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02-12-21 | Feature

Park Design Maximizes Nature Preservation

Atascocita Park
by Tim May, PLA, LEED AP and Jonathan Ward, Halff Associates, Inc.

Atascocita Park, found immediately west of Lake Houston, Texas, was redesigned by the Landscape Architects of Halff Associates to improve drainage issues and enhance the recreation offering. Within the park is the 2.5-acre pond teaming with aquatic wildlife. Multiple species of water turtles, countless fish (bass, perch, bluegill, minnows), and several types of water snakes are native to the area. Snowy egret and great blue heron are also abundant in search of food in the shallows. Alligators were rumored to take up residence in the pond prior to park construction, however none were seen during construction. Additionally, upland wildlife spotted in the park have been identified as land (box) turtles, snakes, many species of songbirds, honeybees, raccoons, coyotes white tail deer, skunk, and red-tailed hawk. Here an observation deck with seating allows visitors to rest and observe the abundant wildlife.
An arcing 240-foot boardwalk was positioned over the existing 2.5-acre pond, and aligned through Bald Cypress trees. Installation of the boardwalk preserved much of the native aquatic vegetation and habitat. The structure of the boardwalk was designed for vehicular loads. 10" marine-grade wood piles were used for foundations, treated pine for the deck substructure, and 1"x 6" pebble grey composite decking planks to finish the walking surface. The handrail was secured to the boardwalk substructure with 4" x 4" cedar posts placed 10' on center. Two 2"x 4" intermediate cedar posts were equally spaced between the primary cedar posts. 13 strands of stainless-steel cabling were used for the railing containment so that views to the pond were not obscured and the aesthetics gave an open feeling to the patron walk experience. The handrail was capped with a 1"x 6" colored plank to closely match the decking. Of particular note, the contractor went to great lengths of installing low voltage lighting on the deck by drilling a vertical shaft the height of each primary post to conceal and protect the wiring.`
Half of the large playground features of the park are accessible year-round over synthetic turf and pour-in-place fall zones from Duraplay. Benches, trash receptacles and a picnic pavilion provide comfort and convenience to playground users and family.
Atascocita park blended many traditional park elements with green infrastructure and the natural setting of the area, including a focal point biofiltration swale for the parking lot drainage, prairie-style park architecture to nestle facilities into the natural setting, and detention that is visually well incorporated into the park planning. Keystone Hardscapes provided the concrete paving for the project.
Springtime in the park brings out many flowering native plants and aquatic vegetation. Water quality is excellent in this pond due to intentional planning to preserve the protective cover in the watershed, buffer the vegetation of the shoreline, direct surface drainage around the pond, and expedite construction for the boardwalk and deck structures.
Detention ponds were carved into the park's master plan and then revegetated to emulate its natural conditions. Native trees were reintroduced to the side slopes and bottoms of the detention ponds, and native grasses and wildflower are allowed to thrive in non-mow conditions, effectively camouflaging the drainage feature and greening much of the required engineering of the park. Nearly half the park's vegetation was preserved. The native trees in the park include bald cypress, American elm, cedar elm, winged elm, water oak, red oak, yaupon holly, possumhaw holly, river birch, loblolly pine, Mexican plum, and Mexican sycamore.
About 55 percent of the park's natural conditions were preserved, generating substantial long-term cost savings for the Precinct. Because the team employed green infrastructure design solutions, it was set up to allow nature to handle ongoing maintenance of the park through improved stormwater quality. Fall foliage provide a seasonal perspective to the family deck area.
Natural bogs were discovered beneath dense vegetation once the park development began. Instead of draining the bog, the trail spanned the narrowest portion of the nearly 1.5-acre bog to preserve the natural drainage feature and provide another nature learning observation point in the park. A reforestation program included a palette of native trees, like the bald cypress seen coming out of the water within the bog. These trees were selected to be similar to those existing on the site to ensure success with plant material known and proven to thrive in the park's diverse environment.

Background
Atascocita is community of about 80,000 located just west of Lake Houston found within Harris County Precinct 2 in Texas. Within it is Atascocita Park, a unique, heavily wooded park that serves as a secluded nature oasis for the local neighborhood. Bound by a major thoroughfare, it is centrally located in a populous and rapidly developing area. It encompasses 21 acres of a second-generation forest and boasts several converging natural water courses.

Landscape architecture firm, Halff Associates from Richardson, Texas created the park's master plan to celebrate its many natural conditions and address numerous challenging drainage situations, both upstream and throughout the area. The plan identified natural opportunities and incorporated a variety of recreational elements without impeding drainage conditions or unnecessarily removing existing vegetation.

After completing the master plan, park improvements required professional expertise from a diverse set of design disciplines, including park planning, landscape design, hydrology, hydraulics and site engineering. The design team was challenged with creating a park that blended engineering improvements into the site's natural landscape and environment. A substantial portion of the planning accounted for disguising drainage improvements by properly siting amenity features related to the specific study of necessary infrastructure.

