12/9/2004; ONRC 1 The property in 2002 before the project 

# Oregon Natural Resources Council

5825 N. Greeley Avenue, Portland

Project Summary

Project Type: Commercial stormwater retrofit – demonstration project

Technologies: Porous paver system; landscape infiltration basin; simple downspout disconnections (to splash blocks).

Major

Benefits: • Runoff from more than 13,000 sq. ft. of impervious surface (roof and pavement) has been removed

from the combined sewer.

• The stormwater facilities remove more than 300,0 00 gallons of runoff from the sewer in a typical rain year, with corresponding reductions in runoff pollutants.

• The project added 4,700 sq. ft. of native landscaping, improving the aesthetic appeal of the property and benefiting the urban environment.

Cost: $82,946 (unit cost of $6.00 per sq. ft. of impervious area managed). The total cost includes some components that were not essential to the stormwater management goals (e.g. a rain harvesting system and a bridge). Environmental Services provided a $30,000 grant.

Constructed: Fall 2002

Project Background The Oregon Natural Resources Council (ONRC), a non-profit conservation organization, moved to the site in 1996. ONRC was planning a comprehensive site re novation project in 2001 when it

received information about the Willamette Stormwater Control Program 1 . ONRC then contracted with a landscape architect to develop a proposal to completely disconnect the site from thecombined sewer system, managing the stormwater entirely onsite. Environmental Services accep ted the project into the Program

in 2001.

ONRC viewed the project as an opportunity to enhance the site renovation project to better exempl ify the sustainability goals of its mission. It wanted to provide an example of the environmental

benefits associated with on-site stormwater management, and save money on its stormwater utility bill.

1 Environmental Services implemented the Willamette Stormwat er Control Program in 2001. The Program offered financial grants and technical support for a series of projects to re trofit existing commercial propertie s with stormwater controls incorporating green technologies. The Prog ram recruited these demonstration projects in order to research the feasibility, cost and performance of commercial stormwater retrofits in the area served by the comb ined sewer. The Program provided grant funds for eleven projects. The projects were completed by July 1, 2003.12/9/2004; ONRC 2 Project Scope

• Removed all existing asphalt (approximately 9,100 sq. ft.)

• Installed a pervious paver system (5,500 sq. ft. of pavers for the parking lot; 250 sq. ft. for the patio).

• Installed a 1,700 gallon rain harves ting system to provide irrigation

water.

• Constructed a landscape infiltration basin to manage roof runoff and any overflow from the paver system.

• Planted almost 5,000 sq. ft. of landscape with native vegetation.

• Re-routed all roof runof f to landscape areas.

• Installed a small bridge and a gravel path.

Notable Features

• The entire site has been comp letely disconnected from the combined sewer system.

• The project includes two relativ ely new technologies - a rain harvesting system and pervious paver system.

• Retrofitting the parking lot resulted in the loss of four non-essential parking spaces.

• The large infiltration basin is in tegral to the landscaping at the building entrance.



### Project Design

ONRC contracted with the La ndo and Associates, Landscape Architecture Inc. to design the project. The stormwater management goal was to provide complete on-site disposal of all stormwater runoff.

Overview of the Stormwater System

• Approximately 1,200 sq. ft. of the roof on the south side of the building drains to adjacent lands caped areas via splash blocks.

• About 3,200 sq. ft. of roof drains to the cistern buried at the west end of the landscape infiltration basin.

• The cistern overflows to the ad jacent landscape infiltration basin.

• The pervious pavers infiltrate all rainfall that lands on the 5,500 sq. ft. parking lot. If the paver system ever reaches capacity, it would overflow to the landscap e infiltration basin. The new sign with the

infiltration basin in the
background; September 2003

View from the NW corner of
the property - note landscape

infiltration basin behind wheel
stops; February 2003

The walkway and the landscape

infiltration basin; June 200412/9/2004; ONRC 3 I. Introduction

The overall stormwater management goal was to meet the Bureau of Development Services (BDS) 2 standards for stormwater disposal. When BDS approved the project in 2002, the di sposal standard was to infiltrate

at least 3 inches of runoff in 24 ho urs (approximately the size of the 10 year design storm). All standards cited in this report were current in 2002.

