PUBLIC WORKS DEPARTMENT David A. Jones, P.E., Director April 7, 2017 Webster Street Sub-Surface Stormwater Storage System Bid No. 2017-022 Bid Date: 4/13/17 ADDENDUM NO 1 Please make the following changes to the Plans and Specifications: 1. The first paragraph in Division 10, Section 10.12 Maintenance of Traffic, shall be changed to the following: Webster Street may be closed to outbound traffic during installation of the stormwater storage system. The inbound lane shall remain open during construction and emergency vehicles shall be allowed to pass in either direction at all times. The contractor shall install detour signs as required by the engineer. Attention is called to Section 30.05 of the Specifications, Maintenance of Traffic for specific traffic control requirements. The Contractor shall submit a traffic control plan to the Department of Public Works for review and approval. 2. The contractor will be required to supply the frames and covers for the structures. However, as noted on sheet 3, setting the finished grade of the structures will be done by others. 3. Inverts will not be required in the storm drain manholes. 4. See attached Geotechnical Report for information on the subsurface conditions. 103 Adams Ave, Lewiston, ME 04240 Tel. (207) 513-3003 Fax (207) 784-5647 Email: djones@lewistonmaine.gov Page: www.lewistonmaine.gov
July 25, 2016 City of Lewiston Department of Public Works 103 Adams Ave. Lewiston, ME 04240 Attn: Re: Mr. Justin Early, P.E. P: (207) 513 3003 ext. 3421 E: jearly@lewistonmaine.gov Subsurface Stormwater Quality Treatment System Webster Street Lewiston, Maine Terracon Project No. J3165011 Dear Mr. Early: Following your request, Terracon Consultants, Inc. (Terracon) is pleased to provide this letter report summarizing our subsurface explorations and laboratory testing services for the abovereferenced project. Site Location Location PROJECT INFORMATION Item Existing Improvements Current Ground Cover Description Between 760 and 766 Webster Street in Lewiston, Maine. Existing city collector street Paved with vegetated shoulder. Existing Topography Relatively level at approximately Elevation 247±. Project Description Item Structures Grading Description Proposed 200-300 foot long subsurface stormwater quality treatment system (Stormceptor) to be constructed below the pavement on Webster Street. Bottom of system elevation is unknown at this time. System is to be designed for storage only. No subsurface infiltration is proposed. Existing site grades to be maintained.
Geotechnical Engineering Services Subsurface Stormwater Treatment System Lewiston, Maine July 25, 2016 Terracon Project No. J3165011 SUBSURFACE EXPLORATIONS AND CONDITIONS 2.1 Typical Profile Based on the results of the explorations and observations at the time of fieldwork, subsurface conditions on the project site can be generalized as follows: Description Approximate Depth to Bottom of Stratum (feet bgs) Material Encountered Consistency / Relative Density Asphalt 0.2 (2.5 in.) Bituminous Concrete N/A Upper Sand & Silty Sand 2.0 to 5.0 (B-2 & B-3) Poorly graded sand with gravel (SP), brown Loose Silt & Clay 5.0 to 15.0 Silt with gravel (ML), mottled, to Silty Clay (CL- ML) to Lean Clay, blue-gray Loose to soft to stiff Lower Sand & Silty Sand 14.1 to 19.0 Poorly graded sand with gravel (SP), Poorly graded sand (SP) to Silty sand with gravel. Medium dense to dense Auger refusal was encountered in each boring, ranging from about 14 to 19 feet from west to east, respectively. Although rock core samples were not obtained, we anticipate refusal to be bedrock. 2.2 Groundwater Groundwater was encountered in the borings at depths of 10 feet in B-2 and B-3, and at 11.6 feet in B-1. A groundwater monitoring well was installed at B-1. The monitoring well may be used to measure seasonal variation in groundwater level by the City of Lewiston DPW staff. Groundwater levels may fluctuate due to seasonal variations in the amount of rainfall, runoff, and other factors, such as possible perched conditions. Grade adjustments on and around the site, as well as surrounding drainage improvements, may affect groundwater levels. Groundwater level fluctuations should be considered when developing the design and construction plans for the project. Responsive Resourceful Reliable 2
Geotechnical Engineering Services Subsurface Stormwater Treatment System Lewiston, Maine July 25, 2016 Terracon Project No. J3165011 2.3 Laboratory Testing Laboratory testing consisting of grain-size distribution tests were performed. The results of the laboratory testing are provided in Appendix B. Sample Identification Depth (feet) USCS Gravel (%) Sand (%) Fines (%) B-1 5-7 ML 0.0 7.0 93.0 B-3 7 9 SM 23.3 59.0 17.6 GENERAL COMMENTS The findings presented in this report are based upon the data obtained from the explorations performed at the indicated location and from other information discussed in this report. This report does not reflect variations that may occur, across the site, or due to the modifying effects of weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified, so that further evaluation can be provided. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing. Responsive Resourceful Reliable 3
APPENDIX A FIELD EXPLORATION
SITE SCALE: 1:24 000 1 1/2 O 1 MILE N 1000 1 0 1000.5 2000 3000 0 4000 5000 6000 1 KILOMETER 7000 FEET CONTOUR INTERVAL 10 FEET NATIONAL GEODETIC VERTICAL DATUM OF 1929 Project Mngr: Drawn By: Checked By: Approved By: CWT MCR CWT LJD Project No. Scale: File No. Date: J3165011 AS SHOWN J3165011.dwg JULY 2016 220 Industrial Way PH. (207)828-5374 Portland, ME 04103 Fax. (207)828-5374 760-766 WEBSTER STREET LEWISTON, MAINE EXHIBIT A-1
B-3 B-2 B-1 B-1 Prepared For: Project Mngr: CWT Project No. J3165011 EXHIBIT CITY OF LEWISTON DPW Drawn By: Checked By: Approved By: MCR CWT LJD Scale: File No. Date: As shown J3165011.dwg JULY 2016 220 Industrial Way Unit 4 Portland ME 04103 PH. (207)828-5374 Fax. (207)828-5374 760-766 WEBSTER STREET LEWISTON, MAINE A-2
Geotechnical Engineering Services Sub-surface Stormwater Treatment System Lewiston, Maine July 25, 2016 Terracon Project No. J3165011 Field Exploration Description Terracon coordinated the advancement of three test borings (B-1 through B-3) on June 27, 2016. Test boring was advanced by Northern Test Boring of Gorham, Maine using an ATV drill rig with hollow-stem augers (HSA). The borings were drilled to refusal at the approximate locations shown on the attached Boring Location Plan (Exhibit A-2). In the split-barrel sampling procedure used to take soil samples in the test boring, the number of blows required to advance a standard 2-inch-outside-diameter, split-barrel sampler from 6 to 18 inches penetration by means of a 140-pound hammer with a free fall of 30 inches, is the Standard Penetration Test (SPT) resistance value N. This N value is used to estimate the insitu relative density of cohesionless soils and consistency of cohesive soils. An automatic SPT hammer was used to advance the split-barrel sampler in the boring performed on this site. A significantly greater efficiency is achieved with the automatic hammer compared to the conventional safety hammer operated with a cathead and rope. This higher efficiency has an appreciable effect on the SPT-N value. The effect of the automatic hammer's efficiency has been considered in the interpretation and analysis of the subsurface information for this report. Information provided on the boring logs attached to this report includes soil descriptions, relative density and/or consistency evaluations, boring depth, sampling intervals, and groundwater conditions. The boring was backfilled with auger cuttings prior to the drill crew leaving the site. A Terracon field engineer prepared field logs of the borings, which included visual classifications of the materials encountered during the explorations, as well as our field engineer s interpretation of the subsurface conditions between samples. The exploration logs included with this report represent further interpretation by the geotechnical engineer of the field logs. Responsive Resourceful Reliable Exhibit A-3
PROJECT: Webster Street Subsurface Stormwater Treatment SITE: 760-766 Webster Street Lewiston, Maine WELL LOG NO. B-1 CLIENT: City of Lewiston DPW Page 1 of 1 GRAPHIC LOG LOCATION: See Exhibit A-2 Latitude: 44.080544 Longitude: -70.167428 DEPTH 0.2 2.5-inches of asphalt SILT (ML), trace sand, loose to medium dense Approximate Surface Elev: 290 (Ft.) +/- ELEVATION (Ft.) 290+/- INSTALLATION DETAILS Road box DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE RECOVERY (In.) 14 FIELD TEST RESULTS 4-5-5-4 N=10 8 5-5-4-4 N=9 Similar, no sand, trace clay PVC Riser Native material/filter sand 5 20 5-5-6-7 N=11 12 6-7-8-9 N=15 10.0 SILTY CLAY (CL-ML), gray, soft 11.5 LEAN CLAY (CL), blue-gray, soft 280+/- 278.5+/- Bentonite seal 10 24 2-2-2-2 N=4 THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-WELL J3165011.GPJ 15.0 SILTY SAND WITH GRAVEL (SM), medium dense 19.0 Auger refusal at 19 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: 2.25-inch hollow stem augers Abandonment Method: Boring backfilled with soil cuttings upon completion. WATER LEVEL OBSERVATIONS 11.6 WD 220 Industrial Way Unit 4 Portland, ME 275+/- 271+/- See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. PVC Screen Filter sand Hammer Type: Automatic Notes: Well Started: 6/27/2016 Drill Rig: Project No.: J3165011 15 Driller: NTB/Mike N. 6-6-4-8 N=10 Well Completed: 6/27/2016 Exhibit: A-4
PROJECT: Webster Street Subsurface Stormwater Treatment SITE: 760-766 Webster Street Lewiston, Maine BORING LOG NO. B-2 CLIENT: City of Lewiston DPW Page 1 of 1 GRAPHIC LOG LOCATION See Exhibit A-2 Latitude: 44.080687 Longitude: -70.167708 DEPTH 0.2 2.5-inches of asphalt POORLY GRADED SAND WITH GRAVEL (SP), loose Approximate Surface Elev: 290 (Ft.) +/- ELEVATION (Ft.) 290+/- DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE RECOVERY (In.) 5 FIELD TEST RESULTS 3-4-3-2 N=7 0 2-3-5-5 N=8 5.0 SILT (ML), gray, loose 285+/- 5 12 4-3-3-4 N=6 8.0 SILTY CLAY (CL-ML), stiff 282+/- 20 5-6-7-6 N=13 9.5 SILTY SAND WITH GRAVEL (SM), gray, medium dense to very dense 280.5+/- 10 12 6-7-10-10 N=17 THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL J3165011.GPJ 17.6 Auger refusal at 17.6 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: 2.25-inch hollow stem augers Abandonment Method: Boring backfilled with soil cuttings upon completion. WATER LEVEL OBSERVATIONS 10' WD See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. 220 Industrial Way Unit 4 Portland, ME 15 8 Driller: NTB/Mike N. 272.5+/- Hammer Type: Automatic Notes: Boring Started: 6/27/2016 Drill Rig: Project No.: J3165011 17-29- 50/4" Boring Completed: 6/27/2016 Exhibit: A-5
PROJECT: Webster Street Subsurface Stormwater Treatment SITE: 760-766 Webster Street Lewiston, Maine BORING LOG NO. B-3 CLIENT: City of Lewiston DPW Page 1 of 1 GRAPHIC LOG LOCATION See Exhibit A-2 Latitude: 44.080883 Longitude: -70.1681 DEPTH 0.2 2.5-inches of asphalt 0.8 POORLY GRADED SAND WITH GRAVEL (SP), brown, loose SANDY SILT (ML), loose 2.0 SILT WITH GRAVEL (ML), trace clay, mottled, loose Approximate Surface Elev: 290 (Ft.) +/- ELEVATION (Ft.) 290+/- 289+/- 288+/- DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE RECOVERY (In.) 12 12 FIELD TEST RESULTS 4-3-3-2 N=6 2-2-5-6 N=7 5.0 SILTY SAND WITH GRAVEL (SM), brown, medium dense to dense 285+/- 5 12 4-6-12-9 N=18 6 7-12- 29-50/2" N=41 10.0 POORLY GRADED SAND (SP), reddish-brown, dense 280+/- 10 14 12-17-24-32 N=41 THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL J3165011.GPJ 14.1 Auger refusal at 14.1 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: 2.25-inch hollow stem augers Abandonment Method: Boring backfilled with soil cuttings upon completion. WATER LEVEL OBSERVATIONS 10' WD See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. 220 Industrial Way Unit 4 Portland, ME 276+/- Hammer Type: Automatic Notes: Boring Started: 6/27/2016 Drill Rig: Project No.: J3165011 Boring Completed: 6/27/2016 Driller: NTB/Mike N. Exhibit: A-6
APPENDIX B LABORATORY TESTING
100 95 90 85 80 75 70 GRAIN SIZE DISTRIBUTION ASTM D422 / ASTM C136 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 4 2 1 1/2 6 3 3/8 3 6 16 30 50 1.5 100 200 4 8 10 3/4 14 20 40 60 140 HYDROMETER LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 J3165011.GPJ 35159097 - ATTERBERG ISSUE.GPJ 7/21/16 PERCENT FINER BY WEIGHT 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Boring ID B-1 B-3 Boring ID B-1 B-3 COBBLES 100 Depth 5-7 7-9 Depth 5-7 7-9 coarse GRAVEL D 100 4.75 37.5 10 fine PROJECT: Webster Street Subsurface Stormwater Treatment SITE: 760-766 Webster Street Lewiston, Maine 1 SAND USCS Classification D 60 0.78 GRAIN SIZE IN MILLIMETERS coarse medium Silt (ML) Silty sand with gravel (SM) D 30 D 10 0.162 220 Industrial Way Unit 4 Portland, ME fine 0.1 0.01 0.001 SILT OR CLAY LL PL PI Cc Cu %Gravel %Sand %Fines 0.0 23.3 7.0 59.0 93.0 17.6 PROJECT NUMBER: J3165011 CLIENT: City of Lewiston DPW EXHIBIT: B-1