Lake Park-CS 950322 254 954
11fi101 ~ICHOL~.~TFtCK$ON DILLRRD HR~ER,.. -> 214 30z/..3fi73 ~o.,~99 I:,ool./oo?
NICHOLS, JACKgON, DILLARD, ,~,!!:!::.: .....
HA(~ER & SMITH, L.L.P.
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1800 Lincoln PAIz~
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Far, simile (214) 954-3334 '-' : '
Please Deliver The Following To:
NAME: MR. KEN GRIFFIN DATE: MaJ~,h 22, 1995
FIRM: CITY ENgINEER/CITY OF COPPELL FAX NO: (214)304.3673
FROM: PETE SMITH
BY: SHAWN LANGE No. of Pages (including Cover) 6
COMMENTS:
THE INFORMATION CONTAINED IN THIS FAC:,~IMILE IS ATTORNEY PRMLEGED AND CONFIOENTIAL, INFORMATION INTENDED
ONLY FOR 'THE L)~E OF' THE lNl~ OR ENTITY NAMF..~ .ll~, iF THE RF-I~IPIENT I,~ NOT THE INTENDED R~C~PIENT, YOU
ARE HEREBY NOTIIq~D THAT ANY DIST'RIBUTION, DIS,~eMINATION OR OOPYINQ OF THIS COMMUNIGATION I~ STRIIb'~TLY
PROHIBITED, IF YOU HAVE REOEIVED THIS IN ERROR, PLEASE NOTIFY US IMMEDIATELY 8Y PHONE AND RETURN THE
ORIGINAL MES~Id]E TO U8 AT THE ABOVE ADORES8 VIA THE U,S, POSTAL SERVIGF_
furnished and functions performed by CMUD NO. I were no longer needed and could be
furnished and performed by COPPELL. Coppell. Tex.. Ordinance 94640. § 2 (Mar. 16. 1994).
Upon adoption of this ordinance, the propert3.' and other assets of CMUD NO. I were vested in
COPPELL, and the liabilities and obligations of C~D NO. I were assumed by COPPELL.
Coppell, Tex., Ordinance 94640, § 4 (Mar. 16, 1994). COPPELL is now liable for all conduct,
acts, and/or omissions of CMUD NO. 1 during times relevant to the instant cause.
D. COPPELL, in the exercise of its governmental functions, as contemplated by the
Texas Tort Claims Act, approved the plat for the development of the Lake Park Addition by
UNIVEST, HINCKLEY, WI$£CO, and WISE.
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the MSE,.
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~e f~ili~. No ~n ~ti~ or o~ t~ely ~ ~ ~v~ m PL~FF.
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"~~"), n ~difion m ~ Ci~ of ~11, Te~ ~~ m ~ pht ~f ~ h
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dines ~le~t ~ ~s ~t ~ P~t of ~VEST. ~VEST ~ ~C~EY e~.~
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16:01 NICHOLS IACKSON DILLARD HAGER... ~ 214 304 3673 N0.499 P002×007
Citstion Database Mode
30 TX ADC s 317.3 FOUND DOCUMENT TX-ADC Page
30 TAG s 31'/.3
Tex. Admin. Code tit. 30 s 317,3
OFFICIAL TEXAS ADMINISTRATIVE CODE
TITLE 30. ENVIRONMENTAL QUAI ~ITY
PART I. TEXAS NATURAL RESOURCE CONSERVATION COMMISSION
CHAPTER 3~?. DESIGN CRITERIA FOR SEWERAGE SYSTEMS
s 317.3. Lift Stations
(a) Site selection. In the selection of a site for a lift station,
consideration shall be given to accessibility and potential nuisance aspects.
The station shall be protected fi.om the 100-year flood and shall be accessible
during a 2S-year flood. All lift stations shall be intruder-resistant with a
controlled access. I irt stations should be located as remotely as possible from
populated areas.
(b) De. sign.
(1) Small lift stations. I.ift stations designed for a discharge capacity of
less than 100 gallons per minute will be renewed on a case-by-case basis by
the commission and shall be used only for in.~titutional use or other locations
where it is necessary to pump the sewage from a single building, school, or
other measurable source establishment into the sauita~y sewer lines. If the
location of the d/scharge does not provide a positive head due to elevation,
then a positive pressure control valve shall be provided. Ejectors may be used
for thh t~/pe of [iff station. Whenever a lift station handles waste from two
or more residential housing units, or from any public establishment, standby
p~mps shall be provided. In the case of ejecWrs or eductor% two air
compressors shall be prov/ded. Grinder pumps should be used for all small
installations.
