CITY OF McALLEN

STANDARD DESIGN GUIDE

FOR

PUBLIC INFRASTRUCTURE IMPROVEMENTS

CITY COMMISSION

RICHARD CORTEZ MAYOR SCOTT C. CRANE COMMISSIONER DISTRICT 1 MARCUS BARRERA COMMISSIONER DISTRICT 2 HILDA SALINAS MAYOR PRO-TEM/COMMISSIONER DISTRICT 3 AIDA RAMIREZ MAYOR PRO-TEM/COMMISSIONER DISTRICT 4 JOHN INGRAM COMMISSIONER DISTRICT 5 JIM DARLING COMMISSIONER DISTRICT 6 MIKE R. PEREZ CITY MANAGER YVETTE BARRERA, P.E., CFM CITY ENGINEER

PUBLIC UTILITY BOARD

CHARLES AMOS CHAIRMAN TONY AGUIRRE VICE-CHAIRMAN TREY PEBLEY TRUSTEE ROGER GARZA TRUSTEE

SCOTT C. CRANE EX-OFFICIO MEMBER / CITY COMMISSIONER

ROY RODRIGUEZ, P.E. GENERAL MANAGER

City of McAllen

ENGINEERING DEPARTMENT

October 2009

PREFACE

The Engineering Department is committed to providing a high quality of life by ensuring properly designed and constructed infrastructure for those who work and reside in the City of McAllen. The condition of streets, sidewalks, driveways, storm drainage, water, and sanitary sewer facilities play an integral part in the everyday life of motorists and pedestrians. By responsibly designing, constructing and maintaining quality infrastructure, the City of McAllen reduces its financial burden from personal injuries and damage to property caused by premature failure of facilities. This document was prepared to assist planners, designers, engineers and architects during the development of infrastructure improvements in public rights of way by standardizing design criteria. NOTE: This document will be reviewed and revised as necessary in order to adapt to the dynamic nature of infrastructure improvements as well as reflect advances and innovations in standard design practices. It is the responsibility of the user to obtain the most recent revision. Copies of this standard are available at the office of the: City of McAllen Engineering Department 1300 Houston Avenue McAllen, Texas 78501 and via the City of McAllen Website at http://www.mcallen.net/files/docs/engineering/Standard_Design_Guide_September_2009.pdf

Table of Contents Introduction….………………………………………………………………………………………1

Pavement Design

Flexible Pavement………………………………………………..........................................2

Concrete Pavement.………………………………………………………………………….3

Alley Design..………………………………………………………………………………..3

Sidewalk Design..……………………………………………………………………………4

Residential Driveway Apron Design..……………………………………………………….5

Commercial Driveway Apron Design..……………………………………………………...6

Drainage Design…....………………………………………………………………………………..7

Water Design………………………………………………………………………………………8-9

Sanitary Sewer Design......………………………………………………………………………10-11

Traffic Control Policy…..…………………………………………………………………………..12

Drainage Policy…..……………………………………………………………………………..13-40

Traffic Impact Analysis Policy.….……………………………………………………………...41-44

Pretreatment / Grease Trap Facilities Policy….………………………………………………...45-59

Cross Connection and Backflow Prevention Policy...…………………………………………..60-72

Standard Details

100 Standard Drainage Details

101 Typical Storm Sewer Bedding Detail 102 Typical Concrete Storm Manhole

103 Storm Sewer Manhole 104 Typical Concrete Storm Sewer Conflict Manhole 105 Type A Inlet

106 Type A Inlet with Extension 107 Type CC Inlet 108 Type F Inlet 109 Type F Inlet with Extension 110 Concrete Slope End Treatment 111 Concrete Pipe Collar 112 Concrete Seepage Collar

200 Standard Pavement Details

201 Typical Local Street Intersection 202 Principal Arterial / Minor Arterial Street Section with Median 203 Principal Arterial / Minor Arterial Street Section Without Median 204 Collector Street Section 205 Local Street Section 206 Typical Concrete Joint Details 207 Concrete Curb & Gutter 208 Concrete Valley Gutter 209 Typical Knuckle Detail 210 Cul-de-sac Detail 211 Temporary Hammerhead Turn-around 212 Typical Alley Section and Driveway Detail

213 Typical Alley Section 214 Concrete Apron Typical Joint Layout 215 Concrete Driveway Apron 216 Curb & Gutter Sawcut for Driveway 217 Residential Gated Driveway 218 Gated Entrance Detail 219 Typical Locations of Sidewalks and Ramps 220 Typical Sidewalk Details 221 Handicap Ramp Options 222 Handicap Ramp Details 223 Stationary and Removable Bollard Detail

300 Standard Details for Erosion Control

301 Construction Exit Sediment Control – Type 1 302 Construction Exit Sediment Control – Type 2 303 Construction Exit Sediment Control - Type 3

400 Standard Detail For Solid Waste

401 Solid Waste / Recycle Container Enclosure, Large 402 Solid Waste / Recycle Container Enclosure, Small 403 Solid Waste / Recycle Container Enclosure, Front Loader Service Configuration 404 Solid Waste / Recycle Container Enclosure, Side Loader Service Configuration

500 Standard Water Details

501 Water Utilities General Notes 502 Water Line and Sewer Forcemain Bedding Detail

503 Typical Fire Hydrant Installation 504 Typical Fire Hydrant Locations 505 Water Tapping Sleeve & Valve Installation 506 Typical Valve & Valve Box 507 Utility Line Bore Detail 508 X 509 Water Line Crossing Detail 510 Water Line Adjustment Detail 511Water Line and Sanitary Sewer Ditch Crossing 512 Typical Service Connection With Meter Box 513 Typical Meter Box Installations 514 X 515 Typical Service Connection 516 Typical 1” Air Release Valve 517 Blow-Off Valve Installation 518 Typical 2” Blow Off Valve 519 Butterfly Valve Detail

518 Typical 2” Blow-Off Valve Butterfly Valve Detail 520 Concrete Thrust Blocks

600 Standard Sanitary Sewer Details

601 Sanitary Sewer (Non-Forcemain) Pipe Bedding 602 Typical Fiberglass Manhole 603 Manhole Cover Adjustment Details 604 Manhole and Valve Box Regrading

605 Standard Service Connection 606 Go-No-Go Deflection Testing Mandrel Detail 607 Utility Separation 608 Typical Lift Station Detail 609 Grease Trap Detail, 3000 Gallon 610 X 611 X 612 X 613 X 614 X 615 X 616 X 617 X 618 X 619 X 620 X

700 Standard Traffic Control Device Details

701Sign Material Standard 702 Sign Location Standards 703 Type III Permanent Barricade 704 Solid Double Yellow Centerline 705 Left-Turn Median Lane Channelization 706 Skipped White Line Detail

707 Skipped Yellow Centerline 708 Solid White Lane Line Detail 709 Solid White Edge Lane 710 Two-Way Left-Turn Detail 711 Street Lighting-Arterial Road 712 Intersection Sight Distance for Intersections

City of McAllen, TX – Standard Design Guide 1 | P a g e

Introduction This document has been prepared to standardize design requirements for streets, storm drainage, water and sanitary sewer facilities that are primarily constructed as part of residential and commercial subdivisions. This document is intended to serve as a design guide for planners, designers, engineers and architects involved in the preparation of plans and specifications, which will be submitted for construction within the City of McAllen. The ultimate goals of this design guide are to:

Maintain a high standard for improvements within public rights of way. Maximize the integrity of public facilities.

Maximize the protection of motorists and pedestrians.

Minimize inconvenience to pedestrians, motoring traffic and landowners adjacent to public

rights of way. Minimize the future maintenance cost to the City.

Back to Table of Contents


Pavement Design Back to Table of Contents

Flexible Pavements The following design criteria shall be applicable to the noted street width. Additional details are noted in Appendix III.

Characteristic

Street Classification

Local

Collector Minor Arterial Principal

Arterial

Street Width

(Measured from back of curb to back of curb, B-B)

32’ B-B to

40’ B-B4

40’ B-B4 to

44’ B-B

52’ B-B

to 65’ B-B

65’ B-B and

Greater

Minimum Structural Section

6 inches

6 inches

12 inches

12 inches

Subgrade1

Flexible Base2 Hot Mix Asphaltic Concrete3 (HMAC)

8 inches

10 inches 12 inches 12 inches

2 inches 2.5 inches 3 inches 3 inches

Min. transverse slope 2 % 2% 2.5% 2.5%

Min. longitudinal slope 0.20 % 0.20% 0.20% 0.20%

Min. width of curb and gutter 24 inches 24 inches 24 inches 24 inches

1. Subgrade should be compacted to 95% maximum dry density, as determined by the standard

proctor (ASTM D698), and treated with lime at an applicable rate if the plasticity index of the soils is greater than 20. All compacted subgrade shall extend to a minimum of 1 foot behind the proposed back of curb.

2. The flexible base shall be compacted to 95% maximum dry density, as determined by the

standard proctor (ASTM D698), and treated with lime at an applicable rate if the plasticity index of the soils is greater than 12. All compacted flexible base shall extend to a minimum of 1 foot behind the proposed back of curb.

3. All hot mix asphaltic concrete shall consist of Type ”D”, crushed limestone aggregate and be

compacted to 95% of the maximum theoretical dry density. 4. 40’ B-B may be designated as a local or collector street depending on the streets function.


If an alternate pavement section is requested, a pavement design analysis will be required for approval by the City Engineer or designee. A minimum 30-year period shall be utilized for all designs. Concrete Pavements Concrete pavements sections for all widths shall be designed utilizing the following criteria:

Thickness designs for Concrete Highways and Street Pavement, Portland Cement Association, EB109P, Reprinted 1995

Concrete Streets: Typical Pavement Sections and Jointing Details, Portland Cement

Association, IS211P, 1980

Design and Construction of Joints for Concrete Streets, Portland Cement Association, IS061P, 1992

Construction Specification Guideline for Concrete Streets and Local Roads, Portland

Cement Association, IS119P, 1998

Guide Specifications for Concrete Curbs and Combined Curbs and Gutters, Portland Cement Association, IS110P, 1983

A minimum 30-year period shall be utilized for all designs

Alley Design In all new subdivisions containing alleys, the developer shall construct alleys in accordance with the engineering requirements of the City. ROW 20 feet Paving width 16 feet Minimum Structural Section Subgrade 6 inches Flexible Base 8 inches HMAC 2 inches Additional details are noted in Appendix III. If an alternate pavement section is requested, a pavement design analysis will be required for approval by the City Engineer or designee. A minimum 30-year period shall be utilized for all designs.

Back to Table of Contents above


Sidewalk Design The following design criteria shall be applicable to sidewalk designs. Additional details are noted in Appendix III.

Sidewalk alignment must match existing alignment in area or be set a minimum of five-foot from the back of curb. Any deviation shall require approval by the City Engineer

Sidewalk shall slope toward the street with a maximum transverse slope of ¼ inch per

foot (2%), 1-inch above the top of curb, and a maximum longitudinal slope of ½ inch per foot (5%).

Sidewalk shall be 4-foot minimum width when placed at an offset behind the curb, and 5-

foot minimum width when placed adjacent to the curb. Sidewalks and ramps shall be constructed of 4” thick concrete reinforced with 6” x 6”

No. 6 gage wire mesh or No. 3 bars @ 8” O.C.E.W.

Bar-lift Plastic Chairs, or approved equal, shall be used to secure steel at center of concrete thickness

Subgrade shall be compacted to 90% standard proctor.