City permit staff did not require site-specific infiltration tests as local drainage characteristics had already been adequately documented by other projects in the vicinity. The Natural Resources Conservation Service (NRCS) Soil Survey for Multnomah County classifies the soils as part of the Latourell Complex. The Survey gives an estimated infiltration range of 0.6 – 2.0 in. per hour.

II. Facility Components (See Site Plan, pg. 6, for more details)

Rain Harvesting System

Catchment Area : 3,200 sq. ft. of roof

Internal Volume (empty): 1,700 gallons (227 cu. ft.) Overflow : Drains to landscape infiltration basin. Capacity : A little under an inch of rain (.85 in.) will fill the cistern. The cistern provides stormwater capacity during the drier months when the stored runoff is used to supplemen t irrigation need s. If plans are

realized to reuse stormwater for to ilet flushing, the cistern will provide additional runoff capacity even duri ng the months when no irrigation is required. Additional Information :

• The cistern is buried at the west end of the landscape infiltration

basin.

• The cistern water is distributed for irrigation via a pump after passing through two sediment filters.

2 BDS is responsible for developing standards for stormwater disposal and inspecting proj ects to confirm compliance with those st andards. Detail of the pavers during

construction; October 2002

Installation of the pavers -
looking south toward the ONRC

office

Excavation of the landscape

infiltration basin - note workers
applying gravel to paver spaces

Excavation of the landscape

infiltration basin12/9/2004; ONRC 4 Landscape Infiltration Basin

Catchment : 3,200 sq. ft. of roof (runoff enters via the cistern) Facility footprint 3 : 520 sq. ft.

Internal volume : 660 cu. ft. (includes sub- surface gravel trench) Overflow : If the basin ever crests in a large storm, it will spill north across the parking lot, away from the building foundation, and fill the sub-base of the paver system before flowing across the surface to the public right-of-way. Capacity : The basin has a capacity much larger than the comparable standard eastside soakage trench 4 that would be required for a similar catchment. The soakage trench would have a footprint of 192 sq. ft.

and an internal volume of 200 cu. ft. Additional Information:

• The basin is linear and deep: in the main body of the facility the centerline is about 3 ft. below grade.

• A narrow gravel trench lies under th e east part of the facility. It is 20 ft. long, has a cross section of 12 in. by 12 in., and is buried

about a foot below the floor of the basin. Neither perforated piping nor filter fabric was used in its construction.

Porous Paver System (Parking Lot)

Catchment : 5,500 sq. ft. (as direct rainfall) Facility footprint : 5,500 sq. ft.

Internal volume : 1,650 cu. ft. (as pore space in the gravel sub-grade). Overflow : The bottom of the gravel laye r under the pavers slopes gently toward the adjacent landscape infiltration basin. While the paver system has an enormous capacity for runoff, overflows to the basin are possible. Capacity : The system has an extremely large internal volume compared to the standard eastside soakage trench 4 that would be required for a catchment of 5,500 sq. ft. (t he soakage trench would have a footprint of 330 sq. ft. and an internal volume of 345 cu. ft.). Additional Information:

• The pavers are 8 in. square and 3 in. thick.

• They are constructed of concrete and recycled fly ash.

• They are set in one inch of pea gravel with an 8-inch sub-base

of crushed rock.

• They were supplied by SF-Rima TM (by WestCon).

• The parking lot is pitched slightly toward the infiltration basis, so if rainfall exceeds th e infiltration rate, it will seep

into the basin.

3 For the purpose of comparing the capacity of the facility with the standard eastside soakage trench, the footprint has been c alculated as the wetted (ponded) surface area when the facility reaches maximum capacity.

4 The standard eastside soakage trench meets the City’s standard for complete stormwater disposal in soils which infiltrate at le ast 2 inches per hour. The City requires 24 feet of trench per 1000 sq. ft. of impervious area (drainage catchme nt). The trench is 3 ft. dee p, 2.5 ft. wide, and filled with drainage rock. Flow enters the trench through a pe rvious pipe that travels the length of the top of the trench. Assuming a porosity of 35%, the trench provides an internal volume of approximately 63 cu. ft. per 1,000 sq. ft. of catchment. The landscape infiltration basin
with final grading; October 2002

Arrival of the cistern

Installation of the cistern;

October 200212/9/2004; ONRC 5 Downspout Disconnections There are nine downspouts on the building. Six of the downspouts drain approximately 3,200 sq. ft. of roof, sending runoff to the cistern. Three downspouts on the south side of the bu ilding have been disconnected to splash blocks, draining to the adjacent landscape.

