REPORT OF SUBSURFACE EXPLORATION AND GEOTECHNICAL ENGINEERING SERVICES

Transcription

1 REPORT OF SUBSURFACE EXPLORATION AND GEOTECHNICAL ENGINEERING SERVICES FAMILY DOLLAR OF ROCKFORD 09 & CHARLES STREET ROCKFORD, ILLINOIS ECS PROJECT NO. 16:1181 FOR NATIONAL RETAIL DEVELOPMENT LLC CHICAGO, ILLINOIS MAY 0, 016

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3 REPORT PROJECT Subsurface Exploration and Geotechnical Engineering Services 09 & Charles Street CLIENT National Retail Development LLC Attn: Mr. Jordan Liss 19 S. LaSalle Street Suite 1007 Chicago, Illinois 6060 SUBMITTED BY ECS Midwest, LLC 17 Barclay Boulevard Buffalo Grove, Illinois Illinois Professional Design Firm No PROJECT #16:1181 DATE May 0, 016

4 TABLE OF CONTENTS EXECUTIVE SUMMARY PROJECT OVERVIEW 1 Introduction 1 Existing Site Conditions 1 Proposed Construction 1 Purposes of Exploration and Scope of Services 1 EXPLORATION PROCEDURES Subsurface Exploration Procedures Laboratory Testing Program EXPLORATION RESULTS Soil Conditions Groundwater Observations 6 ANALYSIS AND RECOMMENDATIONS 7 Overview 7 Subgrade Preparation and Earthwork Operations 7 Fill Placement and Compaction 11 Foundation Recommendations 1 Floor Slab Design 1 Underslab Sub-Drainage Design 1 Pavement Design 1 Pavement Maintenance 16 PROJECT CONSTRUCTION RECOMMENDATIONS 17 General Construction Considerations 17 Construction Dewatering 17 Closing APPENDIX 19 Page

5 EXECUTIVE SUMMARY The subsurface conditions encountered during our exploration and ECS Midwest, LLC. s conclusions and recommendations are summarized below. This summary should not be considered apart from the entire text of the report with all the qualifications and considerations mentioned herein. Details of our conclusions and recommendations are discussed in the following sections and in the Appendix. The project site is located at the site addresses of 09 & Charles Street, in. We understand that the proposed construction at the project site will consist of a single-story, slab-on-grade Family Dollar Store and the associated site amenities. A total of eight (8) soil borings, designated as B-1 through B- and P-1 through P-, were conducted at the project site under ECS direction. The subsurface conditions encountered at the borings performed onsite can be summarized as follows. The surficial materials at the boring locations were observed to consist of approximately ½ to inches of bituminous pavement underlain by to 7 inches of gravel or about 6 to 1 inches of topsoil. No discernable surficial materials were observed at boring locations B-1, B- and P-. The underlying materials below the surficial materials at boring locations B- through B-, P-1 and P- and from the ground surface at borings B-1, B- and P- were observed to consist of various cohesive and granular FILL soils to depths of about 1 to feet below existing site grades. The FILL was observed to be underlain by natural soils, by Fat Clay to about 6 feet below grade (at B-) or by Organic Soil to depths of 6 to 8½ feet (at P-1 and P-). Organic Soil was also observed at boring location B- from beneath the gravel subbase to about 6½ feet below site grades. The unsuitable, near-surface soils were typically observed to be underlain by variations of natural Silty CLAY and granular soil strata to boring termination. The Silty Clay FILL/Silty Clay with Sand FILL exhibited unconfined compressive strength values of 1 to tsf and moisture contents of about 19 to percent. The Debris FILL, Fine to Medium Sand with Gravel FILL and Medium to Coarse Sand FILL exhibited SPT N-values of about to 8 blows per foot (bpf), which is indicative of a very loose to loose relative density for granular soils. Due to the variable nature and consistency of FILL soils, unconfined compressive strength values should not be considered representative of the actual in-place consistencies of the FILL. The Organic Soil observed at borings B-, P-1 and P- exhibited unconfined compressive strengths in the range of ¼ to ¼ tsf (soft to very stiff) and moisture content values of about 6 to 1 percent. The Fat Clay at B- and B- exhibited unconfined compressive strengths in the range of 1 to 1¾ tsf (stiff) and moisture contents of about to percent. The natural Silty CLAY and Silty CLAY with Sand was observed to exhibit hand penetrometer unconfined compressive strengths ranging from ½ to ¼ tsf, which is indicative of medium stiff to hard consistencies (typically stiff to very stiff). Moisture content values were observed in the range of 0 to percent. The natural granular soils exhibited SPT N-values ranging from to 9 bpf (loose). We are aware that complete removal and replacement of the existing FILL, Organic Soil and Fat Clay within the building and parking area footprint may not be feasible from a construction cost perspective. As such, we are providing two options for support of the slab and pavements based on the anticipated cost and the level of risk the owner is willing to accept: Option 1 Partial Removal and Option Proofroll/Replace. ECS strongly recommends complete removal and replacement of the existing FILL, Organic Soil and Fat Clay within the building footprint. Based on the subsurface encountered and anticipated structural loads, a shallow foundation system extended through the existing fill soils bearing on competent natural soils (a variation of natural Silty CLAY exhibiting an unconfined compressive strength of 1¼ tsf or greater or natural Sand or Sand and Gravel with an SPT N-value of at least 6 bpf) or new engineered fill/lean-mix concrete (observed and tested by ECS) overlying competent natural soils can be designed for a maximum net allowable bearing pressure of,00 psf. Based on the building borings (B-1 through B-) competent natural soils for footings will likely be encountered in the range of about to 6½ feet below existing grades. More detailed recommendations with regard to foundations, subgrade preparation and earthwork operations, fill placement, slab and pavement design, underslab drainage and construction dewatering are included herein and must be fully reviewed and understood so that the intent of the recommendations are properly utilized during design and construction of the proposed development. We recommend that ECS be retained during construction of the proposed development to monitor all earthwork/subgrade preparation to verify that the exposed subgrade materials and the soil bearing pressures will be suitable for the proposed structure. Report Prepared By: Rachel E. Miller Project Manager Report Reviewed By: Paul J. Giese, P.E. Principal Engineer

