Northwestern's New Concrete Stormwater Containment Solution

Originally conceived through collaboration, Superior Concrete and National Precast have formed the Environmental Containment Corporation (ECC) to offer cast-in-place detention vaults, precast ponds, and precast vaults. The forming also announced a comprehensive solution for stormwater containment named "Hybrid Vault", available through ECC.

Located in Vancouver, Washington, National Precast was founded in 1974. With sustainability at the core of their business strategy and day-to-day operations, the company is led by CEO and partner Ron Sparks, with Jim Kuroski as president. Based in Lake Stevens, Washington, Superior Concrete is a full-service general contractor for foundation, concrete forming, and site work. The company is lead by President Amy Pickett and General Manager Russ Hannigan. With 22+ years of experience with stormwater vaults and environmental concerns, the companies pairing to create ECC seems to be a well-made match.

ECC offers a comprehensive solution that includes a complete, permit-ready set of sealed structural drawings and calculations, manufacturing, and final site installation. 

Stormwater...

Typical stormwater containment installations involve multiple companies and contractors for engineering, design, production, transport, and installation. Site-specific loading requirements must be considered during design. An installation typically entails a handful of issues like space availability, watertightness, time, cost, and liability. These need to be considered for each project.

Size Needs/Constraints - The available space for land-use construction projects have become more constrained in modern times. These tighter spaces combined with urban growth boundaries and other land-use issues can be significant for municipalities and regulators. And today's developers are pushing to use this limited space more efficiently. This not only affects the problem-solving of allotting space, enough for a new home or parking spot, but it compounds the need to better manage the stormwater within the same constrained space. 

"Based on these trends and evolving regulations for stormwater retention/management, today's construction projects need more stormwater storage in a smaller footprint," says ECC's CEO Ron Sparks. The Puget Sound Stormwater Manual, for example, has been modified to require more vaults and/or bigger and deeper vault structures to meet stormwater retention requirements. He explains that in such developments, there are often limitations on how much area can be used for a pond and often limited by topography.

ECC's Hybrid Vault system addresses this requirement to do more with less by utilizing cast-in-place floor, precast walls, and prestressed lids. This combination can often allow the system to use a smaller footprint by reducing internal walls/chambers and providing a sloped floor to the center and low point. Its efficient shape and small footprint mean less excavation and less land intrusion, reducing land use and maintenance costs down the road. 

Loading Requirements - The structural design of a stormwater retention vault beneath a road or parking lot needs to meet a load rating. The standard for a road is "HS20" though the rating is higher for places with expected heavier transportation such as an airport or firelane. Hybrid Vault's design allows it to be built to meet or exceed the needed rating at hand. 

The non-storable voids with pipe-based systems requiring select imported backfill, not only forces a larger footprint but incurs a cost and liability during construction. Sparks explains that if the imported fill dirt isn’t correctly placed, vehicles and construction equipment are at risk of damaging the piping such that it must be removed and replaced. This may cause an unsafe work environment and additional costs to the installer. The Hybrid Vault's rectangular design eliminates the need for backfill around pipes - not to mention the aforementioned liability during construction. 

This means ECC’s Hybrid Vault systems are rated to a higher, heavier traffic standard than typical structures, resulting in a more structurally sound containment system. Structural precast top slabs are designed to meet loading requirements before they leave the manufacturing facility and don’t rely on backfill or installation to achieve their intended design strength. 

Watertightness - Public agencies, municipalities, and civil engineers need assurance that stormwater retention systems will have both integrity and watertightness. ECC uses the same robust water-tight technology used in precast segmented tunnel liners rather than relying on grouted and/or welded connections. The moving water from a leaking underground water containment structure can erode fine backfill material, possibly creating settlement and sinkholes. The purpose of stormwater detention is to release the water from an impervious area back into the storm ecosystem at a controlled rate; a leak compromises this controlled rate.

Time, Cost, & Liability - The Hybrid Vault is an all-in-one system. Each step of a stormwater vault project (engineering/design, permitting, construction and site preparation, installation) is handled by a specialized engineer and contractor - each bringing different expertise and perspectives. Multiple contractors responsible for different steps create more liability. An all-in-one system, on the other hand, can be ideal for detention vaults because the liability lies with one contractor. "By installing the vaults ourselves, not only do we ensure the end product is constructed properly, we free up our clients’ crews to do other work which is very impactful in today’s labor environment," says Sparks.

...Containment

“ECC’s Hybrid Vault system provided us with a more cost-effective solution than having to piece together the design, engineering, product sourcing and installation of the different components of our stormwater containment system,” says Josh Erholm, project manager, Ram Construction General Contractors. “Because we didn’t have to coordinate across different vendors and service providers, ECC helped our project stay on schedule and budget.” 

ECC stormwater containment vaults are guaranteed watertight, and the company’s precast concrete products are produced in accordance with both NPCA and PCI guidelines. In addition, precast products, through SMaRT Certification, have been deemed to be the most environmentally-sound buried infrastructure product on the market, helping customers achieve their sustainability goals.   

“ECC is the only full-service stormwater containment solution in the Pacific Northwest,” says Sparks. “Because we are responsible for every step of the project, we can truly guarantee the functionality as intended. Our customers have one vendor to deal with, so it both simplifies the process and enables us to significantly reduce the cost while providing our customers with robust, environmentally sound solutions for stormwater management.”