Contraction joints shall be scored every 6 feet and expansion joints every 30 feet.

Sidewalk shall have a broom finish transverse to the walkway. Exposed aggregate,

pavers, tile and stained or painted concrete are not permitted within the right of way.

All concrete shall be 5-sack concrete and shall have a minimum compressive strength of 3000 psi.

Membrane curing compound shall be applied at a minimum of 1 gallon per 180 square

feet of area.

Ramps shall be placed at all intersection with roadways or where required by law / City. Curb and Gutter must be saw cut.

Flatwork is required to meet Texas Accessibility Standards (Texas Civil Statutes, Article

9102). Any admixtures to the concrete mix (i.e. fiber mesh, plasticizers, etc.) shall require approval. Additionally, decorative concrete shall require approval of the pattern and finish from the City Engineer, or designee, prior to construction. Back to Table of Contents


Residential Driveway Apron Design The following design criteria shall be applicable to residential driveway apron designs. Additional details are noted in Appendix III.

Minimum driveway width allowed is 12 ft. and maximum is 25 ft.

Curb cut must be a minimum of 6-feet from a side property line.

Flow line of new gutter shall match existing flow line.

Curb and gutter must be saw cut.

Driveway aprons shall be constructed of concrete with a minimum of 6 inches in thickness, reinforced with 6” x 6” No. 6 wire mesh, No. 3 bars @ 12” O.C.E.W. or No. 4 bars @ 18” O.C.E.W.

Bar-lift Plastic Chairs, or approved equal, shall be used to secure steel at center of

concrete thickness.

Concrete shall have a broom finish. Exposed aggregate, pavers, tile and stained or painted concrete are not permitted within the right of way.

All concrete shall be 5-sack concrete and shall have a minimum compressive strength of

3000 psi.

Membrane curing compound shall be applied at a minimum of 1 gallon per 180 square feet of area.

Subgrade shall be compacted to 90% standard proctor. Expansion joint required at property line and intersection with sidewalks. Longitudinal

expansion joint required at mid-point of driveway if width is greater than 18 feet. If a manhole falls within a driveway pad, the manhole lid shall be placed flush with the

elevation of the driveway. Any driveway placed where a drainage bar ditch exists, shall maintain the flow line of the

ditch with the placement of a concrete culvert.

Driveway wings shall not exceed a 12:1 slope. Any admixtures to the concrete mix (i.e. fiber mesh, plasticizers, etc.) shall require approval. Additionally, decorative concrete shall require approval of the pattern and finish from the City Engineer, or designee, prior to construction. Back to Table of Contents


Commercial Driveway Apron Design The following design criteria shall be applicable to commercial driveway apron designs. Additional details are noted in Appendix III.

Minimum width allowed is 25 ft and maximum is 45 ft. Curb cut must be a minimum of 6-feet inside the property line.

Flow line of new gutter shall match existing flow line.

Curb and gutter must be saw cut.

Driveway aprons shall be constructed of concrete with a minimum of 6 inches in

thickness, reinforced with No. 3 bars @ 12” O.C.E.W. or No. 4 bars @ 18” O.C.E.W.

Driveways exceeding HS-20 loads to be reviewed and approved by City Engineer.

Bar-lift Plastic Chairs, or approved equal, shall be used to secure steel at center of concrete thickness.

Concrete shall have a broom finish. Exposed aggregate, pavers, tile and stained or

painted concrete are not permitted within the right of way.

All concrete shall be 5-sack concrete and shall have a minimum compressive strength of 3000 psi.

Membrane curing compound shall be applied at a minimum of 1 gallon per 180 square

feet of area.

Subgrade shall be compacted to 95% standard proctor. Expansion joint required at property line and intersection with sidewalks. Longitudinal

sawed contraction joint required at 15 ft minimum. See commercial concrete driveway & typical joint layout for details.

If a manhole falls within a driveway pad, the manhole lid shall be placed flush with the

elevation of the driveway. Any driveway placed where a drainage bar ditch exists, shall maintain the flow line of the

ditch with the placement of a concrete culvert.

Driveway wings shall not exceed a 12:1 slope. Any admixtures to the concrete mix (i.e. fiber mesh, plasticizers, etc.) shall require approval. Additionally, decorative concrete shall require approval of the pattern and finish from the City Engineer, or designee, prior to construction. Back to Table of Contents


Drainage Design Back to Table of Contents

All storm drainage designs shall comply with the City of McAllen Drainage Policy as noted in Appendix I and detailed in Appendix IV. The following is a general summary of the requirements:

Calculation of the 10-year storm pre-development runoff is required to be submitted

to the City Engineer. Calculation of the 50-year storm post development runoff to be detained on-site, shall

be submitted to the City Engineer. Scaled maps showing the drainage basins used in the above calculations will need to

be submitted to the City Engineer for review and approval. On-site detention methods shall include ponds or engineered sub-surface systems

Acceptable methods of supplemental detention shall be reviewed and approved by the City Engineer.

Drainage outfalls must flow and/or detain a 50-year storm (i.e. Blueline Ditch). Inlet spacing shall not exceed 600 feet, with a maximum surface run of 300 feet from

the crest to sag of the roadway profile. In the event the longitudinal slope of the roadway is required to exceed 300 feet, inlets shall still be spaced at 300 feet maximum. Minimum slopes for drainage pipes shall be determined utilizing a design velocity of 3 feet per second.

Sites shall be graded in such a manner as to provide positive drainage but shall not

adversely affect adjacent drainage patterns. The rear of residential lots shall slope with a minimum 1% slope to the front. A subdivision lot grading plan shall be provided by the subdivision Engineer prior to issuance of any permits for construction of subdivision improvements.

Final grades along the perimeter of the proposed subdivision that are above or below

the adjacent property elevation shall require installation of a retaining wall. Properties shall be graded to drain away from the grade differential.

Storm sewer lines shall require gravel bedding of six (6) inches minimum and gravel

backfill to the spring line of the reinforced concrete pipe. The remaining trench depth shall be mechanically compacted in one (1) foot lifts to 95% of the maximum dry density as defined by the standard proctor.

As part of the as built plans all inlets and manholes shall be surveyed by an RPLS.

Survey shall include northing and easting coordinates of the inlet and manhole centerline and elevations of tops and inverts referenced to the City of McAllen benchmark grid.


Water Design

All domestic water systems shall be designed in conformance with the most current revision of TCEQ’s Drinking Water Rules (30 TAC Chapter 290) and the City of McAllen Standard Details and Specifications. The most stringent requirements shall apply where the standards conflict. Following is a general summary of the design requirements:

Water line design shall be consistent with the most current MPU Water Master

Plan. Water mains shall be a minimum of 8 inches in diameter. Fire Hydrant lead line

shall be no less than 6 inches in diameter.

Pipe shall conform to AWWA C900, C905, or C909 requirements and have a minimum Pressure Class or Pressure Rating of no less than 150 psi. Pipe diameters 12 inches or smaller shall be AWWA C900 PVC DR18. Pipe diameters 14 inches and larger shall conform to AWWA C905.

Fire Hydrants shall be located with a maximum spacing of 500 feet between fire

hydrants in areas with a residential land use and a maximum 300 feet spacing between fire hydrants in areas with a non-residential land use.

The design of a water line distribution system shall incorporate means to achieve

a two-source water line loop. This may require extensions or off-site utility improvements. Exceptions to the looped water line requirement will be evaluated on a case by case basis.

A single water service connection and meter shall be provided for each single

family residential lot/unit. For land use other than single family residential, an individual water service and meter shall be provided for each unit or suite. In the case of a shell building, the engineer shall provide a reasonable assumption as to the number of potential suites that a shell building may enclose.

Embedment for water lines shall be sand from six (6) inches minimum below the

pipe to six (6) inches above the pipe. The remaining trench depth shall be mechanically compacted in one (1) foot lifts to 95% maximum dry density, as defined by the standard proctor. Trenches may be compacted to minimum density of 90% maximum dry density, as defined by the standard proctor, when the trenches are located further than 5 feet from any existing or proposed structure or pavement.

Water jetting is not allowed under any circumstance for utilities crossing or within

a roadway. An exception may be granted for utilities outside the proposed roadway, upon formal concurrence by a geo-technical engineer that soil is suitable



for jetting AND approval by the Utility Engineer for work outside road right of way, and the City Engineer for work within the road right of way.

Construction Plans for water lines greater than 12 inches in diameter shall include Plan and Profile Sheets of the entire water line.

McAllen Public Utility may request other means for Joint Restraints to replace

and/or supplement Concrete Thrust Block Protection.

Project Close-out documents shall include an electronic and hard copy of Final Record Drawings. Electronic drawings shall be in both AutoCad and PDF Formats.

All water system users shall be required to comply with the latest McAllen Public

Utility Cross Connection and Backflow Prevention Policy document.



Sanitary Sewer Design

All sanitary sewers shall be designed in conformance with the most current revision of TCEQ’s Design Criteria for Sewerage Systems (30 TAC Chapter 217) and the City of McAllen Standard Details and Specifications. The most stringent requirements shall apply where the standards conflict.

In accordance with City of McAllen, Code of Ordinance, Division 3, Sewer Use, Section 106-183, all facilities, with the exception of single family residential units, will be evaluated for the need for a Grease Trap and/or other Pre-treatment System designed to isolate oil, grease, sand, lint and other foreign substances that may adversely impact the wastewater collection and treatment system. Design of a Pre-treatment system shall comply with the latest McAllen Public Utility Policy Guideline Document.

Sanitary sewers (including force mains) shall be designed with a minimum 4 feet

of cover.

The minimum sewer line size is 8 inches. Capacity calculations must be submitted and peaking factors must be justified. Pipe oversizing for the purpose of meeting grade limitations is prohibited.

Gravity sewers shall be designed with straight alignment and uniform grade between manholes. Horizontal curvature of sewer alignment between manholes is prohibited.

Sewer lines shall be bedded with crushed rock or a crushed rock-sand mixture. Refer to the Standard Design Details and Specifications. Embedment shall be 6 inches below the bottom of the pipe and 12 inches above the top of pipe.

Water jetting is not allowed under any circumstance for sewers crossing or within

a roadway. Water jetting for sewers outside roadways may be allowed if a licensed geotechnical engineer has determined the soil is suitable for jetting AND the Utility Engineer approves if work is outside road right of way, and by the City Engineer for work within the road right of way.

Manholes shall be fiberglass including bottoms, benches, and invert channels. All

pipe connections shall be made via factory-installed stubouts except for the clean-out leg of a drop connection which may be field fiberglassed. Doghouse cut-out manholes installed over new or existing sewers are not allowed except in special circumstances by written approval of the Utility Engineer. Contractor shall excavate tie-in lines and confirm design elevation prior to submittal of manhole shop drawings. Contractor shall provide written certification that manhole shop drawings are correct for actual field elevations and locations.


Manhole and frame and cover shall have a 30” clear opening in accordance with TCEQ requirements.

A maximum of 15 inches of manhole grade adjustment rings is allowed, and a

minimum of 5” of grade rings is required between the manhole and the ring. Elevations of existing pipes to be tied-in shall be determined before approval of manhole shop drawings.

Service connections shall be a minimum of 4 inches in diameter for single-family

residential and 6 inches for multi-family residential, commercial, and industrial lots.

