Capital Projects

1.  Was a transportation analysis performed for the proposed school project and what was the City of Sammamish’s role in this analysis?

Heffron Transportation, Inc., a firm with more than 30 years of experience evaluating school projects throughout the Puget Sound region, was hired by the Issaquah School District to perform detailed transportation analysis for the proposed school project. The original Transportation Technical Report was subject to several rounds of agency review by both the City of Issaquah and City of Sammamish (including each City’s contracted transportation consultants). The Revised Transportation Technical Report (February 16, 2021) incorporated comments from both cities, and was accompanied by a comment response matrix listing all city comments and how they were addressed. Key assumptions and findings from the Transportation Technical Report are:

• All analysis was performed for the Full Build condition, which includes an 1,823-student high school plus a 744-student elementary school.
   
• The study area for the transportation analysis covered 23 major intersections, 17 of which are in the City of Sammamish. Analysis was performed for the morning arrival, afternoon dismissal, and commuter PM peak hours to capture times when school traffic and commuter traffic would be highest at area intersections and along 228th Avenue SE. 
   
• Extensive analysis was performed for the 228th Avenue SE / SE 43rd Street corridor to determine the optimal configuration and traffic control to serve both the new schools as well as substantial increases in traffic associated with growth and development in the City of Sammamish. Options such as roundabouts, different lane configurations at the school access, and pedestrian crossing treatments were assessed. The final configuration recommended for the 228th Avenue SE frontage was based on that analysis.
   
• Extensive analysis was also performed for the SE 40th Street / 228th Avenue SE intersection to assess measures that would improve operations without attracting excess cut-through traffic on SE 40th Street. The recommended plan was based on that analysis. 
   
• On-site circulation and load/unload operations were also evaluated, with findings incorporated into the design of the internal site roadway system and student drop-off/pick-up areas. 
   
• Detailed parking analysis was performed to determine parking demand on typical school days and during different types of events. 
   
• Many mitigation measures were recommended in the Transportation Technical Report. All of the physical transportation improvements have been incorporated into the project plans. Additional measures were recommended to manage traffic and parking during construction and once the school is operational.

2. What if the school enrollment boundaries change in the future? 

School attendance boundaries are set by the Issaquah School Board, and any changes in boundaries would be subject to a Board review process. During the course of the traffic analysis described above the City of Sammamish staff raised questions about how any future changes in school boundaries could affect traffic conditions and whether it would change the recommended mitigation measures. To respond to those questions, a sensitivity analysis was performed and presented in a Technical Memorandum: Traffic Impact of School Boundary Changes (Heffron Transportation, Inc., August 18, 2021). 

The sensitivity analysis showed the potential effect of theoretical changes for both the high school and elementary school. The analysis determined that a change in the high school boundary—shifting students who would otherwise attend Skyline High School to the new high school—could alter travel patterns through several intersection with the largest impact at the 228th Avenue SE / Issaquah-Pine Lake Road SE / SE 30th Street intersection during the morning peak hour. However, the analysis showed that even if 100% of the students who now live east of that intersection were shifted to the new high school, it would not result a significant impact to that intersection or require additional mitigation. 

The sensitivity analysis showed that the planned improvements along the school’s 228th Avenue NE frontage would accommodate the full build student enrollment no matter what the school enrollment boundaries are in the future. 

3.  What traffic mitigation conditions are required for full build-out of the project? 

All required traffic mitigation measures were documented in the Final Revised SEPA Mitigation Determination of Non-Significance (MDNS) for the New Issaquah High School #4 and Elementary School #17 (January 17, 2022). This was Attachment 74 to the City of Issaquah’s staff report for the project (Link to MDNS on City of Issaquah website). The following are the transportation mitigation requirements (reference numbers from the MDNS included): 

65.     The project will pay transportation impact fees to the City of Issaquah in accordance with IMC 3.71. The District will provide school bus transportation for both elementary school students and high school students attending the proposed schools. The project would provide approximately 1,700 feet for elementary school queuing (enough space for 85 to 110 vehicles) and about 1,510 feet of available queuing space for the high school (75 to 110 vehicles), all to reduce the potential of backups onto 228th Avenue SE. The project would also provide bike racks to accommodate 68 bicycles on the site. 

66.     Construct roadway improvements on 228th Avenue SE along the site frontage, with a length of approximately 1,700 feet. Improvements would include widening the current two-lane section (one travel lane in each direction) to a four-lane section (two travel lanes in each direction), consistent with the City of Sammamish’s ultimate plans for the street. Additional turn lanes would be constructed at the site driveway intersection as needed to ensure that it would meet the City’s traffic operational standards during all times of day. 

67.     Construct a 6-foot sidewalk and landscaping along site frontage.

68.     Construction of a 6-foot sidewalk and landscaping along the east side of 228th Avenue SE from the project entrance north to SE 40th Street. 

69.     Signalize site driveway intersection at 228th Avenue SE. The intersection improvements will include ADA ramps with crosswalks and pedestrian signals. 

