March 15, 2023

Anna Mann House | Portland, OR | MaxWell Drywell Installation

The Anna Mann House is a historic affordable housing development located in the Kerns neighborhood of Portland, Oregon.

In order to meet the City of Portland’s stormwater management regulations, ten 30 ft deep traditional drywells were originally specified for the project, which would require a large excavation area and a long construction timeline.

To minimize the space needed, Oldcastle Infrastructure technical experts conducted performance modeling, and developed an alternative solution using the MaxWell® deep infiltration drywell that reduced the number of drywells needed from ten to six.

The solution needed to deliver fast installation within a confined project site, utilize a reduced footprint, and provide cost savings over the design based on traditional drywells.

Challenge

Site restrictions such as existing buildings, narrow streets surrounding the property, and limited access to the site made traditional drywell installation difficult and expensive.

Using traditional stormwater management solutions to meet site parameters resulted in the need for 10 Conventional 30’ deep drywells, which required significant space for excavation.

Further, the solution needed to handle the water quality flow rate from 1.4 acres of impervious surface, or 1,300 gpm. The City of Portland required onsite stormwater elimination, which can be challenging when surface soil doesn’t infiltrate.

Solution

A MaxWell® drywell can be precision drilled and installed inside of an 8’ circular footprint, compared to the large excavation area that is typically required to install a standard drywell. These deep infiltration drywell systems are easy to install using one drill rig and onsite equipment.

Through a combination of primary settling chambers and 50 ft deep MaxWell® drywells, the team provided a stormwater management solution that reduced the number of drywells needed from ten to six, which significantly reduced both installation time and footprint.

MaxWell® drywells are an optimal solution for use in the Pacific Northwest when the surface soil doesn’t infiltrate and groundwater is fairly deep, because – at depths of up to 120 ft – the system is able to infiltrate at far greater depth,  providing access to more permeable soils.

Benefits

MaxWell® drywells are an industry-leading, sustainable deep infiltration solution for onsite stormwater management. With more than 50 years experience, Oldcastle Infrastructure’s design-build team has set the standard for drywell stormwater management.

The system’s ability to drill to deeper soil levels creates added head pressure, resulting in better system performance within a smaller footprint than traditional drywell methods.

Unlike traditional drywells, MaxWell® systems are easy to maintain, ensuring optimal performance throughout the life of the installation. Its compact footprint – the shaft is just 4 ft in diameter – leads to faster installation time, and reduced costs due to less area impacted by excavation.

The design-build philosophy ensures correct installation, and improves site safety by removing the need for general contractors to carry out complex and potentially hazardous installation activities.

“The MaxWells allowed us to reduce the footprint of the stormwater system, and since Oldcastle handles the installation, we can feel confident that the work was done correctly. Oldcastle provided great design assistance and remained engaged from concept to construction.”

Alex Wesolovski
Principal
Vega Civil Engineering