AGENDA # 4i
MEMORANDUM
TO: Mayor and Town Council
FROM: W. Calvin Horton, Town Manager
SUBJECT: Stormwater Management Conservation Area Report
DATE: July 5, 2000
This memorandum discusses land acquisition specifically intended to meet objectives of improving stormwater and floodplain management and preserving land for open space and greenway corridors.
The attached resolution would direct the Manager to consider the principles and specifics of this report in preparing the analysis of land that could be acquired to meet the Council’s goals of promoting non-automobile community connectivity, and/or preserving entranceway corridors, scenic vistas, environmentally sensitive areas, Resource Conservation District land, community open space and neighborhood open space. It also authorizes the Manager to pursue funding sources beyond the 1996 Open Space Bonds and to identify opportunities for land acquisition.
BACKGROUND
The Town Council recently adopted a revised Comprehensive
Plan. Chapter Nine of the Plan, entitled Natural Environment, includes a stated
goal to “identify, protect and preserve open spaces and critical natural areas
and enhance the community’s air quality and water resources”..
The Plan recommends actions to implement a variety of programs with similar objectives to those described above. It discusses the 1998 Chapel Hill Greenways Comprehensive Master Plan (Section 9B-1), with the goals of providing environmental protection, recreational benefits, and transportation alternatives. Due to the limited public resources available for land acquisitions, the Plan recommends acquisition of “key” greenway connections and encourages public/private partnerships to restore and enhance environmental resources (Section 9D-1) including woodlands, wetlands and stream corridors.
The Plan also discusses water quality and stormwater management issues (Section 9F). Due to the near “build-out” conditions of the Town’s watersheds and the surface water quality concerns of the Town, special attention must be paid to the remaining riparian open spaces to see that reasonable measures are taken to protect the riparian environment and protect property owners from increased risk of water pollution and/or flooding.
The Plan recommends improving the existing Town of Chapel Hill stormwater management programs and policies. The preservation of selected riparian floodplain areas is important to ensure that they will continue to safely accommodate natural flooding. Although the Resource Conservation District regulation has successfully restricted types and intensity of development in the floodplain, it does not guarantee that critical riparian areas remain completely undeveloped.
Unique natural habitat areas in Chapel Hill have been identified in several publications, including a 1989 report entitled “Inventory of the Natural Areas and Wildlife Habitats of Orange County, North Carolina”. The uniqueness of these areas is attributed to factors such as bio-diversity, unusual landforms and stream characteristics, rare and unusual biological communities, and greenway corridor/habitat connectivity. This report, which was partially funded by the Town, included the charge to identify natural areas significant to Orange County and to the State. Sixteen (16) sites were located in Chapel Hill’s Urban Services Area. Some of these sites are included in the following list of conservation areas. The report was adopted by the Council for use in developing the Town’s long-range open space plans and to guide review of land development applications.
Additional natural habitat inventory publications
referenced are “A Landscape With Wildlife For Orange County, 1997” and “Rating
Land In Orange County By It’s Wildlife Value, 1999”..
This report and its recommendations are consistent with the June 12, 2000 open space resolution authorizing the Manager to investigate land acquisition.
DISCUSSION
The following discussion involves six Stormwater Management Conservation Areas in Chapel Hill which we believe should be considered by the Council for acquisition. The objectives and criteria listed below are the basis for our selection of the conservation areas described later in this report.
Objective One: Improve stormwater and floodplain management practices
This objective includes consideration of all surface water quality and quantity issues such as controlling stormwater runoff through best management practices and reducing the number of at-risk structures located in the regulatory floodplain or special flood hazard areas. The objective criteria are as follows:
a. Hydric soils present. (Poorly drained soils on 0 – 2 percent slopes typically found parallel to major streams.)
b. Undisturbed wetlands present
c. At-risk structures present
Objective Two: Preserve land for open space and greenway corridors
This objective involves selection of potential acquisition areas with reference to adjacent Town-owned property and easements or existing or proposed trail/greenway locations. The objective criteria are as follows:
a. Adjacent to existing Town-owned property or easements
b. Connectivity with existing or proposed trails
c. Area included in the Town Greenways Master Plan
Objective Three: Protect Critical Natural Riparian Areas
This objective considers all aspects of the natural environment determined to be unique, rare or significant to Chapel Hill, Orange County or the State based on a published inventory report or similar document. The objective criteria are as follows:
a. Unique bio-diversity (plant and animal species)
b. Unique geo-/stream morphology (landform and stream characteristics)
c. Wildlife corridor connectivity
Conservation Area Descriptions
Area 1- Dry Creek (Cedar Terrace Bottoms). See Map #1.