6 ECS Project No. 16: May 0, 016 Introduction PROJECT OVERVIEW This report presents the results of our subsurface exploration and geotechnical engineering recommendations for the proposed Family Dollar Store to be constructed at 09 & Charles Street in. A General Location Map included in the Appendix of this report shows the approximate location of the project site. This study was conducted in general accordance with ECS Proposal No. 16:19-GP (dated April 7, 016) and authorized by your office. In preparing this report, we have utilized information from our current subsurface exploration as well as information from nearby sites. Existing Site Conditions The project site is located at 09 & Charles Street in. The property is bound to the north by Charles Street, to the south by commercial buildings, to the east by 1 st Street and to the west by a Subway restaurant and 0 th Street. The western portion of the site appears to be a bituminous parking area. A grassed, undeveloped space occupies the central portion of the site and, based on aerial photograph review, a structure was previously located in this area of the site. We understand the structure occupying the eastern portion of the site (at the address of Charles Street) has partially burned down. Based on our review of available online resources (i.e., Google Earth ), existing site grades appear to be in the range of about EL. +79 feet to EL. +71 feet (+/-). Proposed Construction We understand that the proposed construction at the project site will consist of a single-story, slab-on-grade Family Dollar Store and the associated site amenities (i.e., parking lot, drive lanes, loading zone and dumpster enclosure). The proposed structure will have approximate dimensions in plan view of 10 feet in the northeast-southwest direction by 80 feet in the northwest-southeast direction, for a total area in plan view of about 8,0 SF. The proposed building will be constructed toward the northeastern corner of the site, within the footprint of the existing and former building areas, and will be a steel-framed structure. Based on the information provided to ECS, the maximum column and wall loads are anticipated to be approximately 60 kips and klf, respectively. The maximum floor load will be 10 pounds per square foot (psf). Information regarding the finished floor elevation of the proposed structure was not known at the time this proposal was written. We anticipate the finished floor elevation of the ground floor level will approximately match the existing site grades. ECS was provided with pavement design criteria of 0,76 -Kip EAL s over a 0-year design life for heavy-duty applications and 11,79 -Kip EAL s over a 0-year design life for light-duty pavements. Purposes of Exploration and Scope of Services The purposes of this exploration were to explore the soil and groundwater conditions at the project site and to develop engineering recommendations to guide in the design and

7 ECS Project No. 16: May 0, 016 construction of the project. We accomplished these purposes by performing the following scope of services: 1. Reviewing the geotechnical reports prepared for nearby sites by ECS;. Drilling eight (8) SPT soil borings at the project site using an auger drill rig;. Performing laboratory tests on selected representative samples from the borings to evaluate pertinent engineering properties;. Analyzing the field and laboratory data to develop appropriate engineering recommendations; and,. Preparing this geotechnical report of our findings and recommendations. The conclusions and recommendations contained in this report are based on eight (8) soil borings, designated as B-1 through B- and P-1 through P-, were conducted at the project site under ECS direction. The distribution and depths of the onsite soil borings are as follows: Soil borings B-1 through B- were drilled within the approximate footprint of the proposed building to depths ranging from about 1 feet to 0 feet below existing site grades. Soil borings P-1 through P- were drilled within the limits of the proposed parking lot and drive lanes to a depth of about 10 feet below existing site grades. The subsurface exploration included split-spoon soil sampling, standard penetration tests (SPT) and groundwater level observations in the boreholes. The results of the completed soil borings, along with a Boring Location Diagram are included in the Appendix of this report. The boring locations were selected by ECS based on the layout of the proposed construction, and the borings were located in the field by an ECS representative. The approximate locations of the borings are shown on the Boring Location Diagram. Based on our review of available online resources (i.e., Google Earth ), existing site grades appear to be in the range of about EL. +79 feet to EL. +71 feet (+/-). Ground elevations from Google Earth can vary and may not represent the actual elevations at the project site. Existing site grades should be surveyed prior to project design and construction.

8 ECS Project No. 16: May 0, 016 Subsurface Exploration Procedures EXPLORATION PROCEDURES The borings were located in the field by an ECS representative. The soils borings were selected based on the proposed layout of the proposed construction at locations accessible to the truck drill rig. An ECS subcontracted driller contacted the State of Illinois One Call System, JULIE, to clear and mark underground utilities in the vicinity of the project site prior to drilling operations. The soil borings were performed with a CME truck-mounted rotary-type auger drill rig which utilized continuous flight augers to advance the boreholes. Representative soil samples were obtained by means of conventional split-barrel sampling procedures. Samples were typically obtained at ½-foot intervals to the boring termination depths. In this procedure, a -inch O.D., split-barrel sampler is driven into the soil a distance of inches by a 10-pound hammer falling 0 inches. The number of blows required to drive the sampler through a 1-inch interval, after initial setting of 6 inches, is termed the Standard Penetration Test (SPT) or N-value and is indicated for each sample on the boring logs. The SPT value can be used as a qualitative indication of the in-place relative density of cohesionless soils. In a less reliable way, it also indicates the consistency of cohesive soils. This indication is qualitative, since many factors can significantly affect the standard penetration resistance value and prevent a direct correlation between drill crews, drill rigs, drilling procedures, and hammer-rod-sampler assemblies. The drill rig utilized an automatic trip hammer to drive the sampler. Consideration of the effect of the automatic hammer s efficiency was included in the interpretation of subsurface information for the analyses prepared for this report. A field log of the soils encountered in the borings was maintained by the drill crew. After recovery, each geotechnical soil sample was removed from the sampler and visually classified. Representative portions of each soil sample were then sealed in jars. The soil samples were then delivered to our laboratory in Buffalo Grove, Illinois for further visual evaluation and laboratory testing. After completion of the drilling operations, the boreholes were backfilled with auger cuttings to the existing ground surface. Laboratory Testing Program Representative soil samples were selected and tested in our laboratory to check field classifications and to determine estimate engineering properties. The laboratory testing program included visual classifications, calibrated hand penetrometer unconfined compressive strength testing and moisture content determinations of cohesive soil samples. Each soil sample was classified on the basis of texture and plasticity in accordance with the Unified Soil Classification System. The group symbols for each soil type are indicated in parentheses following the soil descriptions on the boring logs. A brief explanation of the Unified System is included with this report. The various soil types were grouped into the major zones noted on the boring logs. The stratification lines designating the interfaces between earth materials on the boring logs and profiles are approximate; in situ, the transitions may be gradual.

