Case Studies

Project Background

Queenston Manor Apartments sits on a 7.2 acre parcel of land located adjacent to a master planned community on Houston’s northwest side. When Academy Development originally planned the construction of an apartment complex on this site, the economic model required that nine apartment buildings be built in order to generate the required revenue stream. Operating under the premise that all of their detention had been accounted for offsite in the surrounding master planned development, the project came to a screeching halt when it was determined by the County that the volume presumably set aside was no longer available for use by the apartment site. The engineers at EHRA, Inc. rescued this project with Low Impact Development (LID) and the FocalPoint High Performance Modular Biofiltration System (HPMBS).

Why Use Low Impact Development?

One of the lessons from the design competition was that through the use of Low Impact Development techniques such as bioswales and porous pavers, engineers could design a drainage solution that extends time of concentration resulting in a decrease in peak discharge back to predevelopment levels. This decrease in peak runoff allows for up to a 40% decrease in detention volume. If you couple that with integrated drainage into landscaping, developers begin to pick up real estate once lost to detention ponds. In the case of Kolbe Farms, the team of EHRA created a site plan that used porous pavers and the FocalPoint High Performance Modular Biofiltration System (HPMBS) to nearly eliminate a detention pond and in the process gained three additional lots, or 15% more homes. Although there was an increase in cost due to the use of pavers, with the savings provided by the FocalPoint Implementation, these homes which start at $240,000 provided the return needed to make the overall solution viable.

The FocalPoint HPMBS is the first of an influx of Next Generation Low Impact Development solutions provided by Convergent Water Technologies and our Value Added Resellers. The FocalPoint HPMBS moves the designer toward a complete solution based approach to design rather than sourcing various parts and pieces from multiple vendors where quality assurance and quality control are often lacking. This way of thinking gives the designer the peace of mind that every time a FocalPoint HPMBS is specified, they get a consistent, measurable result. For the Kolbe Farms Townhomes, this was critical, as the engineering firm had designed the biofiltration system to manage the 100 yr storm. To ensure success, they needed a solution that could guarantee results; and a solution that was greater than the sum of its parts.

Faced with the harsh reality that this project might no longer be viable due to the amount of site area which would otherwise be lost to a detention pond, the engineering firm of Edminster, Hinshaw, Russ and Associates (EHRA) asked Academy Development if they would be open to a Low Impact Development-based design. The objective would be to reduce peak flows and thereby decrease total detention volume under Harris County’s LID Design Guide which requires post and pre-development hydrograph matching. Doing so would allow the developer to recapture the real estate that would have to be occupied by detention facility in the traditional design, and make the site viable for apartment construction once again. EHRA redesigned the project with extensive use of porous pavers in parking stalls, a directly infiltrated underground detention system fed by the porous paver system, vegetated swales and vegetated depressions throughout the common areas which drain through a series of small, decentralized FocalPoint HPMBS. The design team was able to decrease the surface storage volume requirements for the property enough to reclaim the property needed to build two additional apartment buildings and save the project. For the developers, the 48 additional apartment units meant the difference between success and a cancelled project.

FocalPoint High Performance Modular Biofiltration System (HPMBS)

The FocalPoint HPMBS is a combination of a high performance, open cell underdrain, a clog-proof bridging mesh, bridging stone, and a high performance biofiltration media that flows at a rate of over 100” per hour. What this unique combination of parts creates is a system that provides unsurpassed water quality and drainage characteristics. For the purpose of Queenston Manor Apartments, reliability was an important element in that all of the drainage areas are also common areas and courtyards. It was imperative that the system could be relied upon to drain as designed so that within 24 hours of a rain event, there would be no standing water. By placing the HPMBS at the lowest elevation in the four landscaped swale systems on site, Construction EcoServices was able to give Queenston Manor a reliable drainage and water quality solution.

Quality Solutions

The Queenston Manor Apartments boast extraordinary amenities including a full service bar on site as well as an infinity pool. One of the most impressive and unique features of the site, however is the use of Low Impact Development practices throughout the property.