Gateway BP (1.1)-CS 900212FEB. 12, 1990
DONALD E. DAVIS
CONSULTING ENGINEERS
5506 COCKRELL HILL ROAD
DALLAS, TEXAS 75236
(214) 337-2332
PAGE 1 GF 2
HOWARD PAFFORD
CITY OF COPPELL - DEPARTMENT OF PUBLIC WORKS
732 DEFOREST
COPPELL, TEXAS 75019
RE:
PARK WEST COMMERCE CENTER
SANITARY SEWER STUDY
(C0190022,AHP)
A STUDY OF THE CITY SANITARY SEWER SYSTEMS INDICATES THAT THERE IS ONE 12"
DIAMETER MAIN TRUNK LINE THAT SERVES THE AREA OF THE CITY CONTAINING PARK WEST
COMMERCE CENTER. A STUDY OF THIS AREA WAS DELINEATED AND ANALYZED TO ESTIMATE
THE VOLUME OF SANITARY SEWERAGE EXPECTED IN THE TRUNK LINE WHEN THE AREA IS
FULLY DEVELOPED.
METHOD NO. 1:
LAND AREA DEMAND PEAK PEAK
USE ACRES MGD FACTOR MOD
RESIDENTIAL 1414 1.48 3 4.44
COMMERCIAL 290.6 3.16 I 3.16
INDUSTRIAL 825.4 3.60 1 3.60
TOTAL 8.24 11.20
METHOD NO. 2:
(CITY OF DALLAS FIGURE 3.3.3)
(APPLIES FACTOR TO ENTIRE ACREAGE BASED ON EMPIRICAL VALUES.)
2530 ACRES x 4.55 GAL. PER ACRE PER DAY = 11.5 MOD
USE 11.5 MOB
FEB. 12,
C0190022. AHP
PAGE 2 OF 2
THE REQUIRED PIPE IS 24" DIAMETER WITH A SLOPE OF 0.65% AND VELOCITY OF' 5.8
fps, IF CONSTRUCTED IT WOULD BE ADVISABLE TO CONSIDER THE EFFECT OF A 30" PIPE
WITH A REDUCED VELOCITY,
IF FORCED TO CARRY THE PROJECTED VOLUME - THE EXISTING 12" PIPE WILL HAVE
7.6% HYDRAULIC GRADIENTAND A VELOCITY'OF 15.5 fps. THIS IS TOO HI~H,' IS
UNSATISFACTORY AND WILL RESULT IN OVERFLOW.
A
THE PARK WEST COMMERCE CENTER ANTICIPATED DEMAND IS AS FOLLOWS:
328 ACRES OF INDUSTRIAL PROPERTY.
SANITARY SEWER DEMAND=1.43 MOD
THE IMPACT OF PARK WEST COMMERCE CENTER TO TOTAL IS 1.43 MOD DIVIDED BY
MGD=13%
11.2
ASSUME THAT THE EXISTING 12" TRUNK SEWER REMAINS IN PLACE. THEN THE ADDITIONAL
SEWER NECESSARY IS AS FOLLOWS:
EXISTING 12" DIAMETER SEWER CAPACITY = 4,52 MGD@ 5.8 fps.
FUTURE CAPACITY FOR PROJECTED SEWER PIPE = 11.5 MGD MINUS 4.5 MOD = 7 MOD.
18" DIAMETER SEWER WITH SLOPE OF 1.03% AND VELOCITY OF 6.2 PPS WILL CARRY 7
MOD. A LARGER PIPE SHOULD BE CONSIDERED IN ORDER TO REDUCE THE VELOCITY AND
GRADE REQUIREMENTS.
IN ORDER TO COMPLETE THE STUDY IT WOULD BE NECESSARY TO PROVIDE GAGES AND
RECORD THE FLOW VOLUMES AT VARIOUS LOCATIONS. THEN REFINE THESE CALCULATIONS
SO THAT A CORRELATION BETWEEN THE CALCULATED VOLUME AND THE MEASURED VOLUME IS
OBTAINED. THE OCCUPIED AREAS WOULD THEN BE CAREFULLY MEASURED IN COMPARASON TO
THE UNDEVELOPED AREAS, THE RESULTING VALUES ARE THEN COMPARED TO THE VALUES
CALCULATED HEREIN TO ARRIVE AT THE FINAL VALUES.
THE STUDY SHOULD ALSO INCLUDE THE FIELD MEASURED VALUES AND SLOPES OF THE
EXISTING AND PROPOSED SEWER PIPES.
DONALD E. DAVIS
CONSULTING ENGINEERS
CC: DON GERKEN
LEE HANSEN