Orchard Street Realignment Study

Concept Report | January 2020 Orchard Street Realignment Study Ada County Highway District, Idaho This realignment study was a collaborative effort between the Ada County Highway District and the City of Boise with assistance from Burgess & Niple, Inc., Forsgren Associates, Inc., and Bionomic. Valuable input was contributed to this study by area stakeholders and the general public.

Project Sponsor:

3775 Adams Street Garden City, Idaho 83714 208.387.610

Project No. 519026

ACHD Team Brooke Green, MBA, PCED, Senior Transportation Planner/Project Manager Christy Foltz-Ahlrichs, Senior Communications Specialist Chelsea Miller, Business/Community Relations Coordinator Caitlin Stevens, Environmental Programs Coordinator Joshua Saak, P.E., P.T.O.E., Traffic Design Engineer Matt Degen, P.E., Civil Engineer Michele White, Senior Right of Way Agent Mitch Skiles, Impact Fee Administrator Carson Shaw, Planning and Projects Student Intern

Project City:

150 N. Capitol Blvd. Boise, Idaho 83701 208.384.3830

City of Boise Team Karen Gallagher, Associate Transportation Planner Zach Piepmeyer, P.E., Associate Transportation Planner

Consultant Team:

Burgess & Niple Bionomics 3597 E. Monarch Sky Lane 1045 E. Winding Creek Drive Suite F-240 Eagle, Idaho 83616 Meridian, Idaho 83646

Forsgren

415 S. 4th Street

Boise, Idaho 83702

Consultant Team Steve Thieken, P.E., P.T.O.E., A.I.C.P. Project Manager (B&N) Molly Loucks, P.E. (B&N) Stephen Waldinger, P.E. (Forsgren) Sam Larrondo, P.E. (Forsgren) Ashley Tarter, Environmental Specialist (Bionomics)

Table of Contents Table of Contents ...... 1 List of Figures ...... 2 List of Tables ...... 3 Appendices ...... 3 Executive Summary ...... 4 Chapter 1: Introduction ...... 7 1.1 Study Goals and Objectives ...... 7 1.2 Study Process ...... 7 1.3 Stakeholder and Public Involvement ...... 7 Chapter 2: Existing Conditions ...... 8 2.1 Existing Study Area Characteristics ...... 8 2.2 Existing Utilities ...... 10 2.3 Existing Drainage Features ...... 10 2.4 Previous Studies ...... 10 2.5 Environmental Overview ...... 10 2.6 Initial Stakeholder and Public Input ...... 10 Chapter 3: Traffic Forecasts ...... 11 Chapter 4: Concept Development and Screening ...... 11 Chapter 5: Alternatives Development ...... 15 5.1 Alternatives ...... 16 Alternative 1 ...... 16 Alternative 2 ...... 18 5.2 Traffic Operations ...... 20 5.3 Key Issues ...... 20 Cross Street Impacts ...... 20 Landfill Impacts and Risks ...... 20 Drainage ...... 21 Pedestrian Accommodations over the New York Canal ...... 23 Truck Accommodations at Roundabouts...... 23 Roadway Ownership ...... 27 Utilities ...... 27 Boise Airport Runway Protection Zone ...... 28 5.4 Alternatives Cost Estimates ...... 29 Chapter 6: Evaluation of Alternatives ...... 30 6.1 Public Involvement and Stakeholder Comments...... 30 6.2 Alternatives Evaluation ...... 30 Chapter 7: Recommended Alternative ...... 36 7.1 Recommended Conceptual Drainage Design ...... 37 Chapter 8: Recommended Phasing Sequence ...... 40 Phase 1 ...... 40 Phase 2 ...... 42 Phase 3 ...... 43 Phase 4 ...... 45 Phase 5 ...... 46 Chapter 9: Next Steps ...... 47 Study ...... 47 Preliminary Design ...... 47 Final Design ...... 47

Right-of-Way Acquisition ...... 47 Construction ...... 47

List of Figures Figure ES-1: Study Development Process ..……………………………………………………………………………………………………..……… 4 Figure ES-2: Orchard Street Cross Section .……………………………………………………………………………………………………..……… 4 Figure ES-3: Gowen Road Cross Section .………………………………………………………………………………………………………..……… 4 Figure ES-4: Final Recommendation .……………………………………………………………………………………………………………..……… 5 Figure ES-5: Recommended Phasing Sequence ……………………………………………………………………………………………..……… 6 Figure 2-1: Aerial of Study Area ……………………………………………………………………………………………………………………..……… 9 Figure 4-1: Concept #1 .…………………………………………………………………………………………………..…………………………………… 13 Figure 4-2: Concept #2 ……………………………………………………………………………………………………..…………………………………. 14 Figure 4-3: Concept Cross-Section #1 …………………………………………………………………………..……………………………………… 15 Figure 4-4: Concept Cross-Section #2 ……………………………………………………………………………..…………………………………… 15 Figure 5-1: Orchard Street Cross Section …………………………………………………………………………..………….……………………… 15 Figure 5-2: Gowen Road Cross Section ………………………………………………………………………………..………………….…………… 16 Figure 5-3: Alternative 1 …………………………………………………………………………………………………..………….……………………… 17 Figure 5-4: Alternative 2 ..…………………………………………………………………………………………………..………………….…………… 19 Figure 5-5: Truck Accommodations at a Roundabout …..………………………………………………………………………..……….….. 23 Figure 5-6: Lowboy Detail ………………………..………………………………………………………………………..……………………………….. 24 Figure 5-7: Mountable Curbing ………………………………………………………………………………………..…………………………………. 24 Figure 5-8: Exterior Truck Apron ……………………………………………………………………………………..………………..……..………... 25 Figure 5-9: Gore Striping at Entry of a Multilane Roundabout …..………………………………………………….………..………….. 25 Figure 5-10: Truck Straddling Lanes in Hilliard, Ohio ..……………………………………………………………………………………….... 26 Figure 5-11: OSOW Accommodations at Three Lane Gowen Road/Orchard Street……………………………………………… 26 Figure 5-12: OSOW Accommodations at Two Lane Gowen Road/Orchard Street………………………………………………… 26 Figure 5-13: OSOW Accommodations at Orchard Street/Diamond Street and Orchard Street/Dorman Street or Aeronca Street ..……………………………………………………………………………………………………….……………………………………….… 27 Figure 6-1: Responses for Preferred Alternative ..……………………………………………………………………………………………..… 30 Figure 6-2: Responses for Preferred Option at Harvard Street/Gowen Road/Ex. Orchard Street Intersection …….. 30 Figure 6-3: Responses for Preferred Intersection Type at Gowen Road/Orchard Street ……..………………………………. 30 Figure 6-4: Alternative 1 (Aeronca Street) Evaluation Matrix ….…………………..…………………………………………………….… 32 Figure 6-5: Alternative 1 (Dorman Street) Evaluation Matrix …………………………………………………………………………….… 33 Figure 6-6: Alternative 2 Evaluation Matrix ….………………………………………..………………………………………………………….… 34 Figure 6-7: Harvard Street/Gowen Road/Existing Orchard Street Evaluation Matrix ….….………………………………….… 35 Figure 7-1: Orchard Street Cross Section .……………………………………………….…………………………………………………………… 36 Figure 7-2: Gowen Road Cross Section ….……………………………………………….…………………………………………………………… 36 Figure 7-3: Recommended Alternative ….……………………………………………….…………………………………………………………… 38 Figure 8-1: Construction Phase 1 ….……………………………………………..……………………………………………………………………… 41 Figure 8-2: Construction Phase 2 ….………………………………………………..…………………………………………………………………… 42 Figure 8-3: Gowen Road Cross Section …………………………………………..…………………………………………………………………… 43 Figure 8-4: Orchard Street Cross Section ………………………………………..…………………………………………………………………… 43 Figure 8-5: Construction Phase 3 ….…………………………………………………..………………………………………………………………… 44 Figure 8-6: Construction Phase 4 ….……………………………………………………..……………………………………………………………… 45 Figure 8-5: Construction Phase 5 ….………………………………………………………..…………………………………………………………… 46

List of Tables Table 3-1: Roadway Network Growth (24-hour assignments) ……..………………………………….………………………….….……. 11 Table 6-1: Alternative 1 with Aeronca Street Connection Option Evaluation Summary ………..……………………..……... 32 Table 6-2: Alternative 1 with Dorman Street Connection Option Evaluation Summary ………………………………………… 33 Table 6-3: Alternative 2 Quadrant Roadway Evaluation ………………………………………………..……………………………………. 34 Table 6-4: Existing Orchard Street/Gowen Road/Harvard Street Intersection Realignment Options …...... 35 Table 7-1: Recommended Alternative Cost Estimate ………………………………………………………………………………………….. 39 Table 8-1: Construction Phase 1 Cost Estimate ………………………………………………..………………………..……………………….. 40 Table 8-2: Construction Phase 2 Cost Estimate …………………………………………………..……………………..……………………….. 42 Table 8-3: Construction Phase 3 Cost Estimate …………………………………………………..………………..…………………………….. 43 Table 8-4: Construction Phase 4 Cost Estimate …………………………………………………..…………………..………………………….. 45 Table 8-5: Construction Phase 5 Cost Estimate ………………………………………………..…………………..…………………………….. 46 Appendices Appendix A: Stakeholder Meeting Summary Appendix B: Public Involvement Summary Appendix C: Utility Information Appendix D: Airport Master Plan Appendix E: Environmental Scan Report Appendix F: Traffic Analysis Appendix G: OSOW Truck Turn Analysis Appendix H: Alternative Cost Estimates Appendix I: Drainage Information Appendix J: URS Orchard Realignment Concept Study

Executive Summary The Ada County Highway District (ACHD) developed the Orchard Street Realignment Study in coordination with its partner agencies, area stakeholders, and the general public. The purpose of the study was to develop a preferred concept-level design for a realigned Orchard Street as a Mobility Arterial between Gowen Road and the New York Canal in Boise, Idaho. The Orchard Street Realignment Study Concept Report documents the study process and presents final recommendations for the corridor. ACHD engaged stakeholders and the public during the study process (see Figure ES-1). Stakeholder and public input were used to identify and screen initial concepts for corridor improvements. Following the initial concept screening, two distinct alternatives were developed and evaluated based on the study goals and objectives, potential risk in terms of constructability, and cost.

