HomeMy WebLinkAbout025573 ORD - 12/09/2003Page 1 of 3
AN ORDINANCE
AMENDING THE 1982 STORM DRAINAGE MASTER PLAN FOR THE
AREA WEST OF CALALLEN (FIVE POINTS) TO TRANSFER
APPROXIMATELY EIGHT (8) ACRES FROM BASIN "E" TO AN
UNIDENTIFIED BASIN NEIGHBORING ON THE EAST AS DESCRIBED
IN THE ATTACHED EXHIBIT; PROVIDING FOR PUBLICATION; AND
DECLARING AN EMERGENCY.
WHEREAS, the Planning Commission has forwarded to the City Council its reports and
recommendations concerning the amendment to the Storm Drainage Plan of the City of
Corpus Christi;
WHEREAS, with proper notice to the public, public hearings were held on Wednesday,
December 3, 2003, during a meeting of the Planning Commission, and on Tuesday,
December 9, 2003, during a meeting of the City Council, in the Council Chambers, at
City Hall, in the City of Corpus Christi, during which all interested persons were allowed
to appear and be heard; and
WHEREAS, the City Council has determined that this amendment would best serve
public health, necessity, and convenience and the general welfare of the City of Corpus
Christi and its citizens.
NOW, THEREFORE, BE IT ORDAINED BY THE CITY COUNCIL OF THE CITY OF
CORPUS CHRISTI, TEXAS:
SECTION 1. That the Storm Drainage Plan of the City of Corpus Christi, Texas, is
amended, for the area west of Calallen, to transfer approximately eight (8) acres from
Basin "E" to an unidentified basin neighboring on the east, by incorporating the attached
Exhibit "A" into the Storm Drainage Plan.
SECTION 2. That the Storm Drainage Pan is an element of the Comprehensive Plan
and the Comprehensive Plan is amended to conform to the Storm Drainage Plan, as
amended by this ordinance.
SECTION 3. That all ordinances or parts of ordinances in conflict with this ordinance
are hereby expressly repealed.
SECTION 4. That publication shall be made in the official publication of the City of
Corpus Christi as required by the City Charter of the City of Corpus Christi.
SECTION 5. That upon written request of the Mayor or five Council members, copy
attached, the City Council (1) finds and declares an emergency due to the need for
immediate action necessary for the efficient and effective administration of City affairs
and (2) suspends the Charter rule as to consideration and voting upon ordinances at
two regular meetings so that this ordinance is passed upon first reading as an
emergency measure on this 9th day of December, 2003.
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ATTEST: ~
Armando Chapa
City Secreta~
APPROVED
Josep~H~rney
Assistant City Attorney
For City Attorney
2003
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Corpus Christi~exas
(~ day of ~?.~, 2003
TO THE MEMBERS OF THE CITY COUNCIL
Corpus Christi, Texas
For the reasons set forth in the emergency clause of the foregoing ordinance, an
emergency exists requiring suspension of the Charter rule as to consideration and
voting upon ordinances at two regular meetings. I/we, therefore, request that you
suspend said Charter rule and pass this ordinance finally on the date it is introduced, or
at the present meeting of the City Council.
Respectfully,
Respectfully,
Samuel L. Neal, Jr.
Mayor, The City of Corpus (~3~'risti
Council Members
The above ordinance was passed by the following vote:
Samuel L. Neal, Jr.
Brent Chesney
Javier D. Colmenero _~_.~._
Melody Cooper
Henry Garrett
William Kelly
Rex A. Kinnison
Jesse Noyola
Mark Scott
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Drainage Master Plan Amendment
To: Planning Commission Members or City Council
From: Vernon A Wuensche PE
Dale: 12/2/3
Re: Master Drainage Plan - Amendment
The proposed text for the amendment to the plan is as follows:
Amending the Storm Drainage Plan for the Area West of Caiailen (5-Ponts) to transfer about
8 acres from Basin 'E' to an unidentified basin neighboring on the east.
Back4p'ound
The Storm Drainage Plan for the Area West of Calallen (5-Ponts) was adopted by the City
Council of Corpus Christi per Ordinance # 16927 on March 10, 1982. The plan was prepared by
Naismith Engineers, Inc. of Corpus Christi, Texas.
