CSAH 17 Reconstruction/Rehabilitation I-94 to TH 5 Lake Elmo, Minnesota. Prepared for

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1 Geotechnical Evaluation Report CSAH 17 Reconstruction/Rehabilitation I-94 to TH 5 Prepared for Washington County Public Works Professional Certification: I hereby certify that this plan, specification, or report was prepared by me or under my direct supervision and that I am a duly Licensed Professional Engineer under the laws of the State of Minnesota. Neil G. Lund, PE Project Engineer License Number: October 17, 2014 Project B Braun Intertec Corporation

2 Braun Intertec Corporation Hampshire Avenue S Minneapolis, MN Phone: Fax: Web: braunintertec.com October 17, 2014 Project B Mr. Frank Ticknor, PE Washington County Public Works Myeron Road North Stillwater, MN Re: Geotechnical Evaluation CSAH 17 Reconstruction/Rehabilitation I-94 to TH 5 Dear Mr. Ticknor: We are pleased to present this Geotechnical Evaluation Report for the rehabilitation and reconstruction of County State Aid Highway (CSAH) 17 in. Our results and recommendations in light of the geotechnical issues influencing design and construction follow in the attached report, which we recommend you read in its entirety. Thank you for making Braun Intertec your geotechnical consultant for this project. If you have questions about this report, or if there are other services that we can provide in support of our work to date, please call Neil Lund at Sincerely, BRAUN INTERTEC CORPORATION Neil G. Lund, PE Project Engineer Matthew S. Oman, PE Associate - Senior Engineer AA/EOE

3 Table of Contents Description Page A. Introduction...1 A.1. Project Description...1 A.2. Purpose...1 A.3. Background Information and Reference Documents...1 A.4. Site Conditions...1 A.5. Scope of Services...2 A.5.a. Staking and Surveying...2 A.5.b. Subsurface Exploration...2 A.5.c. Laboratory Testing...2 A.5.d. Ground Penetrating Radar...2 A.5.e. Geotechnical Evaluation, Analysis and Reporting...3 B. Results...3 B.1. Exploration Logs...3 B.1.a. Log of Boring Sheets...3 B.1.b. Geologic Origins...3 B.2. Geologic Profile...4 B.2.a. Pavements, Topsoil and Fill Soil...4 B.2.b. Lacustrine Deposits...4 B.2.c. Glacial Outwash...4 B.2.d. Glacial Till...5 B.2.e. Inferred Geologic Material Properties...5 B.2.f. Groundwater...5 B.3. Laboratory Test Results...6 B.4. Ground Penetrating Radar...7 C. Basis for Recommendations...7 C.1. Design Details...7 C.1.a. Pavements and Traffic Loads...7 C.1.b. Utility Depths...8 C.1.c. Anticipated Grade Changes...8 C.1.d. Precautions Regarding Changed Information...8 C.2. Design and Construction Considerations...8 C.2.a. Utility Construction...8 C.2.b. Road Reconstruction (30th Street to TH 5)...8 C.2.c. Road Rehabilitation (I-94 to 30th Street)...9 C.2.d. Stormwater Ponds...9 D. Recommendations...9 D.1. Utilities...9 D.1.a. Excavation...9 D.1.b. Dewatering...10

4 Table of Contents (continued) Description Page D.1.c. Selection, Placement and Compaction of Backfill...10 D.1.d. Excavation Side Slopes...11 D.1.e. Subgrade Stabilization...11 D.1.f. Corrosion Potential...11 D.2. Pavement Reconstruction (30th Street to TH 5)...12 D.2.a. Pavement Subgrade Preparation...12 D.2.b. Subgrade Proofroll...12 D.2.c. Design Sections...12 D.2.d. Materials and Compaction...13 D.2.e. Subgrade Drainage...13 D.3. Pavement Rehabilitation (I-94 to 30th Street)...13 D.3.a. Design R-value...13 D.3.b. Designing and Performing CIR...13 D.4. Construction Quality Control...14 D.4.a. Excavation Observations...14 D.4.b. Materials Testing...14 D.4.c. Pavement Subgrade Proofroll...14 D.4.d. Cold Weather Precautions...15 E. Procedures...15 E.1. Penetration Test Borings...15 E.2. Material Classification and Testing...15 E.2.a. Visual and Manual Classification...15 E.2.b. Laboratory Testing...15 E.3. Groundwater Measurements...16 E.4. Ground Penetrating Radar...16 E.4.a. Data Collection...16 E.4.b. Analysis...16 F. Qualifications...17 F.1. Variations in Subsurface Conditions...17 F.1.a. Material Strata...17 F.1.b. Groundwater Levels...17 F.2. Continuity of Professional Responsibility...17 F.2.a. Plan Review...17 F.2.b. Construction Observations and Testing...18 F.3. Use of Report...18 F.4. Standard of Care...18 Appendix Boring Location Sketch Log of Boring Sheets (ST-1 through ST-15 and D-1 through D-4) Descriptive Terminology

