17-90 O - Amend Article 10.01 of the Code of Ordinances regarding Water and Wastewater System Design RequirementsTOWN OF PROSPER, TEXAS
ORDINANCE NO. 17-90
AN ORDINANCE OF THE TOWN COUNCIL OF THE TOWN OF PROSPER,
TEXAS, AMENDING SUBSECTIONS (b) AND (c) OF SECTION 10.01.001,
"ENGINEERING DESIGN STANDARDS," OF ARTICLE 10.01, "GENERAL
PROVISIONS," OF CHAPTER 10, "SUBDIVISION REGULATION," OF THE
TOWN'S CODE OF ORDINANCES BY ADOPTING NEW WATER SYSTEM
DESIGN REQUIREMENTS AND NEW WASTEWATER SYSTEM DESIGN
REQUIREMENTS; PROVIDING FOR REPEALING, SAVINGS AND
SEVERABILITY CLAUSES; PROVIDING A PENALTY; PROVIDING FOR
PUBLICATION; AND PROVIDING FOR AN EFFECTIVE DATE.
WHEREAS, the Town Council has determined that the adoption of this Ordinance best
serves the general welfare of the Town and its residents by providing new water and
wastewater system design requirements, which requirements will preserve the public health,
safety, and welfare, and will protect and enhance the Town's design, environmental and
aesthetic quality; and
WHEREAS, the Town Council has further determined that the amendments provided
herein will ensure the existing water and wastewater system design requirements are up-to-date
and will reflect the enduring quality of development in the Town.
NOW, THEREFORE, BE IT ORDAINED BY THE TOWN COUNCIL OF THE TOWN OF
PROSPER, TEXAS, THAT:
SECTION 1
The findings set forth above are incorporated into the body of this Ordinance as if fully
set forth herein.
SECTION 2
From and after the effective date of this Ordinance, existing Subsections (b) and (c) of
Section 10.01.001, "Engineering Design Standards," of Article 10.01, "General Provisions," of
Chapter 10, "Subdivision Regulation," of the Town's Code of Ordinances are hereby amended
to read as follows:
"Sec. 10.01.001 Engineering design standards
(b) There are hereby established, in the Town's Engineering Design Standards Water
System Design Requirements for the purpose of promoting the health, safety, and welfare of the
Town and its inhabitants. The Water System Design Requirements are hereby established as
"Section 2" of the Town's Engineering Design Standards. The Water System Design
Requirements are hereby established as set forth in Exhibit A, attached to this Ordinance and
incorporated for all purposes.
(c) There are hereby established in the Engineering Design Standards Wastewater System
Design Requirements for the purpose of promoting the health, safety, and welfare of the Town
and its inhabitants. The Wastewater System Design Requirements are hereby established as
"Section 3" of the Town's Engineering Design Standards. The Wastewater System Design
Requirements are hereby established as set forth in Exhibit B, attached to this Ordinance and
incorporated for all purposes."
SECTION 3
All provisions of any ordinance in conflict with this Ordinance are hereby repealed to the
extent they are in conflict; but such repeal shall not abate any pending prosecution for violation
of the repealed ordinance, nor shall the repeal prevent a prosecution from being commenced for
any violation if occurring prior to the repeal of the ordinance. Any remaining portion of
conflicting ordinances shall remain in full force and effect.
SECTION 4
If any section, subsection, sentence, clause or phrase of this Ordinance is for any
reason held to be unconstitutional or invalid by a court of competent jurisdiction, such decision
shall not affect the validity of the remaining portions of this Ordinance. The Town hereby
declares that it would have passed this Ordinance, and each section, subsection, clause or
phrase thereof, irrespective of the fact that any one or more sections, subsections, sentences,
clauses, and phrases be declared unconstitutional.
SECTION 5
Any person, firm or corporation violating any of the provisions or terms of this Ordinance
shall be deemed guilty of a misdemeanor and, upon conviction, shall be punished by fine not to
exceed the sum of five hundred dollars ($500.00) for each offense.
SECTION 6
This Ordinance shall become effective and be in full force from and after its passage and
publication, as provided by the Revised Civil Statues of the State of Texas and the Home Rule
Charter of the Town of Prosper, Texas.
DULY PASS , D APPROVED BY THE TOWN COUNCIL OF THE TOWN OF
PROSPER, TEa0,:STH DAY OF DECEMBER, 2017.
�v°�,+'"' ''•.'"r� APPROVED:
Wo .0P
.9Ray Smit ,Mayor
ATTEST: r��i._',rTI�oS*_.�►�`�,�
APPROVED AS TO FORM AND LEGALITY:
Terrence S. We ch, Town Attorney
Ordinance No. 17-90, Page 2
Pll IS- P'Ell R
ENGINEERING DESIGN STANDARDS
SECTION 2 - WATER SYSTEM DESIGN REQUIREMENTS
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2.01. General
ENGINEERING DESIGN STANDARDS
The Town of Prosper shall approve the location of all water lines. The arrangement, character, extent, size
and location of all water lines shall be in general conformity with the Town's Buildout Water System Capital
Improvement Projects, and should be considered in their relation to existing and planned streets,
topographical and environmental considerations, and the land uses proposed to be served by such facilities.
