REPORT. Explorations and Geotechnical Engineering Services

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REPORT September 9, 2015 15-0690 S Explorations and Geotechnical Engineering Services Runway 35 Localizer Slope Reconstruction MHT Airport Goffs Falls Road Manchester, New Hampshire

1 REPORT September 9, S Explorations and Geotechnical Engineering Services Runway 35 Localizer Slope Reconstruction MHT Airport Goffs Falls Road Manchester, New Hampshire PREPARED FOR: Jacobs Attn: Mr. Sean Tiney 2 Executive Park Drive, Suite 205 Bedford, NH PREPARED BY: S. W. Cole Engineering, Inc. 10 Centre Road Somersworth, NH (603)

2 TABLE OF CONTENTS 1.0 INTRODUCTION Scope and Purpose Existing Conditions and Proposed Construction SUBSURFACE EXPLORATION SUBSURFACE CONDITIONS Soils Groundwater SUMMARY OF RECOMMENDATIONS SPECIAL CONSIDERATIONS CLOSURE... 6 Attachment A Limitations Sheet 1 Site Location Map Sheets 2 and 3 Boring Logs Sheet 4 Key to the Notes and Symbols Sheets 5 and 6 Gradation Test Results Appendix A Drawings C1.0 and C5.0

3 S September 9, 2015 Jacobs Attention: Sean Tiney 2 Executive Park Drive, Suite 205 Bedford, NH Subject: Explorations and Geotechnical Engineering Services Runway 35 Localizer Slope Reconstruction MHT Airport Goffs Falls Road Manchester, New Hampshire Dear Sean: In accordance with Proposal dated July 15, 2015 and our subsequent correspondence, we have undertaken subsurface explorations and geotechnical engineering services for the proposed Runway 35 Localizer Slope Reconstruction in Manchester, New Hampshire. This report summarizes our findings and recommendations, and its contents are subject to the limitations set forth in Attachment A. 1.0 INTRODUCTION 1.1 Scope and Purpose The purpose of the work was to explore subsurface conditions at the site of a localized slope failure on a property accessed from Goffs Falls Road in order to provide recommendations for slope reconstruction. Our scope of services included two test borings, soils laboratory testing, a geotechnical evaluation of the findings relative to slope reconstruction, and preparation of this report. 1.2 Existing Conditions and Proposed Construction The site is located on the south side of Goffs Falls Road on a parcel of land referred to as the localizer area, which is in the flight path on the north side Runway for MHT Airport. The runway and localizer parcel are separated by Cohas Brook. The localizer parcel is primarily level at approximately elevations 215 to 216 feet (project datum). The terrain along the southerly edge of the parcel slopes steeply downward to

4 S September 9, 2015 the south to Cohas Brook. The brook in the area of the toe of the slope creates an oxbow feature in its flow path. Based on the Existing Conditions Plan prepared by Jacobs (Drawing C1.0, dated September 2015), the ordinary high water level of Cohas Brook is at about elevation 179 feet. Given this, the south facing bank is on the order of 36 feet in height. Slopes along the bank are as steep as about 1.3:1 (H:V), generally steeper further down slope. The upper portion of the parcel near the bank is reported to be fill used to level the localizer area. In eastern and central portion of the bank, the upper portion of the slope is surfaced with stone rip rap. A wildlife fence is located along the slope face. A localizer beacon light is located along the top of the slope near the centerline of the flight path. A portion of the westerly side of the slope has undergone a localized slope failure. The width of the failure is approximately 20 to 25 feet and extends downhill to about elevations 183 to 184 feet. Based on observations of the soils exposed in the nearvertical face of the failure, the stratigraphy contains granular fill overlying native stratified silt and fine sand with some clay. We understand the approximately 380-foot long south facing slope will be reconstructed and will likely involve maintaining the toe of the slope at its present location and regrading the roughly upper third of the slope to flatten the surface. A horizontal bench will be cut into the new slope to accommodate the wildlife fence at approximately elevations 205 to 206 feet. The localizer beacon light will remain in place and will require a retaining wall to transition its grades into the new slope. We understand a permanent sheet pile retaining wall is planned for this purpose. In conjunction with slope reconstruction, the failed slope section will require repair work. We understand we have been contacted to address remediation of the failed slope area. 2