9 ECS Project No. 16: May 0, 016 The unconfined compressive strength (Qp) of relatively cohesive clayey soil samples was estimated with the use of a calibrated hand penetrometer. In the hand penetrometer test, the unconfined compressive strength of a soil sample is estimated, to a maximum of ½ tons per square foot (tsf) by measuring the resistance of a soil sample to penetration of a small, calibrated spring-loaded cylinder. The soil samples will be retained in our laboratory for a period of 60 days, after which, they will be discarded unless other instructions are received as to their disposal.

10 ECS Project No. 16: May 0, 016 Soil Conditions EXPLORATION RESULTS A total of eight (8) soil borings, designated as B-1 through B- and P-1 through P-, were conducted at the project site under ECS direction. The subsurface conditions encountered at the borings performed at the site can be summarized in the following paragraphs. The specific soil types observed at the boring locations are noted on the boring logs enclosed in the Appendix. The surficial materials at the boring locations were observed to consist of approximately ½ to inches of bituminous pavement underlain by to 7 inches of gravel or about 6 to 1 inches of topsoil. The underlying materials below the surficial materials at boring locations B- through B-, P-1 and P- and from the ground surface at borings B-1, B- and P- were observed to consist of various FILL soils (Silty Clay FILL, Silty Clay with Sand FILL, Fine to Medium Sand with Gravel FILL, Medium to Coarse Sand FILL and Debris FILL) to depths of about 1 to feet below existing site grades. The FILL at these six boring locations was observed to be underlain by natural Silty CLAY/Silty CLAY with Sand to depths of 7½ to 1 feet (at B-1 through B-), by Fat Clay to about 6 feet below grade (at B-) or by Organic Soil to depths of 6 to 8½ feet (at P- 1 and P-). A stratum of natural SAND-based soils was observed near boring termination at B- and B-, and Fat Clay was encountered from about 9 to 1 feet below grade at boring B-. The Organic Soil at P-1 and P- was observed to be underlain by natural Silty CLAY to boring termination at 10 feet below existing site grades. Organic Soil was also observed at boring location B- from beneath the gravel subbase to about 6½ feet below site grades. The Organic Soil at B- was observed to be underlain by natural Silty CLAY and natural Silty Fine to Medium SAND to depths of 8 feet and boring termination at 1 feet, respectively. P- was observed to be comprised of natural Silty CLAY (with some organic content within the upper feet of soils). The Silty Clay FILL/Silty Clay with Sand FILL exhibited unconfined compressive strength values of 1 to tsf and moisture contents of about 19 to percent. The Debris FILL, Fine to Medium Sand with Gravel FILL and Medium to Coarse Sand FILL exhibited SPT N-values of about to 8 blows per foot (bpf), which is indicative of a very loose to loose relative density for granular soils. Due to the variable nature and consistency of FILL soils, unconfined compressive strength values should not be considered representative of the actual in-place consistencies of the FILL. The Organic Soil observed at borings B-, P-1 and P- exhibited unconfined compressive strengths in the range of ¼ to ¼ tsf (soft to very stiff) and moisture content values of about 6 to 1 percent. The Fat Clay at B- and B- exhibited unconfined compressive strengths in the range of 1 to 1¾ tsf (stiff) and moisture contents of about to percent. The natural Silty CLAY and Silty CLAY with Sand was observed to exhibit hand penetrometer unconfined compressive strengths ranging from ½ to ¼ tsf, which is indicative of medium stiff to hard consistencies (typically stiff to very stiff). Moisture content values were observed in the range of 0 to percent. The natural granular soils (Silty Fine to Medium SAND, Fine to Medium SAND with Gravel, Medium to Coarse SAND with Gravel, Fine to Medium SAND) exhibited SPT N-values ranging from to 9 bpf (loose).

11 ECS Project No. 16: May 0, 016 It should be noted that bid quantity estimation by averaging depths and strata changes from boring logs may not be representative of the actual depths and strata changes during earthwork construction. Too many variations exist for such averaging to be valid, particularly in the pavement and base course thicknesses, soil types and condition, depth, and groundwater conditions. Additional scope of professional services may be required to obtain subsurface information needed for land purchase considerations and earthwork bid preparation. This additional scope could include test pit exploration program to better understand the extents (vertical and horizontal) of the materials/soils of concern (such as unsuitable soft soils to be removed and replaced). Even with this additional information, contingencies should always be carried in construction budgets or land purchase agreements to cover variations in subsurface conditions. Soil borings cannot present the same full-scale view that is obtained during complete site grading, excavation or other aspects of earthwork construction. Groundwater Observations Observations for groundwater were made during sampling and upon completion of the drilling operations at the boring locations. In auger drilling operations, water is not introduced into the boreholes, and the groundwater position can often be obtained by observing water flowing into or out of the boreholes. Furthermore, visual observation of the soil samples retrieved during the auger drilling exploration can often be used in evaluating the groundwater conditions. Groundwater was observed in the range of about 1½ to ½ feet below grade during drilling and about 1 to ½ feet after drilling had ceased at boring locations B- and B-. Groundwater was not observed at the remaining six soil boring locations. Glacial till soils in the Midwest frequently oxidize from gray to brown above the level at which the soil remains saturated. The long-term groundwater level is often interpreted to be near this zone of color change. Based on the results of this subsurface exploration, we estimate the long-term groundwater level to be in the range of about 1 to feet below existing site grades (or possible deeper). The highest groundwater observations are normally encountered in late winter and early spring. It should be noted that the groundwater level can vary based on precipitation, evaporation, surface run-off and other factors not immediately apparent at the time of this exploration. Surface water runoff will be a factor during general construction, and steps should be taken during construction to control surface water runoff and to remove water that may accumulate in the proposed excavations as well as floor slab and pavement areas.

