Contractor's Corner

Contractor’s Corner | What a Zoo!

Contractors unite to upgrade koi-feeding exhibit

CACs working together to set this large log in the perfect spot in the wetland area.

In July 2019, we received a phone call from Mary Anne Hahn, owner of the Catoctin Wildlife Preserve and Zoo, a family-owned nonprofit organization in Thurmont, Maryland. She explained that they were experiencing problems with their koi-feeding experience exhibit at the zoo and asked if we could come by and determine what was going on.

Upon arrival, we learned that their main pond pump was not working, and two of their biofalls waterfalls hadn’t been running for years. The water was very murky and green from algae growth. They needed to get their situation resolved quickly. The zoo personnel had built this pond themselves more than a decade ago using a myriad of components and ideas from others. Over the years, different specialists from other zoos — even Sea World — tried different approaches to resolve the pond’s issues, but none of them had worked.

After giving them an initial price quote on getting their systems up and running again, it just was not something that the zoo could afford.

The Catoctin Wildlife Preserve has been a part of the Catoctin Mountain community for more than 50 years, and before that, it was a local snake farm. We care very much for our little mountain community, so after discussing the situation with our team, we gave the zoo one of our used pumps to at least get their water flowing again and provide aeration for the fish until something else could be worked out. We informed Hahn that we would reach out to Aquascape and our local distributor, Turf Equipment and Supply, to see if we could get some help.

After several emails and phone calls back and forth with key Aquascape personnel, the project was approved for an Aquascape Training Event to be held in November 2019. Tim Cleary from Turf Equipment and Supply promoted the event to area contractors and CACs and helped register them for the event.

A view of the Koi pond exhibit from the intake bay while work was still progressing on other areas.

In order to keep their costs down, the zoo’s maintenance staff helped us by removing all the existing vegetation and old pond components and plumbing lines, including a small building that housed many filters and plumbing connections. They pumped out the existing koi pond and relocated their beautiful fish. We made several site visits throughout this time to consult and assist the team as needed. Also, we were able to rent some of the excavation equipment free of charge for about three weeks, thanks to the local dealer’s interest in the project.

The biggest challenge would be our limited access to the location. The koi pond was in the middle of the zoo. Once inside the exhibit area, there was only one narrow pathway with an overhead electrical wire, and you could only access the pond itself with equipment from one side. Needless to say, getting all the stone we needed for this project dumped into the wetland area and shoveled around would be a major undertaking.

The first thing we tackled was the koi pond itself. We removed the old liner and carpet padding and reshaped the pond so that it had distinct vertical pond edges. Then we added woven geotextile (filter cloth underlayment) fabric for underneath the liner. Next, we rolled out (with the help of the zoo crew) a 50-foot-wide roll of EPDM 45 mil “fish safe” liner that weighed about 1,200 pounds. Once the liner was in place, we began covering the liner with rocks and gravel. Thankfully, the zoo already had all the rocks and boulders we needed on the property.

The intake bay was 11 by 15 by 3 feet deep. The weir opening was 9 feet at the mouth of the pond and narrowed down to a 5-foot-wide stream before it enlarged to a 6-foot opening into the intake bay itself. We used a mid-sized excavator to dig the hole as specified.

The next steps were to add the geotextile underlayment and then to install the remaining section of the liner roll into the intake bay. We used one large piece of liner for the pond and intake bay so that there were no liner seams.

The wetland waterfall going into the main pond.

After completing the intake bay, we moved on to the installation of the smaller waterfall. We set the Aquascape Signature Series 2500 Biofalls and shaped the stream coming down into the pond to give it the look of a narrow, meandering mountain stream. We set a large tree stump as an accent piece that would also hide the biofalls from the main viewing area.

The wetland filtration area was custom designed to handle the population of large koi that would be handfed throughout the day. The challenge here was groundwater. When we dug down about 5 feet deep, everything was fine, but that final 6 inches in the trenches for the centipede modules filled up with water overnight due to the many underground springs. This water had to be pumped out, with stone dust added to the trenches before the underlayment and liner could be installed.

While the main waterfall was still under construction when our 4:00 p.m. deadline came and went, we were able to use headlights from several pieces of equipment to keep the area lit while Ed Beaulieu and his dedicated team continued working. At about 6:30 p.m., it was time to flip the switch on the three 9-PL pumps that feed the wetland filter and provide about 21,000 gallons of water per hour over the waterfall spillway. It was a beautiful sight.

The Kingdom Crew – Left to Right – Jodi Tyler, Tabitha Ashby, Michael Tyler, Matt Tyler, and Tom Tyler

When we returned the next day, the water level was down less than ¼ inch, which wasn’t alarming because the rocks and gravel were absorbing water. We checked all the edges in daylight and only found two areas around the wetland that needed to be fixed. We spent the rest of the day trimming liner and underlayment, shaping edges, setting more rocks, backfilling the edges and plumbing lines with soil — basically doing everything we could to make this renovated koi exhibit look at natural as possible.

By the end of the day, we were amazed at how much we had accomplished. Whenever faced with the impossible, just take it one step at a time, and that’s what we did. Even though our crew is small — Jodi, Tabitha, Michael, Matt and Tom — we make up for it in passion, determination, skill and artistry.

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