5 A. Introduction A.1. Project Description This Geotechnical Evaluation Report addresses the proposed reconstruction and pavement rehabilitation of County State Aid Highway (CSAH) 17 in. The location of the project is illustrated in Boring Location Sketch in the Appendix. Between 30th Street North and Trunk Highway (TH) 5, the project will include drainage and corridor improvements (streetscaping) and municipal sanitary sewer upgrade, including on adjacent Lavern Avenue in Lake Elmo. From Interstate 94 (I-94) to 30th Street North, the project will include pavement rehabilitation, possibly in the form of cold in-place recycling (CIR). A.2. Purpose The purpose of our geotechnical evaluation was to characterize the existing pavement thicknesses (rehabilitation area) and subsurface geologic conditions (reconstruction area) at selected exploration locations and evaluate their impact on the design and construction of the Washington County CSAH 17 improvement project. A.3. Background Information and Reference Documents To facilitate our evaluation, we were provided with or reviewed the following information or documents: Proposed Boring Locations provided by SEH, Inc. Geologic Atlas of Washington County available from the Minnesota Geological Society. A.4. Site Conditions Our referenced documents and past project experience in the general area indicate that the site is underlain with sandy and gravelly glacial outwash, with pockets of lacustrine silts, silty-clays and fine sands near the north end of the project (Lake Elmo Old Village area at TH 5).

6 Washington County Public Works Project B October 17, 2014 Page 2 The roadway(s) are currently two-lane and two-way with a mix of pavement widths and curb and crosssection types. Roadway topography is flat to rolling and generally falls from north to south within the project area. MnDOT data (2011 counts) indicates traffic volumes in the corridor vary from 4,150 to 4,500 vehicles per day between 30th Street North and TH 5, and between 3,550 and 4,350 between I-94 and 30th Street North. A.5. Scope of Services Our scope of services for this project was originally submitted as an Proposal to Mr. Frank Ticknor of Washington County Public Works, from whom we received ed authorization to proceed. Tasks completed in accordance with our authorized scope of services are described below. Our scope of services was performed under the terms of an amended contract with Washington County under Contract Number A.5.a. Staking and Surveying Exploration locations and surface elevations at the exploration locations were determined using GPS technology that utilizes the Minnesota Department of Transportation's permanent GPS Virtual Reference Network (VRN). A.5.b. Subsurface Exploration We performed 19 penetration test borings at the locations shown on Boring Location Sketch in the Appendix. The borings were extended to between 10 and 50 below surface grades. Prior to commencing with our subsurface exploration activities, we cleared the exploration locations of underground utilities through Gopher State One Call. A.5.c. Laboratory Testing We performed moisture content tests and sieve analyses (#200 sieve only) on selected penetration test samples. A.5.d. Ground Penetrating Radar In the portion of the project between I-94 and 30th Street, we performed ground penetrating radar scans in both directions of travel.

7 Washington County Public Works Project B October 17, 2014 Page 3 Note that, due to road work at the time of our site visit, which included a lane shift to the west, the scans represented by the northbound and southbound lanes may include portions of centerline or shoulder pavement. Pavement cores, originally proposed to verify GPR thicknesses, were not completed due to this same road work. A.5.e. Geotechnical Evaluation, Analysis and Reporting Information obtained from the soil borings and GPR was used to identify the geotechnical issues influencing design and construction, qualify the nature of their impact, and outline alternatives for their mitigation, including baseline recommendations for: Excavation dewatering. Selecting, placing and compacting on-site or imported earth materials. Designing utility bedding and pavements, including pavement rehabilitations. Providing quality control and evaluating differing site conditions during construction. B. Results B.1. Exploration Logs B.1.a. Log of Boring Sheets Log of Boring sheets for our penetration test borings are included in the Appendix. The logs identify and describe the geologic materials that were penetrated, and present the results of penetration resistance tests performed within them, laboratory tests performed on penetration test samples retrieved from them and groundwater measurements. Strata boundaries were inferred from changes in the penetration test samples and the auger cuttings. Because sampling was not performed continuously, the strata boundary depths are only approximate. The boundary depths likely vary away from the boring locations, and the boundaries themselves may also occur as gradual rather than abrupt transitions. B.1.b. Geologic Origins Geologic origins assigned to the materials shown on the logs and referenced within this report were based on: (1) a review of the background information and reference documents cited above, (2) visual classification of the various geologic material samples retrieved during the course of our subsurface exploration, (3) penetration resistance testing performed for the project, (4) laboratory test results, and

8 Washington County Public Works Project B October 17, 2014 Page 4 (5) available common knowledge of the geologic processes and environments that have impacted the site and surrounding area in the past. B.2. Geologic Profile As revealed by the borings, the site is underlain with a variety of geologic materials including pavements, fill soil (or topsoil in off-road borings), localized lacustrine deposits, glacial outwash and limited glacial till. B.2.a. Pavements, Topsoil and Fill Soil The borings performed for the roadway and utilities (labeled ST ) initially encountered bituminous pavement and aggregate base averaging 5.7 and 11.0 inches thick, respectively. The layers were generally consistent, with the bituminous ranging from 5 to 6 1/4 inches and the aggregate base ranging from 9 1/2 to 13-inches. Two borings performed for stormwater management areas (labeled D D-1 and D-3) first encountered a layer of topsoil between about 7 and 8-inches thick. The topsoil was a mix of silty and clayey sand. Beneath pavement materials and topsoil (and at the surface of borings D-2 and D-4), the borings generally encountered soils identified as fill. These materials were classified as poorly graded sand with silt, silty sand, clayey sand, sandy lean clay and mixes of various soil types. The fill generally appeared to extend to about 3 to 4, with some exceptions such as ST-2 and ST-6 (7 ) and ST-4 (16 ). B.2.b. Lacustrine Deposits Several borings near the north end of the project area (ST-1, ST-2, ST-3, ST-13, ST-14 and ST-15) encountered lacustrine deposits beneath the fill soils. These deposits were generally very fine grained and included poorly graded sand with silt, silty sand, silt with sand, silt, lean clay with sand and silty clay that extended to depths between 9 and 23. B.2.c. Glacial Outwash Glacial outwash soils were the majority of native soils encountered on the project, either below lacustrine soils described in Section B.2.b or below fill soils described in Section B.2.a. (In ST-8 and ST-10, the pavement materials directly overlay native soils identified as glacial outwash).