Design criteria for all water systems shall comply with Texas Commission on Environmental Quality (TCEQ)
Chapter 290 (Rules and Regulations for Public Water Systems), latest revision. All railroad, State Highway
and Dallas North Tollway crossings, etc., shall be as approved by the Executive Director of Development
and Community Services, or his/her designee. Permits to agencies other than the Town must be submitted
through the Town.
Water lines shall be sized and extended through the limits of a property to serve adjacent properties.
Dead end water mains are not allowed unless approved in writing by the Executive Director of Development
and Community Services, or his/her designee however, if approved; a flushing device shall be provided.
2.02. Plan Requirements
Plans for water mains sized twelve inches (12") and larger shall include both plan and profile views, Plans
for water mains sized eight inches (8") and less may require a profile at the discretion of the Executive
Director of Development and Community Services, or his/her designee where crossings or other complex
design scenarios may exist. A full civil construction plan check list can be found in the Development Manual
on the Town of Prosper website.
2.03. Easements
Water mains located outside of public right-of-way shall be centered in a minimum fifteen feet (16) wide
exclusive use water easement. Water easements running parallel to a property line shall be located wholly
on one lot. At highway, railroad, creek, and other crossings or locations where the depth of the water main
measured to bottom of pipe exceeds ten feet (10'), the width of the water easement shall be increased a
minimum of one and one-half (1.5) times the depth of the water main.
Fire hydrants located outside of public easements or right-of-way shall be located in a 10' x 10' exclusive
use water easement. Water meters two inches (2") and smaller shall be located in a 5' x 5' exclusive use
water easement. Water meters three inches (3") and larger shall be located in a 10' x 10' exclusive use
water easement. Easements for other water system appurtenances and facilities not specifically provided for
by this section shall be determined by the Executive Director of Development and Community Services, or
his/her designee.
Parallel public easements and right-of-way may be used to reduce the required width of a water easement
with the approval of the Executive Director of Development and Community Services, or his/her designee
provided that the water main is located wholly within the water easement and a minimum distance of one-
half the required easement width shall be provided from the center of the water main to the outer edge of
the easement.
2.04. Location
Water mains sized sixteen inches (16") and larger located in public right-of-way shall be located five feet (5)
behind the back of curb to provide adequate clearance for curb inlets and sign posts.
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ENGINEERING DESIGN STANDARDS
Water mains sized twelve inches (12") and smaller located in public right-of-way shall be located two feet
(2') behind the back of curb. Water mains in right-of-way near storm inlets shall be constructed behind the
inlet by pulling the pipe using longitudinal bending in accordance with the manufacturers requirements.
Water mains located in easements shall be located in the center of the easement except as allowed
elsewhere in this chapter when a parallel public easement or right-of-way is used to reduce the required
easement width.
2.05. Horizontal Alignment
Water mains constructed in public right-of-way shall follow the alignment of the roadway. Longitudinal
bending of the pipe to match the radius of a roadway may be used, provided the radius is not less than the
pipe manufacturer's recommendation, typically thirty times the diameter (30xD). All other changes in
direction shall be constructed utilizing forty-five degree (450) or smaller bends to reduce head losses and
thrust on the joint.
All junctions on lines sixteen inches (16") and larger shall be three-way junctions. Offset connections or dog-
leg connections shall be used where a four-way junction is desired. Pipe sizing through junctions should be
consistent with the largest pipe size or as determined by the Executive Director of Development and
Community Services, or his/her designee.
2.06. Vertical Alignment
Water mains sized sixteen inches (16") and greater shall have a minimum cover of six feet (6) which is
generally sufficient to allow other utilities to cross over the water main. Water mains sized twelve inches
(12") and less shall have a minimum cover of four feet (4'). Water mains constructed across or adjacent to
rural roadways may be required to have greater cover to allow for future roadway grade changes as
determined by the Executive Director of Development and Community Services, or his/her designee. The
maximum depth of a water main measured to bottom of pipe shall not exceed ten feet (10') unless explicitly
approved by the Executive Director of Development and Community Services, or his/her designee.
Water mains shall be designed to have a consistent profile that avoids excessive numbers of high points
and low points. Air release valves, drain valves, or other appurtenances may be required at high points and
low points as determined by the Executive Director of Development and Community Services, or his/her
designee.
2.07. Clearance to Other Utilities
A. Wastewater
The separation between water mains and wastewater mains, manholes, and other appurtenances is
governed by Title 30 of the Texas Administrative Code, Part 1, Chapter 290, Subchapter D, Rule
290.44(e) and Chapter 217, Subchapter C, Rule 217.53(4). In general, water mains and wastewater
mains, manholes, and other appurtenances shall be installed in separate trenches and shall have a
separation distance of nine feet (9') in all directions measured from the outside surface of each facility,
Crossings of water mains and wastewater mains may be accomplished by using wastewater pipe with
a minimum pressure rating of 150 psi OR by encasing the water or wastewater main for a distance of
nine feet (9') either side of the crossing with a casing pipe having a minimum pressure rating of 150
psi. Under either scenario, a minimum eighteen -foot (18') joint of water pipe shall be centered on the
wastewater main with a minimum separation distance of twelve inches (12").
B. Storm Sewer
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ENGINEERING DESIGN STANDARDS
Water mains shall maintain a minimum clearance of eighteen inches (18") from storm sewer systems
measured from the outside surface of each facility. Where minimum clearance cannot be met, the
water main shall be encased in six inches (6") of concrete.
