WSMU_CARY_WSWP Other Info_20230629 (3)

MEMORANDUM 88/1 . 1 . 1
TO: Charles Wakild, NRCD, Division of Environmental Management Water
Quality Section Chief
FROM: Mayor Larry M. Jordan, Apex
Mayor Koka Booth, Cary
Mayor Joe G. Creech, Garner
Mayor Avery C. Upchurch, Raleigh
Chairman M. Edmund Aycock, Wake County
Steven E. Stewart, Apex Town Manager
Jim Westbrook, Cary Town Manager
Gus M. Ulrich, Garner Town Manager
Dempsey E. Benton, Raleigh City Manager
Richard Y. Stevens, Wake County Manager
SUBJ: Swift Creek Watershed Land Management Plan
DATE: September 8, 1988
BACKGROUND
On February 8, 1988, elected officials and staff from Apex, Cary,
Garner, Raleigh and Wake County agreed to prepare a land management plan
for the Swift Creek watershed west of Highway 50 . A technical committee
(Swift Creek Planning Committee) including planners from Apex, Cary,
Garner, Raleigh and Wake County, and staff from the North Carolina
Department of Natural Resources and-Community Development, Division of
Environmental Management (DEM) , Water Quality Planning Section was
formed to prepare this plan. The attached land management plan was
designed to enable the Swift Creek watershed to attain a WS-II
classification.
The attached plan 1) proposes minimum critical areas and stream buffers,
2) recommends performance standards for different types and densities of
development, and 3) outlines a scenario for future land use patterns in
the watershed. The scenario illustrates each local government' s land
use plans or policies for its existing jurisdiction within the
watershed, and proposes land use patterns for future municipal
jurisdiction expansion into the Swift Creek watershed.
Guidance Requested
Guidance is needed from DEM and the Environmental Management Commission
Water Quality Planning Committee as to whether or not the land
management plan could qualify the Swift Creek Watershed for a WS-II
classification. We request that you review the attached plan and forward
any comments you may have to Jackie Stewart, Planner, Wake County
Planning Department, P.O. Box 550, Raleigh, N.C. 27602, (755-6820) .
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COMPETING OBJECTIVES
It is believed that there are two competing objectives which affect land
use patterns and development standards within the Swift Creek watershed;
the protection of water quality, and the logical extension of urban
development.
LEVEL OF WATER QUALITY PROTECTION
A request has been made by the City of Raleigh to NRCD-DEM to designate
the Swift Creek Watershed as a WS-II watershed. The practical result of
this designation would be that the State would prohibit industrial
wastewater discharges into the watershed. In order to attain the WS-II
designation, each local government involved would need to adopt
appropriate water quality protection measures through a land management
plan and implementing ordinances .
URBAN DENSITIES
Delineation of the Watershed
The Swift Creek watershed, located in southern Wake County, is comprised
of approximately 40, 174 acres. Lakes Benson and Wheeler are the primary
bodies of water within the watershed. Local governments have
jurisdiction in the watershed as follows (refer to Map A, Jurisdictions
within Swift Creek Watershed) :
Apex 1, 976 acres 5%
Cary 11, 126 acres _280
Garner 7, 071 acres 18%
Raleigh 3, 290 acres 8%
Wake County 16, 771 acres _ 410
TOTAL 40,174 acres 100%
Approximately 59% of the watershed is within municipal jurisdictions. In
addition, expansion within the watershed is planned by municipalities.
Cary and Garner plan to extend their jurisdictional boundaries southward
through the Swift Creek watershed. Cary is constructing a wastewater
treatment plant in the Middle Creek watershed, and will run wastewater
lines from their Middle Creek treatment plant through the Swift Creek
watershed to provide service to Cary. Garner also plans to run
wastewater trunk lines through the Swift Creek watershed critical area
(defined below) in order to provide services to an area in the non-
critical portion (defined below) of the watershed on the south side of
Swift Creek.
Given municipal interest in the area, the committee studied whether
residential development greater than one dwelling unit per acre, with
greater than 12% impervious surface area, and non-residential
development should be recommended in the non-critical area of the
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watershed, subject to land use regulations designed to protect the
quality of the water.