12 ECS Project No. 16: May 0, 016 Overview ANALYSIS AND RECOMMENDATIONS The conclusions and recommendations presented in this report should be incorporated in the design and construction of the project to reduce possible soil and/or foundation related problems. The following recommendations have been developed on the basis of the previously described project characteristics and subsurface conditions encountered at the project site. If there are any changes to the project characteristics or if different subsurface conditions are encountered during construction, ECS Midwest, LLC should be consulted so that the recommendations of this report can be reviewed and modified, if necessary. The following sections present specific recommendations with regard to the design of the proposed Family Dollar store. These include recommendations with regard to subgrade preparation and earthwork, fill placement, building foundations, floor slab design, pavement design and construction dewatering. Discussion of the factors affecting the building foundations for the proposed construction, as well as additional recommendations regarding design and construction at the project site are included below. We recommend that ECS review the final design and specifications to check that the earthwork and foundation recommendations presented in this report have been properly interpreted and implemented in the design and specifications. Subgrade Preparation and Earthwork Operations The proposed structure at the project site will be a one-story, slab-on-grade building without a basement level. Based upon the existing topography across the site we have assumed the building finish floor elevation will approximately match the existing site grades. If our assumption for the final grade is incorrect, or if existing grades will be raised, please contact ECS so we can review (and revise if appropriate) our recommendations for subgrade preparation discussed below. Existing Structures Demolition and Backfilling To limit the potential for future settlement of the proposed Family Dollar building, it is important that the existing structure and any remnants of the previous structure at the project site be properly demolished and/or removed and the resulting excavations properly backfilled prior to construction of the new structures. Improper demolition and backfilling could lead to foundation and floor slab/pavement distress caused by unacceptable total and differential settlements. The existing and former structures (i.e., slabs, foundation walls/footings and any below-grade walls/slabs/foundations and underground structures) should be completely removed during demolition activities and resulting excavations backfilled with compacted engineered fill to the final design site grades following the recommendations provided in the Fill Placement section of this report. It has been our experience that demolition contractors sometimes place the debris in excavations and cap the buried debris with soil. These types of activities will not provide a suitable subgrade for foundations, slabs or pavements. The foundation contractor should mobilize appropriate equipment to remove and/or break up existing foundations and other

13 ECS Project No. 16: May 0, 016 obstructions without delay. Any underground utilities to remain should be positively located, properly protected and supported prior to and during excavation and subgrade preparation activities. Underground utilities within the proposed building areas should be relocated or removed and backfilled with engineered fill. We recommend engineered fill consisting of granular material be considered to backfill excavations resulting from demolition of the existing structure and removal of underground utilities. Abandoned utilities should be grouted in place. ECS recommends that the demolition and backfilling operations at the project site be observed on a full time basis by an ECS representative retained on your behalf to confirm and document that work is performed in general accordance with the recommendations detailed herein and the backfill materials used are approved materials and adequately placed and compacted. Initial Subgrade Preparation Slab-on-Grade and Pavements Following demolition activities, the initial site preparation should consist of the complete removal of existing topsoil, bituminous pavement, granular subbase material and other deleterious material. The existing pavement granular subbase materials can be stockpiled for possible reuse (provided it is first reviewed by a qualified professional and determined to be suitable for use). The stripped topsoil can be stockpiled for later use in landscaping and non-structural areas. Once the surficial materials have been removed, the limits of the building footprint, parking lots and drive lanes should be excavated to the design subgrade elevation. ECS does not recommend the slab and pavement subgrades remain exposed to the elements or construction traffic for a prolonged period of time as the subgrade may be disturbed and/or softened. If the slab and/or pavement section is not planned to be constructed within a few days after exposing the final design subgrade, consideration should be given to leaving the subgrade approximately 1 foot above the final design subgrade to help prevent softening of the design subgrade soils (if feasible). We anticipate the soils at the slab and pavement subgrades will typically consist of Silty Clay FILL, Silty Clay with Sand FILL, Fine to Medium Sand with Gravel FILL, Debris FILL, Organic Soil, Fat Clay or natural Silty CLAY after completion of the initial stripping. We do not recommend the building slab and/or pavements be supported on or above FILL, as the fill materials exhibit variable composition and in-situ consistencies, which could result in unfavorable total and differential settlements and corresponding premature distress of the slabs/pavements. Similarly, Organic Soil can settle significantly over time and Fat Clay has a tendency to cause heaving. As such, we highly recommend complete removal of the existing variable FILL, Organic Soil and Fat Clay within the building footprint and replacement with engineered fill or properly manipulated and placed onsite soils. All undercut excavations should be performed with equipment capable of performing the excavation without disturbing the underlying natural soils. Furthermore, undercutting should proceed in a manner that facilitates prompt filling excavations to help limit exposure of the undercut subgrade. Complete removal and replacement of the existing FILL, Organic Soil and Fat Clay should provide the best subgrade support and long term pavement and slab performance. We are aware that complete and removal and replacement of the existing FILL, Organic Soil and Fat Clay materials may not be feasible from a cost perspective (especially for pavement areas). As such, consideration could be given to the following the two alternate site preparation options provided the owner is willing to accept some risk of premature deterioration of the building slab and pavements and long term maintenance issues.

