Graywater Reuse in the Apartments at Bud Clark Commons

Bud Clark Commons is an eight story LEED platinum building, owned and run by Home Forward, previously known as the Housing Authority of Portland. The facility provides 130 studio homes to residents of Portland that are experiencing homelessness – offering them transitional housing and support services while they seek permanent housing. The first floor has a 90-bed men’s shelter, a community resource center that includes shared laundry facilities and a courtyard for residents.

The Greywater recycling system uses wastewater from showers, bathtubs, residential clothes-washing machines, known as graywater, to flush toilets throughout the building.  It uses wastewater from the community laundry machines used by residents, but it does not currently take water from the commercial laundry facility or the sinks in the community laundry room because of the great amount of lint coming from those laundry sources.

The graywater from showers drains to an initial holding tank in the floor of the first floor loading dock, uses ejector pumps to move it through a two stage filtration, then to another holding tank in the floor of the loading dock where it is chlorinated, and then a series of Well-X-Trol pressurization tanks that regulate the flow and pressure into toilets. Blue dye was used to indicate to users that the water is not potable. The two-stage filtration includes self-cleaning filters to remove initial solids (lint, debris, etc.).

The project also uses stormwater swales along the property and within the courtyard to provide attractive greenery and to pre-treat stormwater from buildings’ roofs.

With the combination of low flow fixtures, rainwater pre-treatment in the courtyard planters, and greywater for toilet flushing, the building uses 53% less potable water than a conventional project.

According to Holst Architects:

We chose to install a graywater system rather than a rainwater system for four reasons: 1) The State of Oregon had recently begun to allow graywater recycling in commercial buildings and our client wanted to use this project as a case study. 2) Stormwater management was already being implemented in the design to limit runoff of rainwater. 3) Significant sewer cost savings could be realized by recycling graywater to toilets. 4) Because graywater is produced all year long without a dry season like rainwater, significantly smaller tanks could be installed on the tight urban site conserving space and installation cost

According to PAE, the engineering team for the graywater system:

The initial filtration was not adequate and was updated to better deal with the amount of fine lint collected from the various laundry facilities in the building and the size of debris being collected from the other greywater sources. It was surprising to find bigger debris (corn and hot dogs) that was clogging filters and strainers throwing the system into alarm and causing it to turn off frequently.

The following modifications were made to the initial filtration system:

• Lint traps were added to the laundry machines to mitigate the amount of lint collected in the initial holding tank.
• Grinder type pumps were then installed to break up the lint and solids collected.
• Self-cleaning filters were added to reduce the amount of initial maintenance we observed (Personal Email August 2016).

Operations and Maintenance

Initially the system needed twice a day inspection and maintenance.  After the facility manager reported several days of on and off clogging that shut down the system with a lot of lint and large debris, the above changes were made to reduce maintenance. Daily maintenance is required for the first stage filtration where lint is removed and to check the chlorine tablet dispenser. Chlorine tablets are consumed at different rates and need to be checked visually.  The self-cleaning filters are set to self clean once an hour using city water to flush out the filters. The sewer grinder pumps no longer require routine maintenance. Weekly and twice a week chores include cleaning the second stage filtration, checking the chlorine levels in the greywater storage tank. Every month the greywater pump filter is cleaned.

Financing for the building was provided by City of Portland, State of Oregon, Multnomah County, US Department of Housing & Urban Development, and Wells Fargo.

Some reflections from PAE, the engineering team for the graywater system:

The biggest lesson was regarding filtration – we did not anticipate the quantity and size of the lint collected from the laundry facilities. The lint was very fine and gummed up strainers and filters.

We also did not account for the large debris (corn and hot dogs) collected and the impact on the ejector pump system.

For our project and building type, the greywater system made a lot of sense. We had a great year-long supply of greywater from the various facilities within the building and a constant usage that was consistent throughout the year. We considered a rainwater system but decided to stick with the greywater as rainwater is only available for a part of the year.

PAE posits that one of the reasons there are so few indoor graywater reuse systems is because rainwater treatment systems are more cost effective because there is less treatment and thus less filtration and cleaning needed with rainwater compared to graywater. Another possible reasons for few indoor graywater projects is that graywater goes septic within 24 hours if not treated or used. Treatment must be continual if greywater is to be stored for longer period of time with use, which adds cost and complexity.

• Statewide Alternative Plumbing Method