A single service connection shall be extended to serve each lot, and a cleanout

shall be installed at the property line. For land use other than single family residential, an individual sewer service shall be provided for each unit or suite. In the case of a shell building, the engineer shall provide a reasonable assumption as to the number of potential suites that a shell building may enclose.

All gravity sewers shall be tested using an air test for joint integrity and a mandrel

for pipe deflection. Completed manholes shall be vacuum tested. Test reports must be signed by the Contractor and City inspector. Signed reports must be submitted prior to acceptance of the work and performance of tie-ins.

Construction staking performed by a Registered Professional Land Surveyor

(RPLS) is required for all sewer line construction, and the signed and sealed construction staking documents must be submitted to City’s inspector prior to construction. The construction staking documents, at a minimum, shall include manhole station, northing and easting coordinates, offset distance, top of rim elevation, flowline elevation, existing ground hub elevation, and cut/fill depths.

All manholes shall be surveyed by an RPLS after construction is completed.

Survey shall include northing and easting coordinates of the manhole centerline and elevations of tops and inverts referenced to the City of McAllen benchmark grid.

Acceptance of the work will not be given and tie-ins shall not be made until the

As-Built Drawings and test reports have been approved. As-Built Drawings shall clearly identify the post-construction survey elevations and coordinates in addition to the design values. Provide both electronic and printed copies of the As-Built Drawings.



Traffic Control Policy Policy The Traffic Control Policy applies to the implementation of all traffic control devices placed within the jurisdiction of the City of McAllen. Any variances of this policy are subject to approval by the City Engineer or designee. Requirements I. Traffic Signs It shall be the responsibility of the developer to install all ‘Stop’, ‘Speed Limit’, ‘Street Name’, and ‘Warning’ signs within City of McAllen right-of-way in the bounds of new developments. It shall be the responsibility of the developer to include a ‘Sign & Markings’ plan as part of the construction plans. All traffic signs shall conform to the Texas Manual on Uniform Traffic Control Devices as well as the City of McAllen’s ‘Sign Material Standards’, ‘Sign Installation Details’, and ‘Sign Location Standards’. II. Pavement Markings Pavement markings placed on any street within the jurisdiction of the City of McAllen shall conform to the Texas Manual on Uniform Traffic Control Devices as well as the City of McAllen’s ‘Pavement Marking Standards’. Pavement markings shall be installed on streets that meet the Texas Manual on Uniform Traffic Control Devices pavement markings warrants or as deemed necessary by the City Engineer or designee. It shall be the responsibility of the developer to include a ‘Sign & Markings’ plan as part of the construction plans. III. Temporary Traffic Control All temporary traffic control within the City of McAllen’s jurisdiction shall conform to the Texas Manual on Traffic Control Devices as well as the provisions of this policy including construction work zones, maintenance operations, utility operations, loading and unloading operations, planned road closures, as well as special event traffic control. A traffic control plan shall be included as part of all construction plans, right of way permits, and special event applications. Back to Table of Contents


DRAINAGE POLICY


Table of Contents

1. Intro 2. General 3. Storm water Runoff

3.1 Rational Method Rainfall Intensity-Duration-Frequency Relationships Time of Concentration Estimates Runoff Coefficients

3.2 SCS Unit Hydrograph 4. Street Flow

Gutter Flow Spread Widths

5. Inlet Design Design Considerations

Curb Inlet Hydraulics Grate Inlet Hydraulics

6. Storm Sewer System Design

Design Considerations Capacity Hydraulic Grade Line Analysis

7. Detention Design

Design Considerations Modified Rational Method Example

8. Channel Design

Design Requirements Typical Section

9. FEMA Requirements 10. Water Quality (Reserved) BACK TO HOME


1.0 Introduction Back to Table of Contents

This policy shall govern the planning, design, construction and operation of storm drainage

facilities within the City of McAllen and all areas designated as its extraterritorial jurisdiction.

Any variances to this policy are subject to approval by the City Engineer and/or City

Commission.

The design guidelines presented in this policy were prepared in an effort to facilitate the design,

review and construction of proposed drainage infrastructure improvements. The methodologies

appearing in the following sections are consistent with standard engineering practice and are

intended to serve as guidance in the design of related infrastructure. Interpretation,

implementation and engineering judgment shall be the responsibility of the engineer of record.

2.0 General The following summary presents general drainage policy guidelines. Additional detail may be found in subsequent sections.

1. This design guide shall apply to all drainage improvements within the limits of the City of McAllen (City) and it’s Extraterritorial Jurisdiction (ETJ). When a conflict in design arises with applicable criteria (Hidalgo County Drainage District No. 1, Texas Department of Transportation, etc.) the more restrictive criteria shall govern.

2. All drainage reports and plans shall be prepared by a Licensed Professional Engineer

holding a valid license to practice in the State of Texas.

3. All proposed development within the City and its ETJ shall require a storm sewer outfall designated in accordance with the Master Drainage Plan.

4. In instances where proposed drainage infrastructure improvements require conveyance to

an outfall, the developer shall be responsible for design of the conveyance to accommodate storm water runoff from fully developed conditions within the entire subject drainage basin and all reasonable interconnects. The City shall consider a cost share or reimbursement program for costs associated with the construction of the conveyance.

5. All storm sewer conduit and related appurtenances maintained by the City of McAllen

shall be located within City right-of-way and/or dedicated drainage easements.

6. All drainage facilities including street gutters, inlets, pipes and related appurtenances to the drainage outfall system shall be designed to intercept and convey runoff from a 10-year frequency storm event and checked for a 25-year frequency storm event.


7. The drainage outfall system (“Blue Lines”) shall be designed to convey and/or detain storm water runoff from a 50-year frequency storm. The developer must comply with regulations to attain approval for connection to a drainage outfall system through a jurisdictional entity.

8. Improvements which will increase the frequency of flooding or the depth of inundation of

unprotected structures in the 100-year flood plain or areas of flooding shall not be permitted for construction. The developer must comply with City Ordinance Subpart B “Land Use Regulations and Related Activities”(Chapter 118 Floods).

9. Off-site discharge for post development conditions shall not exceed the pre-development

peak discharge for all storm events up to and including the 10-year storm event.

10. Stormwater runoff generated from developed improvements shall be detained on-site for a 50-year frequency storm event and released into the receiving system at the pre-developed, peak discharge rate for a 10-year frequency storm event.

11. Residential lots shall be graded to provide positive drainage towards the front of the lot at

a minimum slope of 1%.

12. In no instance shall site grading on residential or commercial properties adversely affect neighboring properties.

13. Typical Lot Grading

14. In no instance shall site grading on residential or commercial properties adversely affect

neighboring properties.

15. In the event of a difference in grade between adjacent properties, each property shall be graded to drain away from the deviation. Grade differentials in excess of 1-foot shall require a retaining structure as approved by the City Engineer.

16. Construction activity shall not interfere with the normal operation of existing drainage

systems. Back to Table of Contents


17. Storm drainage designs shall account for off-site drainage patterns affected by any

proposed drainage improvements.

18. Variances from procedures described in this policy shall require approval from the City Engineer and/or City Commission.

19. All formulas and factors appearing in this policy are presented in English units unless

noted otherwise. Minimum Requirements for Drainage Reports and Plans A drainage report and plans, as applicable, shall contain the minimum information described below: Reports

Summary of project location, existing/proposed conditions Location map Location of proposed site with respect to FEMA Floodplain Drainage Area Map

All contributing areas delineated Contours Spot elevations Direction of flow Right-of-way, property lines Existing/proposed storm sewer systems; outfalls Design assumptions

Runoff, detention and hydraulic calculation summary

Time of concentration estimates Runoff coefficient assumptions Storage volume calculations Pipe and inlet capacities Ponded widths and depths Inlet capacities and bypass Hydraulic Grade Line (HGL)

Storm Sewer Plan and Profile Plan Right-of-way/property lines Storm sewer alignment Direction of flow High points Identification of existing and proposed storm sewer Identification of existing and proposed storm sewer inlets, manholes and junctions

Applicable details (other than standard) Profile Back to Table of Contents


Pipe length, size, class, and slope Identification of inlets, manholes, junction boxes Flow lines at structures, outfalls; 100-foot intervals along storm sewer length Finished grade/natural ground Utility crossings, conflicts Hydraulic Grade Line (10-year) Top of curb elevations Manhole rim elevations Trench protection limits Applicable details (other than standard)

Bridge/Culvert Layouts

Plan and Profile Hydraulic calculations Applicable details

Channels and Detention Basins

Grading plan Earthwork Calculations Typical Sections Hydraulic calculations Design water surface elevations Maintenance access Applicable details

3.0 Stormwater Runoff Rational Method Peak flows may be estimated with use of the Rational Method for areas less than 100-acres.

Q = CiA where: Q = flow (cubic feet/second) i = intensity (inches/hour) A = Area (acres) Back to Table of Conte


Rainfall and Intensity Intensity calculations shall utilize Intensity-Duration-Frequency coefficients for Hidalgo County, Texas as presented in Table 3-1 below

Recurrence Interval (years)

IDF Coefficients

e B d 2 0.831 74 9.6 5 0.795 80 9.2 10 0.778 87 9.2 25 0.771 98 9.2 50 0.749 99 9.2 100 0.740 103 9.6

Reference: TxDOT Intensity-Frequency-Duration Coefficients for Texas Counties HDM (2004)

Table 3-1: Intensity-Frequency-Duration Coefficients for Hidalgo County, Texas

Intensity can be calculated by the relationship presented below.

i = b/(tc + d)e where: i = intensity (inches/hour) tc = time of concentration (minutes) Time of Concentration Time of concentration may be estimated by considering the velocity associated with three typical flow regimes; overland/sheet flow, shallow concentrated flow and pipe or channel flow. Time of concentration shall be calculated for each applicable flow regime encountered.

tc = L / 60V where: tc= travel time (minutes) L = watercourse length (feet) V = average flow velocity (feet/second)



Velocity Estimates

Velocities for overland/sheet flow and shallow concentrated flow may be estimated with the following relationship.

V = KukSp0.5

where: Ku = 3.28 V = velocity (feet / second) k = intercept coefficient Sp = slope (%)

Land Cover / Flow Regime k Forest with heavy ground litter; hay meadow (overland flow) 0.076 Trash fallow or minimum tillage cultivation; contour 0.152 or strip cropped; woodland (overland flow) Short grass pasture (overland flow) 0.213 Cultivated straight row (overland flow) 0.274 Nearly bare and untilled (overland flow); alluvial 0.305 fans in western mountain regions Grassed waterway (shallow concentrated flow) 0.457 Unpaved (shallow concentrated flow) 0.491 Paved area (shallow concentrated flow); small upland gullies 0.619

Table 3-2: Intercept Coefficients

Manning’s Equation shall be used to estimate average flow velocities in channels and conduits.