14 ECS Project No. 16: May 0, 016 Proofrolling Option 1 Partial Removal (Building and Pavements) Option 1 consists of replacing the existing near-surface FILL, Organic Soil and Fat Clay materials to a depth of 1 foot below the final pavement subgrade elevation (below the pavement section) and to a depth of feet below the final slab bearing elevation (below the building area). Following removal of FILL, Organic Soil and Fat Clay, the removed soils can be manipulated, screened of Debris FILL, Organic Soils, Fat Clay and any other deleterious materials and particles greater than inches in size, placed back in lifts, and re-compacted in accordance with our recommendations discussed in the Fill Placement and Compaction section of this report. Crushed granular engineered fill may be required to supplement the properly manipulated and replaced onsite soils and fill excavated areas to the desired pavement and slab grades. This partial removal and replacement option would reduce the volume of required undercuts compared to complete removal, but would result in a slightly higher risk of premature deterioration/cracking of the slab and pavements. The undercut subgrade should be densified/compacted to the extent practical and proofrolled prior to placing manipulated onsite soils and/or new engineered fill. Additional removal depths or other suitable measures may be required dependent on the materials encountered and results of proofrolling. For the pavement areas, the use of biaxial or triaxial geogrid could also aid in stabilizing the subgrade and extending pavement service life. Option Proofroll/Replace (Building and Pavements) Once the subgrade soils have been exposed, the subgrade could be proofrolled using a loaded dump truck having an axle weight of at least 10 tons. The intent of the proofroll is to aid in identifying localized soft or unsuitable material which may be required to be removed. If soft or yielding soils are observed during the proofroll of the subgrade, the soft soils should be undercut up to a maximum of 1 foot (in the pavement areas) or feet (in the building slab footprint) and replaced with compacted engineered fill to the design subgrade. This option will only identify near-surface soils that are unsuitable for pavement and slab support. Any deeper pockets of unsuitable FILL, Organic Soil or Fat Clay may not be fully identified, which could lead to premature deterioration/cracking of the building slab and pavements. Therefore, this option must include the acceptance of a higher risk of premature deterioration/cracking of the pavements and slab when compared to either complete removal/replacement of existing FILL, Organic Soils and Fat Clay or partial removal and replacement of the unsuitable soils (Option 1). Proofrolling should take place after the full-depth removal of unsuitable FILL, Organic Soil and Fat Clay materials below the proposed building slab and pavements (most conservative option), after stripping 1 foot (for pavements) or feet (for building slabs) of the unsuitable soils (for Option 1 Partial Removal) or after the existing and former buildings, existing topsoil, pavement and subbase has been removed and the new slab and pavement subgrade has been exposed (for Option Proofroll/Replace). The exposed subgrade should also be proofrolled within the building footprint, once soils have been stripped to the slab elevation. Once the subgrade has been exposed and prior to placing new fill and stone base material, the subgrade should be proofrolled using a loaded dump truck having an axle weight of at least 10 tons. The intent of the proofroll and testing is to aid in identifying localized soft or unsuitable material

15 ECS Project No. 16: May 0, 016 which may be required to be removed. If soft or yielding soils are observed during the proofroll and testing of the subgrade, the soft or yielding soils should be undercut up to a maximum of 1 foot and replaced with compacted and engineered fill to the design subgrade in accordance with the Fill Placement section of this report. Proofrolling of the subgrade should be performed under the observation of an ECS field representative. The final depth of undercutting should be determined by ECS based upon the results of the construction phase evaluations. To help limit the volume of soil removed as a result of the proofrolling and/or testing observations, we recommend soft or yielding soils be evaluated in approximately 6 to 1-inch intervals. That is to say, if soft or yielding soils are identified, the contractor should remove 6 to 1 inches of material in the subject area and then proofroll/evaluate the undercut subgrade. This could potentially limit the need to remove feet of soil at once at all locations where soft or yielding soils are identified. A DCP (dynamic cone penetrometer) or Army Corps of Engineers penetrometer can also be used in conjunction with proofrolling to establish appropriate depths for remedial action. General Steps should be taken by the contractor to control surface water runoff and to remove water from precipitation that may accumulate in the subgrade areas, especially during the wet season. When wet and subjected to construction traffic, softening and disturbance of the exposed subgrade may occur. Construction traffic should be especially limited when the subgrade is wet. During final preparation of the subgrade, a smooth drum roller is often used to provide a flat surface and provide for better drainage to reduce the negative impact of rain events. We also recommend sealing, crowning and sloping the subgrade to provide positive drainage off the subgrades. Exposure to the environment may weaken the subgrade soils if the excavations remain open for too long a period. If the subgrade soils are softened by surface water intrusion or exposure, the softened soils must be removed from the subgrade excavation bottom immediately prior to placement of concrete and/or engineered fill. Excavations should comply with the requirements of OSHA 9CFR, Part 196, Subpart P, "Excavations" and its appendices, as well as other applicable codes. This document states that the contractor is solely responsible for the design and construction of stable, temporary excavations. The excavations should not only be in accordance with current OSHA excavation and trench safety standards but also with applicable Local, State, and Federal regulations. The contractor should shore, slope or bench the excavation sides when appropriate. If problems are encountered during the earthwork operations, or if site conditions deviate from those encountered during our subsurface exploration, ECS should be notified immediately. We recommend that the project geotechnical engineer or his representative be on site to monitor stripping and site preparation operations and observe that unsuitable soils have been satisfactorily removed and observe the proofrolling of the subgrades. These observations are particularly important due to presence of undocumented fill at the site.

16 ECS Project No. 16: May 0, 016 Fill Placement and Compaction All fills should consist of an approved material, free of organic matter and debris, particles greater than -inches and have a Liquid Limit and Plasticity Index less than 0 and 0, respectively. Unacceptable fill materials include topsoil and organic materials (OH, OL), high plasticity silts and clays (CH, MH), fat clays and low-plasticity silts (ML). Under no circumstances should high plasticity soils be used as fill material in proposed structural areas or close to site slopes. We do not recommend the use of pea gravel as engineered fill. Pea gravel has round/smooth characteristics, no fines and does not interlock when compacted which make more susceptible to future movement and instability resulting in excessive and variable settlement. The existing Silty Clay FILL/Silty Clay with Sand FILL, Fine to Medium Sand with Gravel FILL, Medium to Coarse Sand FILL, Silty CLAY, Silty CLAY with Sand, Fine to Medium SAND with Gravel, Medium to Coarse SAND with Gravel and Fine to Medium SAND soils can potentially be used for engineered fill provided it is determined to be free of organics and debris and it is moisture conditioned to within the acceptable range of moisture contents. Similarly the onsite Silty Fine to Medium SAND can potentially be reused as fill, but only if placed below the frost depth. The Debris FILL, Organic Soil and Fat Clay should not be considered potential fill material. Any onsite and offsite soils to be considered for engineered fill at the project site should be approved by the project geotechnical engineer prior to placement at the time of construction. For onsite soils found suitable (after ECS evaluation during construction) for use as engineered fill, the contractor should be prepared to implement discing or other drying techniques (termed manipulation) and recognize and account for increased costs associated with manipulation of the suitable onsite soils. In addition, if construction occurs in late fall to early spring, drying the onsite cohesive soils may not be possible and the contractor should budget for offsite fill, if required. Fill materials should be placed in lifts not exceeding 8-inches in loose thickness and moisture conditioned to within ± percentage points of the optimum moisture content. Soil bridging lifts should not be used, since intolerable settlement of overlying structures will likely occur. Controlled fill soils should be compacted to a minimum of 9% of the maximum dry density obtained in accordance with ASTM D-17, Modified Proctor method. The zone of the engineered fill placed below the foundations should extend 1 foot beyond the outside edges of the footings and from that point, outward laterally 1 foot for every feet of fill thickness below the footing. The expanded footprint of the proposed building pad, pavement and fill areas should be well defined, including the limits of the fill zones at the time of fill placement. Grade control should be maintained throughout the fill placement operations. All fill operations should be observed on a full-time basis by a qualified soil technician to determine that the specified compaction requirements are being met. A minimum of one compaction test per,00 square foot area should be tested in each lift placed. Within trench or other localized excavations, one test for each 0 linear feet of each lift of fill shall be performed. The elevation and location of the tests should be clearly identified at the time of fill placement. Compaction equipment suitable to the soil type used as fill should be used to compact the fill material. Theoretically, any equipment type can be used as long as the required density is achieved; however, the standard of practice typically dictates that a vibratory roller be utilized

