Portland Community College
OP-3: Water Use

The college has two rainwater harvesting systems. The largest one is at the Willow Creek Center where the water is used for irrigation as well as toilet flushing; 56% reduction in potable water consumption compared to a typical building due to landscaping and irrigation systems. 

On our Rock Creek campus, we have a rainwater harvesting tank that offsets the irrigation for the landscape technology program, saving about 23,600 gallons of water annually.

Over time, Oregon’s Phase I NPDES (National Pollutant Discharge Elimination System (NPDES) permitting strategies have become increasingly stringent, while simultaneously emphasizing low-impact development in the form of rain gardens, bioswales, ecoroofs and pervious pavers. Our newest buildings feature more and more of these low impact development features: the ones built in the last five years starting with the most recent developments are: the Opportunity Center at 42nd, the Sylvania Health Technology West remodel, and the Oregon Manufacturing Industry Center. The City of Portland operates under a Municipal Separate Storm Sewer System (MS4) permit and over the past twenty years, Portland's city code has also required increasingly sophisticated stormwater solutions. PCC is applying these solutions beyond city limits.

PCC Planning and Capital Construction has embraced stormwater solutions that emphasize features that slow, filter and infiltrate water on-site and mimic natural stormwater systems. Campus-wide water strategies include reductions in building water consumption, irrigation use, and sanitary sewer wastewater volumes. Stormwater management strategies that would dramatically reduce site runoff and ensure that 100% of site stormwater is treated were also emphasized. 

The Building and Grounds Department, with the help of Planning and Capital Construction, has installed and maintained many new bio-swales throughout the district to slow down, filter and infiltrate stormwater runoff naturally. The use of permeable pavers in our standards has also helped reduce runoff from our PCC FMS parking lots and our Buildings and Grounds team installs buffer zones of plant material to prevent erosion and sediment from getting into the ponds and waterways around the campuses that have them. Additionally, Buildings and Grounds and Environmental Health & Safety has a storm water injection management program (SWIMP) with strict guidelines for maintaining PCC storm water facilities. These landscape and physical features improve water quality across the district campus, in natural waterways and communities downstream. PCC uses techniques to handle stormwater such as engineered drains with filters, dry wells and vegetated swales to mitigate stormwater runoff. Dry wells are currently found across the district.

We created a rough inventory of our green infrastructure using the following sources:

The PCC Facilities Plan Phase 1 through the Landscape Open Space Report and  Utilities Assessment. 

Environmental Health & Safety: PCC’s stormwater program and maps and permits. 

City of Portland Maps, Permits and Operation and Maintenance Drawings.

Additional information about some of the highlights of our green infrastructure can be found here.

CLIMB green roof

Sylvania’s Stormwater Detention Pond

Willow Creek (recently repaired)

We also have the wetlands at the Rock Creek Environmental Center that we maintain as part of the region’s natural systems. 

We are in the process of inventorying the green infrastructure as part of our resiliency assessment; our estimate of the surface area of the green infrastructure alone is at a conservative estimate of 4 acres and growing, although we used a much smaller figure to compute 3.4 as explained below.

PCC has multiple stormwater infiltration systems that were designed to slow and treat stormwater runoff; the majority of campus systems operate with underground injection control (UIC), discharge directly to the ground and do not connect to the City system. On rare occasions there might be an overflow of a UIC to the City system.

The biggest exception is the PCC Sylvania campus and the Oregon Manufacturing and Industry Center where UICs are more challenging due to the soils and terrain. The stormwater facilities at PCC Sylvania meet pollution and flow-control requirements before discharging to the City system or nearby streams/creeks, so less of it is infiltrating to the ground. The OMIC location has a mixture of swales and a UIC.

We used a simple rainwater harvesting calculation (V = R*A*k*e) to estimate the amount of rainwater runoff that is captured by campus green infrastructure, changing parameter (e) dependent on the porosity of ground material (e.g., pavement vs soil). On-campus green infrastructure includes rain gardens, stormwater detention ponds, stormwater planters, vegetated swales; the total area of these constitutes A. Conversion factor k is 7.48 gal/cub ft, and R is the annual average rainfall in for the last three years in Portland, Oregon which was 45.05" over the last three years. The product was then converted to square meters for final reporting.

Square Feet of Green Infrastructure: 22,150.48

Average Annual Rainfall for last three years: 45.05”

K: 7.48

E: .8

Gallons / Year = 7,490,909.35

Cubic Meters/Year =28,353.18

Resources:

• CCAT small rainwater catchment

• Rainwater collection equation

• USGS Hydra Network

Calculating PCC’s Green Infrastructure 

Inventorying PCC’s green infrastructure is an ongoing process and part of the college’s current climate resiliency assessment work. We began with an inventory of campus green infrastructure from the 2017 Facilities Plan in the Utilities Appendix and added locations based on google maps. We attempted to use google maps to estimate the on-campus surface area for qualifying green infrastructure using google maps; however, we found that in comparing them to existing as-built drawings that the estimates were too high. We therefore decided it would be better to rely on the existing as-built drawings knowing that they would exclude much of our green infrastructure. We included the Southeast Campus, the Cascade Campus, parts of the Rock Creek campus and the Opportunity Center at 42nd. We left out green infrastructure from the the wetland at Rock Creek, Oregon Manufacturing Industry Center, Willow Creek (because it’s got a rainwater harvesting system) and the Downtown Center.  We did not include the majority of the green infrastructure from the Sylvania campus at this time, because the UIC system there is only partial. Despite knowing that we have UICs we used an efficiency rate of .8; which is likely closer to .9. Notably, what was not included was the surface area involved in permeable pavers at PCC. For these reasons, we believe our estimate is actually still quite low.