C. Other Utilities
Water mains shall maintain a minimum clearance of twelve inches (12") from other public and private
utilities measured from the outside surface of each facility. Where a water main encroaches into a
private utility easement, the clearance shall be as specified by the private utility operator.
All mains to be installed under existing Thoroughfares must be dry bored. Rust resistant steel casing
minimum one -fourth -inch (1/4") thick shall be used with Raci patented casing spacers, or approved
equal. No wood skids will be allowed.
Open cut crossings with Local roads, Collector roads, and Thoroughfares (where deemed necessary
by the Executive Director of Development and Community Services, or his/her designee) may be
allowed,
2.08. Creek Crossings
Water mains installed under creeks shall be protected by steel encasement at a minimum of ten feet (10')
past the toe of the embankment on each side or otherwise as directed by the Executive Director of
Development and Community Services, or his/her designee. Isolation valves shall be installed for
maintenance and safety purposes.
Any crossing with a creek must be bored. The length of the bore shall be ten feet (10 ft) outside the top of
bank on each side of the creek.
The Executive Director of Development and Community Services, or his/her designee may approve an open
cut crossing for non -major creeks. If an open cut is approved, stream bank stabilization must be provided.
2.09. Size Required
Water mains shall be sized to meet all demands (See Table 2.1) of each specific land use as well as ensure
proper fire flows for all districts are obtained. Fire Flows shall be calculated with a minimum residual
pressure of 20 psi under combined fire and domestic (Maximum Daily Demand) water flow conditions and/or
the latest requirement by the TCEQ.
Mains are to be sized to ensure less than 1 foot of head loss per 1000 feet of water main using a Hazen
Williams coefficient of C = 100 for the Maximum Hourly Demand flow rates within the subdivision internal
distribution system.
TABLE 2.1— Maximum Daily Demand Calculation
Land Use
Maximum Daily Demand Calculation
Single Family
3.5 persons per lot x 230 gallons per person per day
Multi Family
3.0 persons per unit x 230 gallons per person per day
1.0 persons per parking space x 50 gallons per person per day
Commercial
OR
Industrial
1.0 persons per 400 SF floor space x 50 gallons per persons per day
30 gallons per student per day
School
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Nursing Home 240 gallons per day per bed
Hospital 720 gallons per bed per day
ENGINEERING DESIGN STANDARDS
Water main sizing will generally be as follows based on the land use being served:
A. Single Family Residential
A twelve -inch (12") water main shall be required to loop through a single-family district and shall
typically be located along collector streets or at other locations as determined by the Executive
Director of Development and Community Services, or his/her designee. An eight -inch (8") water main
will generally be required to distribute water and provide fire protection within the single-family district.
Where dead-end water mains are explicitly approved by the Executive Director of Development and
Community Services, or his/her designee, a six-inch (6") water main shall be used for the final 200 feet
provided it serves no more than seven (7) lots and one (1) fire hydrant. A blow off hydrant shall be
installed at the end of the dead-end main for use by the Public Works Department.
B. Multi -Family Residential
A twelve -inch (12") water main shall be required to loop through a multi -family district. An eight -inch
(8") water main will generally be required to distribute water and provide fire protection within the multi-
family district provided that the water main does not exceed 600 feet in length or serve more than two
(2) fire hydrants or fire sprinkler connections between water main junctions.
Dead-end mains are not allowed except by Executive Director of Development and Community
Services, or his/her designee's approval. If dead-end mains are allowed, the developer shall install a
blow off hydrant at the end of the dead-end main for use by the Public Works Department.
C. Non -Residential
A twelve -inch (12") water main shall be required to loop through a non-residential district. An eight -inch
(8") water main will generally be required to distribute water and provide fire protection within the non-
residential district provided that the water main does not exceed 1,200 feet in length or serve more
than two (2) fire hydrants or fire sprinkler connections between water main junctions.
Dead-end mains are not allowed except by Executive Director of Development and Community
Services, or his/her designee's approval. If dead-end mains are allowed, the developer shall install a
blow off hydrant at the end of the dead-end main for use by the Public Works Department.
2.10. Materials
Water main materials shall generally be as follows
A. PVC Pipe
Eight -inch (8") and smaller water mains shall be AWWA C900 DR 14. Twelve -inch (12") water mains
shall be AWWA C900 DR18. Sixteen -inch (16") and larger water mains shall be AWWA C905 DR18.
Only potable PVC mains shall be blue in color.
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ENGINEERING DESIGN STANDARDS
All mains supplying fire sprinkler systems outside of utility easements shall be minimum two hundred
(200) psi working pressure and U.L. listed.
Ductile Iron Pipe
Sixteen -inch (16") and larger water mains shall be AWWA C151 / ANSI A21.50 with a minimum
pressure class of 150 psi. It shall be the Engineer's responsibility to determine if a higher pressure
class may be needed.
Polyethylene encasement is required to be installed around the ductile iron pipe and related fittings
and valves. This wrap shall be an eight -millimeter (8 mm) thickness polytube. Seams and overlaps
shall be wrapped and held in place by two inch (2") wide plastic backed adhesive tape. Polyken 900 or
Scotchrap no. 50, or an approved equal, with approximately two -foot (2') laps on the polytube. The
wrap on the barrel of the pipe shall be loose enough to allow the film to shift with the soil. The wrap
shall be installed without breaks, tears, or holes in the film.
