Striking A Happy Chord

The story of Mandolin Gardens Park in Houston, Texas, is one of vision and perseverance. What once was an unsightly, utilitarian detention basin dividing two areas of a suburban community has now become a beautiful, ecologically healthy park that draws residents outdoors, fosters neighborliness, and inspires others in the region to visit. The original basin was minimally maintained, was uninviting due to dense vegetation and unsafe access, and discouraged residents from using the green space. The park now provides recreation while protecting adjacent homes from flood damage. The design also includes wildlife habitat, reclaimed water for lakefill and irrigation (non-potable water use is very important in high drought areas like Texas), and durable native and naturalized plants that withstand inundation during flooding. This is all achieved with a chemical-free landscape and lake installation with ongoing maintenance.

Mandolin Gardens is an 11-acre park in the heart of a 2,000-residence suburban community. The site design retrofitted two existing detention basins and integrated park amenities, including:

• Two miles of ADA-accessible trails
• Experiential play areas for children
• Plazas
• Overlooks
• Native habitat.

The improved site design also provides an additional 13-percent water-holding capacity to help prevent flooding in the adjacent community and downstream. The ponds, streambeds, and vegetated habitat on the edges of the islands have been designed to remove pollutants and sediment. Holding water in the ponds allows for groundwater recharge.

Defining The Project

When the project was initiated by the Harris County Municipal Utility District (MUD) No. 230, it sought to build a trail around the upper bank of the detention basin. With subsequent trails planned to connect adjacent communities, Talley Landscape Architects Inc. was employed to provide the design. As meetings between the utility district and landscape architect Merrie Talley progressed, other possibilities for the site came to light. These included:

• Adding a secondary trail as a lower loop to create elevation change (a desirable characteristic in a landscape as flat as Texas)
• Digging out the detention basin further to allow for constant fill in the bottom of the basin
• Creating ponds to be enjoyed by residents and providing habitat for wildlife
• Constructing habitat islands in the center of the ponds so birds had protected places to nest and forage
• Providing pavilions, benches, sculpture, fountains, and 18 inspirational quotations engraved in the walkways.

Expanding the scope of the project was made possible through collaborative planning with the district’s engineer—Dannenbaum Engineering—including a dialogue with artisans regarding the creative use of boulders to stabilize steep slopes and obscure infrastructure in the basin. The boulders also stabilized slopes for extensive planting of butterfly-friendly plants. Strategies that led to the expansion of the project included using reclaimed water from the water-treatment facility that the district manages for lakefill and irrigation. Eliminating the use of potable water led to a considerable cost savings for the district—not only in saving the cost of potable water—but also because of financial incentives for using reclaimed water in Texas. Other sustainable features include the choice to use biological systems in the park instead of chemicals, such as petroleum-based fertilizers, herbicides, and pesticides. These management practices are anticipated to save money in the long run, although these are cost-competitive with traditional landscape maintenance at this time, partially due to the need for more careful observation of the site, and partially due because maintenance crews must learn new techniques to manage the site.

A Thriving Ecosystem

The site is a functioning ecosystem that provides habitat for many native species, including beneficial insects and native pollinators. The use of bio-augmented soils (on-site soils modified with liquid-compost extract full of beneficial micro-organisms, biological innoculants, microbial foods, and trace elements) and native plant material supports a functioning ecosystem. During construction, all of the topsoil on the site was scraped to the side and reserved so that when construction was complete, the soil was merely redistributed and no new topsoil was needed. This provided a significant cost savings compared with the traditional practice of buying and hauling new topsoil and also preserved the existing microorganisms that had adapted to the site as well as the seedbank already present in the soil. As a result, it was not necessary to reseed much of the area—another large cost savings.

A palette of native and naturalized plants was chosen based on their adaptability to the variable wet and dry conditions of the site, partly due to the fluctuating water levels in the detention pond. Native plants that withstand dry periods and tolerate periodic flooding also help to prevent erosion because they have deep roots, which help hold the friable, living soil. Examples of plants used on the site include river birch, Mexican sycamore, Lantanas (several varieties), Palmettos, hamelias, and Irises. Initially, all grassy areas in the park were mowed. Wildflower meadows are slowly being integrated, including crimson clover, which provides a solid, lush green cover during the winter months and a beautiful crimson bloom in the spring, and naturally fertilizes by fixing nitrogen in the soil. Mosquitoes are not sprayed because enough natural predators, such as dragonflies, ditch minnows, and swallows, thrive in the park and help control the mosquito population.

The project was designed to improve water quality and includes silt drops below inlets and a baffle below outlets, which help to clean and slow the water. The lakes also capture stormwater runoff, which slows the water, allowing the silt and sediment to be filtered out before the water runs further downstream to Cypress Creek. The lake fill keeps the 2.14 acres of water surface filled during summer months and during periods of low rainfall. It provides water for fish, wildlife, and aquatic vegetation.

A Peaceful Gathering Place

The lakes are a calming influence on the community and provide a place where residents can enjoy peaceful reflection, fishing, and play. Fountains in each of the lakes neutralize the traffic noise and aerate the water for fish and other aquatic life. The streambed allows kids to get into the water to see minnows, tadpoles, and frogs up close. One of the design components allowing residents to access the water is a concrete shelf that runs along the edge of the lakes 1.5 feet below water—alleviating the danger of falling into deep water. 

In the end, the project has improved the quality of life for residents and continues to educate them about all of the components that make the park healthy and ecologically sound. Much of this education has been through newsletters and tours through the park. Community members have embraced the park and often use it as a backdrop for taking prom and wedding photos, viewing beautiful birds as they migrate through the state, and holding the annual bike-athon. The park has been especially beneficial for children with chemical sensitivities because they are able to play without the risk of exacerbating their allergies. The overlooks and plazas have become popular for festivals and neighborhood nights, which include eco-tours of the park.

Mandolin Gardens Park has become a model that other communities are trying to emulate. It is a way of rejuvenating past-their-prime subdivisions and improving house prices while providing a backdrop for healthier lifestyles and richly textured lives. 

 Kate Cairoli, MA, LEED, is a project manager for Talley Landscape Architects, Inc., in Orchard, Texas. Reach her at kate@talleyla.com. For more information, visit www.TalleyLA.com.