DEVELOPMENT REGULATIONS
Definition of Critical Area and Stream Buffers
For a water supply watershed WS-II classification, the following minimum
critical. areas and stream buffers are proposed for the Swift Creek
watershed(refer to Map B) :
AREA OF WATERSHED MINIMUM CRITICAL AREA JINIMUM VEGETATIVE
WIDTH BUFFER WIDTH
Lake Benson North side 2000 feet, 100 feet measured from
south side 2640 feet lake conservation pool
measured from lake level
conservation pool level
Swift Creek 500 ft from the center 100 ft measured from
of creek along both creek bank
sides of creek
Lake Wheeler 1000 ft measured from 100 ft measured from
lake conservation pool lake conservation pool
level level
Swift Creek 500 ft from the center 50 ft measured from
of creek along both creek
sides of creek above bank
Lake Wheeler to Holly
Springs Rd. (S.R 1152)
Little Swift Creek(LSC) None 100 f t measured from
and Yates Mill Creek creek bank, measured to
(YMC) Yates Mill Pond Dam for
YMC, and measured to
the dam located
southeast of S.R. 1371
and S.R. 1152 for LSC
Drainageways none 0 ft if area drained is
less than 5 acres, 25
ft if 5 to less than 25
acres, 50 ft if 25 or
more acres; measured
from creek bank or
center of a drainageway
Performance Standards
Table 1, on page 5, summarizes minimum performance standards which could
be applied to the entire watershed and are designed, with appropriate
development densities and stream and vegetative buffers, to attain a WS-
II classification. These standards are recommended to be applied to new
development throughout the watershed. They are not proposed to affect
existing or already approved development. The proposed impervious
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surface limit is 6% in the critical area and 12% in the non-critical
area for areas without stormwater control measures . The proposed maximum
impervious surface limit is 30% except for those areas designated as (a)
critical: urban limited residential, or (b) non-critical: new urban
residential and non-residential, or existing urban (refer to Table 1) .
It should be noted that stormwater impoundments are required when
proposed impervious surface limits exceed 6% in the critical area and
12% in the non-critical area, and that as the amount of impervious
surface increases, the size of the proposed impoundment must also
increase. All impoundments are proposed to be constructed according to
DEM standards. It is believed that private maintenance of impoundments
is sufficient to maintain water quality protection, but that periodic
public inspection according to DEM guidelines should be required, to
monitor impoundment effectiveness, and that public maintenance should be
required when private maintenance fails.
As a further enhancement of water quality protection, it is also
proposed that point source discharges be prohibited within the
watershed. A WS-II classification would prohibit industrial discharges
within the watershed. The performance standards in Table 1 would also
require domestic dischargers, such as public and. community sewer
systems, to pump their effluent out of the watershed. It should also be
noted that in the critical portion of the watershed public sewer is
required for limited residential uses which exceed an impervious surface
ratio of 6%. In addition, in the non-critical portion of the watershed
public sewer is proposed to be required for residential and non-
residential uses which exceed an impervious surface ratio of 12%. These
requirements for public sewer would need to be implemented and enforced
by local governments through local ordinances.
LAND USES
Existing Land Use Patterns
The existing land use patterns were identified and mapped for each local
government jurisdiction in the watershed (refer to Map C, Existing Land
Use Patterns, Swift Creek Watershed) . In general it was found that the
highest intensity of land use in the watershed is north of Lake Benson,
within Garner' s jurisdiction, and in areas west of Holly Springs Road
within Apex' s and Cary's jurisdictions . These areas were developed
primarily for small lot residential uses, but also have some business
and commercial uses. The lowest intensity of land use in the watershed
surrounds Lake Wheeler and the south side of Lake Benson, and is in Wake
County' s jurisdiction. This area is zoned by Wake County to allow about
one dwelling unit per two acres in the critical area (defined by the
County as the area within 1, 200 feet of Lakes Benson and Wheeler,
measured from the lake conservation pool level, and within 600 feet of
Swift Creek between the two lakes and upstream of Lake Wheeler, measured
from the floodway center) , and about one dwelling unit per acre in the
non-critical area. Much of this area is undeveloped. Most of the
remainder of the watershed, the areas north and west of Holly Springs
Road, are developed at a residential density averaging 2 .5 dwelling
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units per acre, and at an impervious surface area of approximately 30%.
