Water Under the Bridge

By John F. Oyler
Copyright © 2016



The Pittsburgh Botanic Garden
September 22, 2016



My daughter Elizabeth, my grand-daughter Rachael, and I visited the Pittsburgh Botanic Garden one recent Saturday afternoon. Getting there turned out to be a bigger challenge than we anticipated. Google Map took us out the Parkway to the Campbells Run exit, then southwest to the site. Right after we encountered a sign saying two miles to the Botanic Garden, we ran into another informing us that Baldwin Road was closed.

No problem, we will detour down McMichael to Rennerdale and take Noblestown west to Pinkerton and we’ll be home free. This we did and were rewarded with a sign saying half a mile to the Botanic Garden, which initiated the sarcastic “That was a long mile and a half!” Almost immediately we encountered a very large tree down across Pinkerton – foiled again!

Confused, we turned around and headed back toward Noblestown Road. There we encountered a man in a Volkswagen who flagged us down and inquired if the road to was indeed blocked. When we confirmed that it was, he replied, “I am the bartender and am going to the Botanic Garden. If that’s where you are going, just follow me.”

Bar tender at the Botanic Garden? Nonetheless we did follow him through narrow, winding back roads till we finally got onto Pinkerton Road on the other side of the Garden and quickly reached our destination. There we found a large group of people who obviously were attending a wedding, and who eagerly awaited the arrival of the bartender.

The Pittsburgh Botanic Garden is the outgrowth of the Horticultural Society of Western Pennsylvania, a well-meaning group of landscape architects and horticulturists who got together in 1988 to effect horticultural improvements in the Pittsburgh region. Their dream of creating a botanic garden came to fruition in 1998 when Allegheny County offered them 432 acres in Settler’s Cabin Park, an area that had suffered from decades of surface and deep coal mining.

They formed a not-for-profit organization, the Pittsburgh Botanic Garden, to take on the challenge of reclaiming this land and remediating it for use as a massive horticultural facility. A major task was removing the remaining coal on seventy two acres of the site and returning the surface to arable land. This “daylighting” process is finally close to completion.

An equally difficult problem was the presence of abandoned mine drainage and its pollution of the water supply on the property. I was aware of this problem because of a senior design project a group of our students did twelve years ago. Someone from the Horticultural Society had contacted us and inquired if we could have some students study several infrastructure problems associated with the botanic garden they were planning.

At that time the proposed site was southwest of the current location, on McGill Road, rather than Pinkerton. We were asked to study access alternatives to the McGill Road site and to recommend a remediation system for an abandoned mine (acid) drainage problem at a source in Kentucky Hollow.

We assembled a team and put its environmental engineering members in contact with Dr. Bob Hedin, whose company, Hedin Environmental, dominates the acid mine drainage remediation field. Our team made numerous visits to the site before coming up with a design, with the help of Hedin Environmental, for a system that would convert this problem stream of water into a useable resource.

The McGill roadway design and the abandoned mine drainage remediation design were submitted to the Horticultural Society folks and helped them justify going ahead with the planning of the Botanic Garden. The final location of the Garden is on Pinkerton Road, and the acid mine drainage remediation system treats a source in a different hollow.

I was particularly eager to inspect the actual system that Hedin Environmental eventually installed and was frustrated that there really was very little to see. The outflow from the treatment system feeds Lotus Pond, a lovely small body of water currently sporting blooming water lilies. The Pond is the centerpiece of an Asian-themed environment, complete with cherry trees, a classic arched Oriental style bridge, and the beginnings of a Zen garden. It is easily the most impressive thing we saw.

Turns out the Zen Garden is built on top of an underground reinforced concrete chamber housing the acid mine drainage remediation system. The chamber contains 450 tons of limestone. The polluted water is fed into the chamber where the acid in it reacts with the limestone and is precipitated. The remediated water then is discharged into the pond at a rate of less than ten gallons per minute. I am pleased that this final design is so similar to what our students had proposed in 2004.

Once a week the chamber is flushed out and the sediment on the limestone is washed down to a pair of settling ponds, well below Lotus Pond. The net result of this remediation project is impressive and should serve as an incentive for further efforts to reduce the impact of acid mine drainage in the Chartiers Creek watershed. The Lotus Pond restoration project received the 2014 Governor’s Award for Environmental Excellence, a well deserved honor.

At this time the Botanic Garden has concentrated its efforts on the sixty acres that make up the Woodlands Garden; we spent most of our time there. The trails are pleasant and there is sufficient signage to help everyone identify trees and plants in it. The complex also includes extensive flower gardens, a “Heritage Apple Orchard”, and a log house dating back to 1784.

When I think about all the pleasure I have received from my twice daily walks in the woods near our house, I realize the remarkable potential of the Pittsburgh Botanic Garden for Allegheny County residents who are not as fortunate as I am. Imagine looking forward to the first trillium bloom of the Spring, the maturity of may apples in the Summer, and the glorious carpet of oak and maple leaves in the Fall.

It is always a special treat for me to visit a completed project and realize that some of our students have made a relevant contribution to its implementation.

Water Under the Bridge

  • "Water Under the Bridge" is a column written by historian John Oyler. It appears weekly in the Bridgeville Area News, a TribTotal Media publication, as well as in a more expanded form on his blog.

The Author

  • Aside from being Bridgeville's foremost historian, Dr. John F. Oyler is also an associate professor at the Univeristy of Pittsburgh, where he teaches classes in civil engineering.

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