17 ECS Project No. 16: May 0, 016 for compaction of granular soils and a sheepsfoot roller be utilized for compaction of cohesive soils. In addition, a steel drum roller is typically most efficient for compacting and sealing the surface soils. All areas receiving fill should be graded to facilitate positive drainage away from the building pad and pavement areas. It should be noted that prior to the commencement of fill operations and/or utilization of off-site borrow materials, the Geotechnical Engineer of Record should be provided with representative samples to determine the material s suitability for use in a controlled compacted fill and to develop moisture-density relationships. In order to expedite the earthwork operations, if off-site borrow materials are required, it is recommended they consist of suitable fill materials in accordance with the recommendations previously outlined in this section. Fill materials should not be placed on frozen soils or frost-heaved soils and/or soils that have been recently subjected to precipitation. All frozen soils should be removed prior to continuation of fill operations. Borrow fill materials, if required, should not contain frozen materials at the time of placement. All frost-heaved soils should be removed prior to placement of controlled, compacted fill, granular subbase materials, foundation or slab concrete, and asphalt pavement materials. Foundation Recommendations Based on the subsurface conditions encountered and anticipated structural loads, the proposed structure can be supported on shallow foundations extended through any existing FILL soils, Organic Soil and Fat Clay and bearing on competent natural Silty CLAY/Silty CLAY with Sand or new engineered fill/lean-mix concrete overlying competent natural soils. A shallow foundation system bearing on competent natural soils (a variation of natural Silty CLAY exhibiting an unconfined compressive strength of 1¼ tsf or greater and natural Sand or Sand and Gravel with an SPT N-value of at least 6 bpf) or new engineered fill (observed and tested by ECS) overlying competent natural soils can be designed for a maximum net allowable bearing pressure of,00 psf. The net allowable soil bearing pressure refers to that pressure which may be transmitted to the foundation bearing soils in excess of the final minimum surrounding overburden pressure. Based on data from the borings performed within the planned building area, competent soils for footings will likely be encountered in the range of about to 6½ feet below existing grades. General We recommend the foundation excavations be filled with concrete the day they are excavated, or if not feasible, the subgrade protected with a crushed stone or lean-mix concrete working mat, if the excavations will be left open overnight. It should be noted that pockets of soils containing organics (roots) were observed at a few locations throughout the project site. If additional fill soils/organic soils are encountered during the foundation excavations, the full depth fill soils must be removed and replaced with engineered fill/lean-mix concrete to the foundation subgrade elevation. If soft/unsuitable soils or soils with elevated moisture contents are encountered at the proposed bearing elevation, the footings should extend until suitable bearing soils are encountered or the unsuitable soils should be removed beneath the base of the footing and replaced with

18 ECS Project No. 16: May 0, 016 compacted engineered fill or lean-mix concrete. If engineered fill is utilized, the engineered fill should be compacted to a minimum of 9 percent of the maximum dry density in accordance with ASTM D17 (Modified Proctor Method). The zone of the engineered fill placed below the foundations should extend 1 foot beyond the outside edges of the footings and from that point, outward laterally 1 foot for every feet of fill thickness below the footing. If lean-mix concrete is utilized to replace weaker/low bearing soils or unsuitable soils, lateral over-excavation is typically not necessary, but the excavation should be 1 foot wider than the footing (6 inches on each side), and the lean-mix concrete should be allowed to sufficiently harden prior to placement of the foundation concrete. We recommend that the excavation/backfill of foundations be monitored full-time by an ECS Geotechnical Engineer or his representative to verify that the soil bearing pressure is consistent with the subsurface information obtained during the geotechnical exploration. We also recommend that supplemental soil testing such as hand augers and DCP or Army Corp of Engineers static cone penetrometer testing be performed during foundation excavations to observe the suitability of the bearing soils. To help reduce the potential for foundation bearing failure and excessive settlement due to local shear or "punching" action, we recommend that continuous footings have a minimum width of inches and that isolated column footings have a minimum lateral dimension of 0 inches. In addition, footings should be placed at a depth to provide adequate frost cover protection. For this region, we recommend the exterior footings and footings beneath unheated areas be placed at a minimum depth of ½ feet below finished grade. Interior footings in heated areas can be placed at a minimum of feet below grade provided that suitable soils are encountered and that the foundations will not be subjected to freezing weather either during or after construction. Settlement of individual footings, designed in accordance with our recommendations presented in this report, is expected to be small and within tolerable limits for the proposed building. For footings placed on suitable natural soils or properly compacted engineered fill, maximum total settlement is expected to be in the range of about 1 inch or less. Maximum differential settlement between adjacent columns is expected to be about ½ of the total settlement. These settlement values are based on our engineering experience with the soil and the anticipated structural loading, and are to guide the Structural Engineer with his design. Floor Slab Design For the design and construction of the slabs-on-grade for the building, the recommendations provided in the section entitled Subgrade Preparation and Earthwork Operations should be followed. The floor slab thicknesses can be determined utilizing an assumed modulus of subgrade reaction of 10 pounds per cubic inch (pci) if all FILL, Organic Soil and Fat Clay is removed within the building footprint, 1 pci for Subgrade Preparation Option 1 Partial Removal and 100 pci if Subgrade Preparation Option Proofroll/Replace is implemented. We recommend the slab be designed with a minimum thickness of inches. We recommend consideration be given to the floor slab being underlain by a minimum of 6 inches of granular material having a maximum aggregate size of 1½ inches and no more than percent soil passing the No. 00 sieve. This granular layer will facilitate the fine grading of the subgrade and help prevent the rise of water through the floor slab. Prior to placing the granular