The exceptions are those central portions of Cary which exceed 2 .5
dwelling units per acre and have no impervious surface limit. Although
some existing development has been constructed to a 30% or greater
impervious surface level, Cary staff estimates that existing
impoundments and lakes meet the size requirements for collecting
stormwater runoff as recommended by DEM. Therefore, Cary staff estimates
that these areas were developed in a manner which could meet recommended
water quality protection measures.
Potential Future Land Use Patterns
The scenario outlined below represents the potential future land use
pattern of the Swift Creek watershed as municipal jurisdictions expand.
Differences among land use patterns reflect the extent of planned water
and sewer line extensions into the watershed. In general, Apex, Cary and
Garner plan to extend sewer trunk lines in the watershed, which could
create the potential for urban development. Raleigh and Wake County do
not plan to extend sewer trunk lines in the watershed.
The general land use patterns in the scenario, and the recommended
performance standards described in Table 1, are designed to enable the
Swift Creek watershed to attain a WS-II classification. It should be
noted that the checkered areas on Map D represent areas which were
developed prior to the establishment of water quality protection
standards, and may not meet the standards proposed in Table 1 .
The performance standards discussed in Table 1 above, are recommended to
be applied to the scenario discussed below.
Land Use Scenario
Vegetative Buffers
Vegetative buffers would be maintained along all streams which drain
into Swift Creek, and Lakes Wheeler and Benson. DEM requires that
vegetative buffers be maintained for water quality protection to attain
a WS-II classification. These buffers would remain undisturbed so that
they could function to filter stormwater runoff.
Critical Area
Limited residential development would be permitted within the critical
area of the watershed. Limited residential development would prohibit
institutional uses such as colleges, places of worship, schools, public
libraries and museums, and art galleries . In order to curb the potential
for future urban development in the critical portion of the watershed,
public sewer trunk line tap-ons also would be prohibited in the critical
area.
Garner and Wake County are the only local governments which maintain
jurisdiction in the critical area of the Swift Creek watershed as
defined in this report. A portion of Garner' s jurisdiction within the
critical area of the watershed is already developed to urban residential
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densities, and part of this area was developed prior to the
establishment of water quality protection standards. For the
undeveloped remainder of the critical area within Garner' s jurisdiction,
Garner allows only limited residential, agricultural, recreational and
public uses, and enforces watershed protection standards which fall
within DEM' s guidelines for adequate water quality protection. In
order to allow development patterns in the undeveloped portion of Garner
Is jurisdiction within the critical area to be consistent with previous
development in that area, limited residential uses at a maximum density
of 2 .5 dwelling units per acre with an impervious surface ratio of over
6% but no greater than 35% would be allowed provided the first 1 inch of
runoff is captured and public sewer is provided.
The portion of the critical area located within Wake County' s
jurisdiction is partially developed to a maximum density of 0 . 5 dwelling
units per acre with limited residential uses (prohibiting all commercial
and institutional uses other than recreational uses) . Because Wake
County' s, like Garner' s, portion of the critical area is adjacent to the
water take-out point, but unlike Garner' s remains largely undeveloped,
this area would be maintained at a maximum residential density of 0 .5
dwelling units per acre, yielding an impervious surface ratio of about
6%.
Non-Critical Area: Current Jurisdictions
The area east of Lake Wheeler Road is within Garners, Raleigh' s and Wake
County' s jurisdictions . Much of the area within Garner' s jurisdiction
was developed prior to the establishment of water quality protection
measures . However, Garner requires that water quality protection
measures be met for all new development in the watershed. For a portion
of those undeveloped areas in the watershed at the intersection of S.R.
1010 and U.S. 401, and at the intersection of U.S. 401 and the proposed
Vandora Springs Road extension, Garner plans to allow residential
development densities of up to 6 dwelling units per acre. The areas
which are planned to be maintained at a maximum density of 1 dwelling
unit per acre are the portion of the NCSU Research Farm designated as
major open space, and those areas east of and adjacent to the NCSU
Research Farm, and between Lake Benson and N.C. 50 .