C. Other Pipe Materials
Twenty -four -inch (24") and larger water mains may be Reinforced Concrete Cylinder Pipe (RCCP)
complying with AWWA C303 with the explicit approval of the Executive Director of Development and
Community Services, or his/her designee. The Design Engineer shall study all conditions that the pipe
will be exposed to and provide corrosion protection for the RCCP.
D. Pipe Fittings
All fittings shall be ductile iron with mechanical joint restraints and thrust blocking where appropriate,
with a minimum rated working pressure of two hundred -fifty (250) psi. All concrete shall be designed
with appropriate sulfate resistant cement or equivalent based on local soil conditions.
E. Valves
Valves shall be Muller Model Series 2360, M&H Model Series 4067/7571 or American Flow Control
Model Series 25000. All valves must meet a one hundred and fifty (150) psi test.
F. Tapping Valves
Connections to an existing line shall be made with full body ductile iron tapping sleeve and valve. In
order to maintain a manageable parts inventory and working knowledge of tapping sleeve and valves,
the following tapping sleeves are approved: Mueller, American Flow Control and U.S. Pipe. With prior
approval by the Executive Director of Development and Community Services, or his/her designee,
stainless steel Smith Blair 623 may be allowed for connection to existing lines twenty inches (20") or
larger.
G. Bends
Two (2) forty -five -degree (450) turns shall be used at corners along mains. Ninety -degree (900) turns
are not permitted.
H. Fire Hydrants
Fire hydrants shall be Kennedy or American Flow Control (Waterous) traffic model WB 67-250, three-
way standard thread with valve in lead or as approved by the Executive Director of Development and
Community Services, or his/her designee. All main steamer nozzles have a nominal inside diameter of
four and one-half inches (4.5") with a Storz cap.
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ENGINEERING DESIGN STANDARDS
Blow Off Hydrants (Flushing Device)
Blow off hydrants shall be Eclipse No. 85 Ground Hydrant or equal as approved by the Executive
Director of Development and Community Services, or his/her designee.
2.11. Fire Hydrants
There shall be sufficient fire hydrants to concentrate the required fire flow, as recommended by the
publication "GUIDE FOR DETERMINATION OF REQUIRED FIRE FLOW" published by the Insurance
Service Office, and as determined by the Town of Prosper Fire Department.
Fire hydrants shall be located at all entrances and at all intersecting streets and/or fire lanes. Fire hydrants
shall be located between two feet (2') and six feet (6) behind back of curb and shall not be located within a
sidewalk. Fire hydrant leads shall be six-inch (6") pipe and shall not exceed one hundred feet (100') in
length.
Fire hydrants shall not be located within thirty-five feet (36) of a non-residential structure except in urban
mixed use or other zero setback districts. Fire hydrants required to supplement water supply for automatic
fire protections systems shall be located within fifty feet (50') of the Fire Department Connection (FDC) for
such a system.
On public streets, fire hydrants at intersections shall be located ten feet (10') in advance of the curb return to
allow adequate room for street lighting, signage, and sidewalk ramps. On fire lanes, fire hydrants at
intersections shall be located at the curb return. Fire hydrants shall not be located within an intersection
radius or along the top edge of a "T" intersection.
All fire hydrants placed on private property shall be adequately protected by either curb stops or concrete
posts or other methods as approved by the Executive Director of Development and Community Services, or
his/her designee and the Fire Department and shall be in easements. Such stops or posts shall be the
responsibility of the landowner on which the fire hydrant is placed.
Major and minor thoroughfares, railroads, retaining walls, screening walls, creeks, dense landscaping, and
other similar features will obstruct the route on which a fire hose will be laid and shall not be crossed to
provide fire protection required by this section.
Fire hydrant spacing will vary based on the land use being served:
A. Single Family Residential
Fire hydrants shall be located at all street intersections and at intermediate locations such that the
spacing between fire hydrants does not exceed five hundred feet (500') measured along the centerline
of the street.
B. Multi -Family Residential
Fire hydrants shall be located at all street and/or fire lane intersections and at intermediate locations
such that the spacing between fire hydrants does not exceed three hundred feet (300') measured
along the centerline of the street and/or fire lane.
C. Non -Residential
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Fire hydrants shall be located at all street and/or fire lane intersections and at intermediate locations
such that the spacing between fire hydrants does not exceed three hundred feet (300') measured
along the centerline of the street and/or fire lane.
D. Major/Minor Thoroughfares
Fire hydrants shall be located at all street intersections and at intermediate locations along arterial
roadways such that the maximum spacing between fire hydrants does not exceed five hundred feet
(500') measured along the centerline of the roadway. Fire hydrants shall be alternate between both
sides of the roadway.
Undeveloped Areas
F. Fire hydrants shall be spaced every 1,200 feet along water transmission mains in undeveloped areas.
Fire hydrants in undeveloped areas outside of public right-of-way shall be marked with a water pipeline
marker approved by the Executive Director of Development and Community Services, or his/her
designee.
2.12. Water Valves
Water valves shall be located on water mains twelve inches (12") and smaller at all junctions, fire hydrant
leads, fire sprinkler connections, and at other locations such that the spacing between valves does not
exceed five hundred feet (500') in residential districts and six hundred feet (600') in non-residential districts.