Proposed Action
This revision was necessitated by the proposed subdivision improvements, which would transfer
drainage of about 8 acres out of Basin E-A-1 to the unidentified basIn bordering on the east.
Recommendation
It is staWs recommendation that the Planning Commission recommend the proposed Amendment
as presented for City Council action
Suooortin~ Documentation
A review of the hydraulics reveals that area A (8 aercs), the ama that would be diverted into the
Hazel Bazemore Basin, plus area B (15 acres), the area inside the Hazel Bazemore Basin and
including the detention pond, would be combined for a total 23 acres.(Subdiwsaon Area Detail B )
Subdivision Area Detail 'B'
The predevelopment Q based on a 2-year for the area with a time of concentration of 50 minutes
would be
Where C = 0.2, I = 2.45 cfs/acre, A = 23 acres
Q = 0.2(2.45)23 = l 1.3 efs
Let the peak discharge Q be 90% of the value determined above or 10.17 and round off to 10.
Use O = l0 els as the maximum allowable discharge from the pond_
®P~e2
Sizing the pond, consider 100-year storm, C = 0.6, and a total basin area of 23 acres including the
pond the pond is sized using the two methods tabulated below.
Cumulative
Total Flow Flow Req
Runoff Rainfall Flow rate Out out of Storage
Duration Area coeff. 100 yr Into Pond of Pond Pond of Pond
(cubic (cubic
(hfs) (acres) (inches) (cubic feet) (CFS) feet) feet)
0.5 23 0.6 3.6 180,338 10 18000 162,338
1 23 0.6 4.6 230,432 10 36000 194,432
2 23 0.6 5.9 295,555 10 72000 223,555
3 23 0.6 6.5 325,611 10 108000 217,611
6 23 0.6 8 400,752 10 216000 184,752
12 23 0.6 9.8 490,921 10 432000 58,921
Detention Pond Sizing Cumulative Rainfall Method
Durati
(min)
Area Runoff Peak Flow Into Flow rate Flow out Required
coeff. Discharge Out of of Pond Storage
Basin of Pond
(acres) (CFS per (cubic feet) (CFS) (cubic feet) (cubic feet)
Acre)
30 23 0.6 6.8 168,912 10 18000 150,912
60 23 0.6 4.5 223,560 10 36000 187,560
120 23 0.6 3.4 337,824 10 72000 265,824
180 23 0.6 2.2 327,888 10 108000 219,888
240 23 0.6 1.8 357,696 10 144000 213,696
Detention Pond Sizing Peak Discharge Method
As shown in the tables above total cumulative rainfall method yields a minimum required pond
storage volume of 224,000 cubic feet and the peak discharge method yields a minimum required
pond storage volume of 267,000 cubic feet.
Let the minimum size of detention pond be 270~000 cubic feet
®P~e3
Consider the impact on the basin into which the water is being diverted
Un-Diverted condition per master plan (Existing before Diversion - 'A')
Existing before Diversion - 'A'
The total area of the basin draining to the Hazel Bazemore Ditch at the park entrance would be
about 74 acres.
· Page 4
Un-diverted peak flow rate w/o diversion, Q~,/o, would be:
Qw/o = C I A
C=0.6
A = 74 acres
I = intensity
So, Qw/o = 0.6(74) x I or 44x I
Eql
Diverted condition as propose (Proposed After Diversion - C)
Proposed After Diversion - C
· Page5
The total area of the basin draining to the Hazel Bazemore Ditch at the park entrance would be the
original 74 acres plus the 8 acres diverted into the basin, being 82 acres total.
The area to be contained within the detention pond, including the pond would be 23 acres.
(Subdivision Area Detail - 'B') If we divide the drainage basin into two components, (one) the 59-
acre area that is to be drained by the main channel (82 acres - 23 acres = 59 acres) and the 23 acre
area that is to be handled by the pond, we could determine the peak discharge as follows:
Diverted peak flow rote w/diversion, Qw/, would be:
Qw/~ C I An + Qp
Where
C = 0.6
A~ = 59 acres
I = intensity
Qp = 10 cfs, Peak discharge fi~m the detention pond
So, Q~/=0.6x(59)xI+Qpor(35xI)+ 10 Eq 2
If we let the Peak Discharge without diversion (Eq 1 ) grater than the Peak discharge with diversion
(Ell 2) we obtain:
44xi >(35xi)+ 10
Solving for I, the crilical intensity, we obtain
I> 1.1 cfs pcr acre
Considering a 2-year storm and TXI)OT hydrology equation:
I = b/(t+d)e Eq 3
WherQ:
I = 1.1, the critical intensity (cfs per acre)
b = 71, d = 9.4, e = 0.824, the standard coefficients
t = time of concentration (minutes)
Substituting and solving Eq 3 for t we obtain t = 150 minutes or 2 ½ hours
· Page 6
If we make a conservative estimation that the time of concentration to the most remote point in the
basin would be 60 minutes this would yield a flow time in the main channel of 90 minutes or 5,500
seconds. With the maximum channel length being about 6,000 feet, the channel flow rate would
be about I foot per second.
