WATERSHED PROTECTION

By Cecily Sakrison, U Water Center

Some come to the Natural History Museum of Utah for the world-class dinosaur exhibit, others are drawn to the vast collection of gems and minerals. But if you’re interested in sustainable engineering and infrastructure, you’ve arrived at your destination the moment you park your car.

PHOTO CREDIT: Cecily Sakrison

Michael Martin, NHMU Facilities Manager shows the 80mm depth of the pavers which are designed to withstand an exceptional amount of pressure.

It could be argued that the museum’s newest exhibit is its “50-year parking lot”—an engineering feat that’s “almost unheard of in Utah,” said David B. Alter, vice president of Ensign Engineering and project manager for the lot upgrade. With the pressures of ice, snow, salt and plows it’s rare that any parking lot in the Beehive state lasts anywhere near the half-century mark. But, this is no ordinary parking lot.

The LEED-certified NHMU building opened in 2011 with a bevy of site-specific, environmentally sensitive design solutions including planted roofs, solar panels, water-catchment cisterns and a pervious concrete parking lot surface designed to let stormwater runoff percolate back into the soil. The original lot’s high porosity was very effective but, over time, the lot started requiring increasingly numerous repairs and additional maintenance expenses due to uneven surfaces.

At the urging of the museum board, NHMU elected to upgrade to highly durable, permeable concrete interlocking pavers. A coarse sand-filled expansion joint around each paver allows water to percolate deep into the soil below, naturally filtering and recharging groundwater and eliminating the need to transport water off-site through additional infrastructure.

“The base layer had already been established,” noted Alter. “To lose that would have been a real shame.” Alter referred to the 2-3 feet of crushed rock that was reverse-slope graded back into the hillside and had been laid for the museum’s original lot. It’s the most important element of a permeable parking lot yet sometimes overlooked. “It’s so important that the whole system is properly engineered,” said Abby Curran, NHMU’s  Chief Operating Officer.

PHOTO CREDIT: Michael Martin

Project managers were able to design the installation plan to keep the museum’s lot open throughout construction with the exception of 3 days when crews worked to pave the entrance.

“When we pave a surface we increase stormwater runoff and that can lead to problems.” said Civil Engineering Professor Christine Pomeroy.  “Excess runoff can cause erosion in urban waterways. It can flush out fish and insects that live in our streams. But it’s not only about bugs, bunnies, and treehugger stuff—erosion from high volumes of runoff can damage infrastructure, creating financial impacts.”

Many Wasatch Front residents don’t realize that, unlike water that’s funneled through the sanitary sewer system, anything that’s flushed down a storm drain goes straight to the valley’s creeks, rivers, ponds and canals. A General Public Stormwater Telephone Survey Report conducted in December 2017 for Salt Lake County found that “only 10 percent of respondents were correct when they said that ‘none’ of the county’s stormwater goes to a treatment plant.”

“Our streams can better maintain a healthy ecosystem if they’re not inundated with excess water,” notes Pomeroy.

Michael Brehm, U environmental compliance manager added “Nearly 10 years ago, the U adopted design standards and initiated policy and programs to accelerate the adoption of best management practices for stormwater. As we develop more of campus, the potential to interrupt the natural infiltration of rain becomes greater.  We’re aware of this and, in response, we’ve updated design standards to replicate natural recharge of water as closely as possible.”

The museum’s respect for and sense of place guided both the re-paving decision and process. Old concrete went to a reuse facility, new pavers were machine-layed for time and cost efficiency and half-pavers that were originally “waste product” of the machine-laying process were repurposed as borders.  “The exterior of the museum is just as important as the interior,” said Curran. “We have many programs that take advantage of our natural, native environment. Being mindful of that space and its natural systems enriches what we can offer our visitors.”


Watershed Stories is a series exploring water work across the University of Utah campus. The stories are curated by the U Water Center, the Sustainability Office and the Global Change & Sustainability Center.