No segment between valves, when closed, shall leave more than one (1) fire hydrant or fire sprinkler
connection out of service. Water valves shall be arranged in a manner such that preferably two (2) and no
more than three (3) valves must be operated to shut down a segment of water main.
Water valves shall be located on water mains sixteen inches (16") and larger at all junctions, fire hydrant
leads, and other locations such that the spacing between valves does not exceed 1,200 feet. No segment
between valves, when closed, shall leave more than one (1) fire hydrant out of service. The only exception
will be along Major/Minor Thoroughfares where no more than two (2) fire hydrants may be out of service.
No water valves shall be installed under parking stalls.
Water valves shall be installed at the end of water mains that are planned to be extended in the future such
that twenty feet (20') of pipe extend beyond the valve to anchor it.
Water valves shall be installed on all fire hydrant leads and fire sprinkler connections.
Water valves twelve inches (12") and smaller shall be resilient seal gate valves. Water valves sixteen inches
(16") and larger shall be butterfly valves.
Water valves located in undeveloped areas or in open spaces shall have pipeline markers installed
indicating the location of the water valve. Water valves installed in developed areas shall be marked on the
nearest curb with a sawed W" pointing toward the water valve,
2.13. Water Services
Water services shall be designed as follows:
A. Residential Subdivision
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ENGINEERING DESIGN STANDARDS
Water services for single-family, duplex, and townhome subdivisions shall consist of a one -inch (1")
diameter service and one -inch 0 ") meter. A one and one-half inch (1 '/2') service and one and one-half
inch (1 Y2") meter shall be used for developments with minimum lot size over one half ('/2) acre and/or
with minimum home sizes over 5,000 square feet. Smaller (1" minimum) meter and service sizes can
be allowed based a technical memo or similar verifying adequate flows and approved by the Executive
Director of Development and Community Services, or his/her designee. Single-family homes requiring
larger meter sizes than the service size installed with development shall be required to replace water
service with same size so meter and service are "size -on -size". Variations from this requirement may
be allowed with approval of the Executive Director of Development and Community Services, or
his/her designee.
Services for single-family, duplex, and townhome lots shall be located two feet (2') off the side property
line and should generally be grouped with the adjacent lot. Water services shall have a minimum
separation distance of ten feet (10') from wastewater services. Services shall consist of PE 4710 pipe
conforming with AWWA C901.
Water meters shall be installed eighteen inches (18") behind the back of curb at a maximum depth of
twelve inches (12"). Water meter boxes shall be plastic with a locking lid and shall be eighteen inches
(18") by fourteen inches (14") for one -inch (1") meters and twenty-eight inches (28") by eighteen
inches (18") for one and one -half-inch (1 '/z') meters. Water meters shall not be located in driveway or
sidewalk pavement.
Multi -Family and Non -Residential Development
Water services for multi -family and non-residential developments shall consist of a minimum one -inch
(1 ") diameter service and one -inch (1 ") meter. Larger services and meters may be used as determined
by the Design Engineer, provided the service and the meter are the same size. All irrigation services
require turbine meters.
Water services shall be located as determined by the Design Engineer. A minimum of one service per
building shall be provided. Water services shall have a minimum separation distance of ten feet (10')
from wastewater services. Services shall consist of PE 4710 pipe conforming with AWWA C901.
When located adjacent to a public street, water meters shall be installed immediately inside the right-
of-way line at a maximum depth of twelve inches (12"). When installed adjacent to an interior
driveway, water meters shall be installed two feet (2') behind back of curb.
Water meter boxes shall be plastic with a locking lid and shall be sized such that the entire meter
assembly is contained within the box with sufficient room to make minor adjustments. Water meters
three inches (T) and larger shall be located in a concrete vault sized such that the entire meter
assembly is contained within the vault with sufficient room to repair and replace the water meter if
necessary. No meter box shall be installed in a paved area.
C. Restrictions
Water services shall not connect to a fire hydrant lead. Water services shall not exceed fifty feet (50')
in length from the water main to the water meter. Bullhead water services shall not be permitted.
Water services and water meters shall be identically sized. Parallel water meters serving the same
facility shall not be permitted.
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ENGINEERING DESIGN STANDARDS
SECTION 3 - WASTEWATER SYSTEM DESIGN REQUIREMENTS
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3.01. General
ENGINEERING DESIGN STANDARDS
The Town of Prosper shall approve the location of all wastewater lines. The arrangement, character, extent,
size and location of all wastewater lines shall be in general conformity with the Town's Buildout Wastewater
System Capital Improvement Projects, and should be considered in their relation to existing and planned
streets, topographical and environmental considerations, and the land uses proposed to be served by such
facilities.
Wastewater lines shall be sized and extended through the limits of a property to serve adjacent properties.
In phased construction of thoroughfares, the sewer lines shall be extended the entire length of the
thoroughfare being constructed.
3.02. Plan Requirements
Plans for wastewater mains shall include both plan and profile views. A full checklist for civil construction
plans can be found in the Development Manual on the Town of Prosper website.
3.03. Easements
Wastewater mains located outside of public right-of-way shall be centered in a minimum fifteen feet (16)
wide exclusive use wastewater easement. Wastewater easements running parallel to a property line shall
be located wholly on one lot. At highway, railroad, creek, and other crossings or locations where the depth
of the wastewater main measured to bottom of pipe exceeds ten feet (10'), the width of the wastewater
easement shall be increased a minimum of one and one-half (1.5) times the depth of the wastewater main.
