## East Holladay Park NE 130th and Holladay Street Portland, Oregon

PROJECT SUMMARY

Project Type: Parking lot construction with pervio us pavement—demonstration project Technologies: Pervious pavers Major Benefits: • Stormwater is infiltrated and treated onsite, rather than entering the piped

storm sewer system.

• The project enhances a neighborhood park and provides a unique educational opportunity.

Cost: $165,000 with $45,000 paid by EPA grant funds

Constructed: December 2005 through May 2006

Overview of the St ormwater System

• Because a new off-leash dog area was approved for East Holladay Park, a new parking lot

was needed to accommodate additional vehicle tr affic. The 5,225 square foot parking lot was surfaced completely with pervious pavers.

• Landscaped areas adjacent to the parking lot we re designed to capture any overflow from the entire parking lot.

• The project results in complete onsite stormwater treatment and infiltration.

Figure 1:East Holladay Park Parking Lot Before Figure 2: East Holladay Park Parking Lot After

1STORMWATER CAPACITY AND SYSTEM COMPONENTS

Stormwater Management Goal

The goal was to provide onsite stormwater infi ltration for the parking lot and demonstrate a stormwater management technique for parking lo ts. East Holladay Park has the first Portland Parks & Recreation parking lot to use perv ious pavers for stormwater management.

System Components

Facility footprint : 5,225 square feet

Catchment area : 5,225 square feet

Pervious Pavers The pervious pavers allow rain to soak into the soil below the parking lot, keeping it out of storm

drains. Fine rock and soil filter the ra in before it recharges the groundwater.

Landscaped Areas Landscaped areas north of the park ing lot are graded to capture overflow stormwater runoff from the parking lot and allow it to infiltrate into th e soil. Curb openings at low points in the parking lot allow the runoff to enter the landscaped areas. The planting bed surface is covered with river

rock instead of the usual bark mulch to slow the water and prevent erosion.

The landscaped areas have drought-tolerant, low-maintenance pl ants that are adapted to Portland’s climate, reducing watering requirement s. The vegetation includes black tupelo, cedar of Lebanon, goldenrain tree, rock rose, rugosa ro se, California lilac, ba rberry, creeping Oregon grape, and red flowering currant . The black tupelo trees tolera te both standing water and summer draught and have beautiful fall color.

BUDGET

The East Holladay Park project cost about $165,000, broken down as follows:

• Construction: $100,400 (61% of the project cost)

• Design and Project Management: $22,000 (13% of the project cost)

• Consultants and other costs outsi de the construction contract (p ermits, printing, water meter): $42,500 (26% of the project cost)

Portland Parks & Recreation provided $119,542, and an EPA Innovative Wet Weather Projects grant to the Bureau of Envir onmental Services provided $45,000.

Because the soils at this site are porous, an addi tional gravel base below the pervious pavers was unnecessary. This was a cost-saving benefit.

2Cost Comparisons

The installed pervious pavers, incl uding aggregate base (which was lo w-cost at this site, as noted above), cost $10.00 per square foot. Conventi onal asphalt paving (including aggregate base) would cost $3.50 to $4.00 per square foot.

MAINTENANCE AND MONITORING

Portland Parks & Recreation maintains this site. Weeding and mowing are incorporated into the regular maintenance schedule. The joints between pavers will be cleaned and refilled with fine crushed rock every few years to ensure long-te rm system infiltration. Once the drought-tolerant plants are established in about two years, irri gation will be limited to reestablishing replacement plants if needed.

The pervious pavers will be monitored to dete rmine how they handle stormwater and how they perform as a parking lot surface.

PUBLIC INVOLVEMENT

The Park Bureau worked with the local commun ity to site and size the parking lot. It was important to Parks to construct a park ing lot that was unique and beautiful.

SUCCESSES AND LESSONS LEARNED

This is the second pervious paver project in a Portland city park. Th is high-quality parking lot is

more suited to the small scale of the site a nd proximity to neighbors than porous asphalt. Neighbors have indicated that they lik e the appearance of the parking lot.

By visibly demonstrating appropriate stormwat er management, the project provides a unique environmental education opportuni ty for outer northeast Portland. An educational sign has been installed to identify the project’s environmental benefits.

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