Figure ES-1: Study Development Process

The final recommendation for the Orchard Street Realignment is to construct a four lane roadway with a raised median and roundabouts at the Diamond Street, Dorman Street, and Gowen Road intersections (see Figure ES-2 on page 5). Gowen Road is recommended to be realigned in the vicinity of its intersection with existing Orchard Street with a curve designed for the 40-mph traffic on the roadway. The existing Orchard Street/Gowen Road/Harvard Street intersection also is recommended to be reconfigured and realigned to tie into realigned Gowen Road. Shared use paths will be provided on both sides of Orchard Street and on the north side of Gowen Road. Figures ES-3 and ES-4 depict the proposed cross sections for the corridor.

Figure ES-3: Orchard Street Cross Section

Figure ES-4: Gowen Road Cross Section 4

* Interim signal until Dorman Street Extension constructed. Figure ES-2: Final Recommendation

Due to the size and cost of the project, a five-phase construction plan is recommended to construct the project over several years. The phasing also includes a recommended roundabout with an interim lane configuration at the intersection of realigned Orchard Street and Gowen Road. Figure ES-5 summarizes the phasing sequence recommended for the Orchard Street Realignment improvements.

Figure ES-5: Recommended Phasing Sequence

Chapter 1: Introduction The Ada County Highway District (ACHD) has completed a study of the realignment of Orchard Street from Gowen Road to just south of the New York Canal in Boise, Idaho. The realignment of this section of Orchard Street is included in ACHD’s 2020-2024 Integrated Five-Year Work Plan. The realignment will facilitate the planned expansion of the Boise Airport to the west and create a more direct connection from I-84 to the recently constructed Orchard Street Extension south of Gowen Road. This report summarizes the study process, analysis and findings, and recommendations. 1.1 Study Goals and Objectives The goals of the study are as follows:

• Identify a new Orchard Street alignment to connect with the Orchard Street Extension south of Gowen Road. • Identify the appropriate roadway cross-section for a Mobility Arterial, including bicycle and pedestrian facilities. • Determine the preferred traffic control and geometric design for the intersection of the realigned Orchard Street, Gowen Road, and Orchard Street Extension. • Determine the preferred connections between the existing and re-aligned Orchard Street, particularly at Diamond Street, Dorman Street, and Harvard Street. • Determine the preferred design for the existing intersection of Orchard Street, Gowen Road, and Harvard Street. • Support the City of Boise’s Airport Master Plan and growth efforts. 1.2 Study Process Traffic Forecasts – Traffic forecasts for year 2040 were developed based on the COMPASS Travel Demand Model. Chapter 3 includes a detailed summary of the traffic forecasts.

Identify and Screen Initial Concepts – Initial concepts for corridor improvements were identified through stakeholder and public input. The concept development and screening process is documented in Chapter 4. Identify and Evaluate Alternatives – Two distinct alternatives were developed for evaluation. Each alternative was analyzed based on the study goals and objectives, potential risk in terms of constructability, and cost. Alternatives were presented to stakeholders and the public for review and comment. Traffic analysis was performed to estimate future traffic delays and backups. The alternatives are detailed in Chapter 5. The evaluation of the alternatives is described in Chapter 6.

Recommendations – Chapter 7 describes the final recommendations of the study including a final cost estimate.

Project Phasing – Project design and construction phasing recommendations, including a cost estimate for each phase, are included in Chapter 8.

Next Steps – Next steps for the project design and construction are detailed in Chapter 9 of this report. 1.3 Stakeholder and Public Involvement Stakeholder Meetings – The study team held three workshop-style meetings with a group of project stakeholders to solicit input on the needs of the project and improvements under consideration. The meetings had the following purpose:

• Meeting 1 – Orient the stakeholders to the study process, discuss existing issues and concerns, and solicit ideas for potential improvements (Chapter 2). • Meeting 2 – Summary and discussion of initial concepts under consideration (Chapter 4). • Meeting 3 – Discussion of the study team’s evaluation of two alternatives for the corridor and comments on the findings of (Chapter 6).

For a list of stakeholders and summaries of stakeholder meetings, see Appendix A.

Public Engagement – Multiple methods were used to solicit input from the public and alert them about surveys and public meetings. These methods included direct mailers, website updates, social media posts, sandwich signs, stakeholder emails, and newspaper ads. An initial online public survey was conducted to solicit information about users’ current experiences in the corridor. One public information meeting was held, in conjunction with a second online survey, to solicit input on the alternatives under consideration. The meeting and surveys were advertised through the project website and flyers that were mailed to residents and businesses in the project area. Public meeting summaries and comment forms are in Appendix B. Chapter 2: Existing Conditions 2.1 Existing Study Area Characteristics This study area is defined by the western edge of City of Boise property on the west, the current Boise Airport on the east, Gowen Road on the south and the New York Canal to the north. The Orchard Street Realignment study limits are from Gowen Road to just south of the Victory Road. Figure 2-1 depicts the approximate study area and Orchard Street realignment limits. The approximately one-mile long section of Orchard Street is currently three lanes wide and uncurbed and runs along the western edge of currently developed Boise Airport property. The current speed limit is 35 mph north of Diamond Street and 40 mph south. Located just north of the portion of Orchard Street being considered for realignment is a four lane bridge over the New York Canal with five-foot (ft) wide sidewalks on each side of the roadway that are separated from the roadway with concrete barrier. Sidewalks continue along Orchard Street from the bridge to the north, but existing Orchard Street south of the bridge does not have sidewalks. Orchard Street north of the New York Canal has dedicated on-street bike lanes. Five streets intersect existing Orchard Street: Wright Street, Diamond Street, Aeronca Street, Dorman Street, and Gowen Road/Harvard Street. All of these intersections are stop controlled on the minor leg except for the Gowen Road/Harvard Street intersection, which is signalized. The Orchard Street realignment will tie into an intersection at the Orchard Street Extension and Gowen Road approximately 1,500 ft to the west of the current Orchard Street and Gowen Road and Harvard Street intersection. Land use in the area consists of the Boise Airport to the east, several industrial sites to the west, and several undeveloped parcels owned by the City of Boise between the existing and proposed realigned Orchard Street. Through the southwest corner of the study area runs Fivemile Creek. Decommissioned sewage lagoons from the Gowen Field Waste Water Treatment Facility are in the southern portion of the study area (Decommissioned 2007). The Historic North Landfill is located north of the sewage lagoons between existing Orchard Street and the proposed realignment. The Historic North Landfill is an old municipal landfill that has not been used in several decades. The landfill is very deep with waste extending in excess of 30 ft below grade. The typical waste expected to be encountered in the landfill includes: variable household waste, glass, asphalt, concrete, and other organic material. There are multiple monitoring wells on the property monitoring groundwater and other contaminants. There is an additional landfill under Cell 2 in the Gowen Field Waste Water Treatment Facility. This landfill is significantly more shallow than the Historic North Landfill and appears to contain mostly organic matter. Figure 2-1 illustrates the locations of these facilities.

Figure 2-1: Aerial of Study Area

2.2 Existing Utilities Utilities located in the study area include gas, electric, water, sewer, cable, fiber, telephone and landfill monitoring wells. A full list of utility companies within the project vicinity and potential impacts are located in Chapter 5. See Appendix C for a more detailed view of the utility basemap. 2.3 Existing Drainage Features The project area is relatively flat, though existing topography slopes gently from north to south. A northern branch of Fivemile Creek runs east to west across the study area south of the landfill and north of abandoned sewage lagoons. The northern branch of Fivemile Creek curves to the south along the north edge of the Gowen Field Waste Water Treatment Facility, connecting with Fivemile Creek approximately 700 ft north of Gowen Road. The Fivemile Creek channel flows southeast to northwest through the southern portion of the project area. Fivemile Creek is the primary conveyance from the Boise Airport stormwater detention pond outfalls southeast of the existing intersection of Aeronca Street and Orchard Street. Fivemile Creek crosses Gowen Road through a 20-ft wide concrete box culvert. Fivemile Creek flows west after it crosses Gowen Road and then north, across the proposed Orchard Street realignment, before it flows to the west through the Knife River, Inc. property. The existing drainage structures are minimal in the vicinity of the project. Stormwater along existing Orchard Street is predominantly managed in roadside borrow ditches. Stormwater along Gowen Road typically flows east to west in the project area. A culvert conveys stormwater along the north side of Gowen Road across the intersection of Gowen Road and Orchard Street. Stormwater in Gowen Road right-of-way (R/W) in the project area ultimately flows into Fivemile Creek. Diamond Street stormwater on the south side of the road is conveyed with curb and gutter prior to being captured in a drop inlet catch basin connected to sand and grease trap and retention basin. The retention basin is privately owned and ACHD has an easement to discharge stormwater to the stormwater retention facility. 2.4 Previous Studies In 2006, a study was completed by the Boise Airport that analyzed relocating Orchard Street to the west along the edge of airport property to accommodate the airport’s expansion plans, including a limited geotechnical investigation along Aeronca Street, realigned Orchard Street, and a portion of Gowen Road; and an environmental scan of the project site. The geotechnical information was used by this study team to evaluate constructability and cost issues related to the improvement alternatives under consideration in this study. Per its Master Plan, the Boise Airport intends to expand airside operations and related development into its property west of existing Orchard Street including the extension of an existing taxiway and additional hanger space, solar farms, and commercial and/or industrial development. Appendix D shows a schematic of the current Airport Master Plan. 2.5 Environmental Overview An environmental scan of the study area is included in Appendix E. Since this project includes a land swap with the Boise Airport, an environmental document meeting the requirements of the National Environmental Policy Act (NEPA) will need to be approved by the Federal Aviation Administration (FAA) to advance the project. This scan is an initial step in the NEPA process. ACHD will coordinate with the FAA through final design to determine the level of environmental documentation required. 2.6 Initial Stakeholder and Public Input The project team held a Stakeholder Meeting on March 21, 2019 to introduce the project and get initial stakeholders’ input. Stakeholders were asked to provide comments on large maps of the project area. These maps can be found in Appendix A. The study team also solicited input related to existing conditions and needs from the general public by conducting an online survey from March 26, 2019 to April 15, 2019. Over 790 responses were provided to the online survey. The survey asked how people currently use Orchard Street, including the purpose of their travel, transportation mode they used most often, and times of day they most often used the street. Most people reported using the corridor for commuting with passenger vehicles being by far the most common vehicle in the corridor. Individual responses can be found in Appendix B.