Easements for wastewater lift stations and other facilities not specifically provided for by this section shall be
determined by the Executive Director of Development and Community Services, or his/her designee.
3.04. Location
Wastewater mains located in public right-of-way shall generally be located in the center of undivided streets
and as determined by the Executive Director of Development and Community Services, or his/her designee
on divided streets. Wastewater mains located adjacent to creeks and other waterways shall generally follow
the alignment of the waterway and be located a minimum of ten feet (10) behind the top of bank.
Wastewater mains located in easements shall be located in the center of the easement.
Wastewater mains shall not be located in alleys unless explicitly approved by the Executive Director of
Development and Community Services, or his/her designee. Wastewater mains shall not cross residential
lots unless explicitly approved by the Executive Director of Development and Community Services, or
his/her designee.
Trees shall not be planted within wastewater easements. Wastewater mains shall not be located within five
feet (6) of any existing tree. Upon approval of the Executive Director of Development and Community
Services, or his/her designee, ornamental trees may be planted within the easement, but no closer than five
feet (6) to a wastewater main.
3.05. Horizontal Alignment
Longitudinal bending of the pipe to match the radius of a roadway shall be used, provided the radius is not
less than the pipe manufacturer's recommendation, typically three hundred times the diameter (3000).
Joint deflection of the pipe to match the radius of a roadway may be used, provided the angle of deflection is
no more than 80% of the pipe manufacturers recommendation. All other changes in direction shall occur at
manholes. When not under a roadway, wastewater mains shall generally be straight from manhole to
manhole.
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ENGINEERING DESIGN STANDARDS
Where a parallel wastewater line is required due to excessive depth, the parallel line shall be offset from the
wastewater main by five feet (6) to the side of the street with the majority of wastewater services.
3.06. Vertical Alignment
Wastewater mains shall be designed with a straight profile from manhole to manhole. No vertical curves or
vertical bends shall be allowed between manholes. Wastewater mains shall have a minimum cover of four
feet (4') within right-of-way or public easements. Additional cover may be required to allow a lateral to
extend at 2% grade from the wastewater main to a minimum five-foot (6) depth at a point ten -feet (10')
beyond property line while maintaining clearance from water line or franchise utility lines. Excessively deep
main lines shall be avoided if not required due to physical constraints.
Wastewater mains shall be designed for a minimum velocity of two feet per second (2 fps) and a maximum
velocity of ten feet per second (10 fps) at peak flow. Under gravity flow conditions, this corresponds to Table
3.1 with minimum and maximum grades using Manning's Equation for PVC pipe with a roughness
coefficient of 0.013:
Table 3.1— Pipe Diameter Grade Limits
Pipe Diameter
inches(percent)
Minimum Grade
Maximum Grade
(percent)
8"
0.33%
8.40%
10"
0.25%
6.23%
12"
0.20%
4.88%
15"
0.15%
3.62%
18"
0.11%
2.83%
21"
0.09%
2.30%
24"
0.08%
1.93%
Where the depth of a wastewater main exceeds twelve feet (12'), a parallel wastewater line shall be
constructed where laterals will be connected.
3.07. Clearance to Other Utilities
A. Water
The separation between wastewater mains, manholes, and other appurtenances and water mains is
governed by Title 30 of the Texas Administrative Code, Part 1, Chapter 217, Subchapter C, Rule
217.53(4) and Chapter 290, Subchapter D, Rule 290.44(e). In general, wastewater mains, manholes,
and other appurtenances and water mains shall be installed in separate trenches and shall have a
separation distance of nine feet (9') in all directions measured from the outside surface of each facility.
Crossings of wastewater mains and water mains may be accomplished by using wastewater pipe with
a minimum pressure rating of 150 psi OR by encasing the water or wastewater main for a distance of
nine feet (9') either side of the crossing with a casing pipe having a minimum pressure rating of 150
psi. Under either scenario, a minimum eighteen -foot (18') joint of water pipe shall be centered on the
wastewater main with a minimum separation distance of twelve inches (12").
B. Storm Drain
Wastewater mains shall maintain a minimum clearance of eighteen inches (18") from storm drain
systems measured from the outside surface of each facility. Where minimum clearance cannot be met,
the wastewater main shall be encased in six inches (6") of concrete.
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r
PI'°PER
C. Other Utilities
ENGINEERING DESIGN STANDARDS
Wastewater mains shall maintain a minimum clearance of twelve inches (12") from other public and
private utilities measured from the outside surface of each facility. Where a wastewater main
encroaches into a private utility easement, the clearance shall be as specified by the private utility
operator.
3.08. Creek Crossings
Wastewater mains shall be designed to cross under creeks and other waterways. The creek crossing shall
consist of a watertight steel encasement pipe and a wastewater main supported by approved spacers.
Manholes shall be provided ten feet (10') outside the top of bank on both sides of a creek crossing. Creek
banks and channels disturbed by construction shall be shall be stabilized to prevent erosion of the backfill
materials. Creek channels shall be analyzed to determine if stabilization is necessary to prevent erosion that
may expose or damage the wastewater infrastructure.