V = 1.49/n R2/3S1/2

Stormwater runoff shall be calculated for fully developed conditions. Minimum inlet time of concentration shall be 10-minutes. Drainage Areas Drainage areas shall be delineated with the aid of available topographic information. Care should be taken when considering existing drainage systems that cross natural drainage divides. Runoff Coefficients Runoff coefficients shall be determined for each drainage area. Where non-homogeneous conditions exist, a weighted coefficient shall be determined with application of the following formula: CW = (C1A1 + C2A2 + C3A3 + … + CnAn) / ATotal Back to Table of Contents


where: CW = Weighted Runoff Coefficient Cn = Runoff Coefficient n-th term An = Area of n-th term (acres) ATotal = Total Area (arces) Table 3-3 on page 4 presents typical ranges for “C”. Runoff coefficients utilized for 25-year and 50-year storm frequencies shall be adjusted by 10% and 20%, respectively. Back to Table of Contents


Type of Drainage Area Runoff Coefficient, C Business Downtown areas 0.70 - 0.95 Neighborhood areas 0.50 - 0.70 Residential: Single-family areas 0.30 - 0.50 Multi-units, detached 0.40 - 0.60 Multi-units, attached 0.60 - 0.75 Suburban 0.25 - 0.40 Apartment dwelling areas 0.50 - 0.70 Industrial: Light areas 0.50 - 0.80 Heavy areas 0.60 - 0.90 Parks, cemeteries 0.10 - 0.25 Playgrounds 0.20 - 0.40 Railroad yard areas 0.20 - 0.40 Unimproved areas 0.10 - 0.30 Lawns: Sandy soil, flat, 2% 0.05 - 0.10 Sandy soil, average, 2 - 7% 0.10 - 0.15 Sandy soil, steep, 7% 0.15 - 0.20 Heavy soil, flat, 2% 0.13 - 0.17 Heavy soil, average, 2 - 7% 0.18 - 0.22 Heavy soil, steep, 7% 0.25 - 0.35 Streets: Asphaltic 0.70 - 0.95 Concrete 0.80 - 0.95 Brick 0.70 - 0.85 Drives and walks 0.75 - 0.85 Roofs 0.75 - 0.95 Reference: FHWA, Urban Drainage Design Manual HEC-22, (2001)

Table 3-3: Runoff Coefficients In order to assist designers, a flow rate determination table is included in Appendix A.


Back to Table of Contents 14

SCS Unit Hydrograph For areas greater than 100-acres, SCS Unit Hydrograph (Ty III rainfall distribution) methodology shall be utilized. The designer shall consult Reference 9 in Appendix A for application of the SCS Unit Hydrograph procedure. In addition, applicable hydrologic software(s) may be utilized with approval from the City Engineer.

4.0 Street Flow In an effort to maintain safe passage of vehicular and pedestrian traffic and to ensure properties are kept reasonably safe from flooding, the designer shall be responsible for determining the depth and width of stormwater runoff. Calculated ponding widths and depths shall be presented on storm sewer plan sheets. The width of spread on a pavement section shall be contained to provide passage of vehicular traffic as specified in Table 4-1 below.

Functional Classification Clear Lanes

Local (a) Collector 1 - 11 foot

Minor Arterial 2 - 11 foot (1 each way) Principal Arterial 2 - 11 foot (1 each way)

(a) No width requirement; depth not to exceed top of curb

Table 4-1: Spread Limits for Roadways

In all cases, depth of flow shall be maintained at or below top of curb. For inlets located at sag points, the designer shall consider the effects resulting depths on existing and/or proposed adjacent grades. Determination of Spread Widths Flow in a gutter section can be calculated with adaptation of Manning’s Equation.(1)

Q = (KU/n) SX1.67SL

0.5T2.67

Spread width can be determined by the formula T = (Qn / KuSX

1.67SL0.5)0.375

where: KU = 0.56 N = Manning’s roughness coefficient Q = flow (cubic feet / second)


T = spread width (feet) SX = cross slope (foot / foot)SL = longitudinal slope (foot / foot) Table 4.2 presents acceptable values of Manning’s roughness coefficient.

Type of Gutter or Pavement Manning's n Concrete gutter, troweled finish 0.012 Asphalt Pavement Smooth Texture 0.013 Rough Texture 0.016 Concrete gutter-asphalt pavement Smooth 0.013 Rough 0.015 Concrete Pavement Float finish 0.014 Broom finish 0.016 For gutters with small slope, where sediment may accumulate, increase above values of “n” by 0.002 Reference: FHWA, Design Charts for Open Channel Flow HDS-3 (1961)

Table 4-2: Manning’s Roughness Coefficient, n

Depth of flow in a gutter section can be calculated by the formula D = TSx

Where: D = depth of flow (feet) T = spread width (feet) Sx = cross slope (foot / foot) The above formulas are applicable for pavement sections with a uniform, straight cross slope. The designer is referred to consult Reference 1 in Appendix A when composite pavement sections or parabolic crowns are encountered. 5.0 Inlet Design Design Considerations

Curb and grate inlets shall be used to facilitate the drainage of pavement sections and open areas.

Placement of inlets shall consider the safety of pedestrian, vehicular and bicycle traffic. Inlets

shall be placed at low points and at intervals necessary to meet maximum permissible spread

limits and inlet capacities. In any case, inlet spacing shall not exceed 600-feet, with a maximum

surface run of 300-feet from crest to sag of the roadway profile. In the event a longitudinal

roadway profile exceeds 300-feet from crest to sag, inlets shall be spaced at a maximum of 300-

feet. Flows shall be intercepted upstream of street intersections where practical. Back to Table of Contents


Runoff across roadway intersections consisting of a minor or principal arterial street is

prohibited. For inlets on grade, by-pass flows shall be limited to 10% of previously intercepted

flows. When curb inlet extensions are required, no more than two extensions shall be used

conjunction with a primary inlet. Inlet hydraulics shall be presented on plan sheets. The use of

inlets other than curb-opening or grate inlets shall require approval from the City Engineer.

Inlet Capacity Capacities for inlets may be determined by the following equations. Curb Opening Inlets on Grade

LT = KUQ0.42SL0.3(1/nSX)

where: LT = curb opening length for 100% interception (feet) KU = 0.6 Q = flow in gutter (cubic feet/second) SL = longitudinal slope (foot/foot) n = Manning’s roughness coefficient SX = cross slope (foot/foot) For curb inlets utilizing a depressed curb opening, the following equation is used.

LT = KUQ0.42SL0.3(1/nSe)

In this case the cross slope, SX is replaced by an equivalent cross slope, Se that accounts for the depressed gutter section. The equivalent cross slope is calculated by

Se = SX + S′WEO where: Se = equivalent cross slope (foot / foot) SX = pavement cross slope (foot / foot) S′W = gutter cross slope; gutter depression/gutter width (foot / foot) EO = ratio of flow in depressed section to total gutter flow upstream of inlet Curb Opening Inlets – Sag Location Curb opening inlets operate under weir or orifice flow conditions. Capacity of a curb opening inlet under weir conditions can be estimated by the following relationship. QI = CW (L + 1.8W) d1.5



Where:

CW = 2.3

L = length of curb opening (feet) W = lateral width of depression (feet) d = depth at curb measured from normal cross slope (feet) This formula is applicable for depths less than the curb opening plus the depth of the depression.

d < h + a/12 where: h = curb opening height (feet) a = depth of depression (inches)

QI = COhL(2gdO)0.5 or

QI = COAg [2g (dl – h/2)]0.5 where: CO = 0.67 (orifice coefficient) dO = head on center of orifice throat (feet) L = length of orifice opening (feet) Ag = clear area of opening (square feet) dl = depth at lip of curb opening (feet) h = height of curb opening orifice (feet) For curb opening inlet other than vertical face use:

dO = dl – (h/2)sinθ h = orifice throat width (feet) dO = effective head on center of orifice throat (feet) Grate Inlets in Sag Locations As weir flow:

QI = CWPd1.5 where: P = perimeter of the grate (feet) disregarding curb side Back to Table of Contents


CW = 3.0

d = average depth across grate (feet) As an orifice,

QI = COAg (2gd)0.5 where: CO = 0.67 (orifice coefficient) Ag = clear opening area of grate (square feet) g = 32.2 (feet/second/second) Grate inlet design shall incorporate a 50% factor to account for clogging. When the use or analysis of combination inlets is required, the designer shall consult Reference 1 in Appendix A.

6.0 Storm Sewer Design Design Considerations

Storm sewer systems shall be designed to convey runoff from a 10-year frequency storm event

and checked for a 25-year frequency storm event. Storm sewer systems shall utilize rubber-

gasketed, Class III reinforced concrete pipe (RCP) with a minimum size of 24 inches. Manholes

or junction boxes shall be utilized at all changes in pipe size and direction in both horizontal and

vertical planes. Manhole spacing shall be maintained as presented in Table 6.1.

Pipe Size (inches)

Maximum Spacing (feet)

12 to 24 300 27 to 36 400 42 to 54 500

60 and greater 1000 Reference: FHWA, Urban Sewerage Design Manual HEC-22 (2001)

Table 6-1: Suggested Manhole Spacing(1)



Pipes shall be matched at soffits when practical. In instances where radial alignment is required,

pipe joints shall not be deflected beyond manufacturer’s suggested tolerances. Pipe slopes shall

be designed to provide a minimum velocity of 3-feet per second and a maximum velocity of 12-

feet per second. Table 6-2 on page 2 presents the minimum slopes necessary to achieve the

minimum velocity.

Diameter (inches)

Slope (foot/foot)

Slope (%)

24 0.00174 0.174 27 0.00148 0.148 30 0.00129 0.129 33 0.00114 0.114 36 0.00101 0.101 42 0.00082 0.082 48 0.00069 0.069 54 0.00059 0.059 60 0.00051 0.051 66 0.00045 0.045 72 0.00040 0.040

Based on Manning’s Equation; v = 3 fps, n = 0.013

Table 6-2: Minimum Pipe Slopes

All outfalls shall incorporate the use of a concrete sloped-end treatment as per the City of

McAllen standard drainage detail. Where outlet velocities exceed maximums, velocity

dissipation shall be required.

Minimum depth of cover for all storm sewer pipe shall be 3-feet from finished grade to the

crown of the pipe. Depth of cover not meeting this requirement shall require structural

calculations as approved by the City Engineer. Trench protection shall be required for storm

sewer system installations exceeding depths of 5-feet.

Hydraulic Grade Line Analysis

A hydraulic grade line (HGL) analysis is required for all proposed storm sewer system

improvements. Back to Table of Contents


The analysis shall include determination and presentation of the 10-year HGL. The HGL shall

be shown on all storm sewer profile plans. The hydraulic grade line shall be maintained at or

below the throat of the inlet. Computations shall include determination of major and minor

losses.

Starting water surface elevations shall be calculated from the best available data. The designer

shall document all assumptions. For starting water surface elevations where an outfall is

provided at a channel, a backwater analysis shall be utilized where no water surface data is

available. Similarly, starting water surface elevations at ties to existing storm sewer systems

shall utilize best available data and shall be reviewed and approved by the City Engineer.

Major Losses Losses due to friction may be calculated by the relationship:

Hf = SfL where: Hf = loss due to friction (feet) Sf = friction slope (feet) L = length of conduit (feet) Slope friction may be calculated by:

Sf = (Qn / KQD2.67)2 where: Sf = friction slope (feet/feet) Q = flow (cubic feet/second) n = Manning’s roughness coefficient KQ = 0.46 D = pipe diameter (feet) Manning’s roughness coefficient may be assumed as 0.013 for concrete pipe. Minor Losses

Minor losses result from flow disturbances at junctions such as inlets, manholes or junction

boxes. Minor losses may be calculated with application of the formula

Hm = K (V2/2g) Back to Table of Contents


where: Hm = minor losses (feet) K = constant of proportionality V = velocity (feet / second) g = gravitational acceleration constant (32.2 feet/second/second)

K = KOCDCdCQCpCB K = adjusted loss coefficient KO = initial head loss coefficient based on relative access hole size CD = correction factor for pipe diameter (pressure flow only) Cd = correction factor for flow depth CQ = correction factor for relative depth Cp = correction factor for plunging flow CB = correction factor for benching

KO = 0.1(b/DO)(1-sinθ) + 1.4(b/DO)0.15sinθ where: θ = angle between pipes (degrees) b = manhole/junction diameter (feet) DO = diameter of outlet pipe

CD = (DO/DI)3 DO = diameter of outlet pipe DI = diameter of incoming pipe Applicable if the ratio of the depth in junction to outlet pipe diameter is greater than 3.2

(depth/DO) and pipe is flowing under pressure.

