Setting new standards for urban improvements, Heartwood Preserve will be a unique walkable hub with a central park, a commercial dis- trict, and new housing — all connected to restored prairies and forest systems. The jewel of the billion-dollar project is an eighty-acre Green- way system featuring thirteen carefully sculpted retention basins. This five-hundred-acre parcel of land lies within a watershed ravaged by storms — an increasingly common weather pattern. In 2019 alone, Eastern Nebraska was devastated by unprecedented flooding that cost over 1 billion dollars in property damages. The new Greenway System furthers traditional stormwater infrastructure design with a dynamic approach that will strengthen existing ecosystems, protect agricultural economies, and offer the people of Omaha an exceptional collection of amenities and experiences. Addressing storm water challenges was a critical aspect of planning for Heartwood Preserve, but from inception, my firm, Meyer Studio - Land Architects (MSLA), was determined to go beyond capturing and managing stormwater. We saw this as an opportunity to shape a more meaningful connection between people and their natural world. Prioritizing both aesthetics and function, we conceived a series of open spaces connected by a progression of 13 sculpted basins that will become a signature of the project. The series of limestone-clad basins will have the capacity to capture and store an estimated fifty- five million gallons — 170 acre-feet — of stormwater runoff. They have all been designed to accommodate 100-year storms with the peak discharge leaving the basins designed to mimic the pre-development agricultural field conditions. The basins have also been designed to provide water quality treatment of the first half inch of runoff (“first flush”), allowing sediment to settle out prior to stormwater runoff en - tering the public sewer system. MSLA collaborated with project civil engineers, Lamp Rynearson, and the engineers provided by the general contractor, Meco-Henne, to design the basins. While watershed calculations and space constraints were the basis for all 13 basin designs, we worked to create a collection of distinct spaces that reflect their immediate surroundings and complement the whole sinuous form. Models helped MSLA refine the size and shape of the basins, which range from elliptical and near-perfect rounds to narrow, linear forms. These iconic spaces will change constantly. Whether full of water, dry, marshy, or frozen solid, the basin clearings will provide a range of experiences and contribute to a unique and timeless place. A HOLISTIC APPROACH TO MANAGING FLOOD WATER Heartwood Preserve, taking shape in Omaha, Nebraska is one of the largest urban spaces under development in the U.S. By David Meyer
Crescent Basic #1 is approximately 500 feet in length and 16 feet deep
Simple materials and careful craftsmanship carry through the system. A noteworthy aspect of Heartwood’s construction is the consistent use of limestone. The stone, quarried, saw-cut and split in Minnesota is largely responsible for Heartwood’s strong, timeless feel. While used throughout the project — as in parks and parkway terraces — the mate- rial is used to reinforce the walls of every retention basin. Due to the basins being close to property lines we could not always stay flatter than 3:1 slopes for basin walls and still meet volume goals. The neces - sary 1:1 and steeper slopes are bolstered with stone blocks that measure 2-feet tall by 2-feet deep with lengths up to 4-feet. The exposed faces of the blocks were split faced while the tops, bottoms and internal faces were saw cut to facilitate leveling and tight-fitting joints. All stonework is dry stacked and pinned with dowels where required to anchor steeply stacked units. In total, the project will use approximately 26,000 tons of stone. To add consistency and further the formality of the forms, storm lines were routed to enter all 13 basins on axis. To call attention to the in - coming water, weathered steel frames were embedded into the stepped Crescent Basin #2 is already hard at work, the basin is recharging the aquifer and serving frogs, birds and all sorts of Nebraska critters
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DECEMBER 2021 csengineermag.com
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