For the portion of Raleigh's jurisdiction within the watershed east of
Lake Wheeler Road, residential use densities of up to 6 dwelling units
per acre are proposed. New urban areas are proposed in the area south of
Tryon Road and east of the NCSU Research Farm adjacent to existing
developed urban areas where public utilities exist or can be easily
extended. The remainder of this area is planned to be maintained as
major open space or to be developed to a maximum residential density of
1 dwelling unit per acre. It should be noted that some of the area east
of Lake Wheeler Road within Raleigh' s jurisdiction was developed prior
to watershed protection standards.
The majority of the area east of Lake Wheeler Road within Wake County' s
jurisdiction is designated as rural residential which allows for a
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maximum density of up to 1 dwelling unit per acre. However, a portion of
this area north of Swift Creek was developed with non-residential uses
prior to the establishment of water quality protection standards.
Within the non-critical portion of the watershed east of Holly Springs
and Jones Franklin Roads, and west of Lake Wheeler Road, residential
development and a limited amount of non-residential development would be
permitted. This area is largely within Wake County' s jurisdiction except
for smaller areas in Cary' s and Raleigh' s jurisdictions. The majority of
this area within Wake County's jurisdiction is rural residential, with
an average density of one dwelling unit per acre. The exceptions are
those portions which are developed to allow non-residential uses
necessary to serve the daily needs of area residents, such as
convenience stores and elementary schools. The area within Wake County
would be maintained at a maximum residential density of 1 . 0 dwelling
unit per acre with a limited number of non-residential uses allowed, and
would not be severed because of the increased potential, once developed,
to adversely affect the water quality of Lakes Benson and Wheeler. This
type of development would yield an impervious surface area of about 12%,
and would be able to maintain an adequate level of water quality
protection without structural devices.
For the area within Cary's jurisdiction east of Holly Springs Road and
west of Campbell Road, residential development would be allowed at a
density of up to 6. 0 dwelling units per acre. Municipal sewer extensions
are planned for this area which is designated by Cary on Map D for new
urban development. Cary proposes to restrict their impervious surface
limits to a maximum of 30% in this area.
For the area within Raleigh' s jurisdiction east of Jones Franklin and
Holly Springs Roads, and north of the NCSU Research Farm, residential
development would be allowed at a density of up to 6. 0 dwelling units
per acre. Although Raleigh does not plan to extend sewer trunk lines
into this portion of the Swift Creek watershed, Raleigh could extend
sewer trunk lines into this area, but would restrict their impervious
surface limits to a maximum of 30%.
Because these areas within Cary' s and Raleigh' s jurisdictions are at the
periphery of the watershed, it is not believed that a limited amount of
residential development at a maximum density of 6. 0 dwelling units per
acre would significantly increase the potential to adversely affect
water quality. (As specified in Table 1, impervious surface limit may be
increased to 30%, and 70%, provided that the first one-half inch or one
inch of rainfall run-off is retained, respectively. )
The remainder of the watershed, the area west of Holly Springs and Jones
Franklin Roads, lies within Apex's, Cary's and Wake County' s
jurisdictions. Much of the area within Apex' s and Cary' s jurisdictions
is developed or has site plans which have already been approved at a
residential density averaging 2 .5 dwelling traits per acre and result in
impervious surfaces of approximately 30%. The exceptions are those
residential portions of Apex and Cary which exceed 2 .5 dwelling units
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per acre, and those non-residential portions which have no impervious
surface limit. Since these areas are located at the periphery of the
watershed, and because the recommended performance standards are not
proposed to affect existing or approved development, these areas would
be allowed to develop at these densities .
The area within Wake County' s jurisdiction west of Holly Springs Road
remains largely undeveloped, but has some large lot single family
subdivisions . Residential uses with a maximum density of 1 dwelling unit
per acre would be allowed for the undeveloped portion.
Non-critical Area: Municipal Jurisdiction Expansion
The potential future land use patterns, (described, below) would be
applied as municipal jurisdictions expand in the watershed. As proposed
above, vegetative buffers would remain undisturbed, and proposed
critical areas would be maintained according to the recommended
performance standards in Table 1 .
Within the non-critical portion of the watershed, new suburban areas
with a maximum average density of 2 .5 dwelling units per acre and non-
residential uses with a maximum impervious surface limit of up to 300
would be allowed in municipal jurisdictions. Portions of these areas,
which are currently in Wake County's jurisdiction, are proposed to be
developed to suburban densities by municipalities.
In the non-critical portion of the watershed east of Holly Springs and
Jones Franklin Roads, residential uses with an average density of 6
dwelling units per acre also would be allowed in municipal
jurisdictions. Existing areas within Cary' s and Raleigh' s jurisdictions
are already proposed to be developed at an average of 6 dwelling units
per acre in this area. Other new urban areas proposed to allow up to 6
dwelling units per acre, and non- residential uses with a maximum
impervious surface of up to 70o would be located along the north shore
of Lake Benson and along U.S. 401 in Garner' s jurisdiction.
In the non-critical portion of the watershed west of Jones Franklin and
Holly Springs Roads, residential uses with a density exceeding 6
dwelling units per acre and non- residential uses with a maximum
impervious surface of up to 70o also would be allowed in municipal
jurisdictions. New urban areas proposed to allow greater than 6 dwelling
units per acre are proposed to be located adjacent to existing central
business districts in Apex and Cary, and on portions of other sites
within Cary' s jurisdiction.
ISSUES FOR ADDITIONAL STUDY
During discussions, several issues were brought up which could have an
effect on the implementation of future land use regulations in the
watershed. No conclusions were reached for these issues. However, it
believed that these issues should be considered as the land management
plan for the Swift Creek watershed is refined.
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Impoundments Serving Multiple Properties : Impoundments serving multiple
properties are proposed to be allowed. This method is used within
individual Planned Unit Developments (PUDs) built within Cary' s
jurisdiction and should be expanded to apply to a runoff impoundment
serving more than one development. It is believed that large
impoundments serving multiple properties are more effective and easier
to maintain than small impoundments serving individual properties.
Removal of Existing Point Source Discharges in the Watershed: The
ability to attain a WS-II classification for the watershed may be
improved if public sewer improvements or land use controls can be
utilized to remove existing point source discharges from the Swift Creek
watershed. There are approximately 7 existing discharges within the
watershed.
Sewer Lines Passing Through Critical Areas : The proposed regulations
specify that the critical area of a water supply watershed (except for
areas already urban) should not be served with public sewer. Garner' s
future growth patterns include the area around and to the south of Lake
Benson. In order to provide sewer service, which is required by State
law for areas within corporate limits, it would be most economical to
run main sewer lines through the critical area rather than around the
critical area. Garner staff believes that the Town could successfully
prohibit trunk line tap-ons in the critical area. There is a concern,
however, that if sewer mains were allowed to run through the critical
area, Garner could be pressured into allowing trunk line tap-ons to
provide service to those properties in the immediate area of the lines.
General Enabling Legislation: General enabling legislation is needed to
allow municipalities to annex within water supply watersheds without the
requirement that they extend water and sewer lines (G.S. 160A-35 (3) b.
and G.S. 160A-47 (3) b. ) , thereby allowing municipal expansion while
also protecting the water quality.
Low Pressure Wastewater Disposal Systems : Because of the recent failure
of a low pressure wastewater disposal system in the Swift Creek
watershed, it was discussed whether or not these systems should continue
to be allowed in a water supply watershed, and, if so, whether public
maintenance should be required if they fail.
Road Construction Standards: Road construction standards were discussed
briefly.
Amount of Non-Residential Development to be Allowed: The land use plans
represented in this report (Map D) concentrate on residential uses as
the predominant use. The amount and nature of proposed non-residential
use areas needs to be further refined. The non-residential areas are not
intended to be major commercial or employment areas. The intensity of
non-residential development could be allowed to increase as the distance
from the critical area increases .
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CONCLUSION
It is believed that good water quality management practices can be
enforced by limiting the types and densities of future growth,
controlling point source discharges, and applying water quality
regulations which meet or exceed those recommended by DEM staff to
maintain a WS-II classification. The performance standards outlined in
Table 1 and the watershed critical areas and buffers defined above are
proposed to meet these water quality management objectives, while
permitting municipal growth. The scenario attempts to present land use
patterns which could be applied to the watershed to attain a WS-II
classification.
c: \js\stdyarea/sc-dem
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