Cd = 0.5 (dmh/DO)0.6

where: dmh = depth in mh/junction DO = diameter of outlet pipe This formulas is applicable when dmh/DO < 3.2 and free surface flow or low pressure. Depth in

the access hole is estimated as HGL at upstream end of outlet pipe.



Relative Flow CQ = (1-2 sinθ)(1-QI/QO)0.75 + 1

where: CQ = relative flow correction factor θ = angle between pipes QI = flow in incoming pipe QO = flow in outgoing pipe The above equation is used only when 3 or more pipes enter the structure at approximately the

same elevation.

Plunging Flow

Cp = 1 + 0.2 (h/DO) (h-dmh/DO) where: Cp = plunging flow correction factor h = elevation difference between the invert of plunging flow pipe to center of outflow pipe DO = outlet pipe diameter dmh = depth of water in manhole relative to outlet pipe invert The above equation is applicable if h > dmh and if the plunging flow is at a higher elevation and

inflow and outflow pipes are at the bottom of the manhole / junction. This correction factor is

also applied at curb and grate inlets functioning as junctions.

Benching The following correction factor is applied to address benching configurations for either

submerged or unsubmerged conditions.

Bench Type

CB Submerged(1) Unsubmerged(2)

Flat or Depressed Floor 1.00 1.00 Half Bench 0.95 0.15 Full Bench 0.75 0.07 (1) pressure flow dmh/DO > 3.2 (2) free surface flow dmh/DO < 1.0 Reference: FHWA, Urban Sewerage Design Manual HEC-22 (2001)

Table 6.3: Bench correction factor, CB Back to Table of Contents


Exit Losses Exit losses shall be accounted for at all outfalls.

HE = 1.0 (V2o/2g – V2r/2/g) where: Vo = average velocity at outlet (feet / second) Vr = velocity of receiving stream (feet / second) All hydrologic and hydraulic design computations may be completed with the aid of design software approved by the City Engineer.



7.0 Detention Design Design Considerations Stormwater runoff generated from developed improvements shall be detained on-site for a 50-

year frequency storm event and released into the receiving system at the pre-developed rate for a

10-year frequency storm event. The Modified Rational Method (MRM) shall be used to

determine stormwater storage requirements for areas less than 10-acres. For areas greater than

10-acres, the MRM may be used to estimate storage requirements. However, final detention

design shall implement appropriate hydrograph routing procedures that account for the storage

characteristics of the basin and discharge characteristics of the outlet structure. Applicable

software programs may be implemented with approval from the City Engineer.

On-site detention facilities shall be situated in dedicated areas. Existing drainage facilities (i.e.

City of McAllen Bluelines, Regional Stormwater Detention Facilities, etc.) shall not take the

place of dedicated facilities unless previously included in the City of McAllen’s Master Drainage

Plan. Methods of on-site detention shall include ponds or engineered sub-surface systems.

Detention areas may be incorporated into landscape and greenbelt areas provided that vegetation

does not adversely affect required design volumes or impede hydraulic efficiency. Areas

designated as dual use areas (detention/landscape, detention/green space, etc.) shall display

appropriate signage indicating so. Maintenance of detention areas shall be the responsibility of

the property owner or home owner’s association as applicable. The City shall have the authority

to assume the responsibility of maintaining the detention areas and impose applicable fees in the

event the property owner or home owner’s association fails to comply with the maintenance

requirements. Back to Table of Contents


Typical Residential Detention Pond Layout

When field conditions permit, supplemental stormwater detention storage may be achieved

within roadway right-of-way. Shallow swale and/or sump side slopes shall not exceed 2:1.

Designs shall incorporate the use of curb cuts to allow and direct overflows onto the roadway.

Storage volumes below gutter lines may be allowed to percolate into the ground if suitable soils

are present. Supplemental stormwater detention shall not interfere with other existing or

proposed uses of right-of-way.

Typical Detention/Retention in Roadway Right-of-Way

Storm water runoff may be conveyed to detention areas via storm sewer networks, flumes and

curb cuts within dedicated right-of-way or flowage easements. Detention pond footprints are

encouraged to incorporate aesthetically pleasing geometries and may be used as a common areas

or green-belt areas as long as there is no interference with the hydraulic function of the pond. Back to Table of Contents

Sidewalk Outfall

Sidewalk Outfall Curb & Gutter

Curb cut

Section

Plan

Property Line


Typical Dry Stormwater Detention Pond

Side slopes shall not exceed 3:1 (H:V). In areas with a potential for vehicular or pedestrian

activity, detention pond depths exceeding 2.5-feet shall require a safety buffer in the form of

benching or fencing around the perimeter of the pond. The bottom of the basin shall be graded

to drain towards the outlet structure. A pilot channel shall be placed along the flow line from

inlet to outlet to ensure positive flow. Trash racks shall be incorporated into outlet structure

design. A minimum of 20-feet shall be maintained around the perimeter of the pond to allow for

routine maintenance and/or repair.

Detention area design shall consider proximity and elevation of adjacent building structures.

Bank areas shall be graded to drain away from such structures. A minimum of 1-foot of

freeboard above design pool elevation shall be required. The design of detention areas shall

incorporate diversion of overflows into street rights-of-way or drainage/flowage easements in the

event of an extreme event or outlet structure failure.

Detention pond areas shall be vegetated to prevent erosion and deposition of silts. Common

Bermuda, Winter Rye or a combination of the grasses may be used. Vegetated areas shall

include provisions for irrigation systems.

Modified Rational Method The Modified Rational Method may be used to estimate storage volumes. The MRM produces a

trapezoidal runoff hydrograph based on the Rational formula. Storage requirements are based

upon differences in volume between pre and post development runoff hydrographs for various

storm durations. Calculations are best carried out in tabular form. Back to Table of Contents

Inlet Pipe

Outlet Structure

Graded to Drain

Pilot Channel


(A) (B) (C) (D) (E) (F) (G)

Duration Intensity Qin Volin Qout Vout Storage (min) (in/hr) (cfs) (ft3) (cfs) (ft3) (ft3)

Column A: Duration in minutes Column B: Intensity for respective duration (50-year event) Column C: Developed conditions peak discharge (Cdev x i50 x Area) Column D: Developed conditions Runoff Volume (Qin x Duration x 60) Column E: Pre-developed peak discharge (Cpre x i10 x Area) Column F: (0.5 x [duration + tc dev] x Qout x 60) Column G: Required storage (Vin – Vout)

The calculations are carried out iteratively until a duration yielding the greatest storage

volume is achieved. The following example illustrates application of the MRM.



Modified Rational Method Example Site Area: 5.3-acres Pre-developed Conditions

C = 0.25 tc = 60 min i10 = 3.22 in/hr Qpeak = 4.27 cfs

Post-developed Conditions

C = 0.60 tc = 20 min i50 = 7.91in/hr Qpeak = 30.18 cfs

Duration Intensity Qin Volin Qout Vout Storage (min) (in/hr) (cfs) (ft3) (cfs) (ft3) (ft3)

10 10.83 41.31 24,786 4.27 3,840 20,945 20 7.91 30.18 36,212 4.27 5,121 31,092 30 6.34 24.20 43,566 4.27 6,401 37,165 40 5.35 20.42 48,997 4.27 7,681 41,317 50 4.66 17.77 53,321 4.27 8,961 44,360 60 4.14 15.81 56,925 4.27 10,241 46,684 70 3.75 14.29 60,027 4.27 11,521 48,506 80 3.43 13.07 62,757 4.27 12,801 49,956 90 3.16 12.07 65,200 4.27 14,081 51,119 100 2.94 11.24 67,416 4.27 15,362 52,055 110 2.76 10.52 69,447 4.27 16,642 52,806 120 2.60 9.91 71,325 4.27 17,922 53,403 130 2.45 9.37 73,072 4.27 19,202 53,870 140 2.33 8.89 74,708 4.27 20,482 54,226 150 2.22 8.47 76,248 4.27 21,762 54,486 160 2.12 8.09 77,704 4.27 23,042 54,662 170 2.03 7.75 79,085 4.27 24,322 54,762 180 1.95 7.44 80,400 4.27 25,603 54,797 190 1.88 7.16 81,655 4.27 26,883 54,772 200 1.81 6.90 82,856 4.27 28,163 54,693 210 1.75 6.67 84,009 4.27 29,443 54,566 220 1.69 6.45 85,117 4.27 30,723 54,394

Required storage = 54,797 ft3 = 1.25 ac-ft with a controlled release of 4.27 cfs. Back to Table of Contents


8.0 Channel Design

City maintained/dedicated Channels shall be designed to convey and or detain stormwater runoff

resulting from the 50-year storm. Typical channel sections shall incorporate maximum side

slopes of 3:1 (H:V). Side slopes shall be vegetated to prevent erosion and degradation of slopes.

Utility crossings within the banks of a channel are discouraged. In instances where such

crossings are unavoidable, utilities shall be designed to maximize the cross-sectional area of the

channel in the vicinity of crossing. Utility crossings shall be protected from floating debris and

scour.

Water surface profiles shall be prepared utilizing standard-step backwater calculations or

hydraulic modeling software such as HEC-RAS. Calculations shall account for losses at bridge

and culvert crossings.

Typical channel sections shall incorporate the use of a pilot channel with a minimum 10-foot

maintenance bench on either side (12’ preferred). Maintenance benches shall be graded to slope

toward the pilot channel at a minimum slope of 12:1 (H:V). Access to maintenance benches

shall be provided at end sections of the channel at grades not exceeding 5%.

Culverts shall be sized to convey the 50-year storm and shall be designed in accordance with

criteria as specified in Chapter 8 of the Texas Department of Transportation Hydraulic Design

Manual.(5)



10. Water Quality

[RESERVED]



References 1. Federal Highway Administration, “Urban Drainage Design Manual, Hydraulic Engineering

Circular No. 22”, FHWA-NHI-01-021, Washington, D.C., August 2001. 2. Federal Highway Administration, “Drainage of Highway Pavements, Hydraulic Engineering

Circular No. 12”, FHWA-TS-84-202, Washington, D.C., March 1984. 3. Gribbin, J.E., “Hydraulics and Hydrology for Stormwater Management”, Delmar, New York,

1987. 4. United States Department of Commerce, “Rainfall Frequency Atlas of the United States,

Technical Paper No. 40”, Washington, D.C., May 1961. 5. Texas Department of Transportation, “Hydraulic Design Manual”, Austin, Texas, March

2004. 6. United States Department of Agriculture Natural Resources Conservation Service, “National

Engineering Handbook, Section 4, Hydrology”, August 1972. 7. Federal Highway Administration, “Design Charts for Open Channel Flow Hydraulic Design

Series-3”, Washington, D.C., August 1961. 8. Federal Highway Administration, “Highway Hydrology, Hydraulic Design Series No. 2”,

FHWA-NHI-02-001, Washington, D.C., October 2002.