The online survey also asked for input about issues with the corridor, priorities for the study, and concerns with the realignment. The primary issues and concerns identified in the survey responses included:

• Congestion • Lack of bike and pedestrian facilities • Speeding • Accommodating truck traffic • Signal timing

Chapter 3: Traffic Forecasts Traffic forecasts for this study were developed by increasing the current traffic volumes in the study area to estimates of 2040 traffic volumes based on the traffic growth predicted by the travel demand model maintained by COMPASS. The detailed forecasting methodology and figures illustrating current and forecasted traffic volumes are included in Appendix F. Significant traffic growth is projected by the COMPASS model in the overall area, and specifically on Orchard Street, given the large amount of vacant land and current trends in rapid housing development in this part of the region. Table 3-1 shows the 2018 and 2040 COMPASS model traffic assignments for the roadway network in the study area. Traffic volume on Orchard Street, south of Gowen Road, is projected to increase by over 15,000 vehicles (416%) between 2018 and 2040. This new roadway link travels through undeveloped land that is anticipated to see significant development over the coming years. Large projected traffic increases on other roadway segments in the study area are due in large part to the growth south of Gowen Road.

Table 3-1: Roadway Network Growth (24-hour vehicle assignments) 2018 Model 2040 Model % Link Volume Volume Change Orchard Street, south of Victory Road 11,300 27,700 145% Orchard Street, north of Gowen Road 8,100 24,600 204% Orchard Street Extension, south of Gowen Road 3,700 19,100 416%

Based on these forecasts traffic analysis volumes at key intersections were developed for a design year of 2040 and an interim year of 2030 for capacity evaluation of alternatives. Traffic forecasts are illustrated in Figures 5 to 10 in Appendix F.

Chapter 4: Concept Development and Screening For this first-level evaluation, the study team created two base concepts for evaluation and discussion with the study team and stakeholders: Concept 1 (Roundabouts) and Concept 2 (Signals). Both concepts provided the same cross-street connection options with the option of either a signal or roundabout at Aeronca Street. However, the Dorman Street connection was only included in Concept 1 since Dorman Street is located too close to the Orchard Street/Gowen Road intersection for a signal to function without causing backups into the Orchard Street/Gowen Road intersection in the long-term. Both concepts realign Gowen Road with a curve that meets an appropriate roadway design speed. In Concept 1, Gowen Road is disconnected from existing Orchard Street and Harvard Street, which would exclusively tie into each other. Concept 1 directs nearly all existing Orchard Street traffic to the new intersection at realigned Orchard Street and Gowen Road. In Concept 2, existing Orchard Street terminates at its southern end at the entrance to Valley Regional Transit. A new intersection where Harvard Street tees into realigned Gowen Road is then formed. A full movement intersection was not included at the intersection of existing Orchard Street and Gowen Road in either concept because of its close proximity to the proposed intersection of the realigned Orchard Street and Gowen Road. Figures 4-1 and 4-2 illustrate the concepts that were shared with the stakeholders for consideration and discussion.

The study team and stakeholders generally preferred roundabouts for intersection treatments. General concerns about making left turns and backups at signals were expressed. Stakeholders also expressed concern about maintaining adequate access for emergency vehicles. Some stakeholders preferred extending Aeronca Street with full access at the realigned Orchard Street with a roundabout, given the more central location for this intersection in providing access to the existing airport facilities and related businesses. Some stakeholders requested a full access intersection be maintained with Gowen Road and existing Orchard Street. Stakeholder feedback received during the concept development and screening phase is included in Appendix A.

There were also two conceptual cross-sections considered. Both sections included a four lane Orchard Street with 14-ft outside lanes and 11-ft wide inside lanes plus a 4-ft wide raised concrete center median to separate the directions of travel and restrict left turning movements to only controlled intersections. The sections included two types of bike and pedestrian accommodations. One included 5-ft wide sidewalks on both sides of the street with a 5-ft wide bike lane in each direction with a 2-ft wide marked buffer to traffic, and the other included 10-ft wide shared-use paths on both sides of the roadway. Figures 4-3 and 4-4 show the two cross sections. Stakeholders primarily preferred the cross sections with multiuse paths. Stakeholders also preferred consistent 12-ft lanes rather than the 14-ft outside and 11-ft inside lanes.

Concept 1:

• Roundabouts at Diamond Street, Dorman Street, and Gowen Road intersections. • Dorman Street cross street connection. • The intersection of Harvard Street/Existing Orchard Street/Gowen Road is eliminated.

Figure 4-1: Concept #1

Concept 2:

• Traditional intersections at Diamond Street, Dorman Street, and Gowen Road intersections. • Aeronca Street cross street connection. • Harvard tees directly into Gowen Road. Existing Orchard Street terminates at the Valley Regional Transit Driveway.

Figure 4-2: Concept #2

Figure 4-3: Concept Cross-Section #1

Figure 4-4: Concept Cross-Section #2

Chapter 5: Alternatives Development Two alternatives for the corridor were developed based on the analysis and feedback received during the concept evaluation process. Both alternatives realign Orchard Street in the same manner. The primary differences are related to the treatment of cross street access and intersection type. The cross-sections in Figures 5-1 and 5-2 were used in both alternatives.

Figure 5-1: Orchard Street Cross Section

Figure 5-2: Gowen Road Cross Section

5.1 Alternatives

Alternative 1 Alternative 1 consists of the following features (see Figure 5-3):

• Four lane Orchard Street with a raised center median • 10-ft wide shared-use paths on both sides of realigned Orchard Street • Pedestrian and cyclist connections between realigned Orchard Street and existing Orchard Street. Facilities vary from wide shoulders to shared-use paths depending on the intersection option selected at existing Orchard Street and Harvard Street/Gowen Road. • Realigned Gowen Road to provide a curve designed for 40 mph in the vicinity of existing Orchard Street/Harvard Street. • Full movement intersection at Diamond Street and realigned Orchard Street with either stop signs for Diamond Street or a traffic signal if warranted by traffic volumes. • Full movement intersection with realigned Orchard Street at either Dorman Street or Aeronca Street o with roundabout control at Dorman Street o with the option of roundabout or signal control at Aeronca Street • Full movement intersection with realigned Orchard Street at Gowen Road with either signalized or roundabout control

As illustrated in Figure 5-3, Alternative 1 was presented with three intersection options at the intersection of existing Orchard Street with Gowen Road and Harvard Street:

• Option 1 – Existing Orchard Street would be disconnected from Gowen Road with Harvard Street realigned to “T” into Gowen Road. • Option 2 – Harvard Street is realigned to “T” into existing Orchard Street. Orchard Street would connect to Gowen Road; however, a raised median would be installed on Gowen Road to restrict access to right turn only from Orchard Street to Gowen Road. • Option 3 – Existing Orchard Street would be fully disconnected from Gowen Road and would be realigned to connect directly into Harvard Street.

The realigned Orchard Street and Gowen Road intersection would impact Fivemile Creek. An additional structure would be needed as well to get Fivemile Creek across realigned Orchard Street or across the intersection.

Figure 5-3: Alternative 1

Alternative 2 Alternative 2 (see Figure 5-4) creates a secondary roadway that would start at the intersection of realigned Orchard Street and Dorman Street, would extend to the east and then curve south and tie into Gowen Road at a signalized intersection. The traffic signal at Gowen Road would only allow southbound left and right turn movements and eastbound and westbound through movements on Gowen Road to maximize the traffic efficiency of the intersection and to avoid backups into the realigned Orchard Street and Gowen Street intersection. With this alternative, southbound to eastbound and westbound to northbound traffic would be encouraged to bypass the new intersection at the realigned Orchard Street and Gowen Road. It is envisioned that the quadrant roadway would be three lanes wide to allow left turn lanes for direct access from the roadway at select locations. The location of the intersection of the quadrant roadway and realigned Orchard Street (Dorman Street extended) is due to this alignment having less potential impact to landfill material, and because it would provide direct access to parcels identified for industrial/commercial development in the Airport Master Plan.

