Last week, the Design-Build Institute of America (DBIA) gave the Judge Patricia H. Clark Children and Family Justice Center a National Award of Merit in the “Federal, State, County, Municipal” category of their annual awards. GeoEngineers provided extensive environmental and geotechnical services as a teaming partner to Howard S. Wright Construction on this important and technically challenging design-build project.
King County’s existing youth services center in downtown Seattle, Washington was badly outdated. The aging facilities required costly regular maintenance, and no longer offered the space or amenities needed for a more modern approach to youth justice. For example, current programs do not require as many detention beds, and instead prioritize crime prevention programs.
In 2012, the project received the green light when voters approved funding for a brand-new replacement facility. As a modern, trauma-informed facility, it includes youth and family courts along with a therapeutic juvenile detention center. The new facilities include a 137,000 square-foot courthouse, 10,200 square feet of youth program space and an acre and a half of pedestrian pathways and outdoor space.
DBIA specifically recognized the Children and Family Justice Center design-build team’s unique approach to community building and inclusion. King County committed to a target of 26 percent of the project’s total craft labor hours going to building apprentices who are veterans, women or people of color. The design-build team also arranged a 12-month mentorship program for small contractors and suppliers.
Like many other sites in Seattle’s Central District, the soil and groundwater contained environmental contaminants from the past. In this case, environmental studies in 2013 and 2015 identified a large perchloroethene (PCE) solvent groundwater plume (from a nearby historical dry cleaners) extending beneath much of the site, along with petroleum hydrocarbons in fill soil.
GeoEngineers’ environmental team, led by Associate Hydrogeologist Jim Roth, completed supplemental investigations to better understand the extent of the PCE plume and assess the risk of vapor intrusion. Solvent vapors from plumes like the one beneath the Children and Family Justice Center can migrate from contaminated soil or groundwater and find their way into structures above, creating an airborne risk to human health. To mitigate this risk, the team delivered detailed recommendations for a vapor mitigation system to capture and redirect potentially harmful PCE. The system included an impermeable chemical vapor barrier and sub-slab ventilation to capture and redirect vapor to vents in the roof.
In addition to vapor intrusion risk analysis and mitigation, our environmental professionals provided comprehensive pre-construction support related to the handling and disposal of dangerous waste, contaminated and impacted soil located at the project site. This included preparing a Contained-In letter request for the Department of Ecology, preparing a Construction Contingency Plan and disposal facility support. During construction, the team provided guidance for the mass excavation, classification and permitted disposal of dangerous waste material—including dewatering support for PCE-contaminated groundwater and stormwater.
GeoEngineers also delivered comprehensive geotechnical services for the Children and Family Justice Center. Matt Smith and his team investigated the site and provided recommendations for shallow foundations, slab-on-grade floors, construction dewatering, below-grade walls, temporary excavation support, temporary and permanent cut and fill slopes and foundation drainage recommendations. The density and gradation of soils located at the foundation elevation varied across the site, complicating the analysis. The team found that the soils were sensitive to moisture and recommended carefully managing the work schedule to avoid earthwork during wet weather. Foundation drainage was also challenging due to the environmental conditions present at the site.
Construction on the first phase of the project ran from 2017 to 2019, and the facility is now partially operational. GeoEngineers is continuing to provide supplemental environmental and geotechnical services as construction moves forward on a parking garage and school that constitute the final phase of the project, which King County officials hope to complete by late 2021.
As a recipient of the DBIA’s National Award of Merit, the Children and Family Justice Center will compete for the National Award of Excellence in the “Federal, State, County, Municipal” category. The winner to be announced in the end of October.