Tanyard Branch

An exercise in stream restoration and redesign

Given by: Sarah Hibbs

September 29, 2003

What is Tanyard Branch?

• An Urban Stream which runs through The University of Georgia campus, beneath Sanford Stadium

• 50% of Tanyard Branch is piped• Channel banks and streambed are highly

eroded• Water does not meet water quality

regulations• Poor habitat for insects and aquatic life• Stream is cut off from human interaction

The University of Georgia

TanyardBranch

Now

History of Tanyard Branch

1874 Map of Athens, Georgia

(Tanyard Branch highlighted in blue)

1909 birds-eye view of Athens, Georgia

1993 aerial photo of Athens, Georgia

and the University of Georgia campus

Major Concerns

• Stormwater– Problems—for urban streams and for

Tanyard Branch– Strategies for repair and management

• Vegetation and aquatic habitat• Geomorphic reference conditions,

watershed and hydrologic assessment

Stormwater concerns in an urban setting

• Channel instability—eroded banks and stream beds

• Increased peak storm flows• Reduced baseflows• Water quality impairment (including

increased temperatures, toxic pollutants, nutrients, turbidity and sediment

• Habitat degradation• Biological impairment

Stormwater and Tanyard Branch

Lumpkin Tanyard culvert

November 10th

Lumpkin Tanyard culvert

Culvert filled to capacity, September 14th

Stormwater and Tanyard Branch

Sanford Tanyard culvert

November 10th

Sanford Tanyard culvert

Culvert filled to capacity, September 14th

How to deal with Stormwater

• Traditional Methods– Conveyance—storm

drains, street gutters, culverts—anything to channelize to the nearest stream

– Detention—wet and dry detention ponds, stormwater wetlands

• Desirable Methods– Infiltration—shifts

balance of water from surface water back to groundwater—uses things like rain gardens, porous pavers and green roofs.

Alternative stormwater strategy 1

• Cisterns that collect stormwater from rooftops and condensate from air conditioners

• Retrofit sidewalks with porous paving• Include green roof design on roof upgrades of

existing buildings

Alternative stormwater strategy 2

• Vegetated infiltration basins (rain gardens) with terraced inflow dissipation

Water from parking lots is collected conventionally, but not shunted into a new storm sewer system.

Water from parking lot is filtered through several stilling wells, and filtered through an Alluvial fan, which slows fast moving water and allows for sediment deposit.From the

alluvial fan, water is infiltrated in a series of rain gardens

Alternative stormwater strategy 3

• Floodplain rehabilitation—replace impervious surfaces in the floodplain with riparian wetlands

• The floodplain is an integral part of biological habitat, as well as stormwater management

NC State’s campus stream, Rocky Branch, once had steep banks, but the floodplain has been reestablished and will soon be reforested.

Vegetation Suggestions

•List of typical plant communities for the riparian zone and uplands

•Drawn from other stream corridors in the Georgia piedmont

Aquatic Habitat

• Clean, large sediment, consisting of pebble and cobble, for spawning and feeding

• Bedrock for feeding and cover• Pools, especially deep pools, to provide

refuge during drought or low flows• Riffles, for feeding and spawning,

especially important for small-bodied fishes• Woody debris for feeding and cover

Geomorphic reference conditions, watershed, and hydrologic

assessment• Tanyard channel is currently south of

historic location—redesign incorporates the relocation back to its previous channel

• Channelization (straightening) is another major problem for Tanyard branch—redesign will use a reference stream in the North Carolina piedmont (data includes: sinuosity, width:depth ratio, and meander belt width:width ratio) to replace the natural curves and meanders previously lost

• Watershed assessment was conducted to assess appropriate channel size. Using a DOQQ for Clark County, watershed parameters were calculated using the ERDAS Imagine GIS software.

Table 1: GIS analysis results for Tanyard branch watershed

Watershed Parameter GIS Analysis Results

Watershed area in square miles

0.782

Watershed % (forested) 20.7

Watershed % (impervious) 73.8

Watershed % (shadow—photo error)

5.4

Tanyard Branch Redesign of Campus

• Using the campus master plan, several conceptual designs were submitted with Tanyard Branch as the focus.

• Changes include: Elevated road extensions, new buildings and dorms, community outreach centers and other important features to the functioning of the center of UGA’s campus

University of Georgia Master Plan

Design Proposal AConceptual Plan

Design Proposal ADetailed Plan

Design Proposal ADetailed Images

Design Proposal ADetailed Images

Design Proposal BConceptual Plan

Design Proposal BDetailed Plan

Design Proposal BDetailed Images

Design Proposal BDetailed Images

Design Proposal BDetailed Images

The Ultimate Goal

GO TECH!