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KLING ENGINEERING & SURVEYING 14.64
Consulting Engineers •Land Surveyors
4101 Texas Avenue, Suite A Post Office Box 4234
Bryan, Texas 77802 Bryan, Texas 77805
Telephone 979/846-6212
Fax 979/846-8252
B.J. Kling, P.E., R.P.L.S.
S.M. Kling, R.P.L.S.
Memo: February 16, 2006
To: City of College Station
Development Engineering
c/o Alan Gibbs, P.E.
Re: The Gateway Subdivision Phases 2-4 Creek Crossing
ZBA Variance Request - upporting Documentation
From: Fred Pain
The following memo is in response to your request to address each item listed in
Section 6.A(1)-(3) and 6.C.(5).(a)-(d) of Chapter 13 - Flood Hazard Protection Ordinance.
The Variance Request is with respect to the provision documented in Section 5.G.(1)
"Special Provisions for Floodways" of Chapter 13 of the Code of Ordinances for the City of
College Station. The text of this provision is as follows:
"Encroachments shall be prohibited, including fill,new construction,substantial improvements
of existing construction, structures, manufactured homes, or other development. Variances
requested on this standard shall be accompanied by a complete engineering report fully
demonstrating that the encroachments shall not result in any increase in water surface elevation
or flood hazard upstream, within, or down stream of the encroachment location. The
engineering report shall conform to the requirements of the Drainage Policy and Design
Standards and shall bear the dated seal and signature of a registered professional engineer;"
Section 6.A.(1): Special Circumstances/Conditions affecting the land such that strict
compliance with the provisions would deprive the applicant of the reasonable use of his land
is as follows:
An unnamed tributary to Burton Creek crosses the subject tracts. This tributary creek
forms the boundary between platted and proposed platted areas of Gateway Phases 2-4
(refer to the approved preliminary plat-attached). Approximately 7.6 acres of property is
isolated on the west side of the channel (proposed Gateway Phase 4, Lot 1, R-4 zoning).
In order to access and utilize this property, the channel must be crossed with a roadway and
utilities. Current access consists of a gravel oil well access road with a low water crossing.
This crossing is inaccessible during larger rainfall events.
Section 6.A.(2): Variance is necessary for the preservation and enjoyment of a substantial
property right of the applicant.
The proposed project specific variation from the ordinance is construction of a private
access drive consisting of roadway embankment fill, 3-10'x7' reinforced concrete box
culverts, 2-48" reinforced concrete pipe culverts, and public waterline. Strict compliance
with Section 5.G.(1) would prohibit the road crossing and render the 7.6 acre lot unusable
by the applicant.
Section 6.A.(3): Variances may be issued for reconstruction, rehabilitation, or restoration
of structures listed on the National Register of Historic Places.
Not Applicable.
Section 6.C.(5).(a): Strict compliance with the provision documented in Section 5.G.(1)
"Special Provisions for Floodways" of Chapter 13 of the Code of Ordinances for the City of
College Station would cause undue hardship on the applicant and deprive him of the
reasonable use of his land. The text of this provision is as follows:
"Encroachments shall be prohibited,including fill, new construction,substantial improvements
of existing construction, structures, manufactured homes, or other development. Variances
requested on this standard shall be accompanied by a complete engineering report fully
demonstrating that the encroachments shall not result in any increase in watersurface elevation
or flood hazard upstream, within, or down stream of the encroachment location. The
engineering report shall conform to the requirements of the Drainage Policy and Design
Standards and shall bear the dated seal and signature of a registered professional engineer;"
Section 6.C.(5).(b):The minimum relief to this hardship is to provide an access road protected
from the 100 year flood event and public utilities to the 7.6 acre tract. Specific measures taken
to relieve the hardship are the construction of a roadway, creek crossing, and waterline
extension. The creek crossing will consist of large culvert structures that will pass the 100
year storm event flows without adversely affecting upstream, downstream or adjacent
properties (Refer to attached plan sheet for depiction of crossing).
Section 6.C.(5)(c): Effects of the variance in terms of channel hydraulic characteristics are as
follows:
Results for Effective FEMA Model
River Station 387 512(Culvert) 554 632
Q total (cfs) 941 /941 NA 941 /941 941 /941
Q channel (cfs) 479.9/627.2 NA 543.3/756.0 323.0/345.8
WSEL(ft) 274.2/275.1 NA 275.0/275.9 275.6/276.5
Depth of Flow(ft) 6.2/7.1 NA 6.0/6.9 8.4/9.3
Ave.Velocity(ft/s) 2.4/3.3 NA 2.7/3.4 2.4/2.5
Results organized as follows (floodplain /floodway)
Results for Proposed Crossing (3-10'x7' RCB & 2-48" RCP)
River Station 387 512(Culvert) 554 632
Q total (cfs) 941 /941 941 /941 941 /941 941 /941
Q channel (cfs) 477.4/625.6 941 /941 500.2/758.1 316.5/347.1
WSEL(ft) 274.2/275.1 275.1 /275.8 275.3/275.9 275.8/276.5
Depth of Flow(ft) 6.2/7.2 5.4/6.1 6.3/6.9 8.6/9.3
Ave.Velocity(ft/s) 2.4/3.3 4.9 (aye) 2.2/4.0 2.3/2.5
As shown in the tables above, the addition of the 3-10'x7' RCTs and 2-48"RCP culvert structure
does not increase the base flood elevation above floodway water surface elevations allowed
for encroachments. The basis of the results described in the above tables are contained in
a report submitted to the City of College Station, Development Engineering November 09,
2005 and approved thereafter.
Section 6.C.(5).(d): Special conditions to be considered as criteria for granting the variance
are as follows:
1. In order for the property to be utilized consistent with it's designated R-4 zoning,
access must be granted which is not rendered impassible by the 100 year flood
event.
2. This access is required to protect the health, safety and welfare of property,
structures, and residents of an R-4 development.
3. This access will not adversely affect water surface elevations or velocities
upstream, downstream, or adjacent to the crossing.
4. An engineering report is on file with the City which conforms to current City
drainage policies.
5. No alternative to provide safe and constant access to the 7.6 acre tract exists.