(2) Dry well snmp pump. The following desip, n considerations shall be
addressed in providing dry well sump pumps.
(A) Two separate sump l~mps should be provided for removal of leakage or
water from the dry w¢ll floor.
(B) The discharge pipe level from the sump pumps shall be above the maximum
liquid level of the wet well. A check valve should be installed on the
d/scharge side of each sump pump.
(C) All floor and walkway surfaces shall have an adequate slope to a point
of drainage with sufficicnt mea,~ures taken to max/mize traction and safety,
(D) Motors to drive sump pumps shall be located above the height of the
maximum liquid level in thc wet well. As an alternate, sump pumps may be of
the submersible type.
(3) l~mp controls. All lift stations shall have automatically operated pump
16:01 NICHOLS SACKSON DILLARD HAOER... ~ 214 304 36?3 N0.499 P003×007
control mechanisms. Pump control mechanisms shall be located so that they will
not be a~ectcd by flow currents in thc wet well. Pr.ovisions shall be made to
prevent grease and other floating materials and rags in the wet well from
interfering with thc operation of the controls. When a float tube is located
in the dry well, its height shall be such as to prevent overflow of the sewage
into the dry well. Pump control mechanisms which depelld on a bubbler in the
wet well shall be equipped with a backup air supply system. All connections to
level controls in the wet well shall be accessible at all times. The circuit
breakers, indicator lights, pump control switches, and other electrical
equipment should be located on a control panel at least three feet above
ground surface elevation. H controls are located in a dry well, the dry well
shall be protected from flooding.
(4) Wet wells.
(A) Wet wells and dry wells, including their superstructure, shall be
separated by at least a waterti~t and gastight wall with separate lockablc
entrances provided to each. Equipment requiring regular or routine inspection
and mslntenance shall not be located in the wet well, unless thc msintenance
can be accomplished without entering the wet well.
(B) Based on design flow, wet weU capacity should provide a pump cycle time
of not less than six minutes for those lift sm/ions tl~illg submersible pumps
and not less than 10 minutes for other nonsubmersible pump lift stations.
(C) All tnflucnt gravity lines into a wet well shall be located where the
invert is above thc "off' setting liquid level of the pumps, and preferably
should be located above the lead p~mp *on" setthi8.
(5) Stairways. Stairways with non-slip steps shall be provided in all
underground dry wells. Removable ladders may be provided in small stations
where it is impractical to install stairways.
(§) Ventilation. Ventilation shall be provided for lift stations, including
both wet and dry wells.
(A) Passive ventilation such as gooseneck type or turbine ventilators
designed to prevent possible entry of insects or birds shall be provided in
all wet wells if mechanical ventilation is not provided. AU mechanical and
electrical equipment in wet wells should be explosion-proof and spark-proof
construction if mcch_s, nlcal ventilation is not provided.
(B) Mechanical ventilation shall be provided for all dry wells below thc
ground surface. The ventilation equipment shall have a minimum capacity of
six air changes per hour under continuous operations. At least a capacity of
30 air changes per hour shall be required where the operation is
intermittent. All intermittently operated venting equipment shall be
interconnected with the stations lighting system-
(7) Wet well dopes. The bottom of wet wells shall have a minimum slope of
10~ to the pump intakes and shall have a smooth finish. There shall be no
projections in thc wet well which will allow deposition of solids under
ordinary operatin8 conditions. Antivortcx baffii~ should bc considered for
the pump suctions in all large sewage pumpin~ stations (greater than five mgd
firm pumping capacity).
03×22×95 1G:O~ NICHOLS IACKSON DILLARD HAGER... a 214 304 3673 N0.499 P004×007
(8) Hoisting equipment. Hoisting equipment or access by hoisting equipment
for the removal of pumps, motors, valves, etc., shall be incorporated ii1 the
station design.
(9) Dry wells and valve vault drains. Drains from dry wells or valve vaults
to the wet well shall be equipped with suitable devices to prevent entry of
potentially hazardous gases.
(c) P~mps.
(1) General. All raw sewal~e pumps shall be of a non-cio§ design, capable of
passing 2 1/2 inch diameter spheres, and shall have no less than three*inch
diameter suction and discharge openings. Inspection and cleanout plates,
located both on the suction and discharge sides of each pumping unit, are
suggested for all nonsubmersible pumps so as to facilitate locating and
removing blockage-causing materials. Where such openings are not provided on
the pumps, a hand hole in thc first fitting connected to the suction of each
pump shall be provided. All pumps shall be securely supported so as to prevent
movement during operation. For submersible pumps, rail-type pump support
systems incorporating manufacturer-approved mechanisms designed to allow the
operator to remove and replace any single pump without first entering or
dewaterln5 the wet well should be providcd.