19 ECS Project No. 16: May 0, 016 material, the floor subgrade should be free of standing water, mud, and frozen soil. Before the placement of concrete, a vapor barrier may be placed on top of the granular material to provide additional moisture protection. Welded-wire mesh reinforcement should be placed in the upper half of the floor slab and attention should be given to the surface curing of the slab to minimize uneven drying of the slab and associated cracking and/or slab curling. The use of a blotter or cushion layer above the vapor retarder can also be considered for project specific reasons. Please refer to ACI 0.1R0 Guide for Concrete Floor and Slab Construction and ASTM E 16 Standard Practice for Installation of Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs for additional guidance on this issue. The floor slab should be isolated from the foundation footings so differential settlement of the structure will not induce shear stresses on the floor slab. For maximum effectiveness, temperature and shrinkage reinforcements in slabs on ground should be positioned in the upper third of the slab thickness. The Wire Reinforcement Institute recommends the mesh reinforcement be placed inches below the slab surface or upper one-third of slab thickness, whichever is closer to the surface. Adequate construction joints, contraction joints and isolation joints should also be provided in the slab to reduce the impacts of cracking and shrinkage. Please refer to ACI 0.1R0 Guide for Concrete Floor and Slab Construction for additional information regarding concrete slab joint design. If problems are encountered during the slab subgrade preparation, or if site conditions deviate from those encountered during our subsurface exploration, ECS should be notified immediately. We recommend that the project geotechnical engineer or his representative should be on site to monitor subgrade preparation and observe that unsuitable soils have been satisfactorily removed and the subgrade soils are suitable to support the slab. Underslab Sub-Drainage Design Based on the groundwater levels observed during the subsurface exploration, we do not anticipate a significant volume of water will persist at the slab subgrade elevation. It should be noted however that surface runoff and limited groundwater seepage may accumulate at the slab subgrade such as the perched water condition. As such, we recommend that positive drainage be implemented around the perimeter of the proposed structure to reduce the potential for water accumulation under the floor slab and foundation elements, which could potentially weaken the bearing soils. Pavement Design We recommend that the pavement subgrade be prepared in accordance with the Subgrade Preparation and Earthwork Operations section of this report. An IBR value of can be used in the pavement design. Once the subgrade has been properly prepared, we recommend the following minimum pavement sections for the proposed development based on the Family Dollar pavement design criteria. All pavement materials and construction should be in accordance with the IDOT Standard Specifications for Road and Bridge Design.

20 ECS Project No. 16: May 0, 016 Table 1: Pavement Section Recommendations Compacted Material Thicknesses (Inches) Flexible Flexible Pavement Material Rigid Pavement Rigid Pavement Pavement Pavement (Light Duty) (Heavy Duty) (Light Duty) (Heavy Duty) Portland Cement Concrete Bituminous Surface Course 1¾ 1¾ Bituminous Base Course Crushed Granular Subbase Total Pavement Section Thickness ¾ *8 *10 *6 *8 11¾ 1½ 1 1 * If Subgrade Preparation Option (Proofroll/Replace) is implemented, we recommend an additional inches of aggregate base for each pavement section to help reduce the potential for premature pavement distress. The pavement sections specified in the table above are based on the Family Dollar traffic loadings provided by the design team: 0,76 -Kip EAL s over a 0-year design life for heavy-duty applications and 11,79 -Kip EAL s over a 0-year design life for light-duty pavements, which are equivalent to Traffic Factors of approximately 0.01 and 0.011, respectively. The table above provides Light Duty and Heavy Duty flexible and rigid pavement recommendations. The light-duty pavement section assumes that typical traffic loading will be limited to standard automobiles and does not account for more heavily loaded vehicles (i.e., multiple axle trucks) and should be used for parking stalls. The Heavy-Duty pavement section is recommended for pavements to be subjected with frequent traffic such as drive lanes, entrance/exit drive areas, delivery areas and loading dock aprons. It should also be noted that the pavement sections specified in the table above were developed for the anticipated in-service traffic conditions only and do not provide an allowance for construction traffic conditions or traffic conditions in excess of typical residential/collector street traffic. Therefore, if pavements will be constructed early during site development to accommodate construction traffic, consideration should be given to the construction of designated haul roads, where thickened pavement sections can be provided to accommodate the construction traffic, as well as the future in-service traffic. Large, front loading trash dumpsters frequently impose concentrated front-wheel loads on pavements during loading. This type of loading typically results in rutting of the pavement and ultimately pavement failures. Therefore, we recommend that the pavement in trash pickup areas consist of the heavy duty rigid pavement section in Table 1. It should be noted that the pavement should be comprised of air-entrained Portland cement concrete with a minimum compressive strength of,000 psi and a minimum flexural strength of 60 psi. Adequate construction joints, contraction joints and isolation joints should be provided in the areas of rigid pavement to reduce the impacts of cracking and shrinkage. Please refer to ACI 0R-9 Guide for Design of Concrete Parking Lots. The Guide recommends an appropriate spacing strategy for the anticipated loads and pavement thickness. It has been our experience