Based on the observation above, the detention pond with diversion into the Hazel Bazemore Basin
in a worst situation could yield detrimental results for very small storms but this would occur when
flooding is unlikely. And this is due to the uniformly discharged 10 cfs that is assumed to facilitate
the computations.
Not only would the peak discharge along Hazel Bazemore Road be reduced but the overland flow
that is now flowing into the existing River Hills Subdivision to the north would be significantly
reduced, by the proposed improvements.
Specific provisions are recommended to be included in a separate agreement after
construction plans are submitted for review to be executed and approved by the City prior to
filing of the plat These provisions include the following:
The two vary important parameters that must be understood and agreed for tl:c
recommendation to be valid are {one} the detention pond shall have a minlmojIl volume of
270~000 cubic feet and the maximnm discharge from the pond shall be 10 cfs
The detention pond should be considered temporary~ but necessar% until a properly sized
outfall can be built along Hazel Bazemore Road. The ponds discharge structure must be
used to control the discharge rate of the pond and not the outfall pipe. The ponds outf~u
pipe shall be designed for a 25-year event and 100 year swale from the pond to the roadsldo
ditch along the west side of Hazel Bazemore Road.
The detention pond and ouffall up to the roadside ditch along the west side of Ha?.~"
Bazemore Road shall be privately malnt~ined_
The cost of removal of the detention pond at such time as it becomes necessary shall be
borne by the property owner.
The removal of the detention pond shall only be injfi~t~l upon approval by the City of
Corpus Christi and at which time an nnd~r~round outfall alonl~ Hazel Bazemore Road is ;-
Removal and replacement of existing pipe culverts on Hazel Bazemore Road ditch to ensure
a positive slope toward the outfall.
Placement of any velocity reduction structures or controls at the outfall of Hazel Bazemore
Road to reduce erosion.
ePee7
State of Texas }
County of Nueces }
SS~
PUBLISHER'S AFFIDAVIT
CITY OF CORPUS CHRISTI
Ad # 4754765
PO #
Before me, the undersigned, a Notary Public, this day personally came Diana
Hinoiosa, who being first duly sworn, according to law, says that she is Credit
Manager of the Corpus Christi Caller-Times, a daily newspaper published at
Corpus Christi in said City and State, generally circulated in Aransas, Bee,
Brooks, Duval, Jim Hogg, Jim Wells, Karnes, Kenedy, Kleberg, Live Oak,
Nueces, Refugio, San Patricio, Victoria and Webb Counties, and that the
publication of, NOTICE OF PASSAGE OF ORDINANCE NO. which the annexed
is a true copy, was inserted in the Corpus Christi Caller-Times and on the World
Wide Web on the Caller-Times Interactive on the 15TH day(s} of DECEMBER,
2003.
366.16
TWO (2) Time(s)
Credit Manager ,.~
Subscribed and sworn to me on the date of ~9
DECEMBER 16, 2003.
Notary Public, Nueces County, Texas
ROSA MARIA FLORES
Print or Type Name of Notary Public
My commission expires on 04/23/05.
D10/Cmpus Christi Caller-Times, Monday, December 15, 2003
NOTICE OF PASSAGE
OF ORDINANCE NO.
025573
Amending the 1982
Storm Drainage Master
Plan for the ama west
of Calallen (Five
Points) to transfer
about 8 acres from
Basin "E" to an
unidentified basin
neighboring on the
east as better
described in the
attached exhibit. This
ordinance was passe~
and approved by th*
City Council of the Cit
of Corpus Chliafi o,
December 9, 2003.
Is/Armando Chapa
City
City of Corpus Christi