conditions that Wort fs Based on existed at the time the study was performed. 1) n0 ay have A Gentechnicai fJ1lneOrindact�rs geotechnical engineering report whose adequacyde events. A Unique Set ©f Prolect'Si10Cif the passage of time; by natural ro ect-spe- been affected by. Geotechnical engineers consider a number of unique. P 1 wakes, or groundwater fluctua- stud .Typical factors such as construction on or adjacent to the site, or by cific factors when establishing the scope of a Y its size, and Lions. Always contact the geotech still arei engineer minor amoujnt include: the client's goals, objectives, and risk m agement pref events, such as floods,t ear t s erences,,the general nature of the structure involved,tother or analysis could prevent major problems. configuration', the location of the structure on the siccessdroaes 'o additional testing grmine t i coolie planned or existing site improvements, such as a parking lots. and underground u�i4eitiesspe fcaHynless thndgatescather Most Geotechnical Findings Ape engineer who conducted the calen engineering report that was: Professional opinions s.onl at those wise. do not rely on a geotechn g samples are • not prepared for you, Site exploration identifies subsurface condition Y • not prepared for your project, points where subsurface tests are conducted or sump t re pared far the specific site explored, or re made. taken. Geotechnical engineers review field and laboratory data • n0 p p and then apply their professional judgment to render an apinion • completed before important project changes were n existing about subsurface conditions throughout the site. Actual sub- surface conditions may differ—sometirnes significantly Typical changes that can erode the reliability of a the ,,technical engi 4 geotechnical engineering report include those that affect: those indicated in your report. t to g function of the proposed structure, as when neer who developed your report to provide construction therisks asses ' thevation is the most effective method of manag g it's changed from a parking garage to an office ciated with unanticipated conditions. building, or from a light industrial plant to a refrigerated warehouse, l 6 Ft's Recommendations Are Nat Final report's accuracy is limited; encourage them to confer with the rrely on the construe#Ian recommendations includedgeotechnical engineer who prepared the report (a modest fee ort. Those recommendations are not final, because may be required) and/or to conduct additional study to obtain geotechnical engineers develop them principally from judgment the specific types of information they need or prefer. A prebid and opinion. Gectechnical engineers can finalize their recom conference can also be valuable. Be sure contractors have sufii- mendations only by observing actual subsurface conditions cient time to perform additional study. Only then might you be in revealed during construction. The geotechnical engineer who a position to give contractors the best information available to developed your report cannot assume responsibility or liability for you, while requiring them to at least share some of the financial ! the report's recommendations if that engineer does not perform responsibilities stemming from unanticipated conditions. construction observation. Read Responsibility Provisions Closely A Geotechnical Engineering Report is Subject Some clients, design professionals, and contractors do not To Misinterpretatlon recognize that geotechnical engineering is far less exact than other engineering disciplines. This lack of understanding has Other design team members' misinterpretation of geotechnical created unrealistic expectations that have led to disappoint- engineering reports has resulted in costly problems. Lower ments, claims, and disputes. To help reduce such risks, geot- that risk by having your geotechnical engineer confer with echnical engineers commonly include a variety of explanatory appropriate members of the design team after submitting the provisions in their reports. Sometimes labeled "limitations", report. Also retain your geotechnical engineer to review perti- many of these provisions indicate where geotechnical engi- nent elements of the design team's plans and specifications. neers responsibilities begin and end, to help others recognize Contractors can also misinterpret a geotechnical engineering their own responsibilities and risks. Read these provisions report. Reduce that risk by having your geotechnical engineer closely. Ask questions. Your geotechnical engineer should participate in prebid and preconstruction conferences, and by respond fully and frankly. providing construction observation. Do Not Redraw the Engineers Logs Ge0envlronmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform a Geotechnical engineers prepare final boring and testing logs geoenvironmental study differ significantly from those used to based upon their interpretation of field logs and laboratory perform a geotechnical study. For that reason, a geotechnical data. To prevent errors or omissions, the fogs included in a engineering report does not usually relate an g geotechnical engineering report should never be redrawn for tal findings, conclusions, or recommendations; e.g., about theinclusion in architectural or other design drawings. Only photo- likelihood of encountering underground storage tanks or regu- graphic or electronic reproduction is acceptable, but recognize lated contaminants. unanticipated environmental problems have that separating logs from the report can elevate risk, led to numerous project failures. If you have not yet obtained your own geoenvironmental information, ask your geotechnical Give Contractors a Complete consultant for risk management guidance. Do not rely on an Report and Guidance environmental report prepared for someone else. Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface condi- Rely on Your Geotechnical Engineer top tions by limiting what they provide for bid preparation. To help Additional Assistance prevent costly problems,give contractors the complete geotech- Membership in ASFE exposes geotechnical engineers to a wide nical engineering report, but preface it with a clearly written let- array of risk management techniques that can be of genuine ben- ter of transmittal. In that letter,advise contractors that the report efit for everyone involved with a construction project, Confer with was not prepared for purposes of bid development and that the your ASFE-member geotechnical engineer for more information. PROFESSIONAL FIRMS PRACTICING A F IN THE GEOSCIENCES 8811 Colesviile Road Suite G106 Silver Spring, MD 20910 Telephone: 301-565-2733 Facsimile: 301-589-2017 email: info@asfe.org www,asie.org Copynght 1998 by ASFE. Inc.unless ASFE grants written permission to do so,duplication of this document by any means whatsoever is expressly pronibiteo, Re-use of the wording in this pocument.in whole or in part,also is expressly prohibited,and may be done only with the express permission of ASFE or for purposes of review or scho3arly research, IIGER069&15M