TRAFFIC IMPACT ANALYSIS POLICY


Traffic Impact Analysis Policy The Traffic Impact Analysis (TIA) policy applies to new development, changes to existing development, and conditional use permits. The TIA shall assist City of McAllen staff in assessing the roadway system’s ability to serve the development. It shall be the responsibility of the developer and shall be submitted with plat/site plan and conditional use permit applications. The TIA will be used by City of McAllen staff to:

Evaluate site access and traffic circulation Evaluate the ability of the roadway system to support the proposed development Determine specific on-site and off-site roadway system mitigation requirements Determine the developer’s share of future roadway improvements

All Traffic Impact Analyses performed under this policy shall be conducted under the direction of a registered/licensed professional engineer. The final report shall be signed and sealed by the registered professional engineer responsible for the document. The Professional Engineer’s license shall be valid in the State of Texas. Engineers performing the study shall discuss study requirements (trip generation, trip distribution, growth rates, e.g.) with the City of McAllen Engineering Department’s designated staff to confirm each of these elements prior to completing the study. TIA Requirements TIA Scope The scope of the Traffic Impact Analysis shall be based on the peak hours trips projected to be generated by the proposed development, as set for in the following table. Nonresidential Peak Hour Trips

Residential Peak Hour Trips

TIA Scope

100 or less 100 or less *Trip Generation Worksheet Required. No TIA Required.

101-300 101-300 The frontage of the property, all access points (including common access), and all intersections within a 1/4 mile radius of the proposed development.

301-500 301-500 The frontage of the property, all access points (including common access), and all intersections within a 1/2 mile radius of the proposed development.

501 or more 501 or more The frontage of the property, all access points (including common access), and all intersections within a 1 mile radius of the proposed development.

* If no TIA is required then intersection sight triangles to be submitted for all intersections.


Trip Generation Trip generation shall be based on the specific site use and calculated using the latest addition of the Institute of Transportation Engineers (ITE) Trip Generation Manual. Trip Distribution Trip distribution shall be based on current peak hour traffic movements and may be adjusted to reflect future, financially assured, roadway improvements. Study Time Frames The analysis should include the following conditions:

Existing traffic volumes and roadway conditions Existing traffic volumes and roadway conditions plus projected site generated traffic Existing traffic volumes with improved roadway conditions plus projected site generated

traffic (when specified by City of McAllen staff) The analysis should be performed for a typical week day unless specified by City of McAllen staff. The analysis shall include both the AM and PM peak hours, 24-hour generations, and special times or days of the week dependant of the land use’s peak traffic generating time periods as determined from the Trip Generation Manual. Access Analysis Intersection needs at all the development’s access points shall be determined. Spacing of the access points shall be determined both by the City of McAllen’s ‘Access Management Policy’ and the operational analysis. This operational evaluation shall include on-site circulation as it may affect access, on-site and off-site turn lanes, required storage, potential for signalization, review of sight distance and other intersection safety aspects. Site distance triangles shall be shown on the site plan/ plat and calculated using the latest addition of the American Association of State Highway and Transportation Officials, “A Policy on Geometric Design of Highways and Streets” (Green Book). Usage of common access driveways is encouraged to reduce the total number of connections to the roadway network. Level of Service Evaluation Both roadway capacity and intersection capacity shall be evaluated as part of the level of service analysis. The level of service evaluation for roadways shall be based on the latest edition of The Highway Capacity Manual (HCM). The volume to capacity ratio (v/c) is an important indicator of roadway capacity and shall be included as part of the level of service tables. Intersection level of service shall be calculated using the latest Intersection Capacity Utilization (ICU) methodologies. The intersection level of service tables shall include volume to capacity ratios (v/c) as well as volume to saturated flow ratios (v/s). Recommendations


Recommendations shall be put forth to preserve existing roadway network operations. The recommendation may include the following incremental improvements:

Left turn bays Increased storage lanes Right turn declaration lanes Conversion of Two-way Stop control to All-way Stop control, if warrants are met and

staff approves Conversion of All-way Stop control to roundabout or traffic signal, if warrants are met

and staff approves The installation of a traffic signal, if warrants are met and staff approves Improved signal timing or phasing Roadway expansion or extension Various access management measures to improve overall circulation and/or safety Any suggested changes to signal timing must evaluate the effects to the entire network of affected signals and not just the signalized intersections in question. Recommendations put forth to expand or extend roadways shall conform to the Foresight McAllen comprehensive plan. Mitigation Mitigation may be required based on the TIA recommendations or to account for the cumulative effect of development on the roadway network. In the case of cumulative mitigation, fees may be charged proportionately to fund future roadway improvements.



POLICY DOCUMENT

FOR SIZING AND INSTALLATION

OF PRETREATMENT FACILITIES/GREASE

TRAPS

August 2009


Table of Contents

1.0 GENERAL SPECIFICATIONS FOR GREASE TRAP SIZING ......................…………….48

2.0 GUIDANCE FOR GREASE TRAP SIZING AND DESIGN CRITERIA .............................49

3.0 OTHER TYPES OF GREASE TRAPS AND SIZING REQUIREMENTS ..........................53

4.0 OPERATION AND MAINTENANCE ......................................................................................57

5.0 GREASE TRAP TREATMENT PRODUCTS .........................................................................58

6.0 INSPECTION AND CLEANING SCHEDULES .....................................................................59

7.0 CLEANING SCHEDULE EXTENSIONS ................................................................................59

BACK TO HOME


List of Figures

Figure 1 Typical Plumbing

Layout…………………………………………………………………………………… ……….55

Figure 2 Typical Grease Trap Schematic ...............................................................................55

Figure 3 Typical Grease Trap / Sample Well Installation .....................................................56


1.0 General Specifications for Grease Trap Sizing

The requirements outlined in these guidelines shall be considered minimum requirements only. It shall be the responsibility of each user to have a grease trap/Pretreatment facility designed; installed and maintained that will produce an effluent in compliance with the requirements of the City of McAllen Code of Ordinances.

In accordance with City of McAllen, Code of Ordinance, Division 3, Sewer Use, Section 106-183, all facilities, with the exception of single family residential units, will be evaluated for the need for a Grease Trap and/or other Pre-treatment System designed to isolate oil, grease, sand, lint and other foreign substances that may adversely impact the wastewater collection and treatment system. Design of a Pre-treatment system shall comply with the latest McAllen Public Utility Policy Guideline Document.

1.01 Pretreatment facilities/Grease traps shall meet or exceed the more stringent of specifications and requirements set forth in the City of McAllen Code of Ordinances and other applicable local, state or federal requirements.

1.02 An existing Pretreatment facility/grease trap which is upgraded or replaced shall meet or exceed the specifications set forth in the City of McAllen Code of Ordinances and other applicable Local, State, or Federal requirements.

1.03 Where a user required under this Ordinance to have a Pretreatment facility/grease trap will occupy an existing building, user shall meet or exceed the requirements in the City of McAllen Code of Ordinances and other applicable Local, State, or Federal requirements.

1.04 Pretreatment facilities/Grease traps shall be constructed of impervious materials capable of withstanding abrupt and extreme changes in temperature and capable of withstanding the traffic load where installed.

1.05 Grease traps shall be installed outside the building wherever possible. Where it is impossible to locate a grease trap outside the building, the trap shall be located in a mechanical room or other separate area where no food is stored or processed.

1.06 Pretreatment facilities/Grease traps shall be located so as to be readily and easily accessible for cleaning and inspection of the pretreatment device and shall be equipped with easily removable covers.

A. Manhole rings and covers shall not be less than twenty-four (24) inches in diameter, shall be installed for each compartment to facilitate easy access for cleaning and inspection. The manholes lids shall be placed so that all internal piping is accessible for maintenance and inspection. The cover shall be at or near, but not below the finished grade, unless grease trap design criteria qualifies/calculates for the need of an alternative size (reference page 2-3, Sec. 2.06). Back to Table of Contents

1.07 Grease traps shall have a total liquid capacity of not less than seven hundred fifty (750) gallons. Grease traps shall be constructed with a minimum of two compartments. Unless

Policy Document for Sizing and Installation of Grease Traps City of McAllen – McAllen Public Utility


grease trap design criteria qualifies/calculates for the need of an alternative size (reference page 2-3, Sec. 2.06).

1.08 Plans for new Pretreatment facilities/Grease traps or modifications to existing shall be submitted to the Pretreatment Department and Building Inspection Department, prior to the purchase and installation of such devices.

1.09 The Pretreatment Department and Building Inspections Department for review, prior to committing and installation of facilities.

A. A description of and number of plumbing fixtures draining to the trap, seating capacity, days & hours of operation, along with a menu shall be included in the submittal.

B. The Pretreatment Department and City of McAllen Building Inspections Department shall be in agreement for approval of the final plans prior to the issuance of any required plumbing or construction permits and subsequent construction.

1.10 Pretreatment facilities/Grease traps shall be installed by a contractor, however all plumbing work must be performed by a licensed plumber. Completed Pretreatment facility/grease trap must be inspection by the Pretreatment Program Supervisor and the City of McAllen Building Inspections Department prior to connecting to the sanitary sewer.

2.0 Guidance for Grease Trap Sizing and Design Criteria

Information contained within this Section is based on standard industry practices and guidance found in the 1997 International Plumbing Code (IPC) Commentary and the Uniform Plumbing Code (UPC), Appendix H. Size, type, and location of grease traps shall be in accordance with the manufacturer’s instructions, the requirements of City of McAllen Sewer Use Ordinance and Plumbing Ordinance.

2.01 All liquid waste lines in food preparation areas such as dishwashing, garbage disposal and soft drink, bar area sinks, dispenser drain lines must discharge through the grease trap, except lines from restroom facilities, cooling unit condensate, and ice maker.

2.02 The minimum size of grease traps shall be determined according to the type of the operating facility, but shall, not have a total liquid capacity of less than seven hundred fifty (750) gallons. Unless grease trap design criteria qualifies/calculates for the need of an alternative size (reference page 2-3, Sec. 2.06).

2.03 These requirements are applicable to all commercial food service establishments, including those that are undergoing:

A. New construction Back to Table of Contents



B. Interior remodeling to accommodate expansion or operational modifications

C. Changes of ownership/occupancy D. Facilities which may be experiencing difficulty in achieving compliance with

maintenance and/or wastewater discharge limitations

2.04 Sizing methods described herein are provided to determine grease trap/Pretreatment facility sizes that will afford the City’s sanitary sewer system a minimum degree of protection against grease and other obstructing materials. Sizing determinations are based on operational data provided by business owners or their contractors. In approving a customer’s plumbing or grease trap design, the City does not accept liability for the failure of a system to adequately treat wastewater to achieve effluent quality requirements specified under the sewer use ordinance. It is the responsibility of the generator and/or contractors to insure the appropriate level of treatment necessary for compliance with the City of McAllen Code of Ordinance and other applicable local, state or federal requirements. Minimum acceptable grease trap sizing shall be accomplished as follows:

Sizing according to formulas found in Section 2.05 below.