Features of Alternative 2 are:

• Four lane Orchard Street with a raised center median • 10-ft wide shared-use paths on both sides of realigned Orchard Street and on both sides of Gowen Road between realigned Orchard Street and existing Orchard Street. • Realigned Gowen Road to provide a curve designed for 40 mph in the vicinity of existing Orchard Street/Harvard Street • Full movement intersection with realigned Orchard Street at Dorman Street with roundabout control • Full movement intersection at Diamond Street and realigned Orchard Street with either stop signs for Diamond Street or a traffic signal if warranted by traffic volumes • Full movement intersection with realigned Orchard Street at Gowen Road with either signalized or roundabout control In this alternative, because significant traffic is expected to bypass it, the intersection of the realigned Orchard Street and Gowen Road will require fewer lanes than Alternative 1. The realigned Orchard Street and Gowen Road intersection would impact Fivemile Creek. An additional structure would be needed to get Fivemile Creek across realigned Orchard Street or across the intersection.

Figure 5-4: Alternative 2 19

5.2 Traffic Operations The number and configuration of traffic lanes at each intersection for the two alternatives (see Figure 5-1 and Figure 5-2) is based on needed capacity analysis to provide efficient operations for at least a 20-year design horizon. The development of the year 2040 traffic volumes used for the analysis, and the capacity analysis methods used, are described in detail in Appendix F.

A notable finding from the analysis for Alternative 1 (see Figure 5-1) is the numerous lanes required at the realigned Orchard Street and Gowen Road intersection to accommodate the projected 2040 traffic volumes, making this a large and complex intersection either as a traffic signal or roundabout. A three lane roundabout or a seven lane intersection would be required. Such large and complex intersections are likely to experience higher numbers of traffic crashes than those with fewer lanes and conflicts. Because of the very large projected rate of growth and the uncertainty of how fast the development will actually occur, it would be prudent to build this intersection with a reduced number of operating lanes that can be expanded to the ultimate configuration when the need arises. The required lane configurations for a 10-year horizon (2030) are included in Appendix F.

An advantage of Alternative 2 with respect to traffic operations is that it results in fewer vehicles through the realigned Orchard Street and Gowen Road intersection. Thus, the intersection can be designed with fewer lanes to accommodate 2040 traffic forecasts, as can be seen when comparing Figure 5-1 and Figure 5-2.

5.3 Key Issues Alternative 1 Cross Street Impacts Two cross street options were offered with Alternative 1:

• Aeronca Street - Aeronca Street extends through the deepest section of the Historic North Landfill. Since Aeronca Street is located farther away from the Orchard Street/Gowen Road intersection, a signalized intersection or roundabout could be implemented at the Aeronca Street/Orchard Street intersection. • Dorman Street - Based on well logs from wells located along the potential Dorman Street alignment, Dorman Street would encounter some waste from either the Historic North Landfill or the landfill under the sewage lagoons. However, the sewer logs indicate that the waste would only impact a small section of the roadway. Further investigation during the design phase will be needed to determine if waste can be avoided entirely. Due to its close proximity to the Orchard Street/Gowen Road intersection, a roundabout is the only recommended intersection option at Dorman Street and Orchard Road.

Landfill Impacts and Risks Dorman Street and Aeronca Street connections shown as options in Alternative 1 would impact the Historic North Landfill. However, the Aeronca Street alignment is expected to encounter much more landfill material than the Dorman Street alignment. Data from the test pits from the prior study completed by the City of Boise Airport indicate that waste extends to at least 30 ft deep, and likely deeper, in some locations under the Aeronca Street alignment. Should a roadway need to be constructed within these deep landfill areas there are two options to address the landfill waste. Option one for construction is to excavate 15 ft below existing grade, transport and dispose of the landfill waste at the appropriate offsite disposal facility, perform “deep dynamic compaction” of the remaining waste, and then backfill with suitable fill. Even with such a special treatment, the road could still experience future settlement due to consolidation of the waste that will remain beneath the alignment. A second option is to utilize geogrid for subgrade stabilization. This will minimize the amount of over excavation needed compared to the deep dynamic compaction option and is potentially a much less expensive solution. Additional geotechnical analysis will be required in preliminary design to determine a pavement build up that utilizes geogrid and determine the cost difference. In this study, deep dynamic compaction was used to determine the cost estimate.

The test pits data did not specifically show hazardous waste within the landfill area, but there is a real possibility that hazardous waste could exist. The extent of hazardous waste cannot be determined until actual excavation occurs. When such a project goes to construction, a soil management plan must be developed to instruct the contractor on how to manage solid or hazardous waste when encountered. A consultant may be required to be onsite during construction to ensure the contractor follows the soil management plan and to test and sample soil for any hazardous contaminants. If the contractor encounters hazardous waste, they must stop excavation and separate the hazardous waste from the other municipal solid waste. The hazardous waste will have to be contained and shipped to a facility that can dispose of it properly. If a substantial quantity of hazardous waste is encountered this could slow construction and increase costs dramatically. It is anticipated that the cost to dispose of municipal waste will be a minimum of $10 per cubic yard, assuming it can be disposed of at the Ada County Landfill. However, disposal of hazardous waste could cost significantly more if the Ada County Landfill cannot accept it and it must be hauled to the U.S. Ecology facility in Grand View, Idaho. The required facility for disposal cannot be determined until hazardous waste is encountered during construction and tested.

The Dorman Street extension is expected to encounter some waste based on well logs in the area of the extension. The waste identified in the well logs is substantially shallower than the waste encountered by the Aeronca Street alignment. The waste under the Dorman Street alignment can be excavated and will not need additional treatments to achieve optimal soil compaction. The waste is also not expected to be hazardous and is identified as organic waste, most likely lawn clippings or another yard waste.

A comprehensive subsurface investigation should be performed during the design phase to determine an optimal alignment to limit exposure to waste and decrease the alignment’s construction cost. In order to limit risk during construction, it is recommended that during preliminary design, ACHD works with the consultant and a contractor to develop a preliminary excavation plan and to start removal, sampling, and disposal while final design continues.

Drainage Two environmental-related items were identified as potential risks and taken into consideration:

• Proximity of the project to the historic landfill • Proximity of project to abandoned sewage lagoons Proximity of the project to Historic Landfill The proposed Orchard Street corridor is anticipated to be aligned along the western edge of the Historic North Landfill for approximately 1,500 ft. The Aeronca Street alignment goes through the middle of this landfill as well. The Dorman Street alignment impacts the northern edge of the landfill located under the large northeast sewage lagoon cell. There is potential risk involved with infiltrating stormwater above the landfill using retention basins, roadside borrow ditches, or seepage beds as infiltrating water could become contaminated with pollutants from the landfill. Stormwater should be collected and piped away from the landfill when in vicinity of the landfill. Options for conveyance include piped conveyance to an area within the project that can infiltrate or convey to a location where stormwater can be treated and discharged offsite to Fivemile Creek at a metered outflow. In the case that gravity storm drain piping elevations do not allow for discharge to Fivemile Creek, conveyance swales may be constructed but will need to be designed with a liner to make the swale impervious.

Proximity of the Project to Abandoned Sewage Lagoons Near Gowen Road, the proposed Orchard Street realignment and Dorman Street alignment pass near two City of Boise abandoned sewage lagoons. It is unknown if the soil has levels of nitrogen, phosphorus, soluble salts, and volatile organic compounds (VOCs) that would inhibit the safe infiltration of stormwater for this portion of the roadway. A prior concept report completed by URS included the Gowen Field Wastewater Treatment Facility Interim Closure Report from HDR. HDR sampled subsurface soils from cells 3 and 4 of the abandoned sewage lagoons. The report stated:

• Nitrate and ammonium concentrations were greatest in the surface sample and decreased with depth, with samples at the 8-ft depth below 100 mg/Kg. Based on soil data from Cells 3 and 4, there is no evidence that inorganic nitrogen has appreciably leached below 4 ft. Furthermore, the levels of ammonium in these soils suggest that there is not a large pool of nitrogen remaining that would act as a source of nitrate. • Phosphorus concentrations were highest in the surface samples and decreased with depth. Concentrations of phosphorus are below recommended Idaho Department of Environmental Quality (IDEQ) action levels. • Soluble salts are below 1.5 mmhos/cm and are in the typical range for soils. There is no evidence that there has been a build-up of salt in these soils.

Additional soil sampling will be required early in the design phase of the project to determine suitability of infiltration near the abandoned sewage lagoons. Refer to Appendix I for an in-depth discussion of individual drainage areas within the project area.

Geotechnical Considerations A Natural Resources Conservation Service (NRCS) soils report for the project vicinity anticipates the two main soil types for the area to be Elijah silt loam and Elijah-Urban Land Complex. Both are well drained soil types with cementation generally to a depth of 4 ft below ground surface and gravelly sand below the cementation. This soil profile was confirmed from soil profiles included in a previous concept report for the re-alignment of Orchard Street prepare by URS for the Boise Airport. Excerpts of this report can be found in Appendix J.

Along the realignment of Orchard Street, near Diamond Street, poorly graded gravel was widely found 3 to 4 ft below ground surface with weak to moderate cementation to a depth of 6-feet. Infiltration tests performed in these pits yielded observation infiltration rates of 6 to 40 inches (in) per hour, which is considered acceptable for stormwater infiltration purposes. Comparable soil profiles were found near the proposed intersection of Orchard Street and Gowen Road. Accordingly, the northern portion of the re-alignment near Diamond Street and roadway improvements along Gowen Road appear to be candidates for infiltration.