5 S September 9, SUBSURFACE EXPLORATION 2.1 Exploration We coordinated and observed two test borings at locations selected and located by Jacobs. Boring B-1 was made along the top of the slope near the localizer beacon light, while Boring B-2 was made closer to the failure area. Ground surface elevations for both borings were estimated from contours shown on Drawing C1.0. The test borings were drilled by S.W.COLE Explorations, LLC working under subcontract and advanced using hollow-stem augers to a depth of 32.0 feet. Soil samples were obtained where shown on the logs using Standard Penetration Testing (SPT) procedures. We have attached a Site Location Map as Sheet 1. The approximate test boring locations are shown on Drawing C1.0, attached in Appendix A. Boring logs are attached as Sheets 2 and 3. A key to the notes and symbols used on the logs is attached as Sheet Laboratory Testing Soil samples retrieved from the test borings were visually classified in our laboratory. We performed two gradation tests on selected samples to assist in our evaluation. Results are attached as Sheets 5 and SUBSURFACE CONDITIONS 3.1 Soils Beneath surficial topsoil, the test borings encountered granular fills overlying native sands and silts. In Boring B-1, made near the localizer beacon light, the fills consist of medium dense silty sands with varying amounts of gravel extending to a depth of approximately 15 feet. A piece of apparent filter fabric was observed in the initial 0 to 2.0-foot sample. The native underlying soils are loose sands and silt with a few clayey silt layers observed well below grade. 3

6 S September 9, 2015 Boring B-2, made closer to the slope failure, encountered approximately 12 feet of loose to medium dense sandy fill with some silt (on the order of 5 to 12 percent of soil particles by weight). An apparent old topsoil layer was observed in Sample 3D (10.0 to 12.0 feet). The underlying native materials are various layers of fine to medium graded sands and finer sands with varying amounts of silt. For more information relative to the test borings findings, please refer to the attached logs. 3.2 Groundwater Soil samples were moist below a depth of approximately 21 feet in Boring B-1 and 15 feet in Boring B-2. These observation likely reflect groundwater levels at the time of the explorations. Long-term groundwater information is not available. Groundwater levels will fluctuate seasonally and in response to precipitation and snowmelt. 4.0 SUMMARY OF RECOMMENDATIONS The slope failure is limited to an approximately 20 to 25 foot wide area, and appears to be on the order of 6 to 8 feet in depth. The failure is likely a result of localized channeling of surface water runoff; groundwater flow at the interface relatively clean sandy fills and native sands overlying less pervious fine sand and silt (see log for Boring B-2); or a combination of both mechanisms. It is of note that on Drawing C1.0, the upper portion of the failed area shows the slope being considerably steeper east of the failure (about 1.3:1) when compared to the west. It is possible this may have contributed to long term channeling of surface water runoff in the years before the failure. We recommend reconstruction of the failed area at a slope of 2:1 or flatter. Given the existing terrain, we understand it will be necessary to blend in the repair surface into steeper slopes on both sides of the failure. Transitions in grading to these edges should be a smooth as practicable. We have previously submitted to you a sketch outlining our recommended repair section for the failed area. You have incorporated these recommendations into your documentation as Drawing C5.0. We have included this drawing in Appendix A. The 4

7 S September 9, 2015 repair scheme is summarized below. Remove loose debris from the failed area Locate the toe of the slide Construct the rip rap key into the toe as shown on the drawing Grade the subgrade to 2:1 or flatter Place and compact at least 3 feet of Structural Fill, compacting to at least 95 percent of its maximum dry density per ASTM D-1557 (Modified Proctor) The Structural Fill should be benched at least 2 feet into the subgrade on all sides during placement. Geogrid reinforcement (Miragrid 5XT or equivalent) should be installed at 2-foot vertical intervals during placement. Grade the finish slope at 2:1 or flatter. Blend into the steeper adjacent slopes as necessary. Structural Fill should meet the following gradation. STRUCTURAL FILL Sieve Size Percent Finer by Weight 4 Inch Inch 90 to 100 ¼ Inch 25 to 90 No to 30 No to 5 It is our opinion that NHDOT Item 508 Structural Fill meets the intention of the Structural Fill specification and is an adequate substitute. 5.0 SPECIAL CONSIDERATIONS Our work focused on the failure area. Other areas of the slope are naturally steeper than what is considered acceptable for an engineered slope. These areas currently appear stable, however similar failures to the one experienced are possible in other areas. 5

15-0690 S September 9, 2015 6.0 CLOSURE We recommend that S.W.COLE be retained during slope failure reparation work to perform soils testing and to observe compliance with the design concepts, plans and specifications.

