Ohiopyle State Park, southeast of Pittsburgh, is well-known for kayaking and rafting through the rapids on the Youghiogheny River, hiking, mountain biking and other activities. As the largest and most-visited park in the Pennsylvania state park system — more than 1.5 million people annually — Ohiopyle needed a visitor’s center capable of serving a wide range of needs. The longstanding focus of park activities has been the waterfall near the borough of Ohiopyle. However, this central location offered limited services and an inadequate set of restrooms. There was no sense of welcome to the park and little information about the availability of activities, such as the mountain biking potential on routes that include part of the Great Allegheny Passage Trail.
In September 2014, the 11,500-square-foot Ohiopyle State Park Office/Laurel Highlands Falls Area Visitor’s Center started serving the public. Its official grand opening took place in June 2015, and the center now provides office space for park staff, restroom facilities for visitors and interpretive displays about the park.
To carry out its mission of environmental stewardship and sustainability messaging, the Pennsylvania Department of Conservation and Natural Resources (DCNR) adopted criteria in which certain buildings are designed to qualify for U.S. Green Building Council LEED certification. DCNR currently has 10 LEED-certified and seven LEED-registered buildings. An unusual water-treatment solution has helped the newly built visitor’s center to gain some LEED points for innovation. As of mid-June 2015, LEED Gold certification has been applied for, but not yet awarded.
Biological Wastewater Treatment, with a Twist
The water-management steps taken at Ohiopyle provide some useful lessons for other organizations seeking to manage their water impacts. As part of the journey toward LEED certification, the design team decided to incorporate biological treatment for sewage. This system would use a primary treatment tank that flows into a constructed subsurface wetland outside the building. The water flowing out of the wetland is then drawn back into the building and run through indoor tanks located in a portion of the building that has large windows to provide natural light for the tropical plants used to help polish the treated water. The treated flow from this process can then be used for flushing toilets and urinals where potable water is not needed.
In order to sustain the plants used in this type of treatment system, there must be a steady, reliable flow of nutrients in the wastewater. As is the case with many public parks, the flow of visitors to Ohiopyle peaks on summer weekends when crowds show up to raft, kayak, hike, bike and just stroll around the grounds and for the many festivals held each year, which bring in tens of thousands of people.
During the workweek and the winter, the significant drop in visitor traffic would have posed a problem for the biological treatment system because of this reduction in wastewater flow. However, to address this issue, the designers capitalized on the location of the center near the borough of Ohiopyle.
The borough has a conventional lagoon-based municipal wastewater treatment plant with a sewer main running directly through the project site that could be tapped into when there was excess sewage flow from the visitor’s center.
Having the public system available to handle overflow events eliminated the need to install large equalization tanks which would have required significant excavations in hard rock and added major costs to the overall project. This solution has resulted in “innovation points” for the facility’s LEED application.
Stormwater Management and Cooling, Thanks to a Green Roof
The location of the visitor’s center near the Youghiogheny River means that it is particularly important to manage stormwater flow from the building’s roof. The solution was to install a green roof, which causes some of the precipitation on the roof to be absorbed by the soil, rather than immediately running off the roof. The soil also helps to clean the water so that it can be collected in a storage system and then used to irrigate the green roof during dry weather. By using captured stormwater for this irrigation, there is no need to use potable water, which would be counter to the project’s overall sustainability efforts.
Part of the building is below grade and is covered with soil and vegetation to form a natural-looking green roof. Many visitors do not even realize that they are walking on the structure’s roof and not on a natural hillside. This extensive part of the green roof has deeper soils, which allow for the planting of ornamental grasses and woody plant material. The remainder of the roof is covered with a tray-based vegetated-cover system, also known as an “intensive” green roof. The vegetation in the trays is limited to groundcovers and, in most cases, is a sedum-based plant palette.
The green roof also has a LEED- oriented benefit in that it reduces the load on the HVAC system, because the sun’s rays do not strike the roof directly. Energy use is also reduced by having part of the building below grade, so it can benefit from the insulating capacity of the earth.
Geothermal HVAC Systems Moves from Exotic to Practical
To further boost the “sustainability quotient” of the building, the designers incorporated a geothermal HVAC system to provide heating and cooling for the building. This energy source has, over the years, moved from being seen as an exotic, leading-edge technology to one that is proven and practical. Depending on the season, the visitor’s center uses vertical geothermal wells to help pre-warm or pre-cool the air in the building.
Since there are no unusual geothermal sources such as geysers or hot springs at this site, the system works on the principle that the temperature several hundred feet below ground is a reasonably constant 52 – 55 degrees Fahrenheit. It starts with drilling multiple vertical boreholes, running piping that conveys a circulating glycol-based liquid from the building down into the ground and then using the surrounding geology as a large underground heat exchanger.
It is important to note that geoenergy is not practical in all locations. But, unlike in an urban setting, most parks have a slight space advantage so they are not constrained by the fact that the wells must be drilled over a wide area.
Working “Green” into the Solution
It is clear from this project that building “green” requires an understanding of a wide range of technological possibilities. It also requires careful analysis of the site, and factoring in the strengths and limitations it offers, to develop a workable solution.
Michael W. Takacs, RLA, ASLA, is Principal in the Pittsburgh, Pennsylvania, office of Civil and Environmental Consultants Inc.