Near the abandoned sewage lagoons, the existing lagoon embankment appear to be constructed of fill that is clayey sand. Infiltration was not tested for in these test pits. Infiltration may be difficult in this area unless fill is excavated to native sand or gravels.

Ground water depths, from review of ground water monitoring wells and previous concept report for the realignment of Orchard Street prepared by URS, is approximately 130 ft below ground surface (BGS). Based on this, separation to ground water for design stormwater facilities is not anticipated to be a limiting consideration.

Conceptual Drainage Design Requirements Conceptual drainage design was guided by ACHD Policy Section 8000 – Drainage and Stormwater Management and ACHD Policy Section 8200 – ACHD Stormwater Design Tools and Approved BMPs. Section 8007 Performance Standards dictate the requirements for Peak Rate Control, Runoff Reduction, Volume Management, Water Quality Treatment, Conveyance, Runoff from Public Streets, and Operation and Maintenance.

The project area has traditionally naturally infiltrated or drained to Fivemile Creek. Where infiltration is feasible, it is desirable to infiltrate stormwater using roadside borrow ditches rather than discharging to Fivemile Creek. Peak runoff discharges to Fivemile Creek are anticipated to be attenuated to pre-development levels for the 2, 5, 10, and 25-year storm events. Stormwater discharged to Fivemile Creek shall be treated to ACHD requirements. Sand or proprietary media filtration is anticipated if piping stormwater discharges to Fivemile Creek.

Stormwater Attenuation It is anticipated that a requirement will be to attenuate peak stormwater runoff discharges to Fivemile Creek to pre- development levels for the 2, 5, 10, and 25-year storm events. Preferably, roadside borrow ditches will be able to be used to detain this water. In the case of piped conveyance, underground attenuation may be required.

Depending on suitability of infiltration potential options for attenuation are anticipated to include below grade storage vaults, lined or unlined below grade storage beds, and dry infiltrating detention basins with metered outflows. ACHD will need further coordination with the Department of Environmental Quality and Federal Aviation Association to ensure appropriate facilities are being used in proximity to the landfill and the Boise Airport.

Pedestrian Accommodations over the New York Canal A gap in the pedestrian and bicycle network between the Orchard Street/Diamond Street intersection and Orchard Street/Victory Road intersection over the New York Canal was identified early in the study. The design team investigated low-cost solutions that would maximize pedestrian and cyclist accommodations on the bridge by reducing travel lane width. Ultimately, it was determined that reducing the travel lanes would not be appropriate due to the high volume of large vehicles that utilized the corridor. As pedestrian facilities already exist across the bridge, it is recommended with the Orchard Street project, that pedestrian facilities be extended north and south from the bridge to provide a complete connection. A review of the bridge facilities should be completed during design to ensure an accessible route is provided across the bridge behind the existing guardrail. Future bike facility extension will need to be accommodated by a separate bridge or when the existing bridge is reconstructed.

Truck Accommodations at Roundabouts The project team received concerns from stakeholders and the public regarding large vehicle (such as sand and gravel trucks) accommodations at the proposed roundabouts. Stakeholders with large trucks stated they have had issues with smaller roundabouts in the past and they expressed concerns that their trucks might off-track in the proposed roundabouts.

Communities in the Treasure Valley and around the United States construct roundabouts in industrial and commercial areas with high percentages of truck traffic. Locally, the roundabout at intersection of Star Road and Franklin Road in Nampa accommodates hundreds of trucks a day. The roundabouts at the intersections of Amity Road/Happy Valley Road in Nampa as well as Pine Avenue/Webb Avenue in Meridian also see significant truck traffic. Figure 5-5 shows a truck at the Star Road/Franklin Road roundabout.

Figure 5-5: Truck Accommodations at a Roundabout

However, stakeholders have indicated that the proposed roundabouts will have to also accommodate oversized and overweight (OSOW) vehicles. Between 2015 to 2019, the Idaho Transportation Department issued permits for approximately 180 OSOW vehicles on Orchard Street south of Victory Road. The maximum length of the trucks was about 135 ft. However, in 2018, there were 16 trips permitted with trucks that were 163 ft long.

The Wisconsin Department of Transportation Facilities Design Manual on Intersections (11-25, Attachment 1.1) and Accommodating Oversize/Overweight Vehicles at Roundabouts by the Kansas Department of Transportation (January 2013) were used as guidance in the OSOW vehicle accommodation evaluation. Figure 5-6 shows the

23 dimensions for the Lowboy used to model OSOW truck movements through the intersections. Oversized vehicles typically range from 10 to 13 ft wide and 13 to 16 ft tall.

Figure 5-6: Lowboy Detail To accommodate OSOW vehicles design features can be incorporated to ensure extra-long trailers can pass through a roundabout without pavement off-tracking.

Mountable truck aprons - Using a short, mountable curb will allow for trailers to track onto the truck apron. Such a design minimizes potential load shift and damage to tires. Figure 5-7 shows ACHD’s standard mountable curbing to be used on the truck apron and any exterior mountable curbs. Mountable curbing can be installed on the exterior of the roundabout as well to help facilitate right turning movements for large vehicles. Figure 5-8 shows mountable curbing on the outside of a roundabout in Pennsylvania. Truck trailers can track on this when circulating through the roundabout. Mountable exterior aprons tighten corners at roundabout and encourage slower speeds for passenger vehicles entering the roundabout. The 4 in rise in the ACHD standard mountable curb and gutter provides enough clearance for the OSOW trucks in the corridor which have a minimum 5 in of ground clearance. It is recommended however to modify the curb height of the ACHD standard mountable curb and gutter to 3 in to provide more driver comfort and make the transition between elevations more less noticeable. This modification will also match the height of the mountable truck apron curb without gutter.

Figure 5-7: Mountable Curbing

Figure 5-8: Exterior Truck Apron

As with traditional intersections, accommodating OSOW vehicles at roundabouts may require additional design features to allow for their clear passage, including: removeable signs and placing light poles and overhead signage supports outside of areas where trailer tracking may impact permanent poles. Designers will use the OSOW simulated truck turns to determine the optimal design and placement of sign and lighting supports. Signs that must be located in the path of tracking trailers will have to be removeable. Striped gores between the entry lanes can be utilized on roundabout entries to provide greater room for truck maneuvers without increasing vehicular speeds. Figure 5-9 shows a multilane roundabout with gores on each entry leg. Typically, striped gores are about 4 ft wide.

The central island of the roundabout can be designed Figure 5-9: Gore Striping at Entry of a Multilane with features to accommodate turning OSOW vehicles Roundabout including: traversable surface though the center of the roundabout or providing extra wide or a tailored shaped truck aprons. Using the ACHD mountable curbing, OSOW vehicles will have sufficient vertical clearance when using the mountable truck apron. The same mountable curbing can be used on exterior truck aprons when OSOW vehicle trailers track outside the roundabout. To create adequate width for extra large trucks to traverse a roundabout, drivers can straddle the lanes entering the roundabout to use multiple circulating lanes when navigating the roundabout. Figure 5-10 shows a driver positioning to use both lanes as he enters a multilane roundabout. One option truck drivers have to generate more room is to straddle the lanes entering the roundabout and take up multiple circulating lanes when turning in the roundabout. The extra space can help the driver’s comfort level and reduce sideswipe crashes. Allowing OSOW vehicles to utilize multiple lanes is recommended by Wisconsin Department of Transportation and the Kansas Department of Transportation in the guidance referenced at the beginning of this section.

Figure 5-10: Truck Straddling Lanes in Hilliard, Ohio

For this concept study, the roundabout at realigned Orchard Street and Gowen Road is shown with a 210-ft inscribed circle diameter and a minimum 15-ft truck apron. The roundabout layout will be refined as part of design. At this intersection, the OSOW vehicles will typically make left turns from southbound Orchard Street to eastbound Gowen Road and right turns from westbound Gowen Road to northbound Orchard Street. Figure 5-11 depicts the turning movements of an OSOW vehicle at a three lane roundabout at Orchard Street and Gowen Road which is the estimated size for the final build phase; however, at Orchard Street/Gowen Road a two lane roundabout is anticipated for the interim build phase. Figure 5-12 shows OSOW truck turning movements at the interim two lane roundabout. The mountable truck apron in the center of the roundabout has been expanded to accommodate the turning movements. The splitter islands will also need to be mountable to facilitate right turning movements.

Figure 5-11: OSOW Accommodations at Three Lane Figure 5-12: OSOW Accommodations at Two Lane Gowen Road/Orchard Street Gowen Road/Orchard Street

Figure 5-13 shows OSOW vehicle tracking through the roundabouts at Orchard Street/Diamond Street and Orchard Street/Dorman Street or Aeronca Street. A 170-ft ICD was used for these roundabouts with a minimum 15-ft truck apron. The mountable truck apron in the center of the roundabout was enlarged to accommodate the left turning movements for the OSOW vehicles. An exterior mountable truck apron was introduced in the southeast quadrant of the roundabout to accommodate the trailer tracking on right turns. All intersections accommodated through movements for OSOW vehicles. Appendix G contains larger exhibits detailing turning movements for OSOW vehicles.

Figure 5-13: OSOW Accommodations at Orchard Street/Diamond Street and Orchard Street/Dorman Street or Aeronca Street

Roadway Ownership ACHD will own and maintain realigned Orchard Street, Diamond Street, and existing Orchard Street. ACHD will also continue to own and maintain Gowen Road. The City of Boise will be responsible for construction and maintenance of the local connection, Dorman Street or Aeronca Street, since it will be a local road that primarily provides access to City/Airport facilities. As part of the Orchard Street realignment, the intersection of Dorman Street and realigned Orchard Street will be constructed by ACHD.

