ReBuilding Center 

3625 N Mississippi Avenue 

Portland, Oregon 

PROJECT SUMMARY 

Project Type: Complete onsite stormwater management for non-profit commercial 

redevelopment—demonstration project 

Technologies: Infiltration planters, flow-through planters, pervious concrete, drywells 

Major Benefits: • Over 870,000 gallons of stormwater infiltrated and treated onsite each year 

instead of entering the combined sewer system 

• Highly visible example of sustainable stormwater approaches 

• Adds green space and habitat to the urban environment 

Cost: $108,232 for stormwater management components, with $45,000 paid by EPA 

grant funds 

Constructed: 2005 

Overview of the Stormwater System 

• The ReBuilding Center is a non-profit community enhancement organization dedicated to the 

reuse of discarded building materials. It is a popular destination for people interested in 

building with affordable, environmentally low-impact materials. When the center built two 

new warehouse-type canopy structures adjacent to an existing warehouse, the design 

included onsite stormwater management for the new buildings and parking lot. 

• Roof runoff from the new Michigan Canopy warehouse is directed into two landscaped 

infiltration planters facing N Michigan Avenue. The infiltration planters have open bottoms, 

so the stormwater filters through plants, soil, and gravel into the ground. 

Infiltration planters along the Michigan canopy structure Infiltration planter 

• Roof runoff from the new Mississippi Canopy is directed into two flow-through landscaped 

planters facing N Mississippi Avenue and one flow-through planter facing the back alley. 

The flow-through planters have solid bottoms. After stormwater filters through plants, soils, 

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and rock sub-base, a perforated pipe at the bottom carries excess water to two drywells 

buried below the parking lot. 

• A 3,800-square-foot pervious concrete parking lot allows rain to soak into the ground. The 

pervious concrete is on top of crushed rock, which temporarily stores water as it soaks into 

the soil below. An inlet at the lowest point of the parking lot conveys overflow to an existing 

catch basin. 

The ReBuilding Center’s existing warehouse before the 

addition of the Mississippi canopy structure 

The flow-through planters in front of the new Mississippi 

Canopy with existing warehouse in the background 

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STORMWATER CAPACITY AND SYSTEM COMPONENTS 

Stormwater Management Goal 

The goal was to provide onsite stormwater infiltration and treatment and reduce the volume of 

stormwater entering Portland’s combined sewer system. The stormwater facilities were designed 

in accordance with the City of Portland’s 2002 Stormwater Management Manual.

System Components 

Facility footprint: 2,125 square feet (planters) 

Catchment area: 38,800 square feet (35,000 roof area and 3,800 parking lot) 

Overflow system: Drywells; existing catch basin 

Landscaping: The largely native vegetation in the planters includes red twig dogwood, Baltic 

rush, highbush cranberry, Pacific ninebark, tufted hairgrass, slender rush, Nootka rose, Pacific 

crabapple, Douglas spiraea or hardhack, common camas, yellow monkey flower, Douglas iris, 

and slough sedge. 
BUDGET 

The cost of stormwater components for this project was $108,232, with $45,000 paid for by an 

EPA Innovative Wet Weather Projects (IWWP) grant. Of this total, an estimated $21,930 (20%) 

was spent on non-construction activities, and $86,302 (80%) was spent on construction activities, 

as shown below. 

Budget 

[Note: Budget elements are estimates from the larger project 

costs.] 

Non-Construction Activities 

Project design and engineering: $18,215 

Project management: 1,675 

Permits and inspections: 2,040 

 

 $ 21,930 

Construction Activities 

Porous concrete parking lot: $34,155 

Infiltration planters: 11,603 

Flow-through planters: 11,171 

A downspout disconnected into the 

infiltration planters on Michigan 

Street Drywell: 6,900 

Landscaping (plants, soil, irrigation): 22,473 

 $ 86,302

MAINTENANCE AND MONITORING 

The property owner is responsible for maintaining the facilities to ensure proper function and 

appearance. Maintenance may involve removal of nuisance and invasive plant species, removal 

of debris and sediment, and preventing impedance of stormwater flow into, or overflow from, the 

facility. The pervious concrete parking lot will require occasional maintenance to ensure it 

doesn’t clog with sediment. 