9 Washington County Public Works Project B October 17, 2014 Page 5 The glacial outwash soils consisted of generally granular deposits including poorly graded sand, poorly graded sand with silt, silty sand, poorly graded gravel and clayey sand. We commonly noted seams of silt and clay within granular layers, as well as possible cobbles in ST-15. B.2.d. Glacial Till In one boring (D-3), we identified the reddish-brown clayey sand encountered at 13 as glacial till. B.2.e. Inferred Geologic Material Properties The results of our penetration resistance testing are summarized below in Table 1. Comments are provided to qualify the significance of the results. Table 1. Penetration Resistance Data Geologic Material Fill Lacustrine Deposits Classification(s) SP-SM, SM, SC, Sandy CL, mixed soils SM, ML w/sand, ML, CL w/sand, ML-CL Penetration Resistances (N, bpf) 2 in 18 inches to 12 (granular); 3 to 16 (nongranular) 2 to 10 Glacial Outwash SP, SP-SM, SM, GP, SC 4 to 30 Comments Generally loose but variable compaction Soft to rather stiff; most commonly rather soft Very loose to medium dense; generally medium dense Glacial Till (one boring) SC 12 Rather stiff B.2.f. Groundwater Groundwater was measured or estimated to be located at the depths shown below in Table 2. Corresponding groundwater elevations were determined from comparisons of the measured/estimated depths to groundwater and surface elevations, and were rounded to the highest 1/2-foot. Table 2. Groundwater Summary Location Surface Elevation Measured or Estimated Depth to Groundwater (ft) Corresponding Groundwater Elevation (ft) ST ST / /2 ST

10 Washington County Public Works Project B October 17, 2014 Page 6 As indicated, groundwater was encountered in the range of elevations 880 to 888. Seasonal and annual fluctuations of groundwater should be anticipated. B.3. Laboratory Test Results Results of our laboratory tests are presented below in Tables 3. Table 3. Laboratory Classification Test Results Location Sample Depth (ft) Classification Moisture Content (w, %) Percent Passing a #200 Sieve ST-2 5 CL CL-ML ST-3 5 ML ST-4 2 1/2 SC ST-5 5 SP ST-7 5 SM SC ST-9 10 SM ST-10 5 SM ST /2 SP-SM SC ST-14 5 SP-SM ST ML D-3 7 1/2 SM SC D-4 5 ML 18 93

11 Washington County Public Works Project B October 17, 2014 Page 7 B.4. Ground Penetrating Radar We estimated bituminous pavement thicknesses from the GPR scans as shown in Table 4. See the Appendix of this report for a plot showing GPR-measured thickness by station. Table 4. GPR-Measured Bituminous Thicknesses NB Bituminous Thickness (inches) Average Minimum Maximum th Percentile th Percentile SB There appear to be three general segments within the scanned portion of CSAH 17. One break is approximately 1.9 miles north of I-94, which appears to correspond to the area where the traffic shift began. Another change is visible at Hudson Road. The minimum section noted for both lanes occurred at the intersection of the entrance to Cimarron Park, just south of CSAH 10. Additional exploration would be required in this small area to evaluate the cause of the discrepancy. We recommend seeing the full scan in the Appendix for detailed information. We recommend comparing the collected data to as-built data or confirming with cores where possible. C. Basis for Recommendations C.1. Design Details C.1.a. Pavements and Traffic Loads We assume replacement pavements will have a bituminous section. Using the MnDOT State Aid ESAL Traffic Forecast Calculator - 04/07/2014, we calculated approximately 474, year equivalent single axle loads (ESALs) for pavement design using the conservative case of 4,500 vehicles per day and a growth factor of 1.3 with an urban traffic distribution.

12 Washington County Public Works Project B October 17, 2014 Page 8 C.1.b. Utility Depths We understand the sanitary sewer extension will be placed at depths of up to 20. C.1.c. Anticipated Grade Changes We assume grades will generally match those of the existing alignment. C.1.d. Precautions Regarding Changed Information We have attempted to describe our understanding of the proposed construction to the extent it was reported to us by others. Depending on the extent of available information, assumptions may have been made based on our experience with similar projects. If we have not correctly recorded or interpreted the project details, we should be notified. New or changed information could require additional evaluation, analyses and/or recommendations. C.2. Design and Construction Considerations C.2.a. Utility Construction The soils in the borings appear reasonably well-suited for excavation and support of the proposed utilities. Typical soils near the likely depths of sanitary sewer consisted of poorly graded sand and silty sand. We anticipate these soils will generally be suitable for support of the utility. However, our borings also encountered layers of silty clay, silt (and silt with sand) and lean clay (plus lean clay with sand), which may very difficult to compact if disturbed or if wet. These soils may require blending, drying or other conditioning before they can be reused as backfill, or may need to be exported and replaced with suitable imported soils. Dewatering will very likely be required along portions of the alignment based on the observed groundwater depths and anticipated utility elevations. C.2.b. Road Reconstruction (30th Street to TH 5) The existing subgrade soils generally consisted of silty sand, clayey sand and poorly graded sand. These soils appear to be suitable for support of the pavements. Note that soils with higher fine contents may be more difficult to compact if wet upon exposure or allowed to become wet or disturbed by construction traffic. If desired, the existing pavement sections can be reclaimed for reuse as an aggregate base for the new pavements. Our borings encountered a relatively consistent, average thickness of pavement materials of