Cedar Terrace Bottoms is a large tract of nearly mature bottomland swamp forest. One threatened and endangered species, Thorey’s grayback dragonfly (Tachopterx thoreyi), is known to breed in the stillwater seeps (where the crystalline rock of the piedmont meets the flat sediment of the Triassic Basin) and other rare (but not endangered) species such as the scarlet tanager (Pirangia olivacea) and the hooded warbler (Wilsonia citrina) are also known to inhabit this area.
While portions of this area is already protected under Chapel Hill’s Resource Conservation District Ordinance, special precautions should be taken to protect the areas directly upslope from the seeps from development that might affect significant breeding areas and habitats. Protection of these areas could also serve as an expanded riparian buffer for stormwater management purposes. This area is one of the best examples of a swamp forest in the county.
Acquisitions in this area would also complement Chapel Hill’s Greenways Master Plan as a valuable trail/corridor area for residents and wildlife within this rapidly growing northern edge of Town.
Area 2 – Bolin Creek: Franklin Street to15-501 By-Pass. See Map #2.
This highly visible and utilized recreation area centers about the Community Center, where the existing Bolin Creek trail begins/ends. Acquisitions of land in this area could enhance the connectivity of Town property and the trail system through Dickerson Court to the east. Currently, the road itself forms a portion of the trail through Dickerson Court. The existing cinderblock structures on Dickerson Court are located in the regulatory floodway and are at-risk of flooding and associated hazards such as floating debris or debris jams during a significant storm event. Acquiring these properties could create trail connectivity and improve stormwater and floodplain management practices along this stream reach.
The Town also owns property to the east along Battle Branch Creek and further downstream along 15-501. Providing an uninterrupted connection to these two areas could provide expanded trail access and improved stormwater and floodplain management practices along Bolin and Battle Branch creeks.
This reach of Bolin Creek is biologically and physically impaired due to urban stormwater runoff. It is also an area of chronic flooding of residential structures. Improved floodplain management in this area could improve water quality and reduce the scope of flooding to residential structures.
Area 3 – Bolin/Booker/Little Creeks (confluence area). See Map # 3
Large tracts of property owned by the Town and UNC-Chapel Hill exist in this area. The Town has recently purchased additional parcels along Cleland, Oakwood and Rogerson Drives. Purchasing additional parcels directly adjacent to the streams could allow the Town to properly manage, and in some cases restore, wetland areas for improved stormwater treatment. The additional publicly owned buffer could provide natural storage areas for floodwaters and could reduce impacts on and complaints from private property owners.
Private property parcels within this area not best suited for development due to their proximity to the regulatory floodplain and floodway. Two tracts located on Cleland Drive are single-home residential parcels experiencing chronic yard flooding year-round. The two parcels are presently for sale on the private real estate market.
The creeks are 303(d) State listed as impaired, primarily due to urban stormwater runoff. The N.C. Division of Water Quality has planned to perform studies in this unique area to assess the effects of urban stormwater on a wetland.
A thin population of nearly mature bottomland hardwood species populates this area along Little Creek. Although this area was heavily damaged by hurricane winds in the past several years, it is still an important habitat and corridor for wildlife leading toward Jordan Lake through the U.S. Corps of Engineers Flowage Easement and the N.C. Division of Water Quality Waterfowl Sub-Impoundment areas. Because much of this area is inundated for a significant portion of the year (due to beaver impoundments and/or wet weather) this is habitat or resting area for many water-dependent fowl such as wood duck. Acquisitions in this area could also be important to future greenway connections in this area of Town.
Area 4 – Bolin Creek @ Umstead Drive. See Map # 4.
This area along Bolin Creek corridor between Airport Road and Umstead Park is important in continuing to procure contiguous greenway easements. The Town owns segments along the creek where several additional purchases would allow for complete easement connectivity. Acquiring necessary easements along this section of stream would allow the Town to extend the trail system to the existing Tanyard Branch trail and to the Bolin Creek Greenway east of Airport Road.
One parcel with a structure is recommended for acquisition due to its proximity to the creek and adjacent Town property.
Area 5 – Morgan Creek Greenway. See Map # 5.