Utilities The following utility owners are located within the project vicinity. Potential impacts, contact information for the utility owners, and a basemap showing the existing utilities are in Appendix C. • Cable One has critical fiber lines running west to east on the south side of Gowen Road throughout the project and approximately 250 ft will need to be relocated along Gowen Road. • Century Link facilities are located along the south side of Gowen Road, along the east side of existing Orchard Street from Gowen Road to Diamond Street, and along the south side of Diamond Street west from Orchard Street. For the realigned Orchard Street, Century Link plans to install new conduits and handholes along the route for future development and may some divert lines from their existing lines to the new corridor. • City of Boise conduit and fiber lines are located along existing Orchard Street right-of-way from just south of the New York Canal to the intersection of Gowen Road and existing Orchard Street, and then continue east within Gowen Road right-of-way.

• City of Boise Public Works (Sanitary Sewer) – Existing pressure sewer line crosses the realigned Orchard Street near the proposed Dorman Street extension intersection and runs from west to east just north of the abandoned sewage lagoons. The pressure sewer empties into a gravity sewer manhole northeast of the existing Orchard Street and Gowen Road intersection where it is combined with gravity sewer from the west of existing Orchard Street. Sewer then gravity flows in the existing Gowen Road right-of-way to the west. o The City has provided a concept sketch of potential improvements and modifications to the City’s sewer system (Appendix C). The City has confirmed that design and construction of the sewer modifications and improvements would be at the City’s expense. ACHD will need to coordinate with the City during Design. • Idaho Power Company has both above and underground electric facilities in the vicinity of the project. • Intermountain Gas Company (IGC) has two high-pressure gas mains on existing Orchard Street right-of- way north of the existing intersection of Gowen Road and Orchard Street. The gas main continues east from that intersection in Gowen Road right-of-way. Intermountain Gas Company requests coordination at the beginning of the roadway design stages because IGC believes that the high-pressure gas mains may need to be relocated to the Orchard Street right-of-way depending on the expansion plans of the City of Boise Airport. Just north of the proposed Dorman Street extension and south of the landfill, a gas service line runs east-west across the City of Boise property to support Knife River’s industrial facility. This service line would cross the proposed Orchard Street realignment. o On the City of Boise property, northeast of the sewage lagoons and west of existing Orchard Street near Dorman Street, there is a joint fire training facility between IGC and the City of Boise. This facility must be removed if the Dorman Street extension is constructed. IGC estimated that to remove the above ground piping and cap the below ground service line would cost approximately $25,000. o Within two years, IGC plans to install a new gas main west along Gowen Road to the existing Orchard Street Extension, south from Gowen Road. Coordination with IGC about the placement of this gas main is requested. • SUEZ North America (Water) has a network of connected water mains, service lines, and hydrants within the study area. A water main is located on the southern end of the project that runs west-east in Gowen Road right-of-way from the New York Canal, east to existing Orchard Street, and further east towards National Guard facilities. A water main runs north from the existing intersection of Gowen Road and Orchard Street to the existing intersection of Diamond Street and Orchard Street. The water main then runs east-west in Diamond Street right-of-way. • Syringa Networks has buried fiber lines located along the south side of Gowen Road, within existing Orchard Street right-of-way from Gowen Road to north of the New York Canal, and in Diamond Street right- of-way to serve Idaho Transportation Department’s maintenance facility. • Idaho Department of Environmental Quality (IDEQ) has multiple monitoring wells across the Historic North Landfill. Three are located near the Dorman Street alignment. There are additional vapor extraction and monitoring wells located along Gowen Road for the decommissioned sewage beds. $45,000 for impacts to the Gowen Road wells and $65,000 for impacts to the wells near the Dorman Street extension have been included in the alternative estimates.

Boise Airport Runway Protection Zone Portions of this project are located within the Boise Airport Runway Protection Zone (RPZ), specifically in the area of the Diamond Street intersection. The RPZ is a trapezoidal area off the end of the runway where aircraft crashes are most likely to occur. RPZs are not considered Object Free Areas (OFA) but do have limitations on obstructions located within their limits. Most of these limitations are related to object height. The goal of the RPZ is to enhance the protection of people and property on the ground. Work within 20,000 ft of a public airport or military airport which exceeds the 100:1 surface from any point on the runway of an airport with a runway of 3,200 ft or more requires the submittal of a FAA form 7460-1 “Notice of Proposed Construction or Alteration.” All work within the RPZ falls within these parameters. This work includes light poles, roadway elevation, and other permanent and temporary vertical obstructions such as cranes, drilling rigs, and power cables and lines. This form must be submitted at least 45 days prior to construction; however, there is a 45 to 60-day review period with the FAA, so it is recommended to submit sooner. The study team recommends

28 coordinating with the FAA early in the design process rather than waiting until closer to construction. The form requires information about the work as well as appropriate attachments showing the type and location of the work. The attachments must include the following items:

• Drawing (preferably scaled) showing location of the object in relation to nearest active runways. This may be a marked up-Airport Layout Plan or Terminal Area sheet. • Perpendicular distance of the proposed object to the nearest active runway center lines. • Distance along center line (actual or extended) from runway end to the perpendicular intercept point • Ground Elevation at the site of the proposed object • Height of the proposed object including antennas or other appurtenances • Accurate geodetic coordinates conforming to NAD 83 (North American Datum of 1983) • Sketches, drawings, etc. showing the type of construction or alteration being proposed Objects within the RPZ determined to be obstructions to the 100:1 surface within the RPZ should typically be marked or lighted. Since this project is located in a fairly urban area with existing street lights, it is recommended to use red obstruction lights on permanent light fixtures that impact the 100:1 surface. Obstruction lights should also be used during construction on structures that impact the 100:1 surface. The FAA Advisory Circular AC 70/7460-1K details the requirements for obstruction marking and lighting. The design team will need to coordinate with the Boise Airport and FAA to ensure the appropriate obstruction lighting and markings are used. 5.4 Alternatives Cost Estimates Construction costs for both alternatives and their options were estimated. Cost estimates include costs of right-of- way acquisition, temporary traffic control estimates, contingency, mobilization, and other costs usually captured through a lump sum quantity. Cost estimate calculations are found in Appendix H. There are several important things to note regarding the cost estimate. Currently the proposed pavement build-up along Orchard Street Realignment is assumed to be concrete. By switching to asphalt pavement (except for the intersections), approximately $600,000 could be saved. ACHD is still determining if concrete or asphalt pavement with geogrid is the appropriate solution. Additionally, by maintaining the existing asphalt pavement north of the Orchard Street New York Canal Bridge, an additional $350,000 could be saved. There is also the potential to extend the Fivemile Creek structure under Gowen Road rather than constructing an entirely new structure. The estimated savings are $300,000.

Chapter 6: Evaluation of Alternatives

6.1 Public Involvement and Stakeholder Comments The project team held a third Stakeholder Meeting (August 13, 2019) and one Public Meeting (August 14, 2019) during the evaluation and refinement of alternatives. In addition, a second online survey was also conducted from August 15-28, 2019 to provide the public with an opportunity to review and comment on the preliminary alternatives. All feedback from the public involvement process is in Appendix B and feedback from the stakeholder meetings is in Appendix A. The exhibits presented to the stakeholders and the public are also included in the appendix. Overall, 50% of individuals that provided feedback preferred Alternative 1 (Figure 6-1) over Alternative 2 and 43% preferred Option 3 (existing intersection of Harvard Street/existing Orchard Street/Gowen Road eliminated) over the other options presented for the Harvard Street/Gowen Road/Existing Orchard Street intersection (Figure 6-2). Over half of commenters (55%) preferred a roundabout option at the Gowen Road/Orchard Street intersection as well (Figure 6-3).

Alternative 1

Alternative 2

Alternatives No Build

0% 10% 20% 30% 40% 50% 60% Percentage of Responders by Alternative Preferred

Figure 6-1: Responses for Preferred Alternative

Option 1 (Harvard Street tees into Gowen Road)

Option 2 (Right in/Right out access at Ex. Orchard Street and Gowen Road.) Option 3 (No Intersection)

Options None

0% 10% 20% 30% 40% 50% Percentage of Responders by Preferred Option Figure 6-2: Responses for Preferred Option at Harvard Street/Gowen Road/Existing Orchard Street Intersection

Signalized Intersection

Roundabout

None

IntersectionTypes 0% 10% 20% 30% 40% 50% 60% Percentage of Responders by Preferred Intersection Type

Figure 6-3: Responses for Preferred Intersection Type at Gowen Road/Orchard Street

6.2 Alternatives Evaluation

The Alternatives were evaluated based on the following criteria: • Traffic Movement/Efficiency • Traffic Safety • Access to Land/Future Plans • Truck Movement • Bicycle & Pedestrian Mobility • Cost • Constructability/Risk In Tables 6-1, 6-2, and 6-3 on the following pages, the evaluation of each alternative and all its options are provided. The three options for the intersection of existing Orchard Street/Harvard Street/Gowen Road were evaluated separately using the criteria below. This evaluation is detailed in Table 6-4. • Traffic Movement/Efficiency • Traffic Safety • Access to Land/Future Plans • Cost

Table 6-1: Alternative 1 with Aeronca Street Connection Option Evaluation Summary

Aeronca Street Connection (see Figure 5-3 on page 17)