2.05 Grease Trap Sizing Formulas: It is the responsibility of the generator and his/her contractors to ensure that the wastewater discharged from their facility is in compliance with the City’s discharge limitations. For the purpose of plans review, a general assessment of grease trap design and size will be performed using the following formulas. (These formulas have been demonstrated as industry standards capable of achieving the City’s discharge criteria when systems are maintained in proper working condition.) A. Method 1: Uniform Plumbing Code, Appendix H

Number of meals x total waste flow x retention x storage = Size Requirement Per peak hour (1) rate (2) time (3) factor (4) (liquid capacity)

Factors:

1. Number of meals served at peak operating hour (Seating Capacity) x Peak Factor

a. Where Peak Factor for Fast Food Restaurant is…....................................................1.33

b. And, Peak Factor for all other food service types is……………….….……………1.00

2. Waste Flow Rate:

a. With Dishwasher……………………………………..………………….... 6 gallon flow

b. Without Dishwasher…………………………………..…………………... 5 gallon flow



c. Single Service kitchen………………..……………..…………………...... 2 gallon flow

d. Food waste disposer…………………….………………………..1 gallon flow

3. Retention Times

a. Commercial kitchen waste/dishwasher….........2.5 hours

b. Single service kitchen/single serving…………1.5 hours

4. Storage Factors

a. Fully equipped commercial kitchen……….…..8 hr operation…………………1

b. ……………………………………………….16 hr operation..………………..2

c. ………………………………………………..24 hr operation……...…………3

d. Single Service Kitchen……………………………….…..…………………...1.5

B. Method 2: Five (5) Hour Detention/Peak Flow 1. Gallons of water used per hour of operation 2. A x 0.75 = average “gray water” flow per hour 3. B x 1.9 peak flow factor 4. C x 5 hours detention = volume of trap Required volume of trap = A x B x C x D

2.06 Alternate Sizing Formula / Proposal: Food service establishments that propose the use of alternate sizing techniques and/or procedures that result in calculations of less than the minimum specification requirements (or are less than the MINIMUM 750 gallon sized requirement, i.e. food service establishments such as sandwich shops) must submit formulas and other bases to support proposed grease trap size/ installation. Submission should also provide documentation of ability to meet effluent quality requirements. This proposal must be signed by a licensed plumbing contractor (master plumber) or professional engineer and must include calculations and justification for non-standard installation, shall be approved on an individual basis. In no cases will an alternate sized Pretreatment facilities/Grease traps be accepted that is less than 100 gallon capacity.

2.07 Construction/Installation of Grease Traps must meet the following installation conditions:

A. The primary chamber shall contain three-fourths (3/4) of the total liquid capacity of the trap.

B. The dividing wall between each chamber shall completely divide the chambers (shall extend top to bottom)




C. The effluent leaving the grease trap shall not have total oil, grease, BOD, TSS concentration, as determined by proper laboratory analytical methods, in excess of the discharge limit specified in the City’s Local Limits for industrial waste discharges.

D. Grease traps shall be equipped with cleanouts on the outside of the trap in both the influent (prior to the trap) and effluent (after the trap) pipes and clean out on service line at the property line. *Inlet and Outlet lines must NOT hold any water once flow to the Pretreatment facilities/Grease trap has ceased. Also clean outs shall be installed at floor level in away as to prevent infiltration into the sanitary sewer or into the Pretreatment facilities/Grease traps.

E. The influent shall enter each chamber below the static water level in accordance with the specifications outlined in this paragraph. The effluent shall discharge from below the static water level of the chamber in accordance with the specifications outlined in this paragraph.

1. The influent line into all chambers shall terminate no greater than twenty four (24) inches from the bottom of the chamber.

2. The effluent from all chambers shall discharge from the lower eighteen (18) inches of the chamber.

3. The influent and effluent inter plumbing shall consist of a T. Inter connection between primary and secondary tanks and additional tanks (when placed in series) will consist of PVC pipe installed at a 45º degree angle.

4. When installing several tanks in series, Pretreatment Department needs to review plans and authorize prior to installation. Pretreatment facilities/Grease traps must to be installed wall to wall interconnecting with a PVC pipe, installed at a 45º degree angle.

5. The static water level shall be maintained throughout the entire trap. F. All permitting, construction, and inspection activities must be completed in

accordance with the City of McAllen code of ordinances. Additionally, the following specifications must be incorporated into grease trap design.

G. The grease trap shall be constructed with a minimum of one baffle. H. Grease traps are to be installed at a minimum distance of 10 ft. from sinks and

dishwashers to allow for adequate cooling of the wastewater. Water temperatures must be less than 120 degrees prior to entering grease trap.

I. All grease bearing waste streams must be routed through an appropriate grease trap, including: three-compartment sinks, pot/pan sinks, soup kettles, hand-washing sinks, dishwashers, mop sinks, bar areas and floor drains. Notable Exceptions: Drains that receive “clear waste” only, such as from ice machines, condensate from coils, may be plumbed to the sanitary system without passing through the grease trap with the condition that the receiving drain is a “hub” type that is a minimum of two inches above the finished floor.

J. Upon the completion of construction and installation of pretreatment device/grease trap all such facilities shall be clean of debris prior to inspection by the City of McAllen Building Inspections Department and or the Wastewater Pretreatment Department.




2.08 Generator Responsibilities:

A. It is the responsibility of the customer (waste generator) to insure compliance with the City of McAllen discharge limitations specified in the City’s Sewer Ordinance.

B. Hazardous wastes, such as acids, strong cleaners, pesticides, herbicides, paint, solvents, or gasoline shall not be disposed of where they would go through grease or grit traps. Commercial dishwashers are discharged through a grease trap, there for care must be taken in system design. Dishwashers use detergents and elevated water temperatures that will melt grease. If the grease trap is either too small or too close to the commercial dishwasher, grease may pass through the grease trap and into the collection system.

C. Generators are responsible for maintaining grease traps in continuous proper working condition. Further, generators are responsible for inspecting, repairing, replacing, or installing apparatus and equipment as necessary to ensure proper operation and function of grease traps and compliance with discharge limitations at all times.

D. The generator must have grease traps serviced (pumped, cleaned, and inspected) by a City of McAllen permitted waste hauler, at a minimum frequency of every 90 days or more often as necessary, to ensure proper function. Records of maintenance are required to be maintained on site for five (5) years. (90 day maintenance frequency assumes proper sizing and installation consistent with this guidance).

E. Enzymes, solvents, and emulsifiers are not permitted as they will only change the form of grease, allowing it to be carried out of the trap with the wastewater and deposited in the collection system. Biological treatment systems must be pre-approved (registered) by the Pretreatment Program Supervisor. These systems will not alleviate the necessity for inspection and proper maintenance.

F. It is the generator’s responsibility when closing the food establishment to have the Pretreatment facility(ies)/Grease trap(s) vacuumed. It is the generator’s responsibility to request an inspection from the Pretreatment Department to verify and have the establishment removed from the High Strength Sewer Surcharge Program.

3.0 Other Types of Grease Traps and Sizing Requirements Traps are required for oil, grease, sand and other substances harmful or hazardous to the collection system or sewage treatment plant. Design, size, and location of pretreatment devices must be submitted by a licensed plumbing contractor or professional engineer for review and approval. Back to Table of Contents



3.01 Laundries: Commercial Laundries, Laundromats, and dry-cleaners shall be equipped with trap in order to reduce the quantity of lint and silt that enter the collection system. The system must be of adequate size and design to allow for cool-down of wastewater so that separation can be more readily achieved. The trap must be installed with a wire basket or similar device, removable for cleaning, that prevents passage into the collection system of solids ½ inch (12.7 mm) or larger in size, string, rags, buttons or other materials detrimental to the public sewerage system.

Sizing must be in accordance with guidance found in the Uniform Plumbing Code (UPC), Appendix H which uses the following formula:

(TGC) x (CPH) x (RT) x (ST) = Size of Lint Grease Trap (gallons)

A. Laundries (continued)

Where: TGC = Total Gallons per Cycle CPH = Cycles per hour RT = Retention time

2.5 For Institutional Laundry 2.0 For Standard Commercial Laundry 1.5 For Light Commercial Laundry

ST = Storage Factor, based on hours of operation; 1.0 For 8 hours of operation 1.5 For 12 or more hours

3.02 Car Washes

A. Where automobiles are washed (including detail shops utilizing hand-wash practices), separators shall have a minimum capacity of 1000 gallons for the first bay, and 500 gallons of capacity for every additional bay.

B. An effluent sample port shall be provided for all traps (sample port must be a sanitary “T” and shall not hold water after flow to the pretreatment device/grease trap as ceased).

3.03 Automotive Repair Facilities (Garages and Service Stations)

A. Where automobiles are serviced, greased, or repaired or where gasoline is dispensed, Chemical discharges. No user shall discharge to the POTW any wastewater which may contain: (1) Petroleum oil, non-biodegradable cutting oil, or products of mineral oil origin in amounts that will cause interference or pass through. (2) Any liquids, solids or gases which create a fire or explosion hazard (such as gasoline or diesel fuel) in the POTW, including but not limited to wastes with a closed cup flashpoint of less than 140 degrees Fahrenheit, using the test methods specified in 40 CFR 262.21.



B. Note: Parking garages in which servicing, repairing, or washing is not conducted, and in which gasoline is not dispensed, shall not require a separator. Areas of commercial garages utilized only for storage of automobiles are not required to be drained through a separator.

46

Figure 1 Typical Plumbing Layout

Figure 2 Typical Grease Trap Schematic Back to Table of Contents



4.0 Operation and Maintenance

4.01 Pretreatment facilities/Grease traps shall be operated in a safe and secure manner at all times.

4.02 Areas surrounding grease traps shall be maintained to facilitate immediate access to the unit for cleaning and for inspection by the Pretreatment department or authorized agent at all times.

4.03 Pretreatment facilities/Grease traps shall be maintained in continuously efficient operation by the owner or operator at his expense and shall produce an effluent in compliance with this or other applicable ordinance.

4.04 A user shall not remove any downpipes or otherwise alter a grease trap in any way which may allow oil and grease, or other objectionable materials, to pass through the device into the sanitary sewer.

4.05 Where the city must clean associated public sewers caused by inappropriate operation or maintenance, inadequate design or installation, or inappropriate alteration of a grease trap. Pretreatment Department may inspect and pin point and require the establishment found to be negligent of the for mentioned, may be required to up size and or repair there pretreatment facility/grease trap

4.06 A User shall not increase the use of water or in any other way attempt to dilute the waste stream in lieu of adequate treatment.

4.07 The addition of hot water or the use of emulsifiers, chemicals, or other agents or devices that may cause oil or grease to pass through a treatment facility or into the sanitary sewer collection system is strictly prohibited.

4.08 Areas surrounding a grease trap or holding tank shall be kept clean and free of grease and odors and other materials at all times.

A. Materials shall not be splashed, spilled, allowed to overflow, or otherwise placed on the area surrounding a grease trap or holding tank.

B. In the event materials are spilled, splashed, overflowed, or otherwise placed on the surrounding area, the generator or owner shall assure the materials are cleaned from the area and properly disposed.

4.09 Pretreatment facilities/Grease traps and pretreatment facilities/grease traps installed in series shall be fully evacuated of all contents during cleaning. If the capacity of the trap or holding tank is greater than the capacity of the transport vehicle where full evacuation is not possible in a single load, then the transporter and the generator shall assure the contents are fully evacuated within twenty-four (24) hours.

A. No liquid waste shall be returned to the trap or holding tank after or during cleaning, either from the same or other trap or holding tank. Back to Table of Contents



B. During cleaning, grease residue shall be removed from piping and walls. The piping and walls shall be inspected to assure the integrity of the device is maintained.

