What criteria is being used to determine site layout and tank placement?
Our goal is to make a well-informed and sustainable decision for the entire community that we serve. We are considering several factors in the siting of the tanks, including:
- Elevation - the top of the water surface must be at 607 feet above sea level
- Proximity to residences - to the extent possible, maximizing distance between tanks and neighbors’ property lines
- Habitat - limiting impacts to sensitive/special plant communities and wildlife
- Compatibility – placing tanks in locations and at buried depths to reduce impacts to neighbors’ viewsheds and enable continued public use of the site
- Cost - ensuring responsible use of public funds
- Access - ensuring adequate access for maintenance and emergency vehicles
- Security - protecting water quality and limiting attractive nuisance behaviors
- Excavation and construction - considering slopes and soil conditions in order to minimize the length and magnitude of disturbance, including tie-in piping and drain construction
- Future planning - designing to accommodate one additional tank in the near term, and space to accommodate future replacement in 50+ years
How many trees could potentially be removed?
It depends on the final tank placement. Based on the preliminary site layout, we estimate that approximately 160 trees could be removed for tank #1 and approximately 100 more for tank #2. In total, that represents about one-quarter of the trees on the 10-acre property. The detailed design process which is happening between now and spring 2021 will confirm the exact placement of tanks as well as the number and location of trees that need to be removed.
Is it possible to save high-value habitat such as the healthy oak woodland on the west side of the property as well as the large, old firs on the ridgeline?
As part of the detailed design process, we are considering all feasible scenarios for tank placement and construction sequencing. We are aware that some very old, large firs live on the east side of the ridgeline, and there is a healthy oak woodland on the west side of the property.
We are looking for ways to site the tanks in a way that preserves as much high-value habitat and natural space as possible, while striving for a responsible balance between multiple criteria.
Will blasting be required as part of the excavation process?
Possibly. We will know more in late spring of 2021.
The decision of whether to use blasting will not be made by EWEB, but by the construction contractor. In our experience, contractors are sometimes reticent to use blasting because of extra safety requirements and specialized staffing who are required to determine how to do the work safely without impacting nearby homes and who need to be on-site to monitor the work while it is being done. However, if the rock is too hard, mechanical excavation could be even more difficult, longer and louder than blasting.
If blasting is going to be the preferred method of excavation, we will be working very closely with the immediate neighbors early in the process.
Upon a suggestion from a neighbor, we intend to include a requirement for the contractor to provide videos of blasting as part of the construction package so that neighbors will have a better idea of what this process entails.
How will the construction process impact neighbors?
We understand that construction impacts are a big concern for neighbors. In general, you can expect dump trucks, large excavators, cranes, front end loaders, skid steers and other typical equipment on site throughout construction.
As you can see from the project timeline, we start getting a clear picture of the construction process and schedule in the spring of 2021. Around that time, we will be communicating and engaging frequently with neighbors in the development of a Construction Mitigation Plan that establishes methods for regular communications with residents, and outlines strategies for noise management, dust control, neighborhood safety, and other construction impacts.
Based on the preliminary layout, is it possible to flip the construction and build the first tank in the meadow to preserve trees on the ridgeline for as long as possible?
Practically speaking, this is not an option we are considering. Assuming the preliminary layout, constructing the first tank on the south/southeast ridgeline would allow us to stage equipment in the meadow away from the critical root zones of nearby trees and give us maximum flexibility for construction of another tank in the future. Conversely, if we were to build in the north/northwest part of the meadow first, we would be constrained down the road—we wouldn’t have easy access to the tank site for construction. Ultimately, this would not only cost more, but could also result in more tree/habitat impact during construction.
The detailed design process which is happening between now and Spring 2021 will confirm the exact placement of tanks and construction sequence.