Emergency Overflow If the basin ever crests in a large storm, it will spill north across the parking lot, away from the building foundation, and fill the sub-base of the paver system prior to flowing across th e surface to the pub lic right-of-way.

Landscaping Most of the plants are natives selected from the plant list in the

Environmental Services Stormwater Management Manual. The plantings meet manual requirements for size and spacing. The designer selected species such as Red Osier Dogwood that grow relatively tall and respond well to pruning.

Irrigation The project included installation of a new permanent irrigation system with pop-up spray heads. It serves a total of 4,700 sq. ft. of landscape with water supplied by the cistern as we ll as City water (as needed).

Other Components A gravel walkway provides handicap access to the front entrance as required by City code. The gravel walkway was easily integrated into the landscape and provides a perv ious surface at a lower cost than pavers or

other Americans With Disabilities Act (ADA)- approved material. The bridge over the north end of the land scape infiltration basin connects the parking lot with the primary building entrance. Installation of rain drains within

two feet of fourndation; Octobe r

2002

Newly planted infiltration basin
after rain; January 2003

Newly planted infiltration basin
after rain; January 200312/9/2004; ONRC 612/9/2004; ONRC 7 

### Budget

ONRC provided the budget, which is detailed on the following page. The total cost for the project was $82,946 including management, design, and construction.

BES contributed $30,000 in grant funds to the project. Bureau costs for admini stering the grant program and providing limited technical suppo rt are not included in the budget.

Parking Lot Paver System – 5,500 Sq. Ft. Cost

Asphalt demolition, removal, export* $ 770.00

Excavation - parking lot subgrade $ 3,693.00

Sub-base - import and compact (8in.) $ 3,400.00

# Pavers - 9790 SF-RIMA pavers * $ 8,910.00

Installation - contractor labor $ 10,378.00

Installation - volunteers @ $10 per hour $ 936.00

Survey, setting bed $ 985.00

Erosion Control* $ 825.00

Wheel stops (7) $ 277.00

Paver protection - plywood rental $ 20.00

Total $ 30,194.00

Cost Per Sq. Ft. $ 5.49

* Calculated as a portion of a larger cost Costs For Parking Lot Paver System12/9/2004; ONRC 8 ONRC Budget Summary

Item Item Cost Total Cost In Kind Cost

Project Management $ 10,957.00 General management (ONRC) $ 9,367.00 Contract management (L.A.) $ 1,590.00
Design $ 2,359.00 Demolition, excavation, grading $ 13,441.00 Asphalt demo, removal, export (9100 sq. ft.) $ 1,325.00 Excavation - parking lot subgrade (6in. depth) $ 3,693.00 Excavation & grading - swale, patio, walk $ 3,140.00 Excavation - trenching for rain drains $ 693.00 Remove catch basin, cap line $ 250.00 Equipment rental $ 400.00 Excavation, etc. - cistern $ 1,720.00 Erosion control $ 1,365.00 Miscellaneous (waste export, recycling, etc.) $ 855.00
Construction Management $ 2,634.00

Construction: $ 31,568.00 Paver System & Patio - 5,750 sq. ft. Sub-base - import and compact (8 in.) $ 3,400.00 Pavers - 10,240 sq. ft.-Rima TM pavers $ 9,357.00 Installation - contractor labor $ 10,378.00
Installation - volunteers $ 936.00 $ 936.00 Survey, setting bed $ 985.00 Wheel stops (7) $ 277.00 Paver protection - plywood rental $ 20.00
Subtotal $ 25,353.00 Bridge Fittings for bridge & ramp $ 500.00 Plastic decking $ 1,072.00
Subtotal $ 1,572.00 Rain Water Harvesting System Concrete Cistern $ 1,850.00 System Pump $ 1,086.00 Piping $ 976.00 Electrical irrigation controls $ 731.00
Subtotal $ 4,643.00 Landscaping (4,670 sq. ft.) $ 16,058.00 Installation - contract labor, mulch, etc. $ 3,280.00 Transplant existing plants $ 600.00 Installation - volunteer labor ($10/hr) $ 320.00 $ 320.00 Irrigation $ 5,891.00 Plant material $ 5,967.00

