Urban Low Impact Development English + Associates Owner Architect Construction EcoServices Storm-water Tank Contractor General Contractor T&T Construction Dominion Interests MEP Engineers Parking Lot Case Study

What is Low Impact Development? ▫ Low Impact Development (LID) is a storm-water management and land development strategy that focuses on conservation and use of on-site natural features to more closely mimic the pre- developed condition of the site. Virtually anything that touches the ground can make its way into the storm water drainage system and flow directly into our bayous, streams and ultimately, into the bay. If storm-water is contaminated by contact with pollutants, it stays contaminated because storm-water is not treated at a treatment plant.

Low Impact Development ▫ Flooding by reducing Storm-water rate and peak flow ▫ Pollution by improving Storm-water quality and reducing total rate ▫ Heat Island Effect by reducing site and local temperature ▫ Destruction of Natural Habitat By retaining or restoring natural habitat Influences

Developer Benefits Community Benefits Protect natural habitats More of the natural landscape remains than in traditional parking lot design. Protect downstream water quality Pollutants are filtered before reaching fishing areas. Increase developable land Less expensive on site storm water cleaning systems More attractive site Increases property values Low maintenance cost Reduce city flash-flood incidents Longer retention of water on site reduces flooding of local waterways. Low Impact Development Benefits

QUANTITY TIME Conventional Developed condition Pre-Developed or LID Condition Maximum water shed capacity Run-off Hydrograph

LEED™ Points contributed To by this technology CategoryCredit number PointsDescription Sustainable Sites (SS)6.11 Option 1-EXISTING IMPERVIOUSNESS IS LESS THAN OR EQUAL TO 50% Implement a stormwater management plan that prevents the post-development peak discharge rate and quantity from exceeding the pre-development peak discharge rate and quantity for the one-& two-year, 24-hour design storms. Option 2- EXISTING IMPERVIOUSNESS IS GREATER THAN 50% Implement a stormwater management plan that results in a 25% decrease in the volume of stormwater runoff from the two-year, 24-hour design storm. Stormwater Design6.21 Implement a stormwater management plan that reduces impervious cover, promotes infiltration, and captures and treats the stormwater runoff from 90% of the average annual rainfall using acceptable best management practices (BMPs). Landscape to reduce Heat islands (SS) 7.11 Provide any combination of the following strategies for 50% of the site hardscape (including roads, sidewalks, courtyards and parking lots): o Shade (within 5 years of occupancy) o Paving materials with a Solar Reflectance Index (SRI) of at least 29 o Open grid pavement system Water Efficient Landscaping (WE) 1.1&1.22 Use only captured rainwater, recycled wastewater, recycled graywater, or water treated and conveyed by a public agency specifically for non-potable uses for irrigation. Recycled Content (MR)4.1& % of materials used in construction have an average of 20% post-consumer recycled content material. Total Points Contributed To: 7

Case study of an Urban Site Site Specific Problems 1.Existing surface conditions did not mitigate storm water by percolation or retention. 2.Presence of expansive clay soils posed a danger to foundation of the adjacent building. 3.Adjacent historical building has a basement which suffers occasional flooding due to underground hydrostatic pressure.

1919 Decatur Parking Lot ▫ Parameters ▫Parking lot with 23 spaces ▫100’ x 100’ Lot – 10,000SF ▫ Conditions ▫Crushed gravel Parking lot ▫Age: 40-50yrs ▫ Goals ▫To provide adequate, smooth parking for office ▫To mitigate storm water run-off ▫Provide green space ▫Retain Storm water for irrigation

Alternatives Considered Conveyance ▫Pervious pavement over gravel/crushed rock ▫Unit pavers with voids and gravel/rock base ▫Conventional concrete sloped to landscaped filtration beds Collection ▫Large pre-constructed metal plastic underground tank. ▫Large aggregate rock bed ▫4’ dia. HDPE closed pipe array ▫Modular Atlantis RainTank System ▫Conventional concrete sloped to gravel filtration beds