The Bureau of Environmental Services (BES) will monitor the flow-through planters facing N 

Mississippi Avenue to determine their effectiveness. Flow monitoring equipment will record the 

amount of water that flows through to the perforated pipe at the bottom of the planters, indicating 

the volume of stormwater runoff that is not absorbed by the plants and soil. Data will be 

downloaded and recorded monthly. A manhole unit will house the equipment and allow BES 

staff to access and record the data. 

BES will provide periodic visual assessment of the pervious parking lot and infiltration planters 

to determine plant viability and facility function. 

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Manhole for accessing monitoring equipment Burying the manhole in landscaping area adjacent to the 

flow-through planters on Mississippi Street 

PUBLIC INVOLVEMENT 

A permanent interpretive sign at the project site provides information about the sustainable 

stormwater management techniques used. 

The project is used as an example of innovative stormwater management on the BES website and 

on BES tours of sustainable stormwater management facilities. 

The ReBuilding Center hosts dozens of tours each year to inform local, national, and 

international groups of its sustainable practices, including the stormwater management features. 

Following its renovation, the ReBuilding Center anticipates up to 300 visitors daily. 

SUCCESSES AND LESSONS LEARNED 

Positive project example: The ReBuilding Center is a good 

example of a successful public/private project. It is in a highly 

visible location in a fast-redeveloping area of the city, with 

other sustainable development projects occurring close-by. 

These projects provide opportunities for the public to become 

more aware of innovative stormwater management t

and other developers have expressed interest in using similar

approaches. In addition, the center’s customers benefit from 

seeing examples of the kind of onsite stormwater management 

they can implement on their own properties. 

echniques, 

Integration into the built environment: The pervious 

concrete parking lot and stormwater planters are commendable examples of how stormwater 

management can be integrated into small urban spaces and fit seamlessly with the building 

design. 

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Modified design: Monitoring by the landscape architect showed that the flow-through planters 

along N Mississippi Avenue were not infiltrating at the minimum two inches per hour rate 

requested by the engineer. Discussions followed about whether this was caused by clogged filter 

fabric, undersized facilities for the catchment drainage (approximately 75% of capacity)*, too 

many fines in the soil mix, or only six to eight inches of storage capacity on top of the soil 

(freeboard). It was also possible that, given time, infiltration may have improved with plant 

establishment.

The landscape architect concluded it was a combination of several of these issues. Because the 

facility sizing could not be modified, the following modifications were implemented to restore 

the function of the flow-through planters: 

• The plants, soil, and filter fabric were removed, and the rock subbase was reduced from 18 

inches to 12 inches (in accordance with the construction specifications and Stormwater 

Management Manual requirements). 

• Freeboard was increased to 12 inches. 

• The clogged filter fabric was replaced with a non-woven fabric, which was layered between 

the gravel subbase and six inches of washed pea gravel; this is expected to serve as an 

additional filter for settling fines. The fabric extends from edge to edge rather than up the 

sides of the planter wall. 

• The soil was replaced with a mix of approximately 70% sandy loam, 20% digested paper 

fiber, and 10% organic compost and installed in six-inch lifts to ensure uniform soil matrix 

distribution. 

• The downspouts were taken off-line temporarily (approximately three months) and diverted 

to the bottom perforated pipe to allow the soil to settle and bind before heavy storm events 

occurred. 

Drywells – The drywells for the flow-through planters are under the parking lot pavement. It is 

typical to place a manhole cover at the surface to allow access for monitoring and occasional 

cleanout when needed. Drywells can potentially fill with sediment, which could reduce their 

capacity to accept overflows from the planters. 

Pervious pavement – Soon after the pervious concrete parking lot was constructed, one third of 

the parking lot needed replacing because rainfall was puddling on top rather than infiltrating 

through the concrete. The manufacturer determined that the replaced section was a more dense 

mixture than was poured for the other two-thirds of the parking lot. 

∗

 The project was approved and constructed under the sizing guidelines in the City’s 2002 Stormwater 

Management Manual. These guidelines considered the entire catchment area rather than the drainage area to 

individual facilities; some planters could be oversized and some undersized as long as the aggregate square 

footage was correct. The subsequent 2004 manual revised the sizing requirements.