Miscellaneous: $ 5,929.00 Permitting Coordination of submittal and appeal $ 2,865.00 Permit - Planning/Zoning/Land use $ 1,369.00
Permit – Environmental Services $ 787.00 Permit - Plumbing $ 423.00 Maintenance agreement $ 248.00
Subtotal $ 5,692.00

Other Porta-potty rental $ 187.00 Handicap paint and signage $ 50.00

Subtotal $ 237.00

TOTAL $ 82,946.0012/9/2004; ONRC 9 I. Budget Elements

Non-construction Activities The total estimated cost for management, design, and permitting was $21,642, comprising approximately 26% of the total budget.

• Project and Construction Management The total for project and construction manage ment was $13,591, comprising 16% of the total budget. Two ONRC staff managed the project, providing a total of 540 hours of effort over 18 weeks. They managed the budget, worked as lia isons between the designe r and subcontractors, and scheduled volunteer labor. Management also includes the landscape architect’s time for managing the contract an d overseeing construction.

• Design The landscape architect’s cost for designing the project was $2,359, comprising 3% of the total budget.

• Permitting Permitting costs, including the labor costs to coor dinate the original submittal and appeal, were $5,692, comprising almost 7% of the total budget.

Construction Activities Demolition, excavation, construction, and landscaping costs totaled $61,304, comprising 67% of the total budget. The paver system for the parking lot is th e largest single component, comprising 80% of total construction costs (see Table 2 at the end of this s ection). The rainwater harvesting system, including the cistern and related components, comp rises 15% of the construction budget.

• Demolition, Excavation, and Grading The site preparation activities, including rem oval of the existing aspha lt (9,100 sq. ft.), cost $13,441, comprising 16% of the total budget.

• Construction

The core construction activitie s, including installation of th e paver system, the rainwater harvesting system, and the bridge cost $31,568, comprising 38% of the total budget.

• Landscaping The project included almost 5,000 s q. ft. of landscaping (about one-t hird of the to tal site). It cost $16,058, comprising 19% of the total budget.

II. Cost Efficiencies

Paver System The cost of the porous paver system was $5.49 pe r sq. ft., including demolition and recycling of the existing asphalt, excavation, and inst allation of an 8-in. sub-base of crushed rock. The unit cost for the paver system is likely lower than typical since ONRC purchased the pavers at a discounted rate.12/9/2004; ONRC 10 Plumbing Extensive sub-surface piping was needed to extend the building’s downspouts to the cistern. The parking lot retrofit required only the capping of the existing stormwater inlet. The landscape infiltration basin did not require any piping for overflow events.

Landscaping Although the overall cost of landscaping was a signi ficant budget component, the unit cost of purchasing and installing the plants was relatively low at $ 2.00 per sq. ft. The permanent irrigation system added substantially to th e total landscaping budget, costi ng an additional $1.21 per sq. ft.

Asphalt Removal The unit cost for removing and exporting 9,100 sq. ft. of asphalt was $0.15 per sq. ft. for a total cost of $1,325. That includes removal of the sub-grade, wh ich was “almost non-existe nt” according to the landscape architect.

III. Cost Comparisons

This project is a good example of the type of inte nsive retrofit that a long-term property owner might undertake as part of a subs tantial renovation project. While part of the runoff is managed in a simple landscape system, the budget is dominated by the in stallation of the paver system. The stormwater harvesting system also makes this a more complex, co stly retrofit. It is clear that for some property owners the many long-term benefits associated with these approaches outweigh their co sts relative to simpler stormwater management approaches.



### Bidding and Permitting

I. Bidding ONRC contracted directly with Lando and Associ ates, Landscape Architects Inc. for design and construction management for the pr oject. Lando and Associates co ordinated the work schedule and approved the completion of work for each sub-contractor.

II. Permits

Plumbing Permit A plumbing permit was required for the following: disconnecting the downspouts; installing the subsurface rainwater harvesting cist ern; installing the backflow prev ention and irrigation system; and removing and capping the stormwater inlet in the parking lot.