Preservation
More than half of the park's natural condition was preserved including most of its existing drainage patterns. Prior to becoming a park, the land served as a natural sump and drainageway for many of the upland neighborhoods. Located less than half a mile from Lake Houston and near the bottom of the watershed, the park land also serves as a backwater area for West Lake Houston Parkway when heavy rains inundate the roadway with stormwater.

Measures were taken to preserve the local ecosystem and the efforts in this area were concentrated on making improvements to the park's western half in order to minimize the perceived development damages to the park. Tree removal was selective, as amenities were placed in locations that preserved desirable vegetation and the site's drainage patterns. Once improvements were made, restoration of the natural vegetation began by planting a pallet of native plants.

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The restoration process was further complemented by a planting program administered over time through Precinct Parks and tree donations from organizations such as the Texas Forest Service. Nature created a unique oasis of water, habitat, vegetation and wildlife. Atascocita Park celebrates those natural attributes by providing amenities that educate the public about the value and beauty natural areas and ecosystems bring to a suburban environment.

Water
Harris County Precinct 2 purchased the primary water tract because of the pristine 2.5-surface-acre pond on the property. The pond was naturally protected by a dense vegetation buffer that filtered out any stormwater entering the water body. An earthen dike around two sides of the pond directed many of the drainage patterns away from the pond edges. The result was a body of water with clarity and a unique ability to heal itself quickly from inordinate rainfall and the park's boardwalk construction.

In addition to the 2.5-acre pond, the park was populated with several low-lying bog areas and narrow sloughs. The bog areas, which were mostly at the upland and lowland areas of the park, encompassed three to four acres at full capacity. The Atascocita bogs were well established with native plant material and adaptive to seasonal inundations and standing water conditions of the park. Instead of draining the bog land (and essentially removing the natural vegetation due to the extensive grading), it was embraced for its natural ecosystem. The land provided sustainable solutions for filtering stormwater and improving water quality on the park site, as well as sending runoff into downstream channels that drain into nearby Lake Houston.

About the Park
Atascocita Park has set a new standard in park planning and green infrastructure for Harris County and Precinct 2. The design team themed the park's many natural attributes when planning its recreational and drainage capacity functions.

Natural park elements included boardwalks and decks stretching over the pond to encourage learning about and observing aquatic ecosystems. A boardwalk over a bog area also lets visitors experience drainage functions, giving patrons a firsthand look at water quality and adaptive vegetation in saturated conditions.

Traditional park furnishings were sited to capture the park's natural feel. Benches were strategically placed for privacy and protection. Playgrounds bridged natural drainage courses and adopted an earth-tone color palette to blend better with the surrounding woods. Families can enjoy outings and picnics with the pavilion and restrooms. Additionally, animal lovers can find second homes for their dogs in the dog parks, which are remotely sited a safe distance from child activities and leisure recreation features. Park architecture was themed with a discrete prairie-style look to seamlessly blend with the nature backdrop and avoid becoming a dominant visual feature.

Resilience
Resilience is built into the park, protecting the park's investments from the devastating drainage and flooding potential. During its 15-month construction, Atascocita Park withstood 72 inches of rain, including an intense 36-hour, 13-inch deluge from Tropical Storm Imelda, the fifth wettest tropical cyclone in the continental United States. This storm proved Atascocita Park can absorb significant rainfall and handle flood conditions exceptionally well. This benefit was realized without the activation of the park's three focal points and properly sized overflow piping in place. Because the park is low in the watershed and naturally floods, the park amenities were sited and elevated to protect the financial investment from flooding conditions.

Many park amenities that experience ponding and flood water inundations during heavy rain events have resiliency elements. Concrete trails were placed on cement-stabilized sand subgrade to provide a stable amenity during high flood events. The concrete parking lot was graded lower than surrounding areas to serve as an overflow detention facility near the park's center should the two primary detention ponds fill beyond capacity; clean-up would be as simple as pressure washing the pavement. The pavilion and $1-million custom-built restroom and maintenance building were elevated 12 inches above the park's perimeter berm that contains storm event flood waters for slow release.

Resiliency is also realized through green infrastructure when addressing code-required stormwater water quality. Low impact development (LID) techniques addressed drainage and detention needs. Focal points, vegetated swales, detention ponds, berms, grading, natural drainage patterns and bog features were part of the master plan's response to resiliency.

The pond's recuperative ability to maintain its excellent water clarity after major rain events and the boardwalk construction demonstrates the effectiveness of natural means to improve and maintain excellent stormwater quality. The park has proven to be resilient during and proceeding its construction with an effective, relevant and responsive green stormwater plan-even with $5 million of park improvements.

Effective resiliency means sustainability. The park's green infrastructure naturally and effectively meets community needs. Drainage and stormwater collection benefit the park by providing soil moisture, protecting the investment and having low-maintenance requirements.

Community Impact
The once-private property that is now Atascocita Park has long been an attraction of natural beauty for the community. These improvements celebrate the park's role as a fixture to facilitate drainage and provide a natural recreation environment. Making the park available for the public's enjoyment and benefit will also provide a place for neighboring residents to enjoy healthy time outdoors.

As seen in LASN magazine, January 2021.

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