Aerial crossings may be used only when alternatives for crossing under a creek have been found to be not
technically feasible. The aerial crossing shall consist of a rust -resistant steel encasement pipe with welded
joints and a wastewater main supported by approved spacers. Manholes shall be provided at the top of
bank on both sides of an aerial crossing.
A structural engineer shall design the aerial crossing to support the dead loads of the structure and the live
loads of the wastewater main under full flow conditions with no deflection. Buoyancy of the aerial crossing
and the impact of debris must be considered if partially of fully submerged by a 100 -year rainfall event.
Supporting piers shall not obstruct the normal channel of the waterway. A scour analysis shall be conducted
and provided to the Town for review. Armoring of the channel may be required to prevent erosion.
3.09. Size Required
Wastewater mains shall be sized for the peak flow of the contributing basin under gravity flow conditions
with no surcharges. Manning's Equation shall be used to determine the full -flow capacity of each segment of
the wastewater system using a roughness coefficient of 0.013 for PVC pipe. No wastewater, other than
laterals or force mains, shall be less than eight -inch (8") diameter. The peak flow shall be calculated based
on Table 3.2 or other industry -standard assumptions approved by the Executive Director of Development
and Community Services, or his/her designee:
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P r`SP`ER
ENGINEERING DESIGN STANDARDS
Table 3.2 — Peak Flow Calculation
Land Use
Assumptions
Peak Flow Dry
Peak Flow Wet**
Single Family
3.5 lots per acre (assumed)
4,900 GPAD*
5,550 GPAD
3.5 persons per lot
100 gallons per person per day
4.0 peak factor
Multi Family
15 units per acre (assumed)
18,000 GPAD
18,650 GPAD
3.0 persons per unit
100 gallons per person per day
4.0 peak factor
Commercial
50 parking spaces per acre
4,000 GPAD
4,650 GPAD
Industrial
(assumed)
1.0 persons per parking space
20 gallons per person per day
4.0 peak factor
School
20 gallons per student per day
80 gal/student/day
80 gal/student/day + 650
4.0 peak factor
GPAD
Nursing Home
100 gallons per bed per day
400 gallons
400 gal/bed/day + 650
4.0 peak factor
per bed er day
GPAD
Hospital
200 gallons per bed per day
800 gallons
800 gal/bed/day + 650
4.0 peak factor
per bed per day
GPAD
*Gallons per acre per day (GPAD)
**Infiltration shall be 650 gallons per acre per day (GPAD).
Where calculated wastewater flows exceed 2 MGD, the peak factor for the basin may be reduced to 3.0.
Where approved zoning or existing development has resulted in densities less than or greater than the
assumed densities indicated above, the density of the approved zoning or existing development may be
substituted for the assumed density. Other peaking factors for larger basins may be approved by the
Executive Director of Development and Community Services, or his/her designee.
3.10. Pipe Materials
Wastewater main materials shall generally be as follows:
A. PVC Pipe (Non -Pressure Rated)
Fifteen -inch (15") and smaller wastewater mains shall be ASTM D3034 SDR 35 (less than 15' deep) or
SDR 26 (greater than 15' deep). Eighteen -inch (18") and larger wastewater mains shall be ASTM
F679.
B. PVC Pipe (Pressure Rated)
Twelve -inch (12") and smaller wastewater mains shall be ASTM D2241 SDR 26 with a minimum
pressure rating of 160 psi. Fifteen -inch (15") and larger wastewater mains shall be AWWA C905 DR25
with a minimum pressure rating of 165 psi. The Design Engineer shall make a recommendation for
any pipe over 165 psi.
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4 3 ,_} P R
C. Other Pipe Materials
ENGINEERING DESIGN STANDARDS
No other pipe materials may be used without the explicit approval of the Executive Director of
Development and Community Services, or his/her designee. A technical memorandum detailing
design criteria and construction methods may be required to support alternative pipe materials.
3.11. Manholes and Cleanouts
Manholes shall be constructed at all junctions of wastewater lines sized six inches (6") and greater; at
changes of grade, direction, and pipe size; at the beginning and end of segments installed by other than
open cut; within thirty feet (30) of the beginning and end of aerial crossings; and at other locations such that
the spacing between manholes does not exceed the following in Table 33:
Table 3.3 — Manhole Spacing
Pipe Diameter
inches
Maximum Manhole Spacing
feet
15" and less
500'
18" thru 30"
800'
33" and larger
1,000'
Manholes shall be sized as shown in Table 3.4.
Table 3.4 — Manhole Diameter
Pipe Diameter
(inches)
Manhole Diameter
(feet)
27" and less
5'
30" and larger
6'
Manholes on mains twelve inches (12") or smaller shall have a minimum drop of 1/10 foot across the invert.
Due to physical constraints, the 1/10 ft drop may be eliminated with the approval of the Executive Director of
Development and Community Services or his/her designee. Where different size pipes enter a manhole, the
pipe crowns shall be at the same elevation or the smaller pipe shall be higher. Drop manholes shall be
required where the inflow elevation is more than two feet (2") above the outflow elevation. New drop
structures shall be constructed on the exterior of the manhole. Interior drop structures will be allowed on
existing manholes.