Signalized Roundabout

Analysis shows that a signalized intersection would Analysis shows the roundabout would serve traffic movements with Traffic efficiently facilitate traffic movement but would result in less delay than signalized option, especially in off-peak times. Movement/Efficiency significantly more traffic delay than the roundabout option, especially in the off-peak times. A traffic signal is an acceptable intersection solution and A roundabout intersection would maximize safety at the intersection should provide reasonable traffic safety. However, the with respect to the potential for serious injury due to reduced speeds risk of higher-speed right angle and left turn crashes, and the near elimination of left turn and right-angle conflicts. Traffic Safety which can lead to serious injuries or potentially fatalities, Roundabout at Orchard Street and Gowen Road for this alternative is higher than for roundabout option. has two or more entry and exit lanes on multiple approaches/departures, which may result in additional minor crashes due to driver confusion. Access to Land/Future This connection is included in the City of Boise Airport Master Plan. It would provide direct cross street access to existing airport Plans parcels as well as the proposed solar farms. However, it does not provide access to the planned commercial/industrial parcels. Signalized intersections do not accommodate large truck Roundabouts are normally sized to accommodate large trucks Truck Movement U-turn movements without special accommodations including U-turn movements. (wide median or other). Shared-use paths are provided along Orchard Street and Shared-use paths are provided along Orchard Street and crossings are crossings are provided at all intersections. The signalized provided at all intersections. The roundabout option is more Bicycle & Pedestrian option is slightly less desirable for pedestrians/cyclists desirable for pedestrian and cyclist crossings since they are required Mobility than the roundabout options since pedestrians/cyclists to cross fewer lanes and only one direction of travel at a time. are required to cross all lanes at the intersection at one time. The Aeronca Street extension results in significant risk compared to the Dorman Street extension due to the impacts to the Historic North Landfill. It is unknown if hazardous waste will be encountered while excavating the landfill. The cost to dispose of the waste Constructability/Risk could balloon if hazardous waste is encountered. There is no way to determine if there is hazardous waste until excavation begins. Hazardous waste remediation could also slow the construction schedule and increase costs. Cost $19,436,000 $19,202,000

Figure 6-4: Alternative 1 (Aeronca Street) Evaluation Matrix

Table 6-2: Alternative 1 with Dorman Street Connection Evaluation Summary

Dorman Street Connection (see Figure 5-3 on page 17)

Signalized Roundabout

Analysis shows it efficiently facilitates traffic Analysis shows the roundabout facilitates traffic movements with movement but results in significantly more traffic delay less delay than signalized option, especially in off-peak times. Traffic Movement/Efficiency than the roundabout option, especially in the off-peak times A signalized intersection is an acceptable intersection A roundabout intersection would maximize safety at the solution and should provide reasonable traffic safety. intersection with respect to the potential for serious injury due to However, the risk of higher-speed right angle and left reduced speeds and the near elimination of left turn and right-angle Traffic Safety turn crashes, which can lead to serious injuries or conflicts. The roundabout at Orchard Street and Gowen Road for potentially fatalities, is higher than for roundabout this alternative has two or more entry and exit lanes on multiple option. approaches/departures, which may result in additional minor crashes due to driver confusion. This connection is included in the City of Boise Airport Master Plan. Dorman provides direct access to parcels that the City and Access to Land/Future Plans the Airport have identified for future industrial or commercial development. It also provides connectivity to the existing airport site. Signalized intersections do not accommodate large Roundabouts are normally sized to accommodate large trucks truck U-turn movements without special including U-turn movements. Truck Movement accommodations (wide median or other).

Shared-use paths are provided along Orchard Street Shared-use paths are provided along Orchard Street and crossings and crossings are provided at all intersections. The are provided at all intersections. The roundabout option is more signalized option is slightly less desirable for desirable for pedestrian and cyclist crossings since they are required Bicycle & Pedestrian Mobility pedestrians/cyclists than the roundabout options since to cross fewer lanes and only one direction of travel at a time. pedestrians/cyclists are required to cross all lanes at the intersection at one time. There is some risk associated with the Dorman Street extension. Logs from existing monitoring wells within the vicinity of the proposed Dorman Street alignment show some organics and waste within a portion of the alignment area. Additional Constructability/Risk geotechnical investigations will be required to determine an alignment that avoids waste. There is a possibility that the alignment may not be able to avoid the waste. In this event, the waste will need to be disposed of. However, there is expected to be significantly less waste than the Aeronca Street extension. Cost $18,612,000 $18,378,000

Figure 6-5: Alternative 1 (Dorman Street) Evaluation Matrix

Table 6-3: Alternative 2 Quadrant Roadway Evaluation

Quadrant Roadway (see Figure 5-4 on page 19)

Signalized Roundabout

Analysis shows that a signalized intersection would Analysis shows the roundabout would serve traffic movements efficiently facilitate traffic movement but would result in with less delay than signalized option, especially in off-peak Traffic Movement/Efficiency significantly more traffic delay than the roundabout times. option, especially in the off-peak times.

A traffic signal is an acceptable intersection solution and A roundabout intersection would maximize safety at the should provide reasonable traffic safety. However, the risk intersection with respect to the potential for serious injury due Traffic Safety of higher-speed right angle and left turn crashes, which to reduced speeds and the near elimination of left turn and can lead to serious injuries or potentially fatalities, are right-angle conflicts. higher than for roundabout option.

Extending Dorman Street accommodates the City of Boise Airport Master Plan which shows Aeronca Street and Dorman Street Access to Land/Future Plans extending to the realigned Orchard Street. Dorman Street provides direct access to parcels that the City and the Airport have identified for future industrial or commercial development. It also provides connectivity to the existing airport site.

Signalized intersections do not accommodate large truck Roundabouts are normally sized to accommodate large trucks Truck Movement U-turn movements without special accommodations (wide inducing U-turn movements. median or other). Shared-use paths are provided along Orchard Street and Shared-use paths are provided along Orchard Street and crossings are provided at all intersections. The signalized crossings are provided at all intersections. The roundabout Bicycle & Pedestrian option is slightly less desirable for pedestrians/cyclists option is more desirable for pedestrian and cyclist crossings Mobility than the roundabout options since pedestrians/cyclists are since they are required to cross fewer lanes and only one required to cross all lanes at the intersection at one time. direction of travel at a time.

There is some risk associated with extending Dorman Street. Logs from existing monitoring wells within the vicinity of the proposed Dorman Street alignment shows some organics and waste within a portion of the alignment area. Additional geotechnical investigations will be required to determine an alignment that avoids waste. There is possibility that the alignment may not be able to avoid the waste. In this event the waste will need to be disposed of. However, there is expected Constructability/Risk to be significantly less waste to deal with than the Aeronca Street extension. There is also a landfill located under Cell 2 in the old sewage lagoons (NE corner). There are no well logs in this area so the study team was unable to confirm the depths of the waste or if the proposed location of Dorman Street will impact the landfill. Additional geotechnical investigations will be required to determine the true extent of the impacts. Cost $20,685,000 $20,685,000

Figure 6-6: Alternative 2 Evaluation Matrix

Table 6-4: Existing Orchard Street/Gowen Road/Harvard Street Intersection Realignment Options Existing Orchard Street/Gowen Road/Harvard Street Intersection Options (see Figure 5-3 on page 17)

Option 1 Option 2 Option 3 Harvard Street will be stop Orchard Street will be stop This option is the most controlled and traffic could controlled but right turn efficient since the roadways experience long delays to make movements are the only are fully separated and no left turns onto Gowen Road. movements that will be vehicles are required to stop Traffic However, those traffic volumes permitted. Gowen Road will at any point. Movement/Efficiency are not expected to be be free flow. Delays are significant based on expected to be minimal due to stakeholder feedback. the low number of users expected at the intersection. Left turns at Harvard Street Safety is maximized at this This option eliminates the create a risk for left turn and intersection by restricting left potential for crashes at Traffic Safety angle crashes that does not turning movements with a Gowen Road. exist for Options 2 and 3. raised median on Gowen Road.

Provides direct access to This maintains access to This option does not allow for properties adjacent to Harvard existing Orchard Street from any connectivity between Street. Restricts business fire westbound Gowen Road for Gowen Road and existing access to existing Orchard the existing airport site and Orchard Street. Fire-only Street from Gowen Road. allows for access from existing access could be provided with Orchard Street to the southern this option. Business access parcel that has been identified to the land west of the Access to for future development. This airport may be restricted. Land/Future Plans also maintains access to adjacent property owners. Though not preferred by Boise Fire due to possible impact on sensitive equipment, a mountable median would also provide fire access. Cost $113,000 $457,000 $138,000

Figure 6-7: Harvard Street/Gowen Road/Existing Orchard Street Evaluation Matrix

Chapter 7: Recommended Alternative Based on the analysis and evaluations completed, and stakeholders and public input, Alternative 1 with Dorman Street extended is recommended as the preferred solution. ACHD plans to construct the intersection of Dorman Street and realigned Orchard Street; however, the Dorman Street local connection is the responsibility of the City of Boise. For the recommended alternative, roundabouts are the recommended traffic control at the intersections of realigned Orchard Street and Diamond Street, Dorman Street, and Gowen Road. It is recommended to initially design and construct an interim two lane roundabout rather than the ultimate three lane roundabout shown previously that would accommodate the projected 2040 traffic volumes. ACHD will acquire the R/W necessary for future intersection expansion and ACHD will monitor and evaluate the appropriate date to expand the roundabout. If traffic volumes do not increase as predicted, there may never be a need to modify the interim roundabout. At the Harvard Street/Gowen Road/existing Orchard Street intersection, Option 2 is recommended. In Option 2, Harvard Street ties into existing Orchard Street and existing Orchard Street/Gowen Road has right in/right out access only. However, until the City of Boise constructs the Dorman Street connection, a temporary signal will be utilized to provide access to properties in the southern section of existing Orchard Street. Once the Dorman Street extension is constructed, the signal will be removed and the median along Gowen Road will be constructed to restrict left turns. During final design, additional right-in, right-out only driveways may be considered along the Orchard Street Realignment. These will be reviewed based on current and proposed land uses, the proximity to intersections, and ACHD policies. No additional full access points should be allowed. Along both sides of realigned Orchard Street, 10-ft wide shared-use paths will be constructed. A 10-ft wide shared- use path will also be implemented between relocated Orchard Street and existing Orchard Street along the north side of Gowen Road. Figures 7-1 and 7-2 depict the proposed cross sections for Orchard Street and Gowen Road.