How it Works

Design superimposed over original parking lot Design of underground water retention and water inlets  arrows reflect direction of water flow            ATLANTIS RAINTANKS  How we fit it in

Breaking Ground Breaking Ground – Basic Drainage slope

Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope Excavation

Sand-Gravel Layer A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope

Atlantis Rain Tanks Ship flat on a truck bed to be assembled onsite. A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope Shipment of Tanks

A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope Assembly is timely and simple. Atlantis Rain Tanks Ship flat on a truck bed to be assembled onsite. Assembly

A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope EcoFabric Liner Assembly is timely and simple. Atlantis Rain Tanks Ship flat on a truck bed to be assembled onsite. Added a under liner to protect the impermeable layer

An impermeable layer at the side and bottom of the tank to keep the water from seeping into the soil A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope Assembly is timely and simple. Atlantis Rain Tanks Ship flat on a truck bed to be assembled onsite. Added a under liner to protect the impermeable layer Impermeable Layer

Layer of the Geo-Textile fabric. An impermeable layer at the side and bottom of the tank to keep the water from seeping into the soil. A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope Assembly is timely and simple. Atlantis Rain Tanks Ship flat on a truck bed to be assembled onsite. Added a under liner to protect the impermeable layer Liner Wrap

Placement of the Atlantis Rain Tanks Layer of the Geo-Textile fabric. An impermeable layer at the side and bottom of the tank to keep the water from seeping into the soil. A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope Assembly is timely and simple. Atlantis Rain Tanks Ship flat on a truck bed to be assembled onsite. Added a under liner to protect the impermeable layer Tank Sequence

Fabric Seams are taped and sand is compacted along the perimeter of the tank. Placement of the Atlantis Rain Tanks Compacted Sand Placement of the Atlantis Rain Tanks Layer of the Geo-Textile fabric. An impermeable layer at the side and bottom of the tank to keep the water from seeping into the soil. A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope Assembly is timely and simple. Atlantis Rain Tanks Ship flat on a truck bed to be assembled onsite. Added a under liner to protect the impermeable layer

The D-Cells convey filtered water from gravel beds to tank D-Cells Water Inlet Fabric Seams are taped and sand is compacted along the perimeter of the tank. Placement of the Atlantis Rain Tanks Layer of the Geo-Textile fabric. An impermeable layer at the side and bottom of the tank to keep the water from seeping into the soil. A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope Assembly is timely and simple. Atlantis Rain Tanks Ship flat on a truck bed to be assembled onsite. Added a under liner to protect the impermeable layer

Concrete placement The D-Cells convey filtered water from gravel beds to tank Concrete Placement Fabric Seams are taped and sand is compacted along the perimeter of the tank. Placement of the Atlantis Rain Tanks Layer of the Geo-Textile fabric. An impermeable layer at the side and bottom of the tank to keep the water from seeping into the soil. A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope Assembly is timely and simple. Atlantis Rain Tanks Ship flat on a truck bed to be assembled onsite. Added a under liner to protect the impermeable layer

Completed Pavement Concrete placement The D-Cells convey filtered water from gravel beds to tank Fabric Seams are taped and sand is compacted along the perimeter of the tank. Placement of the Atlantis Rain Tanks Layer of the Geo-Textile fabric. An impermeable layer at the side and bottom of the tank to keep the water from seeping into the soil. A gravel and sand mixture goes on the bottom of the pit as leveling material Excavation of pit for Rain Tanks Breaking Ground – Basic Drainage slope Assembly is timely and simple. Atlantis Rain Tanks Ship flat on a truck bed to be assembled onsite. Added a under liner to protect the impermeable layer

Before COST COMPARISON Conventional Development ($) Low Impact Development ($) Excavation9,0008,000 Rain Tank-18,000 (w/o liner) Storm pipe and inlets10,500- Irrigation System5,000 System Total (No detention scenario) 24,50029,000 Construct Detention Pond7,500Included in cost above System Total (No additional land for detention) 32,00029,000 Cost of land $20/s.f.24,000Not Applicable System Total (with Separate Detention Pond) 56,00029,000 After