C. Outlet line of the Pretreatment facilities/Grease traps shall be hydro jetted to remove any settled FOG (fats, oil and grease) from the service line to prevent blockages.

4.10 Materials removed from traps shall be utilized by industry, recycled, or disposed at a facility designated by or acceptable to the generator where the owner or operator agrees to receive the wastes and the disposal facility has documentation showing the facility meets all requirements of the State for the proper operation of the disposal facility. All wastes shall be disposed in a suitable manner in accordance with applicable federal, state, and local laws.

4.11 Users with a Pretreatment facilities/Grease traps or holding tanks shall establish a system of training designed to provide employees with appropriate instruction on the proper use of such facilities.

A. Such training system shall provide employees at all levels of responsibility with a complete understanding of the following: 1. Importance and methods of good housekeeping practices such as BMPs (Best

Management Practices); 2. Acceptable waste disposal practices including proper disposal of different types of

wastes; 3. Procedures for preventing prohibited discharges; and 4. Proper response to and notifications in case of spills or other accidental discharges.

5.0 Grease Trap Treatment Products

5.01 Use of grease trap treatment products, including bacteria, designed to digest the grease, is specifically prohibited without prior written consent of the Director or authorized agent.

A. Acceptance of such products for use may be considered only where a valid on site screening test, showing the product's ability to treat the waste and to produce an effluent in compliance with this Ordinance, has been performed in accordance with the methods outlined by the Director or authorized agent.

B. The Director or authorized agent may revoke permission to use such products where the effluent from the trap or basin in which the product is used fails to meet the requirements of this Ordinance.

5.02 Use of accepted grease trap treatment products shall not relieve the User of minimum

cleaning requirements set forth in this Ordinance. 5.03 Use of accepted grease trap treatment products may subject the User to monthly

surcharge fees where such usage causes the effluent concentrations to exceed the definition of normal domestic wastewater. Surcharge fees will be levied for biochemical oxygen demand, chemical oxygen demand, and total suspended solids. Back to Table of Contents



6.0 Inspection and Cleaning Schedules

6.01 Inspection, cleaning, and other necessary maintenance of such facilities shall be conducted as often as needed to assure the discharge is in compliance with the provisions of this or other applicable Ordinance, but not less than once per ninety (90) days.

A. The grease trap and the holding tank shall be cleaned as often as necessary, up to and including daily, to assure compliance with this or other applicable Ordinance.

B. In no case shall the accumulated oil or grease be allowed to occupy more than twenty-five percent (25%) total design grease trap capacity.

6.02 The physical condition of the trap shall be inspected by the User each time the facility is cleaned. Repairs, if needed, shall be made prior to further use.

A. Repairs or modifications shall be approved by the City of McAllen Building Inspections Department and the Wastewater Pretreatment Supervisor or authorized agent and shall not be made without the appropriate city permits.

B. Inspection shall be conducted by the City of McAllen Building Inspections Department and or Pretreatment department after repair and prior to refilling or use.

C. Documentation of repairs shall be submitted to the Pretreatment department or authorized agent within thirty (30) days of the date of repair or earlier if specified.

6.03 Grease traps shall produce an effluent in compliance with this Ordinance at the User's pumping schedule. No User shall discharge wastewater containing oil and grease concentration in excess of the discharge limit specified in the City’s Local Limits for industrial waste discharges. Schedules inadequate to produce such effluent shall be upgraded to as often as necessary. Upgraded traps shall meet all requirements set forth in this or other applicable Ordinance.

6.04 A User shall have any trap cleaned when ordered to do so by the Director or authorized agent.

7.0 Cleaning Schedule Extensions

7.01 The User may apply to the Director or authorized agent for an extension of the required cleaning frequency set forth in this Ordinance. A User who wishes to apply for a cleaning schedule extension shall notify the Director or authorized agent, in writing, of the intent to apply for an extension.

7.02 The Director or authorized agent may grant an extension on a required cleaning frequency on a case-by-case basis where the User has demonstrated, with defensible analytical results, the specific trap will produce an effluent in consistent compliance with this Ordinance if such an extension is granted.

7.03 The notification of intent to apply for an extension shall include:

A. Facility information: Back to Table of Contents



1. The name and address of the facility; 2. Name and telephone number of the facility contact; 3. Normal business hours; and 4. The type of business.

B. Treatment unit information: 1. The type of treatment unit and the capacity, in gallons; 2. A brief description of the treatment unit; 3. The time(s) of day the greatest hydraulic and organic loadings to the treatment unit

normally occur; 4. The date of the most recent cleaning and inspection of the unit; 5. A statement of the physical condition of the unit; and 6. Where applicable, the name of any treatment products used and a copy of the

Director or authorized agent approval letter for the use of the product. C. Other information as may be requested by the Director or authorized agent.

7.04 The Director or authorized agent may grant extensions to the cleaning schedule as follows:

7.05 Extensions granted shall begin on the date the samples for which results were submitted were collected as documented on the chain of custody.

7.06 Where an extension has been granted, the unit shall consistently produce an effluent in compliance with the terms of this or other applicable Ordinance. The Director or authorized agent shall reserve the right to collect and analyze samples of any User’s discharge and may revoke, without notice, any extension where the Director or authorized agent believes it is in the best interest of the proper operation of the POTW.

A. Where an extension has been granted and any sample analysis indicates an exceedance of the oil and grease limitation by twenty-five (25%) percent or more, the User shall immediately clean and inspect the trap and shall return to the original cleaning schedule. Where the User has been required to return to an original cleaning frequency, the User shall be required to submit a new request for extension if desired.

B. Where an extension has been granted and any sample analysis indicates an exceedance of the oil and grease limitation by any magnitude but less than 25%, the User shall immediately clean and inspect the trap and shall increase the established cleaning frequency by at least thirty (30) days.

C. Where an extension has been granted and the City must clean associated public sewer lines and the stoppage is traceable to or known or suspected to be caused by the User's facility, the User shall immediately clean and inspect the trap and shall return to the original cleaning schedule. The User will be required to submit a new request for extension if desired. Back to Table of Contents



Cross Connection and Backflow

Prevention

Policy


August 2009 Section 1 – Introduction

1. Purpose

The purpose of this ordinance

1.1 To protect the public potable water supply of the McAllen Public Utility from the possibility of contamination or pollution by isolating within the customer’s internal distribution system(s) or the customer’s private water system(s) such contaminants or pollutant that could backflow into the public water system.

1.2 To promote the elimination or control of existing cross connections, actual or potential, between the customer’s potable water system(s) and non-potable water systems, plumbing fixtures, and industrial piping system

1.3 To provide for the maintenance of a continuing program of cross-connection control that will systematically and effectively prevent the contamination or pollution of all potable water systems.

2. Policy

The desired control is one of containment of the actual or potential hazard within the consumer’s premises. The hazard is to be contained through the use of an air gap separation or in certain instances, backflow prevention assemblies will be installed between the outlet side of the water meter and the first tap or tee. In some situations, backflow protection of the McAllen Public Utility distribution system can be accomplished at the hazard point or through internal containment backflow prevention assemblies as outlined elsewhere in this program.

Section 3 – References

3.1 References

The following references are adopted and made a part of the McAllen Public Utility Cross-Connection Control and Backflow Prevention Program.

3.2 Prohibited connections and/or line taps: It shall be illegal for any person, corporate or otherwise, or any business enterprise, for profit or otherwise, to connect or tap into a city water line prior to having first applied for a water meter from the city’s planning department. This prohibition shall apply with equal force to connection or tapping into fire hydrant plugs, mains, and/or lines. City of McAllen Code of Ordinance Article III section 106-66.



3.3 McAllen Public Utility Procedures for Non-Compliance. It shall be the responsibility of McAllen Public Utility to apply these procedures any time the provisions of this ordinance are violated.

3.4 The 2006 edition (latest edition) of the Standard Plumbing Code of the International Association of Plumbing and Mechanical Officials, Section 608, Protection of Potable Water Supply.

3.5 Occupational Safety & Health Administration - Federal Register, Number 202 - Part 2 -Page 22234 - Subparts J - General Environmental Controls - 1910.141 Sanitation which states that “(b) Water Supply - (2) Non-potable Water (i) there shall be no Cross Connection; open or potential, between system furnishing non-potable water. (iii) Construction of non-potable substance shall be such as to prevent backflow or back siphonage into a potable water system.

3.6 Texas Environmental Commission on Environmental Quality Rule and Regulations for Public Water Supply System, Sec 290.44 (h) Backflow, siphonage. 290.44(h) (1) thru 290.44 (h) (6), 290.47 (i) Appendix I. Assessment of Hazard and Selection of Assemblies

3.7 The University of Southern California Foundation Manual of Cross-Connection Control and Hydraulic Research Ninth Edition (latest edition).

3.8 AWWA Standard C510 and C511, and AWWA manual M14.

Section 4 – Definitions

4.1 City

Is the City of McAllen, Texas, and its Extraterritorial Jurisdiction.

4.2 Board

Is the Board of Trustees of the McAllen Public Utility authority contained in Vernon’s Ann. Civ. St., Art. 1115. The Board is sometimes referred to as Public Utility Board.

4.3 General Manager

Is the General Manager of the McAllen Public Utility, or his/her authorized representative.

4.4 Local Health Officer


Is the City of McAllen Health Director, his/her assistant, authorized deputy, or any other person appointed as Health Director of the City of McAllen.

4.5 Customer Service Inspector

Customer service inspectors who have completed a commission approved course, passed an examination administered by the Texas Commission on Environmental Quality or its designated agent and hold current professional certification or endorsement as a customer service inspector.

4.6 Backflow Technician

Cross Connection and Backflow Prevention Program authorized representative. The Backflow Technician must be a licensed backflow prevention assembly tester.

4.7 Licensed Backflow Prevention Assembly Tester Any person that receives authorization from the Texas Commission on Environmental Quality (TCEQ) by successfully completing a TCEQ approved certification school. Testers, other than the McAllen Public Utility Backflow Technician(s), are not considered to be employees, agents, or representative of McAllen Public Utility.

4.8 Customer

Is any person to whom water is sold or furnished from the McAllen Public Utility water supply (owner or lessee).

4.9 Water Service

Is the complete range of activities of the McAllen Public Utility in combination with total facilities used by the McAllen Public Utility to provide for the delivery of potable water and water for fire protection in adequate quantity and pressure to the premises of a customer.

4.10 Cross Connection

An unprotected actual or potential connection, mechanical or hydraulic union between a public water system and either another supply of unknown or questionable quality, any source which may contain contaminating or polluting substances, or any source of water treated to a lesser degree in the treatment process.

4.11 Interconnection An interconnection is a physical connection between two public water supply systems.


4.12 Private Water Supply

A private supply is any water supply including a well on or available to the premises other than the McAllen Public Utility’s water supply. These auxiliary waters may include water from another purveyor’s public water supply or any natural source such as a well, spring, river, ponds, etc.

4.13 Contamination

The presence of any foreign substance (organic, inorganic, radiological or biological) in water which tends to degrade its quality so as to constitute a hazard or impair the usefulness of the water. As outlined on Texas Commission on Environmental Quality Rules and Regulation for Public Water Systems.

4.14 Backflow

The term “Backflow” shall mean the undesirable reversal of flow of water or mixtures of water and other liquids, gases or other substances into the distribution pipes of the potable supply of water from any source(s).

4.15 Backpressure

The term “Backpressure” shall mean any elevation of pressure in the downