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CriticalAreasReport.pdf Critical Areas Report City of Edmonds 2015 Waterline Replacement Four Site Locations Edmonds, Washington Applicant: City of Edmonds Ryan Hague, P.E., Capital Projects Manager Report Author: Phil Haberman, P.G, P.E.G. Senior Engineering Geologist, Stantec February 24, 2015 CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Table of Contents Part 1 - Responses to City of Edmonds Community Development Code Critical Area Report Requirements A.Introduction Figure 1 – Sites Vicinity Map Figures 2 – 5 Site Plans Figures 6 – 9 Hazard Locations B.Report Content and Organization C.ECDC 23.40.090D - Minimum Report Contents D.ECDC 23.80.050 - Special Study and Report Requirement - Geologically Hazardous Areas E.ECDC 23.40.120 - Mitigation Sequencing F.ECDC 23.80.070 - Development standards – Specific hazards. G.ECDC 23.80.060 - Development standards – General requirements. Part 2 - Project Drawings Site No. 2 Site No. 4 Site No. 7 Site No. 8 Part 3 - Geotechnical Investigation Report, City of Edmonds, 2015 Waterline Replacement Report Appendix A - Statement of General Conditions Appendix B – Figures Figure 1 – Sites Vicinity Map Figures 2 – 5 Site Plans Figures 6 – 9 Hazard Locations Appendix C - Boring Logs CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 PART 1 – Responses to City of Edmonds Community Development Code Critical Area Report Requirements CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 PART 1 - RESPONSES TO CITY OF EDMONDS COMMUNITY DEVELOPMENT CODE CRITICAL AREA REPORT REQUIREMENTS A.Introduction The City of Edmonds (City) is the water purveyor for the residents of the City. It operates, maintains, replaces and expands the water system to maintain public health, system reliability and to meet current and future water use demands of its customers. In order to fulfill its mission for providing a reliable water supply that meets present and future demand, the City plans to construct the 2015 Waterline Replacement project at 11 locations within the City. Four of these locations occur partially within geologically hazardous critical areas. Figure 1 is a map showing the general locations of the four sites. These four sites are designated as follows: Site No. 2, Sierra Place – A portion of this site is located within undeveloped steep slope in the public right-of-way (ROW) between the paved cul-de-sac at the end of Sierra Place (west extent) and 12 Avenue North (east extent) (Figure 2). th Site No. 4, Daley Street – A portion of this site is located within the steep slope in the Daley Street public ROW, between 8 Avenue North (west extent) and 831 Daley Street (east extent) th (Figure 3). Site No. 7, Edmonds Street - A portion of this site is located within the steep slope along the Edmonds Street public ROW at the southeast side of Hummingbird Park (Figure 4). Site No. 8, 172 Street SW - A portion of this site is located within the steep slope in the nd undeveloped public ROW along 172 Street Southwest, between Meadowdale Beach Road (west nd extent) and 69 Place West (east extent) (Figure 5). th Site No. 2 is located within an erosion hazard area and has slopes on the order of 30 percent, with a total topographic relief of approximately 15 feet (see Figure 6). This Site is vegetated with blackberry vines, grasses, and other herbaceous vegetation, along with evergreen and deciduous trees. Site No. 2 is bordered to the east by an easement and single family residences, to the north by undeveloped land, to the west by Sierra Place developed ROW, and to the south by single family residences. Portions of Site No. 2, within the area of the cul de-sac, are within the buffer of a category 3 wetland; but the work within the slope area is just outside the wetland buffer. Site No. 2 meets the definition of an erosion hazard area because it is underlain by Alderwood- Everett soils (15-30% Slopes). Sites mapped by the NRCS with these soils meet the criteria for erosion hazard areas per the Edmonds Community Development Code (ECDC) 23.80.020. The site is also located within 50 feet of a landslide hazard area. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 There currently exists a 4” CI water main pipe within the landslide hazard area. The City plans to abandon the 4” CI, in place, and use the top 200 feet as a sleeve through which a 1.5 inch diameter copper water service pipe will be sliplined to serve the properties at 701 12 Avenue N. th and at 1139 Sierra Place. Design drawings for the work at this site are identified as drawings C- 2.1 and C-2.2 in Part 2 of this CAR. Because the slope itself will not be disturbed by construction activities, except for shallow trenching of two 1-inch diameter copper water services, erosion control measures are shown on the design drawings and a separate erosion control plan is not provided. Site No. 4 has slopes of 40 to 70 percent with a total height of 58 feet (see Figure 7). This Site is vegetated with blackberry vines, grasses, and other herbaceous vegetation, along with sparse evergreen and deciduous trees. Site No. 4 is bordered to the east by Daley Street, to the north by single family residences and undeveloped land, to the west by 8 Avenue North and Daley th Street, and to the south by single family residences. Site No. 4 meets the definition of a landslide hazard area because its slope is 40 to 70%, which exceeds the 40% threshold per ECDC 23.80.020. The NRCS maps indicate that this site is underlain by Alderwood-Urban Land soils (8-15% Slopes), which do not meet the erosion hazard criteria per the ECDC. However, based on the observed slope conditions and granular nature of the soils at this site, it is our opinion that Site No. 4 meets the intent of the ECDC definition of erosion hazard area. There currently exists a 4” CI water main pipe within the landslide hazard area. The City plans to abandon the 4” CI, in place, and to install an 8-inch diameter water main by directional drilling or open trenching. Design drawings for the work at this site are identified as drawings C-4.4, C-4.5, and C-4.6 in Part 2 of this CAR. Site No. 7 has slopes of 45 t0 53 percent with a total height of 30 feet (see Figure 8). This Site is vegetated with blackberry vines and grasses with sparse deciduous and evergreen trees in the general vicinity. Site No. 7 is bordered to the east by Edmonds Street, to the north and west by Hummingbird Park, to the south by single family residences. Site No. 7 meets the definition of an erosion hazard area because it is underlain by Alderwood- Everett soils (25-70% Slopes). Sites mapped by the NRCS with these soils meet the criteria for erosion hazard areas per ECDC 23.80.020. This site also meets the definition of a landslide hazard area because its slope is 45 to 53%, which exceeds the 40% threshold per ECDC 23.80.020. There currently is no water main pipe within the landslide hazard area. The City plans to install an 8-inch diameter ductile iron (restrained joint) water main by conventional trenching. Design drawings for the work at this site are identified as drawing C-7.1 in Part 2 of this CAR. Because this site is defined as an erosion hazard area, an erosion control drawing is also included in Part 2 of this CAR and is identified as drawing C-7.3. Site No. 8 has slopes of 21 to 26 percent with a total height of approximately 70 feet (see Figure 9). Sewer and power lines extend through this area and the fill materials include native sand with gravel along with larger quarry rock. This Site is vegetated with blackberry vines, ivy, grasses, and ferns; along with Alder, Cedar, Hemlock, and Fir trees. Site No. 8 is bordered to E.2 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 the east by 172nd Street Southwest developed ROW, to the north by single family residences, to the south by single family residences, and to the west by Meadowdale Beach Road. Site No. 8 meets the definition of an erosion hazard area because it is underlain by Alderwood- Everett soils (25-70% Slopes). Sites mapped by the NRCS with these soils meet the criteria for erosion hazard areas per ECDC 23.80.020. The site is also located within 50 feet of a landslide hazard area. There currently is no water main pipe within the landslide hazard area. The City plans to install an 8-inch diameter ductile iron (restrained joint) water main by conventional trenching. Design drawings for the work at this site are identified as drawings C-8.1 and C-8.2 in Appendix A of this CAR. Because this site is defined as an erosion hazard area, an erosion control drawing is also included in Part 2 of this CAR and is identified as drawing C-8.4. The construction work will be performed by a private contractor under a contract with the City. The identity of the private contractor will be unknown until the contract is publically bid and the lowest responsible bidder is identified and awarded the construction contract. B.Report Content and Organization This critical area report (CAR) consists of this first “report” section (Part 1), which includes specific responses to content and questions described within the City of Edmonds Community Development Code (ECDC), and Part 2, which consists of project drawings, and Part 3, which is a geotechnical investigation report (GIR). This CAR is formatted and organized in accordance with the sections of the Edmonds Community Development Code (ECDC) that govern critical area report content requirements, specifically: ECDC 23.40.090D - Minimum Report Contents ECDC 23.80.050 - Special Study and Report Requirement - Geologically Hazardous Areas Additionally, this report includes written responses to ECDC requirements described in the following sections of the ECDC: ECDC 23.40.120 - Mitigation Sequencing ECDC 23.80.060 - Development standards – General requirements. ECDC 23.80.070 - Development standards – Specific hazards. E.3 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 C.ECDC 23.40.090D Minimum Report Contents In this section, we present our responses to the specific criteria from the City of Edmonds Community Development Code (section 23.40.090D) pertaining to critical area report minimum contents. D.Minimum Report Contents 1.The name and contact information of the applicant, a description of the proposal, and identification of the permit requested; The applicant is the City of Edmonds and the City’s project manager is Ryan Hague, P.E., Capital Projects Manager (425-775-2525 or 425-275-4808). The proposal is to construct public water main improvements within four geologically hazardous areas, designated as Sites #2, #4, #7 and #8. Each of the four sites is located within the public right-of-way. The City seeks a land clearing permit to perform the work. The construction contractor will need a ROW construction permit to perform the work. 2.A copy of the site plan for the development proposal including: a.A map to scale depicting critical areas, buffers, the development proposal, and any areas to be cleared; and b.A description of the proposed storm water management plan for the development and consideration of impacts to drainage alterations; Site plans are provided in Part 2 of this report for each of the four sites. A stormwater management plan is not applicable because this is only a buried utilities project and no storm drainage alterations or improvements will be made. 3.The dates, names, and qualifications of the persons preparing the report and documentation of any fieldwork performed on the site; The report’s authors are: Phil Haberman, P.G., P.E.G., Senior Engineering Geologist, Stantec The authors’ qualifications are presented in Part 3, GIR, Appendix D. Fieldwork performed is described and documented in the Part 3 GIR. 4.Identification and characterization of all critical areas, wetlands, water bodies, shorelines, and buffers adjacent to the proposed project area; E.4 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Identification and characterization of each of the four geologically hazardous areas is presented in the Part 3 GIR. Only one of the four sites (Site #2) is located within 50 feet of a wetland buffer (less than 5 feet locally). Site No.’s 2 and 8 are located within 50 feet of landslide hazard areas. Otherwise, there are no other known types of critical areas within or approximate to these four geologically hazardous sites. Figure 2 shows the extents of the category 3 wetland on Site #2. A“Critical Area Study and Wetland Mitigation Plan” dated November 27, 2012, was prepared by Wetland Resources, Inc. for the 1139 Sierra Place undeveloped-property adjacent to Site No. 2. The City holds a copy this report. 5.A description of reasonable efforts made to apply mitigation sequencing pursuant to ECDC 23.40.120, Mitigation sequencing, to avoid, minimize, and mitigate impacts to critical areas; and ECDC section 23.40.120 Mitigation Sequencing, in See responses to the this section of the CAR. 6.Report requirements specific to each critical area type as indicated in the corresponding chapters of this title. The following sections of this report address the specific report requirements described in the ECDC for geologically hazardous critical areas. E.ECDC 23.80.050 Special Study and Report Requirement – Geologically Hazardous Areas In this section, we present our responses to the specific criteria from the City of Edmonds Community Development Code (ECDC 23.80.050) pertaining to critical area reports for geologically hazardous areas. A.Preparation by a Qualified Professional. A critical areas report for a geologically hazardous area shall be prepared by an engineer or geologist licensed in the state of Washington, with experience analyzing geologic, hydrologic, and ground water flow systems, and who has experience preparing reports for the relevant type of hazard. Critical areas studies and reports on geologically hazardous areas shall be subject to independent review pursuant to ECDC 23.40.090(B). This report has been prepared by Phil Haberman, a Washington State licensed geologist and engineering geologist; and reviewed by Jaret Fischer, a Washington State licensed professional engineer. Mr. Haberman has over 16 years of experience in conducting geologic hazard analysis and geotechnical investigations in the Puget Sound region. E.5 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 B.Area Addressed in Critical Areas Report. The following areas shall be addressed in a critical areas report for geologically hazardous areas: 1.The project area of the proposed activity; and 2.All geologically hazardous areas within 200 feet of the project area or that have the potential to be affected by the proposal. This report provides geotechnical and geologic hazard analysis and recommendations for portions of four areas of the 2015 Waterline Project within the City of Edmonds located within steep slope areas. The four sites are designated Site No. 2, Site No. 4, Site No. 7, and Site No. 8. Site No. 2 is located within undeveloped public right of way (ROW) between the cul-de-sac at the end of Sierra Place (west extent) and 12th Avenue North (east extent). See Figure 2 for visual identification of the proposed activity boundaries. Site No. 2 is located within an erosion hazard area and has slopes on the order of 30 percent with a total topographic relief of approximately 15 feet. Site No. 2 is also located within 50 feet of a landslide hazard area (south of the site area). This Site is vegetated with blackberry vines, grasses, and other herbaceous vegetation, along with evergreen and deciduous trees. Site No. 2 is bordered to the east by an easement and single family residences, to the north by undeveloped land, to the west by Sierra Place, and to the south by single family residences. Portions of Site No. 2, within the area of the cul de-sac, are within the buffer of a category 3 wetland; but the work within the slope area is just outside the wetland buffer. Site No. 4 is located within the Daley Street public ROW between 8th Avenue North (west extent) and 831 Daley Street (east extent). See Figure 3 for visual identification of the proposed activity boundaries. Site No. 4 has slopes of 40 to 70 percent with a total height of 58 feet. This Site is vegetated with blackberry vines, grasses, and other herbaceous vegetation, along with sparse evergreen and deciduous trees. Site No. 4 is bordered to the east by Daley Street, to the north by single family residences and undeveloped land, to the west by 8th Avenue North and Daley Street, and to the south by single family residences. Site No. 7 is located along the Edmonds Street public at the southeast side of Hummingbird Park. See Figure 4 for visual identification of the proposed activity boundaries. Site No. 7 has slopes of 45 t0 53 percent with a total height of 30 feet. This Site is vegetated with blackberry vines and grasses with sparse deciduous E.6 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 and evergreen trees in the general vicinity. Site No. 7 is bordered to the east by Edmonds Street, to the north and west by Hummingbird Park, to the south by single family residences. Site No. 8 is located in an undeveloped public ROW along the 172nd Street Southwest between Meadowdale Beach Road (west extent) and 7010 172nd Street Southwest (west extent). See Figure 5 for visual identification of the proposed activity boundaries. Site No. 8 has slopes of 21 to 26 percent with a total height of approximately 70 feet. Site No. 8 is located within 50 feet of landslide hazard areas (relatively short slopes north and south of the site area). Sewer and power lines extend through this area and the fill materials include native sand with gravel along with larger quarry rock. This Site is vegetated with blackberry vines, ivy, grasses, and ferns; along with Alder, Cedar, Hemlock, and Fir trees. Site No. 8 is bordered to the east by 172nd Street Southwest developed ROW, to the north by single family residences, to the south by single family residences, and to the west by Meadowdale Beach Road. Figures 2 through 5 show the site locations, existing topography, and general layout. The location of geologically hazardous within 200 feet of each site can be found in Figures 6 through 9. C.Geological Hazards Assessment. A critical areas report for a geologically hazardous area shall contain an assessment of geological hazards including the following site- and proposal-related information at a minimum: 1.Site and Construction Plans. The report shall include a copy of the site plans for the proposal showing: a.The type and extent of geologic hazard areas, any other critical areas, and buffers on, adjacent to, within 200 feet of, or that are likely to impact the proposal; Shown in Figures 5 through 9 and in the Site Plans in Part 2. b.Proposed development, including the location of existing and proposed structures, fill, storage of materials, and drainage facilities, with dimensions indicating distances to the floodplain, if available; Much of this information is shown in Figures 2 through 5; however, there will be stockpiles of native and imported trench backfill during waterline placement. We anticipate these will be located adjacent to the trenches; however, the precise locations and sizes of soil piles will be determined E.7 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 by the Contractor at a later date. Because this is a linear project, the stockpiles are expected to move with the progress of the work. c.The topography, in two-foot contours, of the project area and all hazard areas addressed in the report; and Shown in Figures 2 through 5 and in the Site Plans in Part 2. d.Clearing limits; Shown on the Site Plans in Part 2. 2.Assessment of Geological Characteristics. The report shall include an assessment of the geologic characteristics of the soils, sediments, and/or rock of the project area and potentially affected adjacent properties, and a review of the site history regarding landslides, erosion, and prior grading. Soils analysis shall be accomplished in accordance with accepted classification systems in use in the region. The assessment shall include, but not be limited to: a.A description of the surface and subsurface geology, hydrology, soils, and vegetation found in the project area and in all hazard areas addressed in the report; Part 3, GIR Sections 3 through 5. b.A detailed overview of the field investigations, published data, and references; data and conclusions from past assessments of the site; and site-specific measurements, tests, investigations, or studies that support the identification of geologically hazardous areas; and Part 3, GIR Sections 4 through 6. c.A description of the vulnerability of the site to seismic and other geologic events; Part 3, GIR Section 6.1.3. 3.Analysis of Proposal. The report shall contain a hazards analysis including a detailed description of the project, its relationship to the geologic hazard(s), and its potential impact upon the hazard area, the subject property, and affected adjacent properties; and Part 3, GIR Section 6 and 7. 4.Minimum Buffer and Building Setback. The report shall make a recommendation for the minimum no-disturbance buffer and minimum building setback from any geologic hazard based upon the geotechnical analysis. We recommend limiting the width of construction to a 30 feet maximum through each site area. There are no buildings requiring setbacks and E.8 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 buffers aren’t applicable since the work will be occurring in critical areas. A 10 feet buffer from landslide areas at Site No.’s 2 and 7 is adequate. D.Incorporation of Previous Study. Where a valid critical areas report has been prepared within the last five years for a specific site, and where the proposed land use activity and surrounding site conditions are unchanged, said report may be incorporated into the required critical areas report. The applicant shall submit a hazards assessment detailing any changed environmental conditions associated with the site. A “Geotechnical Engineering Study”, dated July 16, 2012, was prepared by Earth Solutions NW, LLC for the 1139 Sierra Place undeveloped-property adjacent to Site No. 2. A “Critical Area Study and Wetland Mitigation Plan” dated November 27, 2012, was prepared by Wetland Resources, Inc. for the 1139 Sierra Place undeveloped-property adjacent to Site No. 2. We are not aware of previous critical areas reports for the proposed construction of any of the other three sites. E.Mitigation of Long-Term Impacts. When hazard mitigation is required, the mitigation plan shall specifically address how the activity maintains or reduces the preexisting level of risk to the site and adjacent properties on a long-term basis (equal to or exceeding the projected lifespan of the activity or occupation). Proposed mitigation techniques shall be considered to provide long-term hazard reduction only if they do not require regular maintenance or other actions to maintain their function. Mitigation may also be required to avoid any increase in risk above the preexisting conditions following abandonment of the activity. Of primary importance for long term stabilization is adequate soil compaction in each graded/disturbed work area along with permanent vegetation establishment. Additionally, temporary erosion control measures, such as hydroseed and jute mats, should be in place until vegetation plans have been implemented and the vegetation is in place and has been established adequately. Final inspection of each site should be performed by the geotechnical engineer and City to verify the adequacy of this work. F.Additional Technical Information Requirements for Erosion and Landslide Hazard Areas. In addition to the basic critical areas report requirements for geologically hazardous areas provided in subsections A through E of this section, technical information for erosion and 19.10 landslide hazard areas shall meet the requirements of Chapter ECDC and include the following information at a minimum: 1.Site Plan. The critical areas report shall include a copy of the site plan for the proposal showing: a.The height of slope, slope gradient, and cross-section of the project area; E.9 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 b.The location of springs, seeps, or other surface expressions of ground water on or within 200 feet of the project area or that have the potential to be affected by the proposal; and c.The location and description of surface water runoff features; Figures 2 through 5. 2.Hazards Analysis. The hazards analysis component of the critical areas report shall specifically include: a.A description of the extent and type of vegetative cover; Site No. 2 is nearly fully vegetated with blackberry vines, grasses, and other herbaceous vegetation, along with evergreen and deciduous trees. Site No. 4 is vegetated with blackberry vines, grasses, and other herbaceous vegetation, along with sparse evergreen and deciduous trees. There are wood/concrete steps extending through this site and approximately 5 to 10 percent of the site area consists of exposed soils. Site No. 7 is vegetated with blackberry vines and grasses with sparse deciduous and evergreen trees in the general vicinity. Minimal exposed soils are present at this site. Site No. 8 is vegetated with blackberry vines, ivy, grasses, and ferns; along with Alder, Cedar, Hemlock, and Fir trees. The trees are generally located along the north and south margins of the site. The interior portion has locally exposed soils on the order of 15 to 25 percent of the site. b.A description of subsurface conditions based on data from site-specific explorations; The subsurface soils at Site No. 2 were not explored as part of the study. Site No. 4 is underlain by local areas of fill consisting of loose to medium dense silty-sand with gravel. The weathered soils at this site include loose to medium dense, poorly graded sand with gravel and trace amounts of silt (Outwash). Site No. 7 is underlain by local areas of fill consisting of loose to medium dense poorly graded sand with silt. The weathered soils at this site include loose to medium dense, poorly graded sand with gravel and trace amounts of silt (Advance Outwash). Unweathered soils include dense sands with trace gravel (Advance Outwash). Site No. 8 is underlain by local areas of fill consisting of loose to medium dense silty-sand with gravel. The underlying soils at this site include loose to medium dense, poorly graded sand with gravel and trace E.10 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 amounts of silt to gravelly sand with variable amounts of silt (Undifferentiated Outwash/Esperance Sand). c.Descriptions of surface and ground water conditions, public and private sewage disposal systems, fills and excavations, and all structural improvements; Groundwater was not encountered in any of the site explorations. We are not aware of the location of any private sewer disposal systems within the site areas. Public sewer, storm, and other utilities locally cross or extend through each site area and are shown on the Site Plans. General areas of fill are shown on Figures 2 through 5. An estimate of slope stability and the effect construction and placement of structures will have on the slope over the estimated life of the structure; Described in Part 3, GIR Section 6.1.4. Our slope stability analyses were based on the existing conditions to determine relative factors of safety and stability of the existing slopes. No structures will be placed in these areas so the existing slope stability will be approximately the same as the post-construction slope stability. d.An estimate of the bluff retreat rate that recognizes and reflects potential catastrophic events such as seismic activity or a 100-year storm event; Not applicable. e.Consideration of the run-out hazard of landslide debris and/or the impacts of landslide run-out on down-slope properties; Not applicable. f.A study of slope stability including an analysis of proposed cuts, fills, and other site grading; Provided in Part 3, GIR Section 6.1.4. g.Recommendations for building siting limitations; and Not applicable. h.An analysis of proposed surface and subsurface drainage, and the vulnerability of the site to erosion; Discussed in Part 3, GIR Sections 6.1.2 and 8.3. 3.Geotechnical Engineering Report. The technical information for a project within a landslide hazard area shall include a geotechnical engineering report prepared by a licensed engineer that presents engineering recommendations for the following: E.11 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 a.Parameters for design of site improvements including appropriate foundations and retaining structures. These should include allowable load and resistance capacities for bearing and lateral loads, installation considerations, and estimates of settlement performance; Not applicable. b.Recommendations for drainage and subdrainage improvements; Not applicable other than erosion control related measures in Part 3, GIR Section 8.3. c.Earthwork recommendations including clearing and site preparation criteria, fill placement and compaction criteria, temporary and permanent slope inclinations and protection, and temporary excavation support, if necessary; and Provided in Part 3, GIR Section 8.1. d.Mitigation of adverse site conditions including slope stabilization measures and seismically unstable soils, if appropriate; Included in Part 3, GIR Section 8.3. 4.Erosion and Sediment Control Plan. For any development proposal on a site containing an erosion hazard area, an erosion and sediment control plan shall be required. The erosion and sediment control plan shall be prepared in compliance with requirements 18.30 set forth in Chapter ECDC. Erosion and Sediment Controlmeasures are shown within the water main replacement design plans for Site #2 and on separate TESC Plans for sites #4, #7 & #8 in Part 2. The work within the Site #2 slope is extremely minor trenching to install two short, shallow 1-inch diameter water service lines and water meter boxes. The work is expected to take only two days and involve a small area of clearing necessary to perform the work. Marking of clearing limits, and tree protection area, as well as hydroseeding bare or disturbed soils resulting from construction activities should be sufficient to mitigate the potential effects of this minor construction activity on soil erosion. The work within the steep slope areas of Site No.’s 4, 7 and 8 will be performed during the driest months of the year (mid July to end of September), which greatly diminishes the potential for soil erosion during construction. Immediately upon completion of trenching and water line installation on these slopes, biodegradable straw wattles will be placed to slow stormwater runoff velocities and the bare soils and E.12 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 disturbed soils will be hydroseed. The straw wattles will be left in place to gradually decompose over time. G.Limited Report Requirements for Stable Erosion Hazard Areas. At the director’s discretion, detailed critical areas report requirements may be waived for erosion hazard areas with suitable slope stability. Report requirements for stable erosion hazard areas may be met through construction documents that shall include at a minimum an erosion and sediment 18.30 control plan prepared in compliance with requirements set forth in Chapter ECDC. Not applicable H.Seismic Hazard Areas. In addition to the basic critical areas report requirements for geologically hazardous areas provided in subsections A through E of this section, a critical areas report for a seismic hazard area shall also meet the following requirements: 1.The site map shall show all known and mapped active faults within 200 feet of the project area or that have the potential to be affected by the proposal. 2.The hazards analysis shall include a complete discussion of the potential impacts of seismic activity on the site (for example, forces generated and fault displacement). 3.A geotechnical engineering report shall evaluate the physical properties of the subsurface soils, especially the thickness of unconsolidated deposits and their liquefaction potential. If it is determined that the site is subject to liquefaction, mitigation measures appropriate to the scale of the development shall be recommended and implemented. \[Ord. 3527 § 2, 2004\]. It is our opinion that none of the four site locations are within seismic hazard areas as defined above. The following sections of the Edmonds Community Development Code have been included for review and consideration by the design team and contractor(s). E. 23.40.120 Mitigation Sequencing A.Applicants shall demonstrate that all reasonable efforts have been examined with the intent to avoid and minimize impacts to critical areas. B.When an alteration to a critical area is proposed, such alteration shall be avoided, minimized, or compensated for in the following sequential order of preference: 1.Avoiding the impact altogether by not taking a certain action or parts of an action; 2.Minimizing impacts by limiting the degree or magnitude of the action and its implementation by using appropriate technology or by taking affirmative steps, such as project redesign, relocation, or timing, to avoid or reduce impacts; E.13 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 3.Rectifying the impact to wetlands, frequently flooded areas, and fish and wildlife habitat conservation areas by repairing, rehabilitating, or restoring the affected environment to the historical conditions or the conditions existing at the time of the initiation of the project; 4.Minimizing or eliminating the hazard by restoring or stabilizing the hazard area through engineering or other methods; 5.Reducing or eliminating the impact or hazard over time by preservation and maintenance operations during the life of the action; 6.Compensating for the impact to wetlands, frequently flooded areas, and fish and wildlife habitat conservation areas by replacing, enhancing, or providing substitute resources or environments; and/or 7.Monitoring the hazard or other required mitigation and taking remedial action when necessary. Site No. 2 – Rather than replace the existing old 4” cast iron water main, with a new water main of the same size or larger, the plan is to abandon the existing cast iron water main, in place and to use a portion of the existing cast iron water main as a sleeve for a small 1.5 inch diameter copper service tubing to service two properties located on the slope. Leaving the CI water main in place reduces disturbance to the hill. The two copper services will be placed in relatively short, and narrow, shallow trenches (18 to 24 inches wide by 36 inches deep), either hand trenched or trenched with very small equipment, resulting in minimal disturbance to the site. Construction on the slope, to install the services and abandon the 4-inch CI pipe, is anticipated to take only two days and are not expected to result in soil erosion or any instability of the adjacent slopes. Site No.4 – The very old 4-inch cast iron water main must be replaced to prevent a potentially catastrophic slope failure resulting from a water main leak. Looping the water main is necessary to ensure adequate fire service flow during a fire in this area. Additionally, looping the water main is important for maintaining water quality (reduces stagnant water at water main dead ends). Fire flow requirements have increased over time and the 4-inch diameter size is undersized and does not meet Department of Health sizing guidelines. The proposed 8-inch diameter replacement water main will be installed by either directional drilling or open excavation methods. The trench cut will be made in the direction of the fall line, which substantially minimizes any chance of slope temporary instability. Initial excavation work will be necessary to both remove fill materials, and decrease the overall slope magnitude near the top of the slope. E.14 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 The restrained joint method of pipe connection is chosen to prevent potential pipe joint separation. Upon completion of the construction the surface area will be hydroseeded and vegetation allowed to grow back over the area, resulting in no loss of functions and values for this geologically hazardous critical area (erosion and landslide hazard areas). Site No.7 – The water main presently dead ends west and east of the steep slope area. Dead end water mains pose two problems – water quality (from stagnant water) and insufficient hydraulic performance for the water system from lack of looping. Hydraulic performance requirements are driven by fire flow demands, which have increased since the original water mains were constructed. The only real practical solution is to loop the main (connect the two ends of the dead end mains). Additionally, these are undersized mains not meeting current Department of Health sizing requirements. The plan is replace the very old cast iron mains with 8 inch ductile iron mains and to construct a restrained joint ductile iron main down the steep slope, which will be buried. Construction within the slope area will take less than a week, resulting in a very limited time in which the slope is opened up. The trench cut will be made in the direction of the fall line, which substantially minimizes any chance of slope temporary instability. The restrained joint method of pipe connection is chosen to prevent potential pipe joint separation. Upon completion of the construction the surface area will be hydroseeded and vegetation allowed to grow back over the area, resulting in no loss of functions and values for this geologically hazardous critical area. Site No.8– The water main presently dead ends at both the east side of Meadowdale Beach Road and near the west end of pavement on 172 St SW. nd Dead end water mains pose two problems – water quality (from stagnant water) and insufficient hydraulic performance for the water system from lack of looping. Hydraulic performance requirements are driven by fire flow demands, which have increased since the original water mains were constructed. The only real practical solution is to loop the main (connect the two ends of the dead end mains). The plan is to construct a restrained joint ductile iron main down the undeveloped slope, which will be buried. The trench cut will be made in the direction of the fall line, which substantially minimizes any chance of slope temporary instability. The restrained joint method of pipe connection is chosen to prevent potential pipe joint separation. Upon completion of the construction the surface area will be hydroseeded and vegetation allowed to grow back over the area, resulting in no loss of functions and values for this geologically hazardous critical area (erosion or adjacent landslide hazard areas). Mitigation for individual actions may include a combination of the above measures. C. E.15 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 None of the proposed actions within the geologically hazardous portions of the 4 project sites also occur within identified wetlands, frequently flooded areas, or wild life habitat conservation areas. None of the projects will result in impacts that adversely affect the stability or functions of the geologically hazardous slopes. F. 23.80.060 Development standards – General requirements. A.Alterations of geologically hazardous areas or associated buffers may only occur for activities that: 1.Will not increase the threat of the geological hazard to adjacent properties beyond predevelopment conditions; 2.Will not adversely impact other critical areas; 3.Are designed so that the hazard to the project is eliminated or mitigated to a level equal to or less than predevelopment conditions; and 4.Are certified as safe as designed and under anticipated conditions by a qualified engineer or geologist, licensed in the state of Washington. If the work is performed in accordance with our recommendations and under our supervision, all of the above requirements will be met. G. 23.80.070 Development standards – Specific hazards. A.Erosion and Landslide Hazard Areas. Activities on sites containing erosion or landslide 23.80.060 hazards shall meet the requirements of ECDC , Development Standards – General Requirements, and the specific following requirements: 1.Buffer Requirement. A buffer shall be established from all edges of landslide hazard areas. The size of the buffer shall be determined by the director consistent with recommendations provided in the geotechnical report to eliminate or minimize the risk of property damage, death, or injury resulting from landslides caused in whole or part by the development, based upon review of and concurrence with a critical areas report prepared by a qualified professional. a.Minimum Buffer. The minimum buffer shall be equal to the height of the slope existing within the project area or 50 feet, whichever is greater; b.Buffer Reduction. The buffer may be reduced to a minimum of 10 feet when a qualified professional demonstrates to the satisfaction of the director that the reduction will adequately protect the proposed development, adjacent developments and uses and the subject critical area; c.Increased Buffer. The buffer may be increased where the director determines that a larger buffer is necessary to prevent risk of damage to proposed and existing development; Work will occur within the minimum 10 feet buffer. If performed per plans and specifications, the landslide potential will be the same or slightly less than what currently exists after completion. E.16 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Erosion hazards will be mitigated through construction during dry weather and re-vegetation implementation immediately upon completion of the work. 2.Alterations. Alterations of an erosion or landslide hazard area and/or buffer may only occur for activities for which a hazards analysis is submitted and certifies that: a.The development will not increase surface water discharge or sedimentation to adjacent properties beyond predevelopment conditions; b.The development will not decrease slope stability on adjacent properties; and c.Such alterations will not adversely impact other critical areas; If performed per plans and specifications, along with the recommendation in this report, all of the above conditions should be met during/following waterline placement. 3.Design Standards. Development within an erosion or landslide hazard area and/or buffer shall be designed to meet the following basic requirements unless it can be demonstrated that an alternative design that deviates from one or more of these standards provides greater long-term slope stability while meeting all other provisions of this title. The requirement for long-term slope stability shall exclude designs that require regular and periodic maintenance to maintain their level of function. The basic development design standards are: a.The proposed development shall not decrease the factor of safety for landslide occurrences below the limits of 1.5 for static conditions and 1.2 for dynamic conditions. If stability at the proposed development site is below these limits, the proposed development shall provide practicable approaches to reduce risk to human safety and improve the factor of safety for landsliding. In no case shall the existing factor of safety be reduced for the subject property or adjacent properties; b.Structures and improvements shall be clustered to avoid geologically hazardous areas and other critical areas; c.Structures and improvements shall minimize alterations to the natural contour of the slope, and foundations shall be tiered where possible to conform to existing topography; d.Structures and improvements shall be located to preserve the most critical portion of the site and its natural landforms and vegetation; e.The proposed development shall not result in greater risk or a need for increased buffers on neighboring properties; f.The use of retaining walls that allow the maintenance of existing natural slope area is preferred over graded artificial slopes; and g.Development shall be designed to minimize impervious lot coverage; E.17 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 If performed per plans and specifications, the landslide potential will be the same or slightly less than what currently exists after completion. Erosion hazards will be mitigated through grading and re-vegetation implementation. 4.Vegetation Retention. Unless otherwise provided or as part of an approved alteration, removal of vegetation from an erosion or landslide hazard area or related buffer shall be prohibited; We recommend a maximum 30 feet width site area (disturbance zone) extending through the proposed waterline alignment at Site No.’s 4, 7, and 8. 5.Seasonal Restriction. Clearing shall be allowed only from May 1st to October 1st of each year; provided, that the director may extend or shorten the dry season on a case-by-case basis depending on actual weather conditions, except that timber harvest, not including brush clearing or stump removal, may be allowed pursuant to an approved forest practice permit issued by the city of Edmonds or the Washington State Department of Natural Resources; We recommend seasonal restrictions for trenching activities at Site No.’s 4, 7 and 8 as described above. Work at Site #2 is so minimal and the erosion potential so slight that seasonal restrictions are not necessary and will not result in meaningful improvement in the potential for measureable soil erosion. The size of this project is such that not all of the project work can be performed during the dry season; therefore, seasonal restrictions at Site No. 2 would potentially result in unnecessary delays in overall project completion for no discernible environmental or slope stability benefit. 6.Point Discharges. Point discharges from surface water facilities and roof drains onto or upstream from an erosion or landslide hazard area shall be prohibited except as follows: a.Conveyed via continuous storm pipe downslope to a point where there are no erosion hazard areas downstream from the discharge; b.Discharged at flow durations matching predeveloped conditions, with adequate energy dissipation, into existing channels that previously conveyed storm water runoff in the predeveloped state; or c.Dispersed discharge upslope of the steep slope onto a low-gradient, undisturbed buffer demonstrated to be adequate to infiltrate all surface and storm water runoff, and where it can be demonstrated that such discharge will not increase the saturation of the slope; and 7.Prohibited Development. On-site sewage disposal systems, including drain fields, shall be prohibited within erosion and landslide hazard areas and related buffers. E.18 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Numbers 6 and 7 are not applicable. B.Earth Subsidence and Landslide Hazard Area. In addition to the requirements of this chapter, development proposals for lands located within the earth subsidence and landslide hazard area as indicated on the critical areas inventory shall be subject to the 19.10 provisions of Chapter ECDC. It is our opinion that the four site locations are not located within areas susceptible to subsidence. C.Seismic Hazard Areas. Activities proposed to be located in seismic hazard areas shall meet 23.80.060 the standards of ECDC , Development Standards – General Requirements. \[Ord. 3527 § 2, 2004\]. It is our opinion that the four site locations are not located within seismic hazard areas. E.19 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Part 2 – Project Drawings Site No. 2 C-2.1 Sierra Pl. Sta. 0+40 to 5+60 C-2.2 Sierra Pl. Sta. 5+60 to 12 Ave N. th Site No. 4 C-4.4 Daley St. Sta. 6+00 to 10+00 C-4.5 Daley St. Sta. 10+00 to 14+50 C-4.6 Daley St. TESC Plan Site No. 7 C-7.1 Edmonds St. 10 Pl. to Sta. 5+80 th C-7.3 Edmonds St Hummingbird Hill Park TESC Plan Site No. 8 C-8.1 172 St. SW Sta 0+00 to 2+40 nd C-8.2 172 St. SW Sta 2+40 to 5+00 nd C-8.4 172 St. SW TESC Plan nd E.20 ph v:\\2123\\active\\proposals\\2012\\phil haberman\\2014\\edmonds critical areas\\feb final\\edmonds critical areas\\final\\rpt_edmonds car_draft_tmt_trk chngsfeb.docx 40 C-2.2 8 SIERRAPL.STA.5+60TO12THAVE.N 10 WATERSERVICEPLAN DETAIL3SHT.C-2.2 SITENO.2 5 SCALEINFEET 0 5 20 20 DETAIL2SHT.C-2.1 DETAIL4SHT.C-2.2 10 SCALEINFEET 10 SCALEINFEET 0 0 10 10 20 DETAIL1SHT.C-2.1 10 SCALEINFEET 0 10 MATCHLINESHT.C-2.1STA.5+60 2.PLAN,SEQUENCEANDPERFORMTHEWORKTOMINIMIZEDURATIONOFWATER SERVICESHUTOFFTOHSE#701.IFWATERSERVICESHUTOFFHASPOTENTIAL 1.EX.4"CISHALLNOTBEABANDONEDUNTILNEW8"DI(420ZONE)WATERMAIN,TOEXCEED8HOURS,THENPROVIDETEMPORARYPOTABLEWATERSERVICE MORTAR,NON-SHRINKGROUTOREQUIVALENTAPPROVEDBYENGINEER. EEVE,ATBOTHENDS,WITH12"THICKPLUGOF SERVICESANDHYDRANTSAREFULLYOPERATIONALONSIERRAPLACE. GENERALWATERCONSTRUCTIONNOTES: LOCATIONSOFSIDESEWERSAND 40 BEVERIFIEDBYCONTRACTOR. EX.WATERSERVICEPIPESARE TYPE,LOCATION,DEPTHORCOMPLETENESS.SCHEMATICONLYANDSHOULD GUARANTEEISMADEASTOTHEEXACTSIZE, BURIEDUTILITIESINAREA EXISTINGUTILITIESSHOWNAREFROM CALLBEFOREYOUDIG 1-800-424-5555or811 AVAILABLEINFORMATIONANDNO 020 TOHSE#701BEFORESTARTOFSHUTOFF. SCALEINFEET 3.PLUGANNULUSOF4"CISL 20 CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Part 3 - Geotechnical Investigation Report (GIR), City of Edmonds 2015 Waterline Replacement CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Geotechnical Investigation Report City of Edmonds 2015 Waterline Replacement Four Site Locations Edmonds, Washington February 24, 2015 CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Table of Contents 1.0INTRODUCTION .................................................................................................................. 1 2.0PROJECT DESCRIPTION ...................................................................................................... 1 3.0SITE DESCRIPTION .............................................................................................................. 1 4.0SUBSURFACE DATA ............................................................................................................ 3 4.1.1 Site Investigation Program ................................................................................. 3 5.0SOIL AND GROUNDWATER CONDITIONS ......................................................................... 4 5.1.1Area Geology .................................................................................................... 4 5.1.2Soil Conditions .................................................................................................... 4 6.0GEOLOGIC HAZARDS ...................................................................................................... 6 6.1.1Landslide Hazard ................................................................................................ 6 6.1.2Erosion Hazard .................................................................................................... 7 6.1.4Seismic Hazard ................................................................................................... 8 6.1.4Slope Stability Analyses ...................................................................................... 9 7.0DISCUSSION ......................................................................................................................11 7.1.1General ..............................................................................................................11 8.0RECOMMENDATIONS .......................................................................................................11 8.1 SITE PREPARATION ........................................................................................................11 8.2TEMPORARY EXCAVATIONS ..........................................................................................12 8.3EROSION AND SEDIMENT CONTROL ............................................................................13 8.4UTILITIES ..........................................................................................................................16 8.5GROUNDWATER INFLUENCE ON CONSTRUCTION .....................................................17 9.0CONSTRUCTION FIELD REVIEWS .......................................................................................17 10.0CLOSURE ...........................................................................................................................17 i CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 LIST OF APPENDICES Appendix A — Statement of General Conditions Appendix B — Figures Appendix C — Boring Logs Appendix D – Author Experience ii CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 1.0Introduction At the request of the City of Edmonds, Stantec has completed a geotechnical investigation and critical areas report for portions of the 2015 Waterline Replacement project in Edmonds, Washington (Figure 1). The purpose of our investigation was to evaluate the soil conditions at four geologically hazardous areas where proposed waterlines will be located and to provide a Critical Areas Report and Geotechnical Investigation pertaining to these hazards and the proposed construction per the applicable sections of Chapter 23 of the Edmonds Community Development Code. The scope of work for the study consisted of a field investigation and document reviews followed by cross section development, slope stability analyses, and engineering analyses to prepare this report. Recommendations presented herein pertain to various geotechnical aspects of the proposed development and to provide an overview of the geologic conditions, geologic hazards, and recommendations for hazard mitigation (as needed). 2.0Project Description The proposed construction includes waterline placement through both developed roadways and undeveloped road easements at various locations within the City of Edmonds. We anticipate that new waterlines will be placed using trenched and potentially trenchless construction methods and will be emplaced at depths of 4 to 6 feet below existing grades. We anticipate that trench boxes will be utilized as temporary shoring for open excavation construction. Trenchless work, if utilized, would include directional drilling at two of the sites (Site No.’s 4 and 7). We understand that proposed construction at Site No. 2 (see below for location) will include a slip line through existing pipe; therefore, there will be minimal ground disturbance. 3.0Site Description This report provides geotechnical and geologic hazard analysis and recommendations for four areas of the 2015 Waterline Project within the City of Edmonds. The sites are designated Site No. 2, Site No. 4, Site No. 7, and Site No. 8. 1 CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Site No. 2 is located within undeveloped public right of way (ROW) between the cul-de-sac at the end of Sierra Place (west extent) and 12 Avenue North (east extent) (Figure 2). For the th purposes of this report, Site No. 2 has dimensions of 80 feet in the north-south direction and 250 feet in the east-west direction. Site No. 2 is located within an erosion hazard area and has slopes on the order of 30 percent with a total topographic relief of approximately 15 feet. There are local slopes greater than 40 percent magnitudes south of the site area. This Site is vegetated with blackberry vines, grasses, and other herbaceous vegetation, along with evergreen and deciduous trees. Site No. 2 is bordered to the east by an easement and single family residences, to the north by undeveloped land, to the west by Sierra Place, and to the south by single family residences. Portions of Site No. 2, within the area of the cul de-sac, are within the buffer of a category 3 wetland; but the work within the slope area is just outside the wetland buffer. Site No. 4 is located within the Daley Street public ROW between 8 Avenue North (west extent) th and 831 Daley Street (east extent) (Figure 3). For the purposes of this report, Site No. 4 has dimensions of 80 feet in the north-south direction and 240 feet in the east-west direction. Site No. 4 has slopes of 40 to 70 percent with a total height of 58 feet. We also understand that there is a buried rockery/rock buttress at this location, near the 150 feet elevation contour. This Site is vegetated with blackberry vines, grasses, and other herbaceous vegetation, along with sparse evergreen and deciduous trees. Site No. 4 is bordered to the east by Daley Street, to the north by single family residences and undeveloped land, to the west by 8 Avenue North and th Daley Street, and to the south by single family residences. Site No. 7 is located along the Edmonds Street public ROW at the southeast side of Hummingbird Park (Figure 4). For the purposes of this report, Site No. 7 has dimensions of 120 feet in the north-south direction and 120 feet in the east-west direction. Site No. 7 has slopes of 45 t0 53 percent with a total height of 30 feet. This Site is vegetated with blackberry vines and grasses with sparse deciduous and evergreen trees in the general vicinity. Site No. 7 is bordered to the east by Edmonds Street, to the north and west by Hummingbird Park, to the south by single family residences. Site No. 8 is located in an undeveloped public ROW along the 172 Street Southwestbetween nd Meadowdale Beach Road (west extent) and 7010 172 Street Southwest (west extent) (Figure 5). nd For the purposes of this report, Site No. 8 has dimensions of 80 feet in the north-south direction and 350 feet in the east-west direction. Site No. 8 has slopes of 21 to 26 percent with a total height of approximately 70 feet. There are local slopes with magnitudes greater than 40 percent north and south of the site area. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Sewer and power lines extend through this area and the fill materials include native sand with gravel along with larger quarry rock. This Site is vegetated with blackberry vines, ivy, grasses, and ferns; along with Alder, Cedar, Hemlock, and Fir trees. Site No. 8 is bordered to the east by 172 Street Southwest developed ROW, to the north by single family residences, to the south by nd single family residences, and to the west by Meadowdale Beach Road. 4.0Subsurface Data 4.1.1 Site Investigation Program The geotechnical field investigation program was completed on November 3, 2014 and included drilling and sampling a total of seven hollow stem auger borings drilled by a Stantec subcontractor using a limited access drill rig. The borings were located at or near pre- determined locations at Site No.’s 4, 7, and 8 and extended to depths ranging from approximately 11.5 to 21.5 feet below the existing site grades. Additionally, several hand borings were advanced in areas where access was very limited in order to confirm soil composition and density similar to the drilled borings. The soils encountered were logged in the field during the exploration and are described in accordance with the Unified Soil Classification System (USCS). Disturbed soil samples were obtained by using a 140 pound hammer free falling a vertical distance of 30 inches for the borings. The summation of hammer-blows required to drive the sampler the final 12-inches of an 18-inch sample length is defined as the Standard Penetration Resistance, or N-value for a 140 pound hammer and 2 inch outside diameter split spoon sampler. The uncorrected blow count is presented graphically on the boring logs in this appendix. The resistance, or “N” value, provides a measure of the relative density of granular soils of the consistency of cohesive soils. Our report discussions regarding soil density as well as engineering parameters are based on the N values. A Stantec field representative directed the drilling program, collected disturbed soil samples from split spoon sampler tubes, classified the encountered soils, kept a detailed log of each auger hole, and observed and recorded pertinent site features. The results of the drilling and sampling are presented on the boring logs enclosed in Appendix C. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 5.0Soil and Groundwater Conditions 5.1.1Area Geology The site lies within the Puget Lowland. The lowland is part of a regional north-south trending trough that extends from southwestern British Columbia to near Eugene, Oregon. North of Olympia, Washington, this lowland is glacially carved, with a depositional and erosional history including at least four separate glacial advances/retreats. The Puget Lowland is bounded to the west by the Olympic Mountains and to the east by the Cascade Range. The lowland is filled with glacial and nonglacial sediments consisting of interbedded gravel, sand, silt, till, and peat lenses. The Preliminary Surficial Geologic Map of the Edmonds East and Edmonds West Quadrangles, Snohomish and King Counties, Washington, indicates that Site No. 2 is underlain by Vashon Glacial Till, Site No.’s 4 and 7 are underlain by Vashon Recessional Outwash at the surface and at depth by Vashon Advance Outwash, and Site No. 8 is located near the contacts between Vashon Glacial Till and Esperance Sand. Vashon Glacial Till is typically characterized by an unsorted, nonstratified mixture of clay, silt, sand, gravel, cobbles and boulders in variable quantities. These materials are typically dense and relatively impermeable. The poor sorting reflects the mixing of the materials as these sediments were overridden and incorporated by the glacial ice. Vashon Recessional Outwash is typically medium dense and consists of sand with variable amounts of silt and gravel. These materials are commonly found in valley areas and on till planes. Esperance Sand, sometimes known as Vashon Advance Outwash or Undiffentiated Outwash in many new publications and maps, consists of stratified sands with minor amounts of gravel to areas of relatively coarse gravel with variable amounts of sand. These materials are typically dense to very dense and underlie Vashon Glacial Till. Typically, outwash deposits have moderate to high permeability rates while glacial till has very low to low permeability rates. Conversely, outwash deposits have a tendency to erode readily by surface water while glacial till is typically resistant to erosion. 5.1.2Soil Conditions Details of the encountered soil conditions are presented on the boring logs in Appendix C. The detailed soil description on these logs should be referred to in preference to the generalized descriptions below. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Site No. 4 Boring B-1 In Boring B-1, we encountered approximately 6 inches of topsoil and vegetation underlain by approximately 2 feet of loose, silty-fine to medium grained sand to poorly graded sand with trace amounts of silt (Fill). This layer was underlain by approximately 4 feet of loose, silty-fine to medium grained sand with variable amounts of gravel and debris (Fill). This layer was underlain by loose to medium dense, fine to medium grained sand (Vashon Recessional Outwash), which continued to the termination depth of the boring. Borings B-2 and B-3 In Borings B-2 and B-3, we encountered approximately 4 to 10 inches of vegetation and topsoil underlain by approximately 7 to 9 feet of very loose to loose, fine to medium grained sand with variable amounts of silt and gravel (Weathered Vashon Recessional Outwash). This layer was underlain by medium dense, fine to medium grained sand with trace amounts of gravel (Vashon Recessional Outwash), which continued to the termination depths of these borings. We drilled several hand borings and used soil probes in an attempt to locate the extents of the buried rockery near the 150 feet elevation contour. Based on our observations, it appears that the rockery is loosely constructed with 1 to 4 man sized rocks at a relatively low angle (1-2H:1V). While the large rocks extend through the area where the waterline will be located, it is our opinion that the rocks could either be removed with a large excavator, or be avoided by directionally drilling below the rocks. The rockery is not a retaining feature and its partial removal will not significantly affect slope stability. Site No. 7 Boring B-4 In Boring B-4, we encountered approximately 8 inches topsoil and grass underlain by approximately 8 feet of very loose to loose, silty-fine to medium grained sand with minor amounts of gravel (Fill). This layer was underlain by medium dense to dense, fine to medium grained sand with trace amounts of gravel (Vashon Advance Outwash), which continued to the termination depth of the boring. It should be noted that this site appears to be underlain by advance outwash and not the less dense, recessional outwash as indicated on the geologic map. Site No. 8 Borings B-5 through B-7 In Borings B-5 through B-7, we encountered 4 to 8 inches of topsoil and vegetation underlain by approximately 1 to 3 feet of loose, fine to medium grained sand with variable amounts of gravel (Weathered Esperance Sand/Undifferentiated Outwash). This layer was underlain by medium dense to dense, fine to medium grained sand with variable amounts of gravel (Esperance Sand/Outwash), which continued to the termination depth of these borings. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Groundwater Groundwater was not encountered in any of the explorations at the date and time of our investigation. The groundwater level at each of the site locations will depend on a variety of factors that may include seasonal precipitation, land use, climatic conditions, and soil permeability. Water levels at the time of the field investigation may be different from those encountered during the construction phases of the project. 6.0 Geologic Hazards 6.1.1Landslide Hazard Per the City of Edmonds Community Development Code (23.80.020), landslide hazard areas are areas potentially subject to landslides based on a combination of geologic, topographic, and hydrologic factors. They include areas susceptible because of any combination of bedrock, soil, slope (gradient), slope aspect, structure, hydrology, or other factors. Within the city of Edmonds landslide hazard areas specifically include: 1.Areas of ancient or historic failures in Edmonds which include all areas within the earth subsidence and landslide hazard area as identified in the 1979 report of Robert Lowe Associates and amended by the 1985 report of GeoEngineers, Inc.; 2.Any area with a slope of 40 percent or steeper and with a vertical relief of 10 or more feet except areas composed of consolidated rock. 3.Any area potentially unstable as a result of rapid stream incision or stream bank erosion; and 4.Any area located on an alluvial fan, presently subject to, or potentially subject to, inundation by debris flow or deposition of stream-transported sediments. Site No.’s 4 and 7 have slopes with magnitudes greater than 40 percent and vertical relief of more than 10 feet. Site No.’s 2 and 8 are located within 50 feet of areas with slopes greater than 40 percent magnitude and a vertical relief of more than 10 feet. None of the sites have active streams in their vicinity, were identified on any subsidence/landslide mapping, or located on an alluvial fan. During our field assessment, we traversed slope areas at all of the site locations, where accessible. As we conducted the traverses, we looked for any signs that would indicate past slope failures or features indicating possible future instability. Overall, the steep slope areas and adjacent areas within 200 feet of the slopes appear stable at this time with no evidence of severe erosion, exposed soils, curved tree trunks, hummocky terrain, or other signs of landslide activity. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 The native soils that underlie all four areas are generally medium dense or firmer and do not appear to have ongoing issues related to landslide activity. It is our opinion that detailed slope stability analyses are only warranted for the steep slopes at Site No.’s 4 and 7 due to overall slope magnitude and presence of undocumented fill in the upper portions of these slopes. The results of these analyses can be found in Section 6.1.5. 6.1.2Erosion Hazard Per the City of Edmonds Community Development Code (23.80.020), erosion hazard areas include sites containing soils that may experience severe to very severe erosion. These soils include, but are not limited to, the following when they occur on slopes of 15 percent or greater: a.Alderwood soils (15 to 25 percent slopes); b.Alderwood/Everett series (25 to 70 percent slopes); c.Everett series (15 to 25 percent slopes); 2.Any area with slopes of 15 percent or greater and impermeable soils interbedded with granular soils and springs or ground water seepage; and 3.Areas with significant visible evidence of ground water seepage, and which also include existing landslide deposits regardless of slope. The Natural Resources Conservation Services (NRCS) maps for Snohomish County indicate that the site areas are underlain by the following units: Site Soil Unit Slopes* Erosion Hazard* No. 2 – Sierra Place Alderwood Gravelly Sandy 15 to 30 percent Severe to Very Severe Loam No. 4 – Daley Street Alderwood-Urban Land 8 to 15 percent Slight to Moderate Complex No. 7 – Edmonds Street Alderwood-Everett Gravelly 25 to 70 percentSevere to Very Severe Sandy Loam No. 8 – 172 Street SWAlderwood-Urban Land 8 to 15 percent Slight to Moderate nd Complex (West Half) Alderwood-Everett Gravelly 25 to 70 percentSevere to Very Severe Sandy Loam (East Half) *Per NRCS Web Soil Survey web site CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 We reviewed each site with regard to surficial soil erosion. In general, we did not observe significant areas of exposed soils or evidence of erosion with the exception of Site No. 8. Between two site visits within a two week period, we observed significant changes in the surficial soils at this site. We observed erosion, shallow channeling, and local deposition of the surficial sand and gravel soils. We also observed local voids in the upper materials. For the most part, the erosion and channeling was observed in the area of the existing sewer line trench and backfill zones. In these areas, we observed lesser amounts of vegetation which could have contributed to the high erosion patterns. While Site No. 4 is not mapped by the NRCS has having slopes greater than 15%, we recommend it be included as an erosion hazard area due to the magnitude of the site slopes and observed soil conditions. The soils at this site are consistent with those found at Site No. 7. It is our opinion that soil erosion potential at the project sites can be reduced through surface water runoff control and Best Management Practices (BMPs). Typically erosion of exposed soils will be most noticeable during periods of rainfall and may be controlled by the use of normal temporary erosion control measures, such as silt fences, coir logs, jute mats, hay bales, mulching, control ditches and diversion trenches. The typical wet weather season, with regard to site grading, is from October 31st to April 1st. Erosion control measures should be in place before the onset of wet weather. Additional, more specific erosion control recommendations and mitigation options are presented in Section 8.3. 6.1.3Seismic Hazard The overall subsurface profile for all four site areas correspond to a Site Class Das defined by Chapter 20 of ASCE 7 (Table 20.3-1) and referenced in Table 1613.3.2 of the 2012 International Building Code (2012 IBC). A Site Class Dapplies to an overall profile consisting of medium dense/stiff to very dense/hard materials within the upper 100 feet. We referenced the U.S. Geological Survey (USGS) Earthquake Hazards Program Website (seismic calculator) to obtain values for S and S for the two sites where slope stability analyses S1 are warranted. The USGS website includes the most updated published data on seismic conditions. The site specific seismic design parameters and adjusted maximum spectral response acceleration parameters are as follows: Site No. 4 PGA (Peak Ground Acceleration, in percent of g) 30.50 (10% Probability of Exceedence in 50 years) 53.74 (2% Probability of Exceedence in 50 years) S 120.50% of g S S 42.30% of g 1 CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Site No. 7 PGA (Peak Ground Acceleration, in percent of g) 30.48 (10% Probability of Exceedence in 50 years) 53.69 (2% Probability of Exceedence in 50 years) S 120.40% of g S S 42.20% of g 1 Additional seismic considerations include liquefaction potential and amplification of ground motions by soft/loose soil deposits. The liquefaction potential is highest for loose sand with a high groundwater table. The relatively dense, coarse grained soils that underlie all of the four site areas have a low potential for liquefaction. 6.1.4 Slope Stability Analyses Based on our observations and the subsurface soils, it is our opinion that slope stability analyses are warranted for the relatively steep slope located at the east (upper) end of Site No. 4 and the slope at Site No. 7. At these locations, the upper portions of the slopes have been oversteepened with loose undocumented fill materials. All of the other slope areas at each of the site locations are either underlain by relatively dense granular soils or do not have slope magnitudes greater than 40 percent. The commercially available slope stability computer program Slope/W was used to evaluate the global stability of the slopes at these two site locations. The slope stability was analyzed under static and seismic (pseudo-static method) conditions for the existing topography. The computer program calculates factors of safety for potential slope failures and generates the potential failure planes. This software calculates the slope stability under seismic conditions using pseudo-static methods. The stability of the described configuration was analyzed by comparing observed factors of safety to minimum values as set by standard geotechnical practice. A factor of safety of 1.0 is considered equilibrium and less than 1.0 is considered failure. The required factor of safety for global stability is 1.5 for static conditions and 1.2 for seismic conditions (City of Edmonds Community Development Code). In accordance with typical engineering standards, we used a horizontal peak ground acceleration of 0.2g. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 The following estimated soil parameters were used in our analyses for Site No. 4: Soil Description Unit Weight Cohesion Friction (pcf) (psf) (degrees) Loose to Medium Dense 110 50 32 Fill (SP-SM) Loose to Medium Dense 115 0 32 Sands (SP) MediumDense Sands (SP) 115 50 34 The following estimated soil parameters were used in our analyses for Site No. 7: Soil Description Unit Weight Cohesion Friction (pcf) (psf) (degrees) Loose Fill (SP-SM) 110 0 30 Dense Sands (SP) 115 50 34 Dense to Very Dense 115 50 36 Sands (SP) Slope Stability Results Site No. 4 Cross Section A to A’ Static Factor of Safety 0.2g Seismic Factor of Safety Existing Conditions 2.042 1.214 Site No. 7 Cross Section B to B’ Static Factor of Safety 0.2g Seismic Factor of Safety Existing Conditions 1.889 1.222 The analyses indicate that the Factor of Safety (FS) for global slope stability of the existing slopes at Site No.’s 4 and 7 are above the minimum required values. The permanent slope configurations following waterline placement will be the same or lower than currently exist. We can provide additional slope stability analyses once final grading plans have been developed if CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 trenching will occur at these locations. Figures showing the results of these analyses can be found in Appendix B, Figures 10 and 11. 7.0Discussion 7.1.1General It is our opinion that waterline placement through each of the four sites described in this report is feasible. Additional excavation and slope re-construction will be necessary within the upper (steepest) portion of Site No. 4, due to the presence of fill materials and steeper slopes in that area. Initial re-grading will create a more stable slope configuration during construction. All four sites are underlain by soils with severe to very severe erosion hazards. Specific erosion control measures, seasonal work considerations, and erosion mitigation work will be necessary as part of project planning and construction for Site No.’s 4, 7, and 8. Ground disturbance is not anticipated at Site No. 2, therefore, erosion control mitigation is not anticipated to be necessary. The risk of landslide activity at all of the site areas is relatively low, provided the recommendations in this report are implemented and verified through geotechnical oversight during construction. 8.0Recommendations 8.1SITE PREPARATION Based on observations from the site investigation program and the results of the exploration program, it is anticipated that the stripping depth will range from approximately 4 to 12 inches within the proposed development areas. The excavated material will not be suitable as fill material within areas with structural development. During wet weather conditions, which typically occur from October through May, subgrade stability problems and grading difficulties may develop due to excess moisture, disturbance of sensitive soils and/or the presence of perched groundwater. Construction during the extended wet weather periods will likely create the need to overexcavate exposed soils as they become disturbed and cannot be recompacted due to elevated moisture contents. The near-surface on site soils have moderate to high silt contents that could result in moisture sensitivity for these materials. If earthwork occurs during the months of October through May, additional overexcavation may be necessary to achieve proper bearing surfaces for pavements and foundations. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 If overexcavation is necessary, it should be confirmed through monitoring and testing by a qualified geotechnical engineer or senior geologist. Soils that have become unstable may require drying and re-compaction. Selective drying may be accomplished by scarifying or windrowing surficial material during extended periods of dry, warm weather (typically during the summer). If the soils cannot be dried back to a suitable moisture content, remedial measures may be required. General project site protection during wet weather should include the placement of aggregate base and the protection of exposed soils during the construction phase. If the native soils are used as structural fill, we recommend that the soils are relatively free of organic material and debris, and that the materials are within ±3 percent of the optimum moisture content. Aeration and drying of the native soils may be necessary to achieve near optimum moisture conditions. Upper weathered glacial outwash and fill soils primarily consist of silty-sand. These materials will likely be over-optimum in moisture content and may not be able to be dried during a typical summer. If the native soils are stockpiled for later use as structural fill, the stockpiles should be covered to protect the soil from wet weather conditions. We recommend that a representative of Stantec be on site during the excavation work to determine which soils are suitable for structural fill. Imported structural fill material should consist of well-graded gravel or a sand and gravel mixture with a maximum grain size of 3 inches and less than 5 percent fines (material passing the U.S. Standard No. 200 Sieve). All structural fill material should be submitted for approval to the geotechnical engineer prior to delivery to the site. Fill soils should be placed in horizontal lifts not exceeding 12 inches loose thickness, moisture- conditioned as necessary, and compacted to at least 90 percent of the maximum dry density based on ASTM Test Method D1557. The upper most 2 feet of structural fill should be compacted to at least 95 percent of the modified proctor. In place density tests should be performed on all structural fill to verify proper moisture content and adequate compaction. Additional lifts should not be placed if the previous lift did not meet the compaction requirements or if soil conditions are not considered stable. Observations of fill materials could indicate excessively wet, pumping soils which would warrant non-passing evaluation, even if the minimum compaction requirement is met. 8.2 TEMPORARY EXCAVATIONS Based on our understanding of the project, we anticipate that excavation work could include local cuts of up to 12 feet below existing grades for trenchless pit excavation work and utility placement. For excavations that extend more than 4 feet below grade, we recommend that they be sloped no steeper than 1.5H:1V (Horizontal:Vertical) in loose to medium dense fill and weathered glacial soils and 1H:1V in medium dense to dense native soils. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 If an excavation is subject to heavy vibration or surcharge loads, we recommend that the excavations be sloped no steeper than 2H:1V in loose to medium dense soils and 1.5H:1V in all other soils, where room permits. All temporary cuts should be in accordance with the Washington Administrative Code (WAC) Part N, Excavation, Trenching, and Shoring. The temporary slopes should be visually inspected daily by a qualified person during construction activities and the inspections should be documented in daily reports. The contractor is responsible for maintaining the stability of the temporary cut slopes and reducing slope erosion during construction. Temporary cut slopes should be covered with visqueen to help reduce erosion during wet weather, and the slopes should be closely monitored until the permanent retaining systems or slope configurations are complete. Materials should not be stored or equipment operated within 10 feet of the top of any temporary cut slope. Soil conditions may not be completely known from the geotechnical investigation. In the case of temporary cuts, the existing soil conditions may not be completely revealed until the excavation work exposes the soil. Typically, as excavation work progresses the maximum inclination of the temporary slopes will need to be re-evaluated by the geotechnical engineer so that supplemental recommendations can be made. Soil and groundwater conditions can be highly variable. Scheduling for soil work will need to be adjustable, to deal with unanticipated conditions, so that the project can proceed and required deadlines can be met. If any variations or undesirable conditions are encountered during construction, Stantec should be notified so that supplemental recommendations can be made. If room constraints or groundwater conditions do not permit temporary slopes to be cut to the maximum angles allowed by the WAC, temporary shoring systems may be required. The contractor should be responsible for developing temporary shoring systems, if needed. We recommend that Stantec and the project structural engineer review temporary shoring designs prior to installation, to verify the suitability of the proposed systems. 8.3 EROSION AND SEDIMENT CONTROL Erosion and sediment control (ESC) is used to reduce the transportation of eroded sediment to wetlands, streams, lakes, drainage systems, and adjacent properties. Erosion and sediment control measures should be implemented and these measures should be in general accordance with local regulations. At a minimum, the following basic recommendations should be incorporated into the design of the erosion and sediment control features for the site: Schedule the soil, foundation, utility, and other work requiring excavation or the disturbance of the site soils, to take place during the dry season (generally May through September). However, provided precautions are taken using Best Management Practices (BMP’s), grading activities can be completed during the wet season (generally October through April). Given the relatively high fines content and moisture sensitivity of some of the shallow subsurface soils at this site, we expect that wet season grading would add significant cost to the project construction. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 All site work should be completed and stabilized as quickly as possible. Additional perimeter erosion and sediment control features may be required to reduce the possibility of sediment entering the surface water. This may include additional silt fences, silt fences with a higher Apparent Opening Size (AOS), construction of a berm, or other filtration systems. Any runoff generated by dewatering discharge should be treated through construction of a sediment trap if there is sufficient space. If space is limited other filtration methods will need to be incorporated. Specific Erosion Control Recommendations – Site No. 2 The proposed construction at Site No. 2 (Sierra Place) does not include significant areas of surface disruption. If minor excavation work occurs at this location, we recommend utilizing the following erosion control measures as the situation requires: Temporary straw or visqueen when work is not ongoing Hydroseed placement followed by jute mat and coir log placement Additional measures may be needed depending on the extent of any grading/clearing work. We should be provided with plans so that we may review the proposed construction at this site. Specific Erosion Control Recommendations – Site No. 4 Portions of the construction may involve trenchless pipe placement techniques in the upper portion of the Site No. 4 slope area. Specifically between Stations 9+35 and 9+70. In this area, the amount of site disturbance required to place the waterline and restore the site and steps would be very significant. If trenching is conducted in this area, significant grading excavations will be necessary and should only be performed in the summer months. At Site No. 4, we recommend minimizing site disturbance to a 30 feet width down the slope. Temporary erosion control measures, such as silt fences, straw, visqueen, and coir logs/check dams should be utilized during construction. At the end of each day, all exposed soils should be covered with clear visqueen if precipitation is forecasted. Permanent site mitigation should include the following elements: Finished grading and compaction to at least 95 percent of the modified proctor Coir log placement every 10 feet vertically down the affected slope area(s) across level topographic contours through the cleared/disturbed area. Each end should be curved upslope slightly and staking should be in accordance with the manufacturer’s recommendations Hydroseed should be placed on the slope and all exposed soil areas CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Jute mat should be placed over all slope areas. Mats should be overlapped and stapled in accordance with the manufacturer’s recommendations and should be placed flat against the soils Construction areas should be re-vegetated per plan and maintained until fully established (typically 3 years) Permanent slope configurations no steeper than 2H:1V Specific Erosion Control Recommendations – Site No. 7 Waterline placement through the steep slope area at Site No. 7 could consist of open trenching or trenchless technologies. Mitigation recommendations for trenchless work would include erosion control around each trench pit and sealing the drill hole with bentonite fluid (or equivalent). For trenched waterline placement, we recommend minimizing site disturbance to a 30 feet width down the slope. Trenching work should only occur during the summer months (May through September). Temporary erosion control measures, such as silt fences, straw, visqueen, and coir logs/check dams should be utilized during construction. At the end of each day, all exposed soils should be covered with clear visqueen if precipitation is forecasted. Permanent site mitigation should include the following elements: Finished grading and compaction to at least 95 percent of the modified proctor Coir log placement every 10 feet vertically down the affected slope area(s) across level topographic contours through the cleared/disturbed area. Each end should be curved upslope slightly and staking should be in accordance with the manufacturer’s recommendations Hydroseed should be placed on the slope and all exposed soil areas Jute mat should be placed over all slope areas. Mats should be overlapped and stapled in accordance with the manufacturer’s recommendations and should be placed flat against the soils Construction areas should be re-vegetated per plan and maintained until fully established (typically 3 years) Specific Erosion Control Recommendations – Site No. 8 Waterline placement at Site No. 8 may consist of open trenching. We recommend minimizing site disturbance to a 30 feet width down the slope and trenching work should only occur during the summer months (May through September). Temporary erosion control measures, such as silt fences, straw, visqueen, and coir logs/check dams should be utilized during construction. At the end of each day, all exposed soils should be covered with clear visqueen if precipitation is forecasted. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Permanent site mitigation should include the following elements: Finished grading and compaction to at least 95 percent of the modified proctor Coir log placement every 10 feet vertically down the affected slope area(s) across level topographic contours through the cleared/disturbed area. Each end should be curved upslope slightly and staking should be in accordance with the manufacturer’s recommendations Hydroseed should be placed on the slope and all exposed soil areas Jute mat should be placed over all slope areas. Mats should be overlapped and stapled in accordance with the manufacturer’s recommendations and should be placed flat against the soils Construction areas should be re-vegetated per plan and maintained until fully established (typically 3 years) 8.4 UTILITIES Utility trenches should be excavated according to accepted engineering practices following OSHA (Occupational Safety and Health Administration) standards, by a contractor experienced in such work. The contractor is responsible for the safety of open trenches. Traffic and vibration adjacent to trench walls should be reduced; cyclic wetting and drying of excavation side slopes should be avoided. Depending upon the location and depth of some utility trenches, groundwater flow into open excavations could be experienced, especially during or shortly following periods of precipitation. In general, sandy soils were encountered at shallow depths in the borings at the three sites. These soils have low cohesion and have a tendency to cave in excavations. Shoring or sloping back trench sidewalls is required within these soils. Shoring boxes will be necessary in these areas and dewatering may be required depending on the season in which the construction takes place. All utility trench backfill should consist of imported structural fill or suitable on-site material. The upper 2 feet of utility trench backfill placed in pavement areas should be compacted to at least 95 percent of the maximum dry density based on ASTM Test Method D1557. Below 2 feet, utility trench backfill in pavement areas should be compacted to at least 90 percent of the maximum dry density based on ASTM Test Method D1557. Pipe bedding should be in accordance with the pipe manufacturer's recommendations and City specifications. The contractor is responsible for removing all water-sensitive soils from the trenches regardless of the backfill location and compaction requirements. The contractor should use appropriate equipment and methods to avoid damage to the utilities and/or structures during fill placement and compaction procedures. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 8.5 GROUNDWATER INFLUENCE ON CONSTRUCTION At the time of our investigation, groundwater was not encountered in any of the borings or hand borings. Perched groundwater may develop at any of the four site locations above less permeable soils or within undocumented fill materials. We anticipate that light amounts of perched groundwater could exist within 2 to 3 feet of the existing ground surface during the wetter months of the year at Site No.’s 4, 7 and 8. If temporary dewatering systems to remove groundwater are used, their design should be the responsibility of the contractor. We should review any dewatering design prior to their use on site. 9.0Construction Field Reviews Stantec should be retained to provide part time field review during construction in order to verify that the soil conditions encountered are consistent with our design assumptions and that the intent of our recommendations is being met. This will require field and engineering review to: Monitor temporary excavation stability and clearing Observe temporary and permanent erosion control implementation Density testing to verify compaction of structural fills Geotechnical design services should also be anticipated during the subsequent final design phase to support the structural design and address specific issues arising during this phase. Field and engineering review services will also be required during the construction phase in order to provide a Final Letter for the project. 10.0Closure This report was prepared for the exclusive use of the City of Edmonds and their appointed consultants. Any use of this report or the material contained herein by third parties, or for other than the intended purpose, should first be approved in writing by Stantec. The recommendations contained in this report are based on assumed continuity of soils with those of our test holes, and currently proposed construction. Stantec should be provided with final civil drawings when they become available in order that we may review our design recommendations and advise of any revisions, if necessary. CRITICAL AREAS REPORT CITY OF EDMONDS 2015 WATERLINE REPLACEMENT February 23, 2015 Use of this report is subject to the Statement of General Conditions provided in Appendix A. It is the responsibility of the City of Edmonds who is identified as “the Client” within the Statement of General Conditions, and its agents to review the conditions and to notify Stantec should any of these not be satisfied. Respectfully submitted, Stantec Consulting Services, Inc. Original signed by: Phil Haberman, P.G., P.E.G. Senior Engineering Geologist PH/jf APPENDIX A Statement of General Conditions Statement of General Conditions USE OF THIS REPORT: This report has been prepared for the sole benefit of the Client or its agent and may not be used by any third party without the express written consent of Stantec Consulting Services, Inc. and the Client. Any use which a third party makes of this report is the responsibility of such third party. BASIS OF THE REPORT: The information, opinions, and/or recommendations made in this report are in accordance with Stantec Consulting Services, Inc.’s present understanding of the site specific project as described by the Client. The applicability of these is restricted to the site conditions encountered at the time of the investigation or study. If the proposed site specific project differs or is modified from what is described in this report or if the site conditions are altered, this report is no longer valid unless Stantec Consulting Services, Inc. is requested by the Client to review and revise the report to reflect the differing or modified project specifics and/or the altered site conditions. STANDARD OF CARE: Preparation of this report, and all associated work, was carried out in accordance with the normally accepted standard of care in the state of execution for the specific professional service provided to the Client. No other warranty is made. INTERPRETATION OF SITE CONDITIONS: Soil, rock, or other material descriptions, and statements regarding their condition, made in this report are based on site conditions encountered by Stantec Consulting Services, Inc. at the time of the work and at the specific testing and/or sampling locations. Classifications and statements of condition have been made in accordance with normally accepted practices which are judgmental in nature; no specific description should be considered exact, but rather reflective of the anticipated material behavior. Extrapolation of in situ conditions can only be made to some limited extent beyond the sampling or test points. The extent depends on variability of the soil, rock and groundwater conditions as influenced by geological processes, construction activity, and site use. VARYING OR UNEXPECTED CONDITIONS: Should any site or subsurface conditions be encountered that are different from those described in this report or encountered at the test locations, Stantec Consulting Services, Inc. must be notified immediately to assess if the varying or unexpected conditions are substantial and if reassessments of the report conclusions or recommendations are required. Stantec Consulting Services, Inc. will not be responsible to any party for damages incurred as a result of failing to notify Stantec Consulting Services, Inc. that differing site or sub-surface conditions are present upon becoming aware of such conditions. PLANNING, DESIGN, OR CONSTRUCTION: Development or design plans and specifications should be reviewed by Stantec Consulting Services, Inc., sufficiently ahead of initiating the next project stage (property acquisition, tender, construction, etc), to confirm that this report completely addresses the elaborated project specifics and that the contents of this report have been properly interpreted. Specialty quality assurance services (field observations and testing) during construction are a necessary part of the evaluation of sub-subsurface conditions and site preparation works. Site work relating to the recommendations included in this report should only be carried out in the presence of a qualified geotechnical engineer; Stantec Consulting Services, Inc. cannot be responsible for site work carried out without being present. APPENDIX B Figures: Vicinity Map, Site Plans, & Slope Stability Analyses Site No. 8 Site No. 2 Site No. 4 Site No. 7 N 2015 Waterline Replacement Vicinity Map 11130 NE 33rd Place, Suite 200 Edmonds, Washington Bellevue, WA 98004 (425) 869-9448 Figure 1 (425) 869-1190 (Fax) Dec., 2014 2002005232 www.stantec.com Site No. 2 Approximate Graphic Scale 0 20 2040 (In Feet) 1 inch = 40 feet 2015 Waterline Replacement Site No. 2 11130 NE 33rd Place, Suite 200 Edmonds, Washington Bellevue, WA 98004 (425) 869-9448 Figure 2 (425) 869-1190 (Fax) Dec., 2014 2002005232 www.stantec.com Approximate West Extent of Fill A B-2 B-1 B-3 A Toe of Slope Top of Slope El. 106 El. 164 Site No. 4 Approximate Boring Location B-1 B-1 Fill (SM) 160 B-2 140 B-3 120 Recessional Outwash (SP) 100 Weathered Recessional Outwash (SP-SM) A A Approximate Graphic Scale SP Poorly Graded Sand 0 20 2040 SM Silty Sand (In Feet) 1 inch = 40 feet 2015 Waterline Replacement Site No. 4 11130 NE 33rd Place, Suite 200 Edmonds, Washington Bellevue, WA 98004 (425) 869-9448 Figure 3 (425) 869-1190 (Fax) Dec., 2014 2002005232 www.stantec.com Toe of Slope El. 201 B Approximate North Extent of Fill B-4 Top of Slope El. 232 B Site No. 7 Approximate Boring Location B-4 Fill (SP-SM) B-4 230 220 210 200 Advance Outwash (SP) Weathered Advance Outwash (SP-SM) B B Approximate Graphic Scale SP Poorly Graded Sand 0 20 2040 SM Silty Sand (In Feet) 1 inch = 40 feet 2015 Waterline Replacement Site No. 7 11130 NE 33rd Place, Suite 200 Edmonds, Washington Bellevue, WA 98004 (425) 869-9448 Figure 4 (425) 869-1190 (Fax) Dec., 2014 2002005232 www.stantec.com ApproximateGraphicScale 2040 SiteNo.8 Figure5 1inch=40feet (InFeet) 0 2015WaterlineReplacement Dec.,20142002005232 20 Edmonds,Washington SPPoorlyGradedSandwithGravel GPPoorlyGradedGravelwithSand BoringLocation Approximate 11130NE33rdPlace,Suite200 B-5 (425)869-1190(Fax) Bellevue,WA98004 www.stantec.com (425)869-9448 C’ C’ Esperance(SP-GP) Fill/Weathered B-5 B-5 B-4 B-6 B-6 EsperanceSand (SP) B-7 B-7 SiteNo.8 C 350’330’ 370’ 310’ C ApproximateLocationofDelineatedWetland PotentialLandslide/ ErosionHazardArea HazardAreas ApproximateSite (localizedareas) (BasedonNRCS) SiteNo.2 Figure6 HazardArea SteepSlope Location 2015WaterlineReplacement 2002005232 CityofEdmonds Dec.,2014 11130NE33rdPlace,Suite200 (425)869-1190(Fax) Bellevue,WA98004 www.stantec.com (425)869-9448 GravellySandyLoams Alderwood-UrbanLandComplex Alderwood-Everett (15-30%Slopes) (8to15%Slopes) Landslide/SteepSlope ErosionHazardArea HazardAreas ApproximateSite (BasedonNRCS) SiteNo.4 Figure7 HazardArea Location 2015WaterlineReplacement 2002005232 CityofEdmonds Dec.,2014 11130NE33rdPlace,Suite200 (425)869-1190(Fax) Bellevue,WA98004 www.stantec.com (425)869-9448 SandyLoams(25-70%Slopes) Alderwood-EverettGravelly Alderwood-UrbanLandComplex Complex(8-15%Slopes) Alderwood-UrbanLand (2-8%Slopes) Landslide/SteepSlope ErosionHazardArea HazardAreas ApproximateSite (BasedonNRCS) SiteNo.7 Figure8 HazardArea Location 2015WaterlineReplacement 2002005232 Alderwood-UrbanLandComplex CityofEdmonds Dec.,2014 (8to15%Slopes) 11130NE33rdPlace,Suite200 (425)869-1190(Fax) Bellevue,WA98004 www.stantec.com (425)869-9448 GravellySandyLoams Alderwood-Everett (25-70%Slopes) (localizedslopeareas) ErosionHazardArea PotentialLandslide/ HazardAreas (BasedonNRCS) ApproximateSite SiteNo.8 Figure9 HazardArea SteepSlope Location 2015WaterlineReplacement 2002005232 CityofEdmonds Dec.,2014 11130NE33rdPlace,Suite200 (425)869-1190(Fax) Bellevue,WA98004 www.stantec.com (425)869-9448 GravellySandyLoams Alderwood-Everett (25-70%Slopes) Complex(8-15%Slopes) Alderwood-UrbanLand GravellySandyLoams Alderwood-Everett (25-70%Slopes) Site No. 4 Static Site No. 4 Seismic 2015 Waterline Replacement Slope Stability 11130 NE 33rd Place, Suite 200 Edmonds, Washington Bellevue, WA 98004 Site No. 4 (425) 869-9448 (425) 869-1190 (Fax) Dec., 2014 2002005232 Figure 10 www.stantec.com Site No. 7 Static Site No. 7 Seismic 2015 Waterline Replacement Slope Stability 11130 NE 33rd Place, Suite 200 Edmonds, Washington Bellevue, WA 98004 Site No. 7 (425) 869-9448 (425) 869-1190 (Fax) Dec., 2014 2002005232 Figure 11 www.stantec.com APPENDIX C Boring Logs CityofEdmonds2015WaterlineReplacement PROJECT: BORINGNO.: SiteNo.4 LOCATION: B-1 2002005232 PROJECTNUMBER:PAGE1OF1 NORTHING(ft):EASTING(ft): EXCAVATION/INSTALLATION: LAT:LONG: 11/3/1411/3/14 STARTEDCOMPLETED: 162 GROUNDELEV(ft):TOCELEV(ft): CNDrilling EXCAVATIONCOMPANY: --- NotEncountered INITIALDTW(ft):WELLDEPTH(ft): LimitedAccess EQUIPMENT: 16.5 NotEncountered STATICDTW(ft):DEPTH(ft): HollowStemAuger METHOD: ---6 WELLCASINGDIA.(in):SIZE: SplitSpoon PHGS SAMPLINGEQUIPMENT: LOGGEDBY:CHECKEDBY: Headspace Measured Recov. Graphic Sample Count(units) Time& (feet)(feet)(feet) DepthDepth USCS Blow Log PID Time Description SampleID SP-SP-SM;Loose,silty-finetomediumgrainedsandwithtracegravel,dark 2 SMyellowishbrowntoreddishbrown,moist.(Fill) 2 2 N=4 SMSM;Loose,silty-finetomediumgrainedsandwithtracegravel,yellowish brown,moist.(Fill) 55 6 5 2 SPSP;Loosetomediumdense,finetomediumgrainedsandwithtrace N=7 gravel,yellowishbrowntograyishbrown,moist.(AdvanceOutwash) 1010 2 4 5 N=9 GEOFORM304EDMONDS.GPJSTANTECENVIROTEMPLATE010509.GDT12/19/14 4 6 9 N=15 1515 7 9 9 N=18 Boreholeterminatedat16.5feet. CityofEdmonds2015WaterlineReplacement PROJECT: BORINGNO.: SiteNo.4 LOCATION: B-2 2002005232 PROJECTNUMBER:PAGE1OF1 NORTHING(ft):EASTING(ft): EXCAVATION/INSTALLATION: LAT:LONG: 11/3/1411/3/14 STARTEDCOMPLETED: 156 GROUNDELEV(ft):TOCELEV(ft): CNDrilling EXCAVATIONCOMPANY: --- NotEncountered INITIALDTW(ft):WELLDEPTH(ft): LimitedAccess EQUIPMENT: 16.5 NotEncountered STATICDTW(ft):DEPTH(ft): HollowStemAuger METHOD: ---6 WELLCASINGDIA.(in):SIZE: SplitSpoon PHGS SAMPLINGEQUIPMENT: LOGGEDBY:CHECKEDBY: Headspace Measured Recov. Graphic Sample Count(units) Time& (feet)(feet)(feet) DepthDepth USCS Blow Log PID Time Description SampleID Topsoil/Vegetation 2 1 1 SP-SP-SM;Veryloosetoloose,silty-finetomediumgrainedsandwithtrace N=2 SMgravel,yellowishbrown,moist.(WeatheredRecesionnalOutwash) 55 3 4 4 N=8 SPSP;Loosetomediumdense,finetomediumgrainedsandwithtrace gravel,yellowishbrowntograyishbrown,moist.(RecessionalOutwash) 1010 4 5 6 N=11 GEOFORM304EDMONDS.GPJSTANTECENVIROTEMPLATE010509.GDT12/19/14 1515 8 7 8 N=15 Boreholeterminatedat16.5feet. CityofEdmonds2015WaterlineReplacement PROJECT: BORINGNO.: SiteNo.4 LOCATION: B-3 2002005232 PROJECTNUMBER:PAGE1OF1 NORTHING(ft):EASTING(ft): EXCAVATION/INSTALLATION: LAT:LONG: 11/3/1411/3/14 STARTEDCOMPLETED: 120 GROUNDELEV(ft):TOCELEV(ft): CNDrilling EXCAVATIONCOMPANY: --- NotEncountered INITIALDTW(ft):WELLDEPTH(ft): LimitedAccess EQUIPMENT: 21.5 NotEncountered STATICDTW(ft):DEPTH(ft): HollowStemAuger METHOD: ---6 WELLCASINGDIA.(in):SIZE: SplitSpoon PHGS SAMPLINGEQUIPMENT: LOGGEDBY:CHECKEDBY: Headspace Measured Recov. Graphic Sample Count(units) Time& (feet)(feet)(feet) DepthDepth USCS Blow Log PID Time Description SampleID Topsoil/Vegetation 1 1 1 SP-SP-SM;Veryloosetoloose,silty-finetomediumgrainedsandwithtrace N=2 SMgravel,yellowishbrown,moist.(WeatheredRecesionnalOutwash) 55 2 3 3 N=6 SPSP;Loosetomediumdense,finetomediumgrainedsandwithtrace gravel,yellowishbrowntograyishbrown,moist.(RecessionalOutwash) 1010 3 4 5 N=9 GEOFORM304EDMONDS.GPJSTANTECENVIROTEMPLATE010509.GDT12/19/14 1515 7 8 8 N=16 2020 8 8 10 N=18 Boreholeterminatedat21.5feet. CityofEdmonds2015WaterlineReplacement PROJECT: BORINGNO.: SiteNo.7 LOCATION: B-4 2002005232 PROJECTNUMBER:PAGE1OF1 NORTHING(ft):EASTING(ft): EXCAVATION/INSTALLATION: LAT:LONG: 11/3/1411/3/14 STARTEDCOMPLETED: 232 GROUNDELEV(ft):TOCELEV(ft): CNDrilling EXCAVATIONCOMPANY: --- NotEncountered INITIALDTW(ft):WELLDEPTH(ft): LimitedAccess EQUIPMENT: 16.5 NotEncountered STATICDTW(ft):DEPTH(ft): HollowStemAuger METHOD: ---6 WELLCASINGDIA.(in):SIZE: SplitSpoon PHGS SAMPLINGEQUIPMENT: LOGGEDBY:CHECKEDBY: Headspace Measured Recov. Graphic Sample Count(units) Time& (feet)(feet)(feet) DepthDepth USCS Blow Log PID Time Description SampleID Topsoil/Vegetation 1 0 SP-SP-SM;Veryloosetomediumdense,silty-finetomediumgrainedsand 1 SMwithtracegravel,yellowishbrown,moist.(Fill) N=1 55 1 2 2 N=4 SPSP;Dense,finetomediumgrainedsandwithtracegravel,yellowish browntograyishbrown,moist.(AdvanceOutwash) 1010 10 16 17 N=33 GEOFORM304EDMONDS.GPJSTANTECENVIROTEMPLATE010509.GDT12/19/14 1515 12 18 20 N=38 Boreholeterminatedat16.5feet. CityofEdmonds2015WaterlineReplacement PROJECT: BORINGNO.: SiteNo.8 LOCATION: B-5 2002005232 PROJECTNUMBER:PAGE1OF1 NORTHING(ft):EASTING(ft): EXCAVATION/INSTALLATION: LAT:LONG: 11/3/1411/3/14 STARTEDCOMPLETED: 351 GROUNDELEV(ft):TOCELEV(ft): CNDrilling EXCAVATIONCOMPANY: --- NotEncountered INITIALDTW(ft):WELLDEPTH(ft): LimitedAccess EQUIPMENT: 16.5 NotEncountered STATICDTW(ft):DEPTH(ft): HollowStemAuger METHOD: ---6 WELLCASINGDIA.(in):SIZE: SplitSpoon PHGS SAMPLINGEQUIPMENT: LOGGEDBY:CHECKEDBY: Headspace Measured Recov. Graphic Sample Count(units) Time& (feet)(feet)(feet) DepthDepth USCS Blow Log PID Time Description SampleID Topsoil/Vegetation 3 3 SMSM;Loosetomediumdense,silty-finetomediumgrainedsandwith 3 gravel,yellowishbrown,moist.(Fill) N=6 SPSP;Mediumdense,finetomediumgrainedsandwithgravelandsilt, yellowishbrowntograyishbrown,moist.(EsperanceSand/Outwash) 55 11 14 13 N=27 1010 8 9 10 N=19 GEOFORM304EDMONDS.GPJSTANTECENVIROTEMPLATE010509.GDT12/19/14 1515 12 14 15 N=29 Boreholeterminatedat16.5feet. CityofEdmonds2015WaterlineReplacement PROJECT: BORINGNO.: SiteNo.8 LOCATION: B-6 2002005232 PROJECTNUMBER:PAGE1OF1 NORTHING(ft):EASTING(ft): EXCAVATION/INSTALLATION: LAT:LONG: 11/3/1411/3/14 STARTEDCOMPLETED: 326 GROUNDELEV(ft):TOCELEV(ft): CNDrilling EXCAVATIONCOMPANY: --- NotEncountered INITIALDTW(ft):WELLDEPTH(ft): LimitedAccess EQUIPMENT: 16.5 NotEncountered STATICDTW(ft):DEPTH(ft): HollowStemAuger METHOD: ---6 WELLCASINGDIA.(in):SIZE: SplitSpoon PHGS SAMPLINGEQUIPMENT: LOGGEDBY:CHECKEDBY: Headspace Measured Recov. Graphic Sample Count(units) Time& (feet)(feet)(feet) DepthDepth USCS Blow Log PID Time Description SampleID Topsoil/Vegetation 2 3 SMSM;Loosetomediumdense,silty-finetomediumgrainedsandwith 5 gravel,yellowishbrown,moist.(Fill?/WeatheredEsperanceSand?) N=8 SPSP;Mediumdensetodense,finetomediumgrainedsandwithgravel andsilt,yellowishbrowntograyishbrown,moist.(Esperance Sand/Outwash) 55 6 9 9 N=18 1010 10 12 13 N=25 GEOFORM304EDMONDS.GPJSTANTECENVIROTEMPLATE010509.GDT12/19/14 1515 14 18 16 N=34 Boreholeterminatedat16.5feet. CityofEdmonds2015WaterlineReplacement PROJECT: BORINGNO.: SiteNo.8 LOCATION: B-7 2002005232 PROJECTNUMBER:PAGE1OF1 NORTHING(ft):EASTING(ft): EXCAVATION/INSTALLATION: LAT:LONG: 11/3/1411/3/14 STARTEDCOMPLETED: 303 GROUNDELEV(ft):TOCELEV(ft): CNDrilling EXCAVATIONCOMPANY: --- NotEncountered INITIALDTW(ft):WELLDEPTH(ft): LimitedAccess EQUIPMENT: 11.5 NotEncountered STATICDTW(ft):DEPTH(ft): HollowStemAuger METHOD: ---6 WELLCASINGDIA.(in):SIZE: SplitSpoon PHGS SAMPLINGEQUIPMENT: LOGGEDBY:CHECKEDBY: Headspace Measured Recov. Graphic Sample Count(units) Time& (feet)(feet)(feet) DepthDepth USCS Blow Log PID Time Description SampleID Topsoil/Vegetation 3 SMSM;Loosetomediumdense,silty-finetomediumgrainedsandwith 4 gravel,yellowishbrown,moist.(Fill?/WeatheredEsperanceSand?) 6 N=10 SPSP;Mediumdensetodense,finetomediumgrainedsandwithgravel andsilt,yellowishbrowntograyishbrown,moist.(Esperance Sand/Outwash) 55 6 9 7 N=16 GEOFORM304EDMONDS.GPJSTANTECENVIROTEMPLATE010509.GDT12/19/14 1010 9 12 13 N=25 Boreholeterminatedat11.5feet. APPENDIX D Experience of Professionals PhilHaberman PG,PEG SeniorEngineeringGeologist Mr.HabermanisaSeniorEngineeringGeologistworkinginStantec’sBellevue,Washingtonoffice.Mr. Habermanspecializesingeotechnicalengineering,fluvialandhillslopegeomorphology,geologichazard analysis,subsurfaceinvestigations,andretainingsystemdesign.Withover16yearsofexperiencethroughout thePacificNorthwest,Mr.Habermanconductshydrogeologicevaluations,erosionpotentialanalysis,geologic mappingandreconnaissance,landslidepotentialdeterminations,andconstructionmonitoringtoensure compliancewithplansandspecifications. Hehasmanagedandledcountlessgeotechnicalprojectsinvolvingroadways,bridges,industrialfacilities,utility construction,militaryinstallationsandbunkers,schools,firestations,aswellasresidential,mixeduse,and commercialdevelopments.Thesehaveincludedmidtohighrisebuildingswithmultiplelevelsofbelowgrade parking,belowgradebunkers,andsewerliftstations.Philhasbeeninvolvedinalltypesofgeologichazard analysisandmitigation,includingslopestabilityanalyses,coalminehazard/subsidenceanalyses,liquefaction andseismichazards,andgroundwatermitigation;andhehasprovidedexpertwitnesstestimony,emergency facilityseismicdesignandconstruction,aswellasshoring,gravitywall,andreinforcedretainingwalldesignand monitoringoftheirinstallation. Mr.Habermanisinvolvedincoordinatingandsupervisingsubsurfaceexplorations,leveeandearthdam conditionsurveys/evaluations/assessments,hydraulicandhydrologicmodeling,constructionmonitoringand inspection,constructionplanpreparation,specificationsandbiddocumentpreparation;seepageanalyses, andearthdam/leveeandembankmentdesign. EDUCATIONPROJECTEXPERIENCE B.Sc.(GeologicalSciences),Universityof Washington,Seattle,Washington,1997ColmanUtilitySystemUpgrades,Seattle, Washington Monitoredexcavationworkandutilityinstallationwithina CertifiedErosionandSedimentControlLead PugetSoundshorelineenvironment.Evaluatedtheerosion (CESCL),Seattle,Washington,2008 potentialofthesurfacesoilsalongwithgroundwater fluctuationsduetotidalfluctuations.Providedraft REGISTRATIONS foundationandde-wateringrecommendationduring construction. ProfessionalGeologist&EngineeringGeologist #2513,WashingtonState KingStreetStationOdorControlFacility,Seattle, Washington MEMBERSHIPS Installedandmonitoredpiezometerspriortoandduring AssociationofEngineeringGeologists installationofsheetpileshoringforasubterraneanodor controlfacilityrelatedtotheCityofSeattlesewersystemfor KingCountyMetro.Monitoredwellstoensureminimal Member,GeologicalSocietyofAmerica fluctuationsingroundwaterlevelsthatcouldcausesettlement andstructuraldistressoftheadjacentKingStreetStation,a historicalbuilding. MemberRepresentative,SocietyofAmerican MilitaryEngineers,SeattlePost Designwithcommunityinmind PhilHaberman PG SeniorGeologist CoalCreekPark,Bellevue,Washington ConductednumerousgeotechnicalinvestigationsfortheCity ofBellevueandprovidedslopestabilityanalyses,erosion evaluations,andengineeringdesignparametersforuseinthe constructionofnumerousbridgesandrailsystemsinCoal CreekPark.Determinedsetbackrequirementsforbridge abutmentsinanactivelyincisingfluvialenvironment. Providedcoalminesubsidenceanalysesandslopestability analysesformultipleprojectswithintheBellevueParks System. SylvanMeadowsDam,Bremerton,Washington Provideddetailedslopestabilityandbreachanalysesforan earthfilldamatalargescaleresidentialdevelopment, includingdownstreamhazardriskassessmentsandpotential lossoflifedetermination.Designedanimpermeabledamcore andlateralresistanceparameterswithinthenaturaldrainage coursetobefilled. LeewardDevelopment,Anacortes,Washington Conductedsubsurfaceexplorations,instrumentation installation,dataacquisitionandevaluationforproposed commercialandresidentialdevelopmentona10acresiteon PugetSound.Provideddetailedslopestabilityanalysesand evaluatedancientandrecentlandslidestodetermine appropriateandcosteffectivelandslidemitigationmethodsto allowfordevelopment.Monitoredpiezometersandslope inclinometersforaperiodoftwoyears.Final recommendationsincludedsoldierpileshoringsystemswith tiebackanchors,multipledeepdrainagesystems,and surchargematerialremovalthroughmassgrading. Highway101BridgeandCulvertReplacement, Blyn,Washington Conductedageotechnicalstudyofthereplacementofasteel culvertthatwasdestroyedbyaflood.Conductedasubsurface explorationprogramconsistingoftwoboringstoevaluatethe subsurfaceconditionsintheareaofthenewculvertand bridgeabutments.