13 Washington County Public Works Project B October 17, 2014 Page 9 approximately 17-inches. Due to the apparent thickness of the existing bituminous (5.7 inches), we recommend a 10-to 12-inch reclamation depth. C.2.c. Road Rehabilitation (I-94 to 30th Street) Based on information obtained from the GPR, it appears there is adequate pavement section thickness to allow for the CIR approach between I-94 and 30th Street. For CIR, the average bituminous thickness of approximately 7.2-inches will allow for a 3-inch-thick recycled mat and 2-inch pre-mill assuming relatively intact bituminous layer (i.e. one free of significant bottom-up stripping and other materials defects). A detailed visual assessment of the pavement surface condition of CSAH 17 between I-94 and 30th Street was not included in the scope of this evaluation; if not yet completed, we recommend a review of surface conditions to evaluate whether CIR will be an effective rehabilitation strategy. C.2.d. Stormwater Ponds Soils encountered at depth at potential pond locations included silty sand, poorly graded sand, clayey sand and silt. The infiltration rates of these soils will vary significantly. If an estimate of infiltration is required, we recommend performing an in-situ test such as the double-ring infiltrometer (ASTM D3385) at the proposed pond bottom depth. D. Recommendations D.1. Utilities D.1.a. Excavation Excavation should be achievable using backhoes and typical open-cut trenching methods. Based on the borings and anticipated depths, the majority of the sanitary sewer will bear on native sand and silty sand soils and we anticipate these soils will be suitable for support of the utility. Exceptions include areas were silt and silty clay soils were encountered, which we do not recommend leaving in place below utilities. The following is a list of borings where soils considered unsuitable for direct support of the utilities were encountered.

14 Washington County Public Works Project B October 17, 2014 Page 10 ST-1: Silt with sand (9-11 ) ST-2: Silty clay (10-18 ); Silt with sand (18-23 ) ST-3: Silt (4-6 ) ST-4: Possible debris around 15 ST-13: Silty clay (3-4 ) ST-14: Silt with sand (9-11 ) ST-15: Silt with sand (7-12 ) D-4: Silt (4-7 ) D.1.b. Dewatering Based on groundwater observations made in the borings (Table 2) and anticipated excavation depths, groundwater will likely be encountered in the excavations at about 0 in select locations (elevations 880 to 888). We recommend removing groundwater from the excavations. Sumps and pumps can be considered for excavations where groundwater can be drawn down 2 below the bottoms of excavations (in advance of excavating) in more permeable sands. In large excavations, or where groundwater must be drawn down more than 2, a well contractor should review our logs to determine if wells are required, how many will be required, and to what depths they will need to be installed. D.1.c. Selection, Placement and Compaction of Backfill Onsite soils excavated as part of utility installation may generally be used as backfill material. Organic materials such as topsoil or buried topsoil, silt or silty-clay soils should not be used as backfill below any utilities. Additionally, we encountered soil layers in several locations that may prove difficult to recompact once disturbed as noted in Section D.1.a. We do not recommend reusing those or similar soils in trench backfill unless they can be improved with granular soils in order to improve their workability and stability under load. This may include mixing them with granular soils excavated for the stormwater control ponds (Borings D-1 through D-4) or by blending them with imported materials. We recommend spreading backfill and fill in loose lifts of approximately 12-inches maximum in accordance with the criteria presented below in Table 5. The relative compaction of utility backfill should be evaluated based on the structure below which it is installed and vertical proximity to that structure.

15 Washington County Public Works Project B October 17, 2014 Page 11 Care should be taken to compact against the utilities using hand-operated equipment. A geotechnical engineer or geotechnical engineering assistant should closely monitor backfill placement and compaction. Table 5. Minimum Recommended Compaction Levels Area of Backfill Placement Minimum Compaction Level, percent (ASTM D 698) Within 1:1 oversize zone of roadways, below upper 3 of subgrade 95 Within 1:1 oversize zone of roadways, within 3 of subgrade 100 Below utilities 95 Green areas and other areas not supporting structures 92 D.1.d. Excavation Side Slopes All excavations must comply with the requirements of OSHA 29 CFR, Part 1926, Subpart P, Excavations and Trenches. This document states that excavation safety is the responsibility of the contractor. Reference to these OSHA requirements should be included in the project specifications. The borings indicate that at the anticipated excavation depths the soils in the sidewalls of the excavations will generally be Type C soils under the OSHA guidelines. Excavations in excess of 20 are required to be designed by a licensed engineer. These recommendations are not intended to be that design. D.1.e. Subgrade Stabilization To help support the installation of the sanitary sewer and improve long-term support of the utility in the presence of groundwater, we recommend bedding the pipe on at least 12-inches of MnDOT Coarse Aggregate Bedding (3149.G2). We recommend following manufacturing bedding requirements for shallower utilities as needed. D.1.f. Corrosion Potential Corrosion protection should not be required for ductile iron pipe. Type I cement may also be specified for concrete utilities.