8 S September 9, CLOSURE We recommend that S.W.COLE be retained during slope failure reparation work to perform soils testing and to observe compliance with the design concepts, plans and specifications. It has been a pleasure to be of assistance to you with this phase of your project. If you have any questions or we may be of further assistance, please do not hesitate to contact us. Sincerely, S. W. Cole Engineering, Inc. Anthony J. Hersh, P.E. Senior Geotechnical Engineer AJH:cbm 6

9 ATTACHMENT A Limitations This report has been prepared for the exclusive use of Jacobs for specific application to the Runway 35 Localizer Slope Reconstruction project in Manchester, New Hampshire. S.W.COLE has endeavored to conduct the work in accordance with generally accepted soil and foundation engineering practices. No warranty, expressed or implied, is made. The soil profiles described in the report are intended to convey general trends in subsurface conditions. The boundaries between strata are approximate and are based upon interpretation of exploration data and samples. The analyses performed during this assessment and recommendations presented in this report are based in part upon the data obtained from subsurface explorations made at the site. Variations in subsurface conditions may occur between explorations and may not become evident until construction. If variations in subsurface conditions become evident after submission of this report, it will be necessary to evaluate their nature and to review the recommendations of this report. Observations have been made during exploration work to assess site groundwater levels. Fluctuations in water levels will occur due to variations in rainfall, temperature, and other factors. S.W.COLE s scope of work has not included the investigation, detection, or prevention of any Biological Pollutants at the project site or in any existing or proposed structure at the site. The term Biological Pollutants includes, but is not limited to, molds, fungi, spores, bacteria, and viruses, and the byproducts of any such biological organisms. Recommendations contained in this report are based substantially upon information provided by others regarding the proposed project. In the event that any changes are made in the design, nature, or location of the proposed project, S.W.COLE should review such changes as they relate to analyses associated with this report. Recommendations contained in this report shall not be considered valid unless the changes are reviewed by S.W.COLE.

$APPROXIMATE SITE LOCATION R:\2015\15-0690\GIS\MXDs\15-0690 SLM.$ INCLUDING USGS AND 2007 NATIONAL GEOGRAPHIC SOCIETY. Job No.

10 APPROXIMATE SITE LOCATION R:\2015\ \GIS\MXDs\ SLM.mxd, 9/8/ :02:49 PM, 1:24,000, NOTE: SITE LOCATION MAP PREPARED FROM ESRI ArcGIS ONLINE AND DATA PARTNERS INCLUDING USGS AND 2007 NATIONAL GEOGRAPHIC SOCIETY. Job No. Date: Copyright: 2013 National Geographic Society, i-cubed 2, ,000 4, /08/2015 Scale in Feet MHT AIRPORT SITE LOCATION MAP RUNWAY 35 LOCALIZER SLOPE RECONSTRUCTION GOFFS FALLS ROAD MANCHESTER, NEW HAMPSHIRE Scale Sheet 1:

11 BORING LOG BORING NO.: SHEET: PROJECT NO.: B-1 OF PROJECT / CLIENT: JACOB / RUNWAY 35 LOCALIZER SLOPE RECONSTRUCTION DATE START: LOCATION: MHT AIRPORT, GOFFS FALLS ROAD, MANCHESTER, NH DATE FINISH: DRILLING CO. : S.W.COLE EXPLORATIONS, LLC DRILLER: BOB MARCOUX ELEVATION: 8/10/2015 8/10/ ' +/- CASING: SAMPLER: CORE BARREL: TYPE SIZE I.D. HAMMER WT. HAMMER FALL HSA 2 1/4" SS 1 3/8" 140 LB 30" SWC REP.: AJH WATER LEVEL INFORMATION SAMPLES MOIST BELOW 21' CASING BLOWS PER FOOT SAMPLE SAMPLER BLOWS PER 6" DEPTH STRATA & TEST DATA DEPTH NO. PEN. REC BOT 0.2' TOPSOIL 1D 24" 61" 2.0' BROWN SILTY SAND, SOME GRAVEL, PIECE OF FILTER FABRIC IN SAMPLE 1D (FILL) ~ MEDIUM DENSE ~ 6.0' 2D 24" 12" 7.0' ' DARK BROWN SILTY SAND WITH ORGANICS (FILL) BROWN GRAVELLY SILTY SAND (FILL) 3D 24" 4" 12.0' ~ MEDIUM DENSE ~ 15.0' 4D 24" 12" 17.0' BROWN SAND AND SILT 5D 24" 20" 22.0' ~ LOOSE ~ 6D 24" 16" 27.0' ' BROWN SILT AND FINE SAND, FEW CLAYEY SILT LENSES AND LAYERS 7D 24" 16" 32.0' ' ~ MEDIUM DENSE ~ BOTTOM OF EXPLORATION AT 32.0' SAMPLES: SOIL CLASSIFIED BY: REMARKS: D = SPLIT SPOON C = 2" SHELBY TUBE DRILLER - VISUALLY STRATIFICATION LINES REPRESENT THE S = 3" SHELBY TUBE X SOIL TECH. - VISUALLY APPROXIMATE BOUNDARY BETWEEN SOIL TYPES U = 3.5" SHELBY TUBE X LABORATORY TEST AND THE TRANSITION MAY BE GRADUAL. BORING NO.: B-1 2

12 BORING LOG BORING NO.: SHEET: PROJECT NO.: B-2 1 OF PROJECT / CLIENT: JACOB / RUNWAY 35 LOCALIZER SLOPE RECONSTRUCTION DATE START: LOCATION: MHT AIRPORT, GOFFS FALLS ROAD, MANCHESTER, NH DATE FINISH: DRILLING CO. : S.W.COLE EXPLORATIONS, LLC DRILLER: BOB MARCOUX ELEVATION: 8/10/2015 8/10/ ' +/- CASING: SAMPLER: CORE BARREL: TYPE SIZE I.D. HAMMER WT. HAMMER FALL HSA 2 1/4" SS 1 3/8" 140 LB 30" SWC REP.: AJH WATER LEVEL INFORMATION SAMPLES MOIST BELOW 15' CASING BLOWS PER FOOT SAMPLE SAMPLER BLOWS PER 6" NO. PEN. REC. BOT DEPTH STRATA & TEST DATA 0.1' TOPSOIL 1D 24" 15" 2.0' BROWN SAND, SOME SILT, TRACE GRAVEL (FILL) ~ LOOSE TO MEDIUM DENSE ~ 2D 24" 8" 7.0' D 24" 7" 12.0' ' 12.5' 16.0' 4D 24" 14" 17.0' PROBABLE OLD TOPSOIL BROWN SAND, TRACE SILT ~ MEDIUM DENSE ~ BROWN FINE SAND AND SILT ~ MEDIUM DENSE ~ 21.0' 5D 24" 15" 22.0' BROWN SILTY FINE SAND WITH LAYERS OF FINE SAND, SOME SILT ~ MEDIUM DENSE ~ 25.0' 6D 24" 18" 27.0' BROWN FINE SAND, SOME SILT WITH SILTY FINE SAND LAYERS ~ MEDIUM DENSE ~ 7D 24" 12" 32.0' ' BOTTOM OF EXPLORATION AT 32.0' SAMPLES: SOIL CLASSIFIED BY: REMARKS: D = SPLIT SPOON C = 2" SHELBY TUBE DRILLER - VISUALLY STRATIFICATION LINES REPRESENT THE S = 3" SHELBY TUBE X SOIL TECH. - VISUALLY APPROXIMATE BOUNDARY BETWEEN SOIL TYPES U = 3.5" SHELBY TUBE X LABORATORY TEST AND THE TRANSITION MAY BE GRADUAL. BORING NO.: B-2 3

