URBAN REDEV 21182 Competition Submittal

Houston Land/Water Sustainability Forum Low Impact Development Design Competition

Design Overview ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],An existing building on Block 222, currently used as artist lofts, is adjacent to a proposed “Arts Plaza” that can be used for public gatherings and showcasing art. Each block contains accessible and non-accessible landscaped zones. Each accessible landscaped zone contains a potential pad that can be used for display; there are a total of 16 display pads for Houston's Sister Cities. With the combined use of layout, porous materials, and bioretention cells (in the event of a 100 Year Flood) the walkways that run parallel to the block fronts as well as the composite wood decked “nodes” would remain usable. The only ponding would occur along the middle of the promenade. The stormwater run-off from the promenade and cross streets makes its way through rain gardens and bioretention cells, filtering it and slowing it down, into subsurface harvesting tanks strategically placed all along the promenade. The storage tanks hold excess water, making it usable for irrigation, as well as other grey water uses for the development on either side of the promenade. The LID makes it possible to allow for 100% development to occur on each of the blocks adjacent to the promenade without the need of detention ponds or basins. The need for “green roofs” or “green walls” is not a requirement for the system to work, but of course they would be a welcome addition and would benefit an environmentally-conscious outlook.

Landscape & Irrigation Strategies The landscape concept is to bring natural areas back into the urban environment. The rain gardens systems designed are to mimic a natural stream system both visually and functionally. The landscape plantings have been selected based on their natural requirements to the local climate and the availability from growers. All landscape areas, other than the turf areas, do not require permanent irrigation systems. Within the rain garden areas there three levels of water. Simply put, there are the lower areas which receive the typical storm event and the selected species must withstand standing water. There is the middle area which is somewhat drier. The species in this area will be submerged for a short amount of time and can tolerate fluctuating water levels. Lastly, there is the upper area of the rain garden. This zone contains plant species that prefer drier soils. The irrigation system would be a mixture of drip irrigation and surface irrigation with spray heads. Irrigation system for the project would be limited to establishing the proposed vegetation. The selected landscape plantings are regional and native to the area and therefore are accustomed to the rainfall amounts of the region. The use of irrigation would be to supplement the naturally occurring rainfall with the retained subsurface water in the storage tanks under the central plazas. Link to detailed recommended planting list.

Landscape & Irrigation Strategies Bald Cypress White Oak River Birch Muhly - October Sweetbay Magnolia Prairie Wildrye Switchgrass Bluestem

Overall Site Plan & Section Service Yard Service Yard Service Yard Market Market Market Outdoor Market Outdoor Market Outdoor Market

Sections Street Section – Tree Boxes & Bioswale Street Section – Bioswale & Permeable Paving

Sections Promenade Section – Mid-block Water Collection Promenade Section – Water Collection Detail

H&H Strategies Interconnected Channel and Pond Routing ("ICPR") software, Version 3.10, created by Streamline Technologies, Inc. was used to model the proposed hydrologic and hydraulic conditions for this project. The software enabled us to accurately represent the Low Impact Design hydrologic techniques including the SCS Unit Hydrograph Method. The main advantage of using the SCS Method is it allows the properties of the soils to affect the hydrograph and the storm run-off calculations. In the proposed LID design analysis, the benefits of the engineered soils were reflected by adjusting the Curve Number to reflect a Type A soil in the improved areas. The hydraulic benefits of the Low Impact Design elements were modeled using a stage-area component which accounted for the total storage volume provided in the planter boxes, rain gardens and infiltration basins.

H&H Strategies Percent reduction of storm-water runoff volumes from existing conditions: 5 -Year: -51.0% 10 -Year: -61.9% 100 -Year: -75.6% Link to Engineering Modelling Data

Low Impact Development Notes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

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Cost Comparisons - Summary Estimate includes the cost of promenade and cross streets to the project limits. It does not include any costs associated with the buildings and land adjacent to the promenade. It was assumed that the aesthetic design intent would remain the same for the Traditional as well as the Low Impact Development. Factors to be noted are that any Traditional Development would require a large amount of Detention. If detention were to be provided within the project site, then close to 3 Acres of land would not be available for development resulting in significant loss in opportunity costs. If detention were to be provided off-site, then there would be a significant additional cost for pipe work. Another significant difference is maintenance and irrigation costs between the two types of development. LID has significantly lower long term maintenance costs and irrigation costs than the traditional model. The sub-surface grey water harvesting tanks, although an additional cost at the front-end would provide for the limited irrigation needs for the promenade as well as the cross streets passing through the promenade. ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

URBAN REDEV 21182 Competition Submittal

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URBAN REDEV 21182 Competition Submittal