Figure 7-1: Orchard Street Cross Section

Figure 7-2: Gowen Road Cross Section

Figure 7-3 on the following page depicts the recommended alternative. The estimated cost for the improvements is approximately $18,079,000. The costs are broken out in Table 7-1. These costs assume only the two lane interim roundabout will be built at Orchard Street and Gowen Road. An additional $1,400,000 is the estimated cost to expand the roundabout in the future. The cost to expand the roundabout is detailed in Construction Phase 5 on page 46.

7.1 Recommended Conceptual Drainage Design The recommended conceptual drainage design was guided by ACHD Policy Section 8000 – Drainage and Stormwater Management and ACHD Policy Section 8200 – ACHD Stormwater Design Tools and Approved BMPs. Section 8007 Performance Standards dictate the requirements for Peak Rate Control, Runoff Reduction, Volume Management, Water Quality Treatment, Conveyance, Runoff from Public Streets, and Operation and Maintenance. Individual drainage basins have been identified within the project area and are shown in Appendix I. The primary recommended stormwater management approach is infiltration using roadside borrow ditches. For areas where infiltration is determined to be unfeasible due to environmental concerns and geotechnical observations during the design process, stormwater can be conveyed, treated, attenuated, and discharged to Fivemile Creek. For Orchard Street, preliminary stormwater calculations show roadside borrow ditch widths of approximately 10 ft. Key drainage features recommended as part of this project include: • Replacement of the 20-ft wide concrete stiff leg box culvert beneath Gowen Road for Fivemile Creek. • Installation of a new 20-ft wide concrete stiff leg box culvert for Fivemile Creek beneath proposed Orchard Street approximately 700 ft north of Gowen Road. • Re-alignment of the northern branch of Fivemile Creek that is the City of Boise’s drainage basin outfall.

* Interim signal until Dorman Street Extension constructed. Figure 7-3: Recommended Alternative 38

Table 7-1: Recommended Improvements Cost Estimate

Chapter 8: Recommended Phasing Sequence The consultant recommends keeping the design in one contract. The same design team generating the entire plan set will lead to more design cost efficiencies and better project cohesiveness. The temporary traffic control plans can detail the project phases and one plan set can be used to construct everything over multiple seasons. Having one contractor receive the award and construct the project in phases will also lead to additional cost efficiencies. For construction, it is recommended to break the project up over five phases. The phases are detailed below. With construction phasing over multiple years, the project costs are anticipated to be more than if the project were to be constructed at one time under one contract. The estimated cost difference is approximately $180,000. This difference primarily stems from the additional mobilization work for each phase and interim treatments between phases such as temporary pavement. An additional $1,400,000 is estimated to expand the intersection at a future date.

Phase 1 In Phase 1 the study team recommends constructing the Diamond Street roundabout and constructing all the Orchard Street improvements from Diamond Street north to the concrete pavement limits just south of the Victory Road/Orchard Street intersection. Sidewalk to fill in the gap between the New York Canal Bridge and the Victory Road intersection will also be constructed. It is also recommended that the excavation of Orchard Street Realignment within the limits of the North Historic Landfill be completed in this phase so that, in the event hazardous waste is encountered in the landfill, the remediation of the waste does not slow down the construction schedule of the other phases. A consultant will be needed on site to make sure the soil management plan is executed correctly during the excavation and to test and sample the soil excavated for hazardous contaminants. In order to complete the excavation, the right-of-way for the corridor will need to be acquired. Once the excavation is complete, the contractor will cap the exposed waste with a dirt cap. This is accounted for in the cost estimate under the line item “backfill landfill with borrow.” The estimated construction cost for this phase is $6,366,000. Figure 8-1 on page 41 shows the extents of the proposed work for this phase. Table 8-1 details the associated costs.

Table 8-1: Construction Phase 1 Cost Estimate

Figure 8-1: Construction Phase 1 41

Phase 2 Phase 2 includes the construction of the two lane interim roundabout at Orchard Street/Gowen Road and all the associated widening along the existing Orchard Street Extension to the south and Gowen Road to the east. The improvements for this phase are shown in Figure 8-2. Figure 8-3 on page 43 shows the cross section that will be used for Gowen Road in this phase. Everything except the shared-use path will be constructed at this time. In this phase, the culvert for Fivemile Creek under Gowen Road will also be reconstructed. The shared-use path to facilitate crossings at the roundabout will also be constructed. The paths will be placed in their ultimate location in anticipation of future roundabout widening. The estimated construction cost for this phase is $4,234,000. The cost is broken down in Table 8-2 below. Table 8-2: Construction Phase 2 Cost Estimate

Figure 8-2: Construction Phase 2

Figure 8-3: Gowen Road Cross Section Phase 3 This phase connects the intersections built in Phases 1 and 2. Realigned Orchard Street will be fully constructed and opened at the end of this phase. The shared-use path along the west and east side of the roadway will also be constructed. Since this roadway can be constructed without any additional traffic control concerns, it should be able to be constructed in a single construction season. The Orchard Street/Dorman Street roundabout will also be constructed in this phase. A stub will be provided into which the City of Boise can tie the Dorman Street connection. Figure 8-5 on page 44 shows the limits of this phase. Figure 8-4 shows the Orchard Street cross section that will be used in this phase. The estimated costs for this phase are $6,063,000. Costs are shown in Table 8-3.

Table 8-3: Construction Phase 3 Cost Estimate

Figure 8-4: Orchard Street Cross Section 43

Figure 8-5: Construction Phase 3 44

Phase 4 Phase 4 is the final interim phase for the initial implementation of the improvements recommended in this study. This phase involves the construction of the reconfigured intersection at existing Orchard Street/Gowen Road/Harvard Street. A temporary signal will be utilized at the intersection until the completion of the Dorman Street extension by the City of Boise. The median along Gowen Road will not be constructed until the Dorman Street extension is built in order to allow for convenient access to the southern portion of the airport site. Once the Dorman Street extension is constructed, the median, restricting left turn movements, will be constructed, and the signal will be removed. The shared-use path between this intersection and the intersection of realigned Orchard Street/Gowen Road will also be constructed in this phase. The estimated cost for these improvements is $1,598,000 (shown in Table 8-4). Figure 8-6 shows the limits of these improvements.

Table 8-4: Construction Phase 4 Cost Estimate

Figure 8-6: Construction Phase 4

Phase 5 This final phase is to expand the roundabout to a three lane roundabout at realigned Orchard Street and Gowen Road to accommodate anticipated 2040 traffic volumes. Additional investigation will determine if the larger roundabout is the best solution or if another intersection configuration is preferred. Figure 8-7 shows the potential roundabout configuration for this intersection based on estimated traffic volumes. These improvements are not anticipated to be necessary until about 2030 or later. The cost to expand the intersection is estimated to be about $1,407,000. The costs are detailed in Table 8-5 below.

Table 8-5: Construction Phase 5 Cost Estimate

Figure 8-7: Construction Phase 5

Chapter 9: Next Steps As the project moves forward into design and construction, the following next steps will be required:

Study • An additional study will be needed to determine the appropriate pedestrian and cyclist structure and placement over the New York Canal.

Preliminary Design • Geotechnical evaluation to determine pavement build up with the use of geo-grid for soil stabilization and provide information for the design of structure foundations. • Perform soil sampling to determine if soils are suitable for infiltration near sewage lagoons. • Coordination with the FAA to determine the appropriate document type to comply with NEPA regulations. • Begin coordination with FAA and Boise Airport on preparing FAA form 7460-1. • To mitigate risk associate with hazardous waste within the project limits, prepare preliminary excavation plan. Work with a consultant, contractor, and IDEQ to use preliminary excavation plan and start removal, sampling, analysis, and disposal while detail design proceeds. • Coordinate with IDEQ and FAA to confirm appropriate drainage facilities are being used in proximity to the landfill and Boise Airport.

Final Design • Additional public involvement will need to be conducted during the design phase. • During design, the full extent of the impacts to Fivemile Creek will need to be determined. The consultant and ACHD will determine if a Nationwide Permit or Individual Permit will be needed for construction. Coordination will be needed between ACHD, IDEQ and the USACE for the Section 401 Water Quality Certification and any other water related permits needed for the project. • Continue Coordination with FAA and Boise Airport to finalize and submit FAA form 7460-1. Additional coordination with the Boise Airport will also be needed to ensure permanent and temporary vertical structures are lighted and marked correctly in order to limit interference with aircraft navigation. • Consultant will need to develop a soil management plan for hazardous materials for use during construction. Coordination with IDEQ will be required.

Right-of-Way Acquisition • Depending on the outcomes of the right-of-way vacation process for this project, some existing utilities may end up being located on property not owned by ACHD. ACHD will need to work with existing utility owners to make sure proper easements are set in place for these utilities.

Construction • Prior to commencing construction, a consultant will need to be hired to monitor project excavation and adherence to the project soil management plan that addresses the process for handling hazardous waste. Consultant will be in charge of testing and sampling excavated waste.

47 Ada County Highway District 3775 Adams St. Garden City, ID 83714

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