16 Washington County Public Works Project B October 17, 2014 Page 12 D.2. Pavement Reconstruction (30th Street to TH 5) D.2.a. Pavement Subgrade Preparation The upper portion of subgrade soils encountered in the borings generally consisted of poorly graded sand, silty sand and clayey sand. These soils are considered suitable for pavement support. After removal or reclamation of the existing pavement, we recommend surface-compacting the resulting subgrades (or residual aggregate base) with a vibratory compactor. Areas that cannot be compacted properly should be moisture conditioned and recompacted or removed and replaced with materials that can be compacted. On-site soils free of organic soil and debris, with the exception of silt soils, can be considered for placement within pavement subgrades. Note again that any fine-grained soils will be more difficult to compact if wet or allowed to become wet, or if spread and compacted over wet surfaces. We recommend compacting excavation backfill (including utility backfill) and additional required fill placed within 3 of pavement subgrade elevations to at least 100 percent of their maximum standard Proctor dry densities (ASTM D 698). Backfill and fill placed more than 3 below pavement subgrade elevations should be compacted to at least 95 percent. D.2.b. Subgrade Proofroll Prior to placing aggregate base material, we recommend proofrolling pavement subgrades to determine if the subgrade materials are loose, soft or weak, and in need of further stabilization, compaction or subexcavation and recompaction or replacement. A second proofroll should be performed after the aggregate base material is in place, and prior to placing bituminous or concrete pavement. D.2.c. Design Sections Laboratory tests to determine an R-value for pavement design were not included in the scope of this project. However, we have previous Falling Weight Deflectometer (FWD) from the roadway (Braun Intertec Project BL ), which indicates a 15th percentile R-value of 24 for the segment between 30th Street and TH 5. We recommend using an R-value of 30 for pavement thickness design, which assumes soils in the upper 4 of the embankment will remain similar in composition to those currently in place but will receive some additional compaction and correction. Based upon the aforementioned traffic loads and the design R-value of 30, we recommend the following minimum pavement section and materials: 3 inches SPWEB240C

17 Washington County Public Works Project B October 17, 2014 Page 13 2 inches SPNWB230C 9 inches Class 5 aggregate base (MnDOT Specification 3138) The above pavement designs are based upon a 20-year performance life. This is the amount of time before major reconstruction is anticipated. This performance life assumes maintenance, such as seal coating and crack sealing, is routinely performed. The actual pavement life will vary depending on variations in weather, traffic conditions and maintenance. D.2.d. Materials and Compaction We recommend pavement materials as shown in the previous section. We recommend compacting the aggregate base to meet the requirements of MnDOT specification D.2.c. (Penetration Index Method). We recommend compacting bituminous pavements per the Maximum Density Method (Specification B). D.2.e. Subgrade Drainage We recommend installing perforated drainpipes throughout pavement areas at low points and about catch basins where storm sewer is installed. The drainpipes should be placed in small trenches extended at least 8 inches below the aggregate base material. D.3. Pavement Rehabilitation (I-94 to 30th Street) D.3.a. Design R-value As detailed above, we have backcalculated R-value results from FWD testing (Section D.2.c.), which represent in-situ values and will tend to be conservative relative to laboratory tests on re-molded soils. The 15th percentile R-value from previous FWD testing in the rehabilitation area was 24. We therefore recommend that an R-value of 24 for thickness design purposes assuming no change to subgrade R-value. D.3.b. Designing and Performing CIR Structurally, it appears CIR can feasibly be performed on CSAH 17. We highly recommend taking the following factors into consideration:

18 Washington County Public Works Project B October 17, 2014 Page 14 CIR will interrupt the existing crack pattern and mitigate reflective cracking to a degree an overlay or mill-and-overlay will not, resulting in reduced maintenance frequency and costs and additional pavement life. Often, though, CIR is not recommended for pavements with extensive surface cracking indicative of structural failure and pavement conditions should be reviewed prior to proceeding with design of CIR rehabilitation. Subgrade corrections will generally not be necessary or possible as part of the CIR process, though in the case of extreme subgrade issues, additional evaluation and possible supplementary repair may be warranted. We recommend preparing a laboratory mix design to establish the quantities necessary for the stabilized emulsion, add rock and moisture to meet specified strength requirements. D.4. Construction Quality Control D.4.a. Excavation Observations We recommend having a geotechnical engineer observe all excavations related to subgrade preparation and utility and pavement construction. The purpose of the observations is to evaluate the competence of the geologic materials exposed in the excavations and the adequacy of required excavation oversizing. D.4.b. Materials Testing We recommend density tests be taken in excavation backfill and additional required fill placed below pavements and utilities. We recommend compacting the aggregate base to meet the requirements of MnDOT specification D.2.c. (Penetration Index Method). We recommend Gyratory tests on bituminous mixes to evaluate strength and air voids, and density tests to evaluate compaction. We also recommend slump, air content and strength tests of Portland cement concrete. D.4.c. Pavement Subgrade Proofroll We recommend that proofrolling of the pavement subgrades be observed by a geotechnical engineer to determine if the results of the procedure meet project specifications, or delineate the extent of additional pavement subgrade preparation work.