Where multiple wastewater pipes enter a manhole, the minimum distance between pipes, measured along
the outer surface of the manhole, shall be eighteen inches (18") for cast -in-place manholes and per the
manufacturer's recommendation for precast manholes. If a lesser clearance is necessary, a special
structural design may be required as determined by the Executive Director of Development and Community
Services, or his/her designee.
Where manholes must be constructed in a floodplain, sealed manholes shall be provided to prevent the
inflow of storm water. Where more than three (3) consecutive manholes are to be sealed, every 3rd
manhole shall be vented two feet (2) above the ultimate 100 -year water surface elevation or six feet (6)
above the adjacent ground elevation, whichever is greater. The Engineer shall provide the 100 -year water
surface elevation on the plans, along with a reference to the source of information.
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ITOSP`ER
ENGINEERING DESIGN STANDARDS
A cleanout may be installed at the end of a line provided it is no more than 250 feet upstream of the nearest
manhole. For a line to be extended in the future, a cleanout or manhole may be installed at the end of the
line or a single joint of pipe may be installed and capped, provided that the future connection point is located
outside or roadway paving,
3.12. Lift Stations and Force Mains
The wastewater system shall be laid out so that all wastewater mains shall be gravity flow. The use of a
wastewater lift station and force main may be approved by the Executive Director of Development and
Community Services, or his/her designee and the Director of Public Works where terrain and/or municipal
boundaries prohibit the extension of a wastewater main by gravity flow. All wastewater lift stations and force
mains shall be designed in accordance with TCEQ requirements.
The Engineer shall prepare a technical memorandum detailing the technical characteristics and design
features of the wastewater lift station, including service area map with flow analysis, sizing of the wet wells,
pumps, and force main. The lift station shall be connected to the Town's Supervisory Control and Data
Acquisition (SCADA) system for remote monitoring of the lift station's status. The Developer shall be
responsible for all costs associated with design, implementation, and testing of the lift station and related
systems, including integration with the Town's existing SCADA system.
Wastewater lift stations shall be surrounded by an eight -foot (8) decorative metal fence with masonry
columns and a sixteen -foot (16') sliding gate. A twelve -foot (12') wide concrete drive with a twenty -foot (20')
long turnaround consisting of reinforced concrete subgrade that meets the current fire lane standards shall
be provided. This drive shall be used for maintenance access to the lift station and shall provide access to
the control panel and wet wells. A landscape and irrigation plan shall be provided around the lift station as
determined by the Executive Director of Development and Community Services, or his/her designee, All lift
stations shall provide the ability for odor control (charcoal canisters or other).
Wastewater force mains shall be white -colored pressure rated PVC pipe. The minimum size for force mains
shall be six inches (6") unless explicitly approved by the Executive Director of Development and Community
Services, or his/her designee. Force mains shall include plug valves at 1,200' spacing along the force main
to isolate segments for repair. Where force mains connect to the wastewater main, the manhole shall have a
sulfate resistant coating.
3.13. Wastewater Laterals
Wastewater laterals shall be designed as follows:
A. Residential Subdivision
Every lot shall have a minimum of one (1) wastewater lateral, Wastewater laterals for single-family,
duplex, and townhome subdivisions shall consist of a minimum five -inch (5") diameter pipe on a
minimum one percent (2%) grade for each lot. Laterals for single-family lots shall be located at the
center of the lot. Laterals for duplex and townhome lots shall be consistently located within the
development. Laterals shall have a minimum separation distance of ten feet (10') from the water
service.
Wastewater laterals for residential subdivisions shall be extended to a point ten feet (10) beyond the
property line at a minimum depth of five feet (6) to bottom of lateral. The lateral shall then be extended
upward at a 1:1 slope to a point four feet (4') above the ground elevation and capped.
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tRip
Multi -Family and Non -Residential Development
ENGINEERING DESIGN STANDARDS
Wastewater laterals for multi -family and non-residential developments shall be minimum six-inch (6")
diameter pipe on a minimum two percent (2%) grade. A minimum of one lateral per building shall be
provided. Laterals shall have a minimum separation distance of ten feet (10') from water services. A
manhole shall be provided where the lateral connects to the wastewater main.
A larger wastewater lateral may be required where peak flows are anticipated to exceed 350 gallons
per minute (gpm). Examples of this may include hospitals, nursing homes, athletic facilities, hotels,
high-density apartments, and manufacturing facilities.
C. Restrictions
Wastewater laterals shall be connected via wye fittings only. Tees and boots will not be allowed.
3.14. Trenchless Construction
A. Launching and receiving pits for trenchless construction shall be a minimum of five feet (5') from the
edge of pavement.
B. The location, size and depth of the launching and receiving pits for trenchless construction shall be
evaluated during construction plan review.
C. Approved Methods
1. Horizontal Boring: All horizontal bores shall be dry bored unless approved by the Executive
Director of Development and Community Services, or his/her designee. Rust resistant steel
casing minimum of one forth inch (1/4") thick, or thicker if deemed necessary by the Design
Engineer, shall be used with Raci patented casing spacers, or approved equal.
2. Pipe Jacking: Pipe shall be designed to withstand all jacking forces with a factor of safety of two
(2.0) during construction.
3. Tunneling: Tunneling maybe used after approval from the Executive Director of Development and
Community Services, or his/her designee.
D. All mains installed under existing roadways shall be installed by bore unless otherwise approved by
the Executive Director of Development and Community Services, or his/her designee.
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