(2) Lift station pumping capacity. The firm p-roping capacity of all lift
stations shall be such that the expected peak flow can be pumped to its
desired destination. Firm pumping capacity is defined as total station maximum
p-roping capacity with the largest pumping unit out of service.
(3) Variable capacity p**mps. I i~t stations or transfer pumping facilhies at
a wastewater treatment plant or those discharging directly to the treatment
plant where the plant's permitted daily average flow is equal to or greater
than 100,000 gallons per day shall be provided with three or more pumps or
with duplex automatically controlled variable capacity pumps or other
automatic flow control devices. The pumps or other devices shall be adjusted
for actual flow conditions and controlled to operate so as to minimiTe surges
in the treatment units. No single pumping unit shall have a capacity greater
than the design peak flow of the wastewater treatment plant unless flow
splitting/cq, sli~atlon is provided.
(4) Pump head calculations. The engineering design report accompanying the
plans shall include system curves, pump curves, and head calcuIatiorm.
Calculations and pump curves at both minhnum (all pumps off) and maximum (last
normal operating pump on) static heads and for a C value of both 100 and 140
must be provided for each p,.~.mp and for thc combination of pumps (modified pump
curves). Where a suction lift is required, thc report shall include a
calculation of the available net positive suction head (NPSH) and a comparison
of that value to the required N-PSH for the pump as furnished by the pump
manutacturer.
(:5) Serf-priming pumps. Only self-priming pumps or pumps with acceptable
priming systems, as demonstrated by a reliable record of satisfactory
operation, shall be used where thc suction head is negative. All Self-prlmlng
pumps shall include a means for venting thc air back to the wet well when the
16:03 NICHOLS IACKSON DILLARD HAGER... ~ 214 304 36?3 N0.499 P005/007
p~mp is priminE.
(6) Pump positiop_ing. All raw sewage pumps, other than submersible p-raps
without "suction" piping and self-priming units capable of satisfactory
operation under any negative suction heads anticipated for the lift station
under consideration, shall be positioned such that thc pumps always
experience, during their normal on-off cycling, a positive static suction
head.
(~) Grinder p-raps. See s31?.2(d) of this title (relating to Sewage Collection
System).
(d) Piped.
(1) Pump suctions. Each pump shall have a separate suction pipe. Cavitation
may be avoided by using eccentric reducers in lieu of typical reducers in
order to prevent air pockets from forming in the suction line.
(2) Valves. Full closin~ valves shall bc installed on the discharge piping of
each pump and on the suction of all dry pit pumps. A check valve shall be
installed on the dischari~e side of each pump, preceding thc full closin~
valve. Check valves should be of a swing check type with external levers.
Rubberball check valves may be used for grinder pump installations in lieu of
the swing check type. Butterfly valves, tilting disc check valves, or other
valves with a pivoted disc in the flow line are not allowed. Thc design shall
consider surge effects and provide protection where necessary. Surge relief
shall be contained in thc system.
(3) Valve position indicators. Gate valves should be risir~-stem valves. If
other than rising-stem gate valves and check valves with externsl levers ~e
used, the valves shell include a position indicator to show their open and
closed positions.
(4) li~ station piping. Flan~ed pipe and fitting or welded pipe shall be
used for exposed piping inside of lift stations. A flexible or flanged
connection shall be in~.t.s, lled iii the piping to each pump so that the pump may
be removed easily for repairs. Provisions shall be made in the design to
permit flexure where pipes pass through walls of the station. Piping should
normally be sized so that the maxim,,m suction velocity docs not exceed five
feet per ~econd and the maximum discharge velocity does not exceed eight feet
per second.
(5) Force main pipe selection. Force mains shall be a minimum of four inches
in diameter, **nless justified, as with the use of ~rinder pumps. In no case
shall the velocity be less than two feet per second with only the smallest
pump operatin& unless special facilities are provided for cleaning the line
at specified intervals or h can be shown that a flushirq~ velocity of five
feet per second or greater will occur one or more times per day. Pipe
specified for force mains shall be of a type havin8 an expected life at least
as long as that of the lift station and shall be suitable for the material
being l~mped and the operating pressures to which it will be subjected. All
pipe shall be identified in the technical specifications with appropriate
ASTM, ANSI, or AWWA specifications numbers for both quality control
(rllmen~iOns, tolerances, etc.) and installation Coeddin& backfill, etc.). All
83."22×95 16:03 ~.~C~9'._S ~aCKSOI--I [~:--~RD HFaGES... --> ~14 304
pipe and fittings shall have a minimum working pressure rating of 150 pounds
per square inch.