13 KEY TO THE NOTES & SYMBOLS Test Boring and Test Pit Explorations All stratification lines represent the approximate boundary between soil types and the transition may be gradual. Key to Symbols Used: w - water content, percent (dry weight basis) q u - unconfined compressive strength, kips/sq. ft. - laboratory test S v - field vane shear strength, kips/sq. ft. L v - lab vane shear strength, kips/sq. ft. q p - unconfined compressive strength, kips/sq. ft. pocket penetrometer test O - organic content, percent (dry weight basis) W L - liquid limit - Atterberg test W P - plastic limit - Atterberg test WOH - advance by weight of hammer WOM - advance by weight of man WOR - advance by weight of rods HYD - advance by force of hydraulic piston on drill RQD - Rock Quality Designator - an index of the quality of a rock mass. γ T - total soil weight γ B - buoyant soil weight Description of Proportions: Description of Stratified Soils Parting: 0 to 1/16 thickness Trace: 0 to 5% Seam: 1/16 to 1/2 thickness Some: 5 to 12% Layer: ½ to 12 thickness Y 12 to 35% Varved: Alternating seams or layers And 35+% Occasional: one or less per foot of thickness With Undifferentiated Frequent: more than one per foot of thickness REFUSAL: Test Boring Explorations - Refusal depth indicates that depth at which, in the drill foreman's opinion, sufficient resistance to the advance of the casing, auger, probe rod or sampler was encountered to render further advance impossible or impracticable by the procedures and equipment being used. REFUSAL: Test Pit Explorations - Refusal depth indicates that depth at which sufficient resistance to the advance of the backhoe bucket was encountered to render further advance impossible or impracticable by the procedures and equipment being used. Although refusal may indicate the encountering of the bedrock surface, it may indicate the striking of large cobbles, boulders, very dense or cemented soil, or other buried natural or man-made objects or it may indicate the encountering of a harder zone after penetrating a considerable depth through a weathered or disintegrated zone of the bedrock 4

14 Report of Gradation ASTM C-117 & C-136 Project Name Client Exploration Material Source 15' - 17' MANCHESTER ME - MHT AIRPORT RUNWAY 35 LOCALIZER SLOPE REHABILITATION - GEOTECHNICAL ENGINEERING SERVICES JACOBS ENGINEERING GROUP, INC. B-1, 4D Project Number Lab ID 13818S Date Received 8/11/2015 Date Completed 8/12/2015 Tested By MURRAY SWINDELL STANDARD DESIGNATION (mm/µm) SIEVE SIZE AMOUNT PASSING (%) 6.3 mm 4.75 mm 2.00 mm 850 um 425 um 250 um 150 um 75 um 1/4" 100 No No No No No No No % Gravel 59.6% Sand 40.4% Fines 100% 3" 2" 1" 1/2" 1/4" #10 #20 #40 #100 #200 90% 80% AMOUNT PASSING 70% 60% 50% 40% 30% 20% 10% 0% SIEVE SIZE - mm Comments: Sheet 5

15 Report of Gradation ASTM C-117 & C-136 Project Name Client Exploration Material Source 5' - 7' MANCHESTER ME - MHT AIRPORT RUNWAY 35 LOCALIZER SLOPE REHABILITATION - GEOTECHNICAL ENGINEERING SERVICES JACOBS ENGINEERING GROUP, INC. B-2, 2D Project Number Lab ID 13819S Date Received 8/11/2015 Date Completed 8/12/2015 Tested By MURRAY SWINDELL STANDARD DESIGNATION (mm/µm) SIEVE SIZE AMOUNT PASSING (%) 6.3 mm 4.75 mm 2.00 mm 850 um 425 um 250 um 150 um 75 um 1/4" 100 No No No No No No No % Gravel 89.6% Sand 9.7% Fines 100% 3" 2" 1" 1/2" 1/4" #10 #20 #40 #100 #200 90% 80% AMOUNT PASSING 70% 60% 50% 40% 30% 20% 10% 0% SIEVE SIZE - mm Comments: Sheet 6

16 APPENDIX A DRAWINGS C1.0 AND C5.0

17 Jacobs - P:\2015\E2X74702 MHT RW 35 Localizer Slope Repair\700 CADD\plans\03 - Existing Conditions Plan.dwg [Layout1] September 04, :54am [stiney] LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC LOC C1.0

18 Jacobs - P:\2015\E2X74702 MHT RW 35 Localizer Slope Repair\700 CADD\plans\ Typ. Sections and Details.dwg [layout1] September 09, :29pm [stiney] C5.0

Town of Brunswick, Maine

1. Project Presentation Town of Brunswick, Maine Miller Point Shoreline Stabilization Project Rob and Nancy King Applicant Staff Meeting 6:00 P.M. June 27, 2016 Room 206 Town Hall 85 Union Street Open