19 Washington County Public Works Project B October 17, 2014 Page 15 D.4.d. Cold Weather Precautions If site grading and construction is anticipated during cold weather, all snow and ice should be removed from cut and fill areas prior to additional grading. No fill should be placed on frozen subgrades. No frozen soils should be used as fill. Concrete delivered to the site should meet the temperature requirements of ASTM C 94. Concrete should not be placed on frozen subgrades. Concrete should be protected from freezing until the necessary strength is attained. E. Procedures E.1. Penetration Test Borings The penetration test borings were drilled with truck- and track-mounted core and auger drill equipped with hollow-stem auger. The borings were performed in accordance with ASTM D Penetration test samples were taken at 2 1/2- or 5-foot intervals. Actual sample intervals and corresponding depths are shown on the boring logs. Penetration test boreholes that met the Minnesota Department of Health (MDH) Environmental Borehole criteria were sealed with an MDH-approved grout. A sealing record for those boreholes will be forwarded to the Minnesota Department of Health Well Management Section. E.2. Material Classification and Testing E.2.a. Visual and Manual Classification The geologic materials encountered were visually and manually classified in accordance with ASTM Standard Practice D A chart explaining the classification system is attached. Samples were placed in jars or bags and returned to our facility for review and storage. E.2.b. Laboratory Testing The results of the laboratory tests performed on geologic material samples are noted on or follow the appropriate attached exploration logs. The tests were performed in accordance with ASTM or AASHTO procedures.

20 Washington County Public Works Project B October 17, 2014 Page 16 E.3. Groundwater Measurements The drillers checked for groundwater as the penetration test borings were advanced, and again after auger withdrawal. The boreholes were then backfilled as noted on the boring logs. E.4. Ground Penetrating Radar E.4.a. Data Collection GPR scans of the pavement were collected according to GSSI, Inc. (manufacturer) SIR-20 processor settings established by MnDOT at an interval of one scan per lineal foot, approximately in the center of each travel lane where possible. A calibration file, required for data post-processing, was collected at the beginning of the testing day. The RoadScan system from GSSI, Inc. allows for real-time monitoring of the GPR scan during testing, as well as for the entry of user marks to note roadway events such as bridges and intersections. This capability was used to mark and tie in the future pavement core/boring locations with GPS coordinates and the GPR scan to the extent possible. GPS data was also collected continuously along each route during the GPR scan. E.4.b. Analysis Pavement layer identification was accomplished using RADAN 7.0, a software package included with the GSSI, Inc. RoadScan system. The software includes tools to aid in delineating pavement layer transitions and automatically calculates their depths from the pavement surface using the calibration file(s) collected prior to or following testing. The identified layers were compared to the measured thicknesses from borings to validate the accuracy of those calculated by the software.

21 Washington County Public Works Project B October 17, 2014 Page 17 F. Qualifications F.1. Variations in Subsurface Conditions F.1.a. Material Strata Our evaluation, analyses and recommendations were developed from a limited amount of site and subsurface information. It is not standard engineering practice to retrieve material samples from exploration locations continuously with depth, and therefore strata boundaries and thicknesses must be inferred to some extent. Strata boundaries may also be gradual transitions, and can be expected to vary in depth, elevation and thickness away from the exploration locations. Variations in subsurface conditions present between exploration locations may not be revealed until additional exploration work is completed, or construction commences. If any such variations are revealed, our recommendations should be re-evaluated. Such variations could increase construction costs, and a contingency should be provided to accommodate them. F.1.b. Groundwater Levels Groundwater measurements were made under the conditions reported herein and shown on the exploration logs, and interpreted in the text of this report. It should be noted that the observation periods were relatively short, and groundwater can be expected to fluctuate in response to rainfall, flooding, irrigation, seasonal freezing and thawing, surface drainage modifications and other seasonal and annual factors. F.2. Continuity of Professional Responsibility F.2.a. Plan Review This report is based on a limited amount of information, and a number of assumptions were necessary to help us develop our recommendations. It is recommended that our firm review the geotechnical aspects of the designs and specifications, and evaluate whether the design is as expected, if any design changes have affected the validity of our recommendations, and if our recommendations have been correctly interpreted and implemented in the designs and specifications.

22 Washington County Public Works Project B October 17, 2014 Page 18 F.2.b. Construction Observations and Testing It is recommended that we be retained to perform observations and tests during construction. This will allow correlation of the subsurface conditions encountered during construction with those encountered by the borings and provide continuity of professional responsibility. F.3. Use of Report This report is for the exclusive use of the parties to which it has been addressed. Without written approval, we assume no responsibility to other parties regarding this report. Our evaluation, analyses and recommendations may not be appropriate for other parties or projects. F.4. Standard of Care In performing its services, Braun Intertec used that degree of care and skill ordinarily exercised under similar circumstances by reputable members of its profession currently practicing in the same locality. No warranty, express or implied, is made.

23 Appendix

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25 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth 0.0 M. Takada ASTM Symbol FILL FILL FILL SP- SM METHOD: 3 1/4" HSA, Autohammer Description of Materials (ASTM D2488 or D2487) SILTY CLAYEY SAND MIX, fine-grained, dark brown, moist to wet. (Topsoil) FILL: Silty Sand, fine- to medium-grained, trace Gravel, brown, moist. FILL: Silty Sand, fine-grained, brown, moist. BORING: POORLY GRADED SAND with SILT, fine- to medium-grained, trace Gravel, brown, moist, medium dense. LOCATION: Offset 5 from staked location (Gas). See attached sketch. DATE: D-1 9/12/14 SCALE: 1" = 4' BPF WL Tests or Notes 23 LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16: B END OF BORING. Water not observed with 15 of hollow-stem auger in the ground. Water not observed to cave-in depth of 10 immediately after withdrawal of auger. Boring then backfilled. 23 Braun Intertec Corporation D-1 page 1 of 1