70.     Capacity improvements at SE 40th Street / 228th Avenue SE to be either of the following options: 

70.1. New median and striping to create a Flying T configuration and construction of a 6-foot sidewalk and landscaping along the east side of 228th Avenue SE from the project entrance north to SE 40th Street or 

70.2. New Signal and intersection improvements at the SE 40th Street/ 228th Avenue SE intersection

71.     The District shall construct roadway improvements on SE 43rd Way to extend a four-lane road section from its existing location north of the Providence Point Drive SE intersection to the project frontage. 

72.     The District shall extend a 6- foot sidewalk from the project frontage south along the west side of SE 43rd Way to connect to the existing sidewalk north of the Providence Point Drive SE intersection 

73.     The District shall post a school-zone speed limit sign on 228th Avenue SE in the vicinity of the project site. 

74.     Develop a construction management transportation plan that addresses traffic and pedestrian control during school construction. 

75.     Develop a transportation management plan to educate families about transportation options as well as the access and load/ unload procedures for the site layout. 

76.     Develop a school-event management plan for evening events with more than 1,000 expected attendees to mitigate parking impacts and ensure coordination between the schools. 

77.     ISD will discourage vehicle idling during student drop-off and pick-up times. Waiting vehicles will be monitored by a staff member, and signs shall be installed that state “no idling.”

4.  What transportation improvements are proposed for the Phase 1A portion of the proposed school project? 

All of the measures from the MDNS would be implemented for Phase 1A. The only exception is that the quantity of vehicle and bicycle parking will be reduced to reflect the smaller school associated with the phase, and no facilities will be constructed for the elementary school in this phase. The event management plan will also be tailored for the smaller school and parking supply. 

The District’s completion of the frontage improvements along 228th Avenue SW as a part of Phase 1A fulfill the City of Sammamish’s planning for that portion of the street and provides for overall project efficiencies.  

5.  What is the project doing with stormwater and how will it impact the downstream tributaries and salmon population.

The school project is designed to improve stormwater management compared to existing conditions, with the goal of protecting downstream tributaries and supporting salmon habitat.  The existing site includes access roads, parking lots, and building pads that discharge stormwater to the downstream system.  Reflecting the historic construction of the previous improvements on the site prior to modern stormwater requirements, there is no treatment or flow control currently.  The project is designed to improve this existing condition by limiting runoff rates to the forested condition and treating stormwater to an enhanced level.  The water leaving the site will meet the strictest stormwater requirements of any development in the basin since stormwater codes and requirements have continued to evolve of the past 40-years. 

Key elements include:

Modern stormwater treatment and flow control: Runoff from roofs, pavement, and landscaped areas will be captured, treated, and released at controlled rates that reduce erosion and protect stream channels downstream.

• Water quality improvements: Stormwater facilities are designed to remove sediment and pollutants before water leaves the site, improving the quality of water entering downstream tributaries.
   
• Construction-phase protections: During construction, required erosion and sediment control measures will be in place to prevent soil and debris from entering the drainage system.
   
• Regulatory review and compliance: The stormwater system has been designed to meet or exceed current City of Issaquah and State of Washington requirements, which specifically address protection of aquatic resources, including salmon-bearing waters.  The improvements to 228th are designed to meet the City of Sammamish stormwater requirements.

Overall, the completed project will replace older, less-controlled drainage conditions with a comprehensive stormwater system that reduces peak flows, improves water quality, and provides better long-term protection for downstream tributaries and salmon habitat.

6.  Why can’t the initial phase (Phase 1A) be constructed without removing all the trees?

Although building construction is phased, the site earthwork, stormwater systems, utilities and access must be constructed as a single, coordinated operation, which requires tree removal across the site early in the project.

Key reasons include:

• Earthwork volumes must be balanced across the entire site:
  The project involves large volumes of cut and fill that are designed to minimize soil export on site. Soil excavated in one area is reused elsewhere to build pads, roads, and stormwater facilities. If tree removal were limited to Phase 1A, this balance could not be achieved, resulting in significantly more truck hauling, longer construction duration, and greater overall environmental impacts.
   
• Stormwater infrastructure depends on complete on-site grading:
  Stormwater facilities, conveyance routes, and overflow paths rely on finished grades that extend beyond the Phase 1A footprint. These systems cannot be installed or function correctly without clearing and grading the site as designed.
   
• Environmental protection during construction:
  Performing earthwork in a single, coordinated phase allows erosion control measures to be installed comprehensively and maintained effectively. Phased clearing would require repeated disturbance and re mobilization, increasing the risk of sediment reaching downstream waters.
   
• Safety, constructability, and efficiency:
  Partial clearing would require temporary slopes, stockpiling, and rehandling of soil, which increases safety risks and construction impacts compared to a single, planned earthwork operation.  If the earthwork was phased, future work including tree clearing and mass grading on an occupied school campus would also create safety risks for students.

While tree removal occurs early, it supports shorter construction duration, fewer truck trips, reduced disturbance and environmental impacts overall, and better stormwater performance. The project also includes landscape restoration and replanting once construction is complete to establish a stable, functional, and environmentally compliant campus.