21 ECS Project No. 16: May 0, 016 that joint spacing closer to the minimum values results in a pavement with less cracking and better long term performance. We recommend the crushed granular base course should be compacted to at least 9 percent of the maximum dry density obtained in accordance with ASTM D17, Modified Proctor Method. During bituminous pavement construction, the wearing and leveling course should be compacted to a minimum of 9 percent of the theoretical density value. Prior to placing the granular material, the pavement subgrade soil should be properly compacted, observed to be stable during a final proofroll and free of standing water, mud, and frozen soil. The pavements should be designed and constructed with adequate surface and subsurface drainage. Where standing water develops, either on the pavement surface or within the base course layer, softening of the subgrade and other problems related to the premature deterioration of the pavement can be expected. Furthermore, good drainage should minimize the possibility of the subgrade materials beneath the pavement becoming saturated over a long period of time. We recommend pavement subgrades should be crowned, or sloped, a minimum of 1 to percent to help promote subsurface water flow across the clay subgrades (where encountered) and avoid the creation of bathtubs beneath the pavements, trapping water. The trapped water or standing water in the bathtubs can result in saturation of the aggregate base course and Silty CLAY subgrade soils leading to softening of the subgrade, and pavement cracking, depression or rutting and settlement. Pavement Maintenance Regular maintenance and occasional repairs should be implemented to keep pavements in a serviceable condition. In addition, to help minimize water infiltration to the pavement section and within the base course layer resulting in softening of the subgrade and deterioration of the pavement, we recommend the timely sealing of joints and cracks using elastomeric caulk in rigid pavements and hot poured emulsified asphalt sealant in flexible pavements. We recommend exterior pavements should be reviewed for distress/cracks at least twice a year, once in the spring and once in the fall. Sound maintenance programs should help maintain and enhance the performance of pavements and attain the design service life. A preventative maintenance program should be implemented early in the pavement life to be effective. The standard in the industry supported by research indicates that preventative maintenance should begin within to years of the construction of the pavement. Failure to perform preventative maintenance will reduce the service life of the pavement and increase the costs for both corrective maintenance and full pavement rehabilitation.

22 ECS Project No. 16: May 0, 016 General Construction Considerations PROJECT CONSTRUCTION RECOMMENDATIONS We recommend that the subgrade preparation, installation of the foundations, and construction of slabs-on-grade and pavement be monitored by an ECS geotechnical engineer or his representative. Methods of verification and identification such as proofrolling, hand auger probes with in-situ DCP testing will be necessary to further evaluate the subgrade soils and identify unsuitable soils. The contractor should be prepared to over-excavate slab-on-grade and pavement subgrades at isolated locations (as necessary). We recommend that excavations of new foundations be monitored on a full-time basis by an ECS geotechnical engineer or his representative to verify that the soil bearing pressure and the subgrade materials will be suitable for the proposed structure and are consistent with the boring log information obtained during this geotechnical exploration. We would be pleased to provide these services. All unsuitable materials and environmentally impacted soils (if any) should be removed and legally disposed offsite and replaced with environmentally clean, inorganic fill and free of debris or harmful matter. Unsuitable materials and environmentally impacted soils removed from the project site should be disposed of in accordance with all applicable Federal, State, and Local regulations. The contractor should avoid stockpiling excavated materials immediately adjacent to the excavation walls. We recommend that stockpile materials be kept back from the excavation a minimum distance equal to the excavation depth to avoid surcharging the excavation walls. If this is impractical due to space constraints, the excavation walls should be retained with bracing designed for the anticipated surcharge loading. Excavations should comply with the requirements of OSHA 9CFR, Part 196, Subpart P, "Excavations" and its appendices, as well as other applicable codes. This document states that the contractor is solely responsible for the design and construction of stable, temporary excavations. The excavations should not only be in accordance with current OSHA excavation and trench safety standards but also with applicable local, state, and federal regulations. The contractor should shore, slope or bench the excavation sides when appropriate. Site safety is the sole responsibility of the contractor, who shall also be responsible for the means, methods and sequencing of construction operations. Construction Dewatering Based on the groundwater conditions encountered at the project site, we do not anticipate that significant dewatering efforts will be required during construction of shallow foundations, slabon-grade and at grade parking lot/pavement. The general contractor should be prepared to remove any accumulated water prior to the placement of fill and concrete. We anticipate that the removal of any accumulated water can be achieved utilizing drainage trenches and a sump and pump system. Exposure to the environment may weaken the soils at the footing bearing level if the foundation excavations remain open for too long a period. If possible, foundation concrete should be placed the same day that excavations are dug. If the bearing soils are softened by surface

23 ECS Project No. 16: May 0, 016 water intrusion or exposure, the softened soils must be removed from the foundation excavation bottom immediately prior to placement of concrete. Closing This report has been prepared to aid in the evaluation of this property and to assist the architect and/or engineer in the design of this project. The scope is limited to the specific project and locations described herein and our description of the project represents our understanding of the significant aspects relative to soil and foundation characteristics. In the event that any change in the nature or location of the proposed construction outlined in this report are planned, we should be informed so that the changes can be reviewed and the conclusions of this report modified or approved in writing by the geotechnical engineer. It is recommended that all construction operations dealing with earthwork and foundations be reviewed by an experienced geotechnical engineer to provide information on which to base a decision as to whether the design requirements are fulfilled in the actual construction. If you wish, we would welcome the opportunity to provide field construction services for you during construction. The analysis and recommendations submitted in this report are based upon the data obtained from the soil borings and tests performed at the locations as indicated on the Boring Location Diagram and other information referenced in this report. This report does not reflect variations, which may occur between the borings. In the performance of the subsurface exploration, specific information is obtained at specific locations at specific times. However, it is a wellknown fact that variations in soil conditions exist on most sites between boring locations and also such situations as groundwater levels vary from time to time. The nature and extent of variations may not become evident until the course of construction. If variations then appear evident, after performing onsite observations during the construction period and noting characteristics and variations, a reevaluation of the recommendations for this report will be necessary. In addition to geotechnical engineering services, ECS Midwest, LLC has the in-house capability to perform multiple additional services as this project moves forward. These services include the following: Environmental Consulting; Geophysical Testing (ReMi and PHSA) Project Drawing and Specification Review; and, Construction Material Testing / Special Inspections We would be pleased to provide these services for you. If you have questions with regard to this information or need further assistance during the design and construction of the project please feel free to contact us.

24 APPENDIX General Location Plan Boring Location Diagram Boring Logs Unified Soil Classification System Reference Notes for Boring Logs

25 Approximate Project Site Location Figure 1 GENERAL LOCATION PLAN ECS Project No. 16: & Charles Street

26 Service Layer Credits: ² Legend Boring Locations ft Boring Location Diagram FAMILY DOLLAR OF ROCKFORD ROCKFORD IL ENGINEER SCALE 1 " = 60 ' PROJECT NO. 16:1181 SHEET 1 OF 1 DATE /17/016