26 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth 0.0 M. Takada ASTM Symbol FILL FILL SP- SM METHOD: 3 1/4" HSA, Autohammer BORING: Description of Materials (ASTM D2488 or D2487) FILL: Silty Sand, fine- to medium-grained, with Gravel, dark brown, moist. FILL: Poorly Graded Sand with Silt, fine-grained, dark brown, moist. POORLY GRADED SAND with SILT, fine- to medium-grained, trace Gravel, brown, moist, loose to medium dense. LOCATION: Offset 5 North of staked location. See attached sketch. DATE: D-2 9/12/14 SCALE: 1" = 4' BPF WL Tests or Notes Clay seam at 12 1/2. 13 LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16: B END OF BORING. Water not observed with 15 of hollow-stem auger in the ground. Water not observed to cave-in depth of 10 immediately after withdrawal of auger. Boring then backfilled. 16 Braun Intertec Corporation D-2 page 1 of 1

27 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth 0.0 M. Takada ASTM Symbol FILL FILL SM METHOD: 3 1/4" HSA, Autohammer BORING: Description of Materials (ASTM D2488 or D2487) FILL: Silty Sand, fine-grained, dark brown, moist. (Topsoil) FILL: Poorly Graded Sand with Silt, fine-grained, light brown, dry to moist. SILTY SAND, fine-grained, with Clayey layers at 5, brown, moist, medium dense. LOCATION: See attached sketch. DATE: D-3 9/12/14 SCALE: 1" = 4' BPF WL MC % P200 % 23 Tests or Notes 14 LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16: B SC CLAYEY SAND, reddish brown, wet, rather stiff. (Glacial Till) END OF BORING. Water not observed with 15 of hollow-stem auger in the ground. Water not observed to cave-in depth of 11 immediately after withdrawal of auger. Boring then backfilled. 12 Braun Intertec Corporation D-3 page 1 of 1 11

28 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth 0.0 M. Takada ASTM Symbol FILL FILL ML SP- SM SP METHOD: 3 1/4" HSA, Autohammer Description of Materials (ASTM D2488 or D2487) FILL: Poorly Graded Sand with Silt, fine-grained, with Gravel, brown, moist. FILL: Sandy Silt, brown, moist. SILT, reddish brown, moist, very loose. BORING: POORLY GRADED SAND with SILT, fine- to medium-grained, with Silt inclusions, brown, moist, medium dense. POORLY GRADED SAND, fine-grained, brown to light brown, moist, medium dense. LOCATION: Offset 280 East of staked location. See attached sketch. DATE: D-4 9/12/14 SCALE: 1" = 4' BPF WL MC % P200 % 93 Tests or Notes 21 LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16: B END OF BORING. Water not observed with 15 of hollow-stem auger in the ground. Water not observed to cave-in depth of 9 immediately after withdrawal of auger. Boring then backfilled. 22 Braun Intertec Corporation D-4 page 1 of 1

29 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth J. Chermak ASTM Symbol PAV FILL CL ML METHOD: Description of Materials (ASTM D2488 or D2487) 5 inches of bituminous over 11 1/2 inches of aggregate base. FILL: Clayey Sand, brown, moist. LEAN CLAY with SAND, brown, wet, rather soft. (Lacustrine Deposit) SILT with SAND, brown, wet, rather stiff. (Lacustrine Deposit) END OF BORING. 3 1/4" HSA, Autohammer BORING: LOCATION: See attached sketch. DATE: ST-1 8/20/14 SCALE: 1" = 4' BPF WL Tests or Notes LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16:33 B Water not observed with 11 of hollow-stem auger in the ground. Water not observed to cave-in depth of 7 1/2 immediately after withdrawal of auger. Boring then backfilled. Braun Intertec Corporation ST-1 page 1 of 1

30 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth J. Chermak ASTM Symbol PAV FILL FILL SM CL- ML METHOD: Description of Materials (ASTM D2488 or D2487) 5 3/4 inches of bituminous over 11 inches of aggregate base. FILL: Clayey Sand, slightly organic, black, moist. FILL: Clay, brown, moist. 3 1/4" HSA, Autohammer SILTY SAND, fine-grained, brown, moist, loose. (Lacustrine Deposit) SILTY CLAY, Sand seams, brown, wet, soft to rather soft. (Lacustrine Deposit) BORING: LOCATION: See attached sketch. DATE: BPF WL MC % 20 ST-2 SCALE: P200 % 92 1" = 4' Tests or Notes 2 LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16: B ML SP SILT with SAND, brown, wet, rather stiff. (Lacustrine Deposit) POORLY GRADED SAND, fine-grained, light brown, moist, medium dense. END OF BORING.* *Water not observed with 31 of hollow-stem auger in the ground. Boring then grouted. Braun Intertec Corporation ST-2 page 1 of 1

31 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth J. Chermak ASTM Symbol PAV FILL ML CL SP METHOD: 3 1/4" HSA, Autohammer Description of Materials (ASTM D2488 or D2487) 6 inches of bituminous over 13 inches of aggregate base. FILL: Silty Sand, fine-grained, dark brown, moist. SILT, dark brown, moist, dense. (Lacustrine Deposit) LEAN CLAY with SAND, dark brown, moist, rather soft. (Lacustrine Deposit) POORLY GRADED SAND, fine-grained, light brown, moist, loose. END OF BORING. BORING: LOCATION: See attached sketch. DATE: ST-3 8/20/14 SCALE: 1" = 4' BPF WL MC % P200 % 89 Tests or Notes Water not observed to cave-in depth of 7 1/2. LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16:34 B Boring then backfilled. Braun Intertec Corporation ST-3 page 1 of 1