Building Permit The City issued a commercial buildi ng permit for the project because it was part of a larger renovation project. The process included reviews for the adequacy of erosion control and grad ing plans, a review for compliance with the Environmental Services Stormw ater Management Manual (for water quality and flow control requirements), and a review for the cap acity of the system since the goal was to provide complete on-site disposal.

Planning and Zoning Review Due to the cost of the renovation project, the City required ONRC to meet curr ent parking lot standards for setbacks and landscaping. The project did not trigger other requirements related to conditional uses or12/9/2004; ONRC 11 overlay districts (such as tr ails, e-zones, plan district s, etc.). No reviews were required for transportation, pedestrian issues, or seismic issu es. A review for ADA access was required.

Appeals An appeal was required for the grav el path between the building and the infiltration basin. The City required a special review for the gravel walkways due to concerns about slope, gravel movement/failure and the safety of wheelchair access. The City also required an appeal fo r the commercial installation of a rain harvesting cistern. Note: rain washers (to treat the first flush of roof runoff) were not required

because the cistern water will be us ed for landscaping. Rain washers will be required if the water is used for indoor applications.

III. Permitting Issues

The City expressed initial concer n about the lack of a piped em ergency overflow for the landscape infiltration basin. ONRC then doubled the capacity of th e basin and demonstrated that if it ever reaches capacity it will overflow to the pe rvious parking lot without threatening any structures. City inspectors confirmed that the paver system was installed consiste nt with the manufacturer’s guidelines – the City did not have standards for paver syst ems at the time of the project.



### Construction

I. Summary

ONRC contracted for the installation of the pavers in the parking lot and patio, although a volunteer labor force provided some assistance. Volunteers also he lped with installation of the landscape. ONRC staff helped oversee the work and acted as a liaison to the desi gner. Construction began in September 2002 and was completed in December 2002.

II. Issues Paver protection - After the pavers were installed, the parking lot continued to se rve as a staging area for

other construction activities. To ensure the paver system was pr otected during construction, ONRC covered the pavers with plywood and tarp s to prevent sedimentation and clogging.

Rain harvesting system – The origin al plans specified a plastic cister n, however a decision was made in the field to replace it with a c oncrete cistern in order to accommoda te discrepancies between survey

information and actual field elevations. There were al so concerns about the buoya ncy of a plastic cistern and resistance to vehicle load (the cistern sits next to the parking lo t). The concrete cistern required an additional 16 in. of depth to provide clearance for its overflow pipe. The difference resulted in a corresponding deepening of the landscape infiltration basin.



### Maintenance and Monitoring

ONRC owns the facility and is responsible for main tenance. BES will monitor the performance of the facilities at ONRC for five years or more. Confirming the hydraulic performance of the facility will be a primary focus. The Bureau will also regularly evaluate the level of effort required to maintain the facility, the success of the planting regime, and comments from the owner. ONRC staff has volunteered to gather information about how visitors are influenced by the project and how they incorporate similar techniques

at their own sites.12/9/2004; ONRC 12 

### Successes and Lessons Learned

Good design – The landscape infiltration basin is an integr al part of the surrounding near the building’s entrance. The project demonstrates that stormwater ma nagement features can be integrated into attractive landscape areas rather than be ing designed as “facilities” re legated to peripheral areas.

Overall demonstration value – The project provides an example for ot hers interested in similar projects. In addition to being an importa nt educational tool that advances the City’s interests in sustainable site design, the project provides important lessons about the cha llenges of integrating new technologies given the existing City codes.

Space-efficiency of the paver system – This project demonstrates the space-efficiency of pervious parking surfaces. They do not require additional adjacent areas for stormwater treatment and disposal.

Pavers and clogging during construction – The project confirmed the paver systems may be vulnerable to clogging as a result of construction ac tivities, and that prot ecting the pavers should be a priority for any paver installation project.

Downspout rain drain pipes A couple of the downspouts are more than 40 ft. from the rain harvesting system (cistern) to which their drainage is piped. The designer successfully kept th e pipes at an acceptable elevation by positioning them

within two feet of the foundation for most of the di stance. At the time the project was implemented the City allowed stormwater pipes within two feet of a foundation at grades of less than 1%.

Owner motivation – ONRC viewed the project as an opport unity to support its environmental mission, improve the neighborhood, and reduce its stormwater utility bill.12/9/2004; ONRC 13