(6) Force main tests. Final plans and specifications shall describe and
require pressure testing for all installed force mains. Minimum test pressure
shall be 1.5 times the maximum design pressure.
(7) Air release valves. Air release valves or combination air release/vacuum
valves suitable for sewage service shall be provided at all peaks in
elevation. The final engineering drawings must depict all proposed force mains
in both plan and profile.
(e) Emergency provisions. Lift stations shall be designed such that there is
not a substantial hazard of stream pollution from overflow or surcharge onto
public or private property with sewage from the lift station. Options for a
reliable power source may include the following.
(1) Power supply. The commission will determine the reliability, of the
existing commercial power service. Such determinatious shall be based on power
outage records obtained from the appropriate power company and presented to
the commlsslon. When requesting outage records for submittal to the
commission, it iS important to note that the records be in writing, bear the
signature of an authorized utility employee, identify, the location of the
wastewater facilities being served, list the total number of outages that have
occurred during the past 24 months, and indicate the duration of each recorded
outage. The facility will be deemed reliable if the demonstrated wastewater
retention capacity, in the station's wet well, spill retention facility, and
incoming gravity sewer lines, is sufficient to insure that no discharge of
untreated wastewater will occur for a length of time equal to the longest
electr/cal outage recorded in the past 24 months. If records for the service
area cannot be obtained, a 120 minute worst case outage duration will be
assumed. Provisions for a minimum wastewater retention period of 20 minutes
should be considered even in those cases where power company records indicate
no actual outages of more than 20 minutes occurred during the past 24 months.
(2) Alternative power supply. If the existing power supply is found to be
unreliable, an emergency, power supply or detention facility shall be provided.
Options include:
(A) electrical service from two separate commercial power companies,
provided automatic switchover capabilities are in effect:
(B) electrical service from two independent feeder lines or substations of
the same electric utility, provided automatic switchover capabilities are in
effect;
(C) on-site automatic starting electrical generators;
(D) reliance on portable generators or pumps. Proposals for the utilization
of portable units shall be accompanied by a detailed report showing
conclusively the ability of such a system to function satisfactorily.
Portable units Mil be approved only in those cases where the station is
equipped with an auto-dialer, telemetry device, or other acceptable operator
notification device, operators knowledgeable in acquisition and start-up of
the portable units are on 24-hour call, the station is accessible in all
03/22/95 16:84 N!CHOL~ Ym~-~-~'~ DILL~P2 ~GER... + 214 304 3~.73 N0.4~9 P0~'807
weather conditions, reasonable assurances exist as to the timely availability.
and accessibility of the proper portable equipment, and the station is
equipped with properly designed and tested quick connection facilities. This
option is usually acceptable only for smaller lift stations.
(3) Restoration of lift station. Provisions should be made to restore the
lift station to service within four hours of outage.
(4) Spill containment structures. A spill containment structure should be
considered together with in-system retention in determining a total wastewater
retention time. Because separate spill retention facilities are not suitable
for all locations, cng/ricers should check with the commission prior to
designing such structures. The design shall provide:
(A) a minimum storage volume of average design flow from the contributing
area and the longest power outage during the most recent consecutive 24-month
period or, if power records are not available, an assumed 24-hour outage;
(-B) an impermeable liner (such as concrete or synthetic fabric (20 mil
thickness)) and should have an energy dissipator at the point of overflow
from the lift station to prevent scour;
(C) a fence with a controlled access; and
(D) a plan for routine cleaning and inspection.
(5) Alarm system. An audiovisual alarm system (red flashing light and horn)
shall be provided for all lift stations. These alarm systems should be
telemetered to a facility where 24-hour attendance is available. The alarm
system shall be activated in case of power outage, pump failure, or a
specified high water level.
Authority: The provisions of this Chapter 317 issued under the Texas Water
Code, s5.103 and s5.105.
Source: The proxdsions of this s317.3 adopted to be effective _April 16, 1990,
15 TexReg 1801.
Cross References: This Section cited in 30 TAC s317.1, (relating to General
Provisions); 30 TAC s317.4, (relating to Wastewater Treatment Facilities).
Cross References: This Chapter cited in 30 TAC s293.331, (relating to
General); 30 TAC s313.5, (relating to Organized Sewage Collection Systems);
30 TAC s313.6, (relating to Wastewater Treatment and Disposal Systems).
30 TX ADC s 317.3
END OF DOCUMENT
Copr. (C) West 1995 No Claim to Orig. U.S. Govt. Works