32 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth 0.0 J. Chermak ASTM Symbol PAV FILL FILL METHOD: 3 1/4" HSA, Autohammer Description of Materials (ASTM D2488 or D2487) 5 3/4 inches of bituminous over 11 1/2 inches of aggregate base. FILL: Clayey Sand, brown, wet. FILL: Poorly Graded Sand with Silt, fine- to medium-grained, brown, moist. BORING: LOCATION: See attached sketch. DATE: ST-4 8/22/14 SCALE: 1" = 4' BPF WL MC % Tests or Notes 2/18" LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16: B SP SM Brick and concrete debris; Silt seams at 14. POORLY GRADED SAND, fine-grained, light brown, moist, medium dense. Cobbles, brown and light brown at 25. SILTY SAND, trace Gravel, brown, moist, medium dense Braun Intertec Corporation ST-4 page 1 of 2

33 L O G O F B O R I N G Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: J. Chermak METHOD: 3 1/4" HSA, Autohammer BORING: ST-4 (cont.) LOCATION: See attached sketch. DATE: 8/22/14 SCALE: 1" = 4' (See Descriptive Terminology sheet for explanation of abbreviations) Elev Depth ASTM Symbol GP SM POORLY GRADED GRAVEL, fine-grained, light brown, moist, medium dense. SILTY SAND, fine-grained, dark brown, moist, medium dense. END OF BORING. Water not observed to cave-in depth of 40 immediately after withdrawal of auger. Boring then grouted. Description of Materials (ASTM D2488 or D2487) BPF WL MC % Tests or Notes LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16:34 B Braun Intertec Corporation ST-4 page 2 of 2

34 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth 0.0 J. Chermak 1.5 ASTM Symbol PAV SP METHOD: Description of Materials (ASTM D2488 or D2487) 6 inches of bituminous over 11 1/2 inches of aggregate base. POORLY GRADED SAND, fine- to medium-grained, trace Gravel, light brown, moist. Clay seams at 7 1/2. Silt seams at 10 to /4" HSA, Autohammer BORING: LOCATION: See attached sketch. DATE: BPF WL MC % 1 ST-5 SCALE: 1" = 4' Tests or Notes 7 LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16: B END OF BORING. Water not observed with 16 of hollow-stem auger in the ground. Water not observed to cave-in depth of 11 1/2 immediately after withdrawal of auger. Boring then backfilled. 10 Braun Intertec Corporation ST-5 page 1 of 1

35 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth J. Chermak ASTM Symbol PAV FILL SC SP METHOD: Description of Materials (ASTM D2488 or D2487) 6 inches of bituminous over 11 1/2 inches of aggregate base. FILL: Clayey Sand, trace Gravel, brown and dark brown, moist. CLAYEY SAND, brown, wet, rather stiff. POORLY GRADED SAND, fine- to medium-grained, Clayey at 11, brown, wet, medium dense. END OF BORING. 3 1/4" HSA, Autohammer BORING: LOCATION: See attached sketch. DATE: ST-6 8/20/14 SCALE: 1" = 4' BPF WL Tests or Notes No sample recovery. LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16:34 B Water not observed with 11 of hollow-stem auger in the ground. Water not observed to cave-in depth of 8 immediately after withdrawal of auger. Boring then backfilled. Braun Intertec Corporation ST-6 page 1 of 1

36 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth 0.0 J. Chermak ASTM Symbol PAV FILL CL SM SP METHOD: 3 1/4" HSA, Autohammer Description of Materials (ASTM D2488 or D2487) 6 inches of bituminous over 10 inches of aggregate base. FILL: Poorly Graded Sand with Silt, fine- to medium-grained, trace Gravel, brown, wet. LEAN CLAY with SAND, brown, wet, rather stiff. SILTY SAND, fine- to medium-grained, brown, wet, loose. POORLY GRADED SAND, fine- to medium-grained, brown, waterbearing, very loose to medium dense. BORING: LOCATION: See attached sketch. DATE: ST-7 8/22/14 SCALE: 1" = 4' BPF WL MC % Tests or Notes No sample recovery. 9 LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16:34 B Waterbearing at An open triangle in the water level (WL) column indicates the depth at which groundwater was observed while drilling. Groundwater levels fluctuate. Braun Intertec Corporation ST-7 page 1 of 2

37 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION CSAH 17 Reconstruction Rehab 30th Street North to TH5 (Recon) DRILLER: Elev Depth J. Chermak ASTM Symbol SC METHOD: Description of Materials (ASTM D2488 or D2487) POORLY GRADED SAND, fine- to medium-grained, brown, waterbearing, very loose to medium dense. (continued) CLAYEY SAND, trace Gravel, brown, wet, medium. END OF BORING. 3 1/4" HSA, Autohammer BORING: Water observed at 20 with 20 of hollow-stem auger in the ground. Jetting water used to wash sand out of the auger below the 35-foot depth. LOCATION: See attached sketch. DATE: 6 6 ST-7 (cont.) 8/22/14 SCALE: 1" = 4' BPF WL MC % 12 Tests or Notes LOG OF BORING-DRAFT N:\GINT\PROJECTS\AX PROJECTS\2014\05958.GPJ BRAUN_V8_CURRENT.GDT 10/7/14 16:34 B Boring then grouted. Braun Intertec Corporation ST-7 page 2 of 2