Due to the geology of the area, Morgan Creek forms one of the steepest valleys in the county. Because of its unique topography (with the creek running east - west), many steep slopes with rocky outcroppings face directly north or south, creating unusual biological communities. At least one State-listed significantly rare plant species; the sweet pinesap (Monotropsis odorata), can be found on north-facing slopes of Morgan Creek along with regionally rare rhododendrons. South or southwest facing slopes include some of the driest plant habitats in the county, one of which contains the extremely rare and threatened and endangered State-listed plant, Southern Thimble-weed, Anemone berlandieri (found in the county at only one site on Morgan Creek).
The riparian area along Morgan Creek is one of the more preserved riparian areas remaining in Orange County. Seen within this area during breeding season is the state-endangered species, Cooper’s Hawk (Accipiter cooperi).
Any sites along Morgan creek will help protect the general status of this corridor as one of the county’s prime natural areas. As stated in the Greenways Master Plan, it is not recommended that a greenway be established in the area downstream of Merritt Pasture due to the narrowness of the valley and the fragility of its features.
The area between Merritt Pasture and Smith Level Road is recommended for trail connectivity toward University Lake. Easement acquisition would be required from approximately Frank Porter Graham Elementary School to the existing Town-owned property adjacent to Dorset Place.
Area 6 – Wilson Creek Greenway. See Map # 6.
The riparian area around Wilson Creek is comprised of mixed semi-mature tree stands, nestled in a relatively steep valley. Although the natural habitat is not especially remarkable, its location makes it an important greenway corridor for wildlife and as a low-impact trail.
The areas immediately adjacent to Wilson Creek are experiencing significant development at this time. With the recent construction of Southern Village and the widening of U.S. 15-501), urban stormwater runoff likely will begin to adversely affect this stream reach. Riparian acquisition now could secure Wilson Creek as not only a valuable byway for wildlife and an important trail and greenway system, but also as a valuable buffer to treat stormwater prior to entering into the creek.
Funding and Process
In January, 1999, the Council identified $112,000
of U.S. Department of Housing and Urban Development Disaster Recovery Initiative
Grant funds available for acquisition of land in flood prone areas. We think
that there are certain land parcels located in Area 3 (as shown on Map 3) which
could be pursued for acquisition utilizing these grant funds as an initial step
in a long-term program for acquiring Stormwater Management Conservation Areas.
Additionally,
Another funding source could be the 1996 Open Space
Bond funds targeting non-automotive community connectivity and preservation
of entranceway corridors, scenic vistas, environmentally sensitive areas, Resource
Conservation District land and community open space. We
will be considering the Stormwater Management Conservation Areas
Report
The Manager will also investigate acquisition of parcels
in the other areas as well as continue to look for other opportunities meeting
the above criteria.
MANAGER’S RECOMMENDATION
That the Council adopt the attached resolution authorizing the Manager to begin investigating potential property acquisitions associated with Stormwater Management Conservation Areas.
ATTACHMENTS
1. Proposed Acquisition Map (p. 8)
1. Conservation Area Maps # 1 through # 6 (p. 9)
2. June 12, 2000 memorandum, Acquisition of Open Space (begin new page 1)
A RESOLUTION AUTHORIZING THE TOWN MANAGER TO BEGIN INVESTIGATING POTENTIAL PROPERTY ACQUISITIONS ASSOCIATED WITH STORMWATER MANAGEMENT CONSERVATION AREAS (2000-07-05/R-7)
WHEREAS, the Chapel Hill Town Council is interested in improving and maintaining surface water quality including steams, lakes, and ponds; and
WHEREAS, the Council desires to mitigate flooding problems and protect sensitive riparian environments; and
WHEREAS, certain Stormwater Management Conservation Areas have been identified which should be protected and preserved to the extent possible in keeping with the Council’s objectives.
WHEREAS, on June 12, the Council requested the Manager to prepare a report to be presented in the fall which would include an analysis of undeveloped land that could be acquired to meet the Council’s goals of promoting non-automobile community connectivity, and/or preserving entranceway corridors, scenic vistas, environmentally sensitive areas, Resource Conservation District land, community open space and neighborhood open space,
NOW, THEREFORE, BE IT RESOLVED by the Council of the Town of Chapel Hill that the Council authorizes the Manager to consider the principles and specifics of this Stormwater Management Conservation Area Report in preparing the analysis noted above.
BE IT FURTHER RESOLVED that the Manager is authorized to pursue funding sources beyond the 1996 Open Space Bonds, to identify opportunities for land acquisition and to report to the Council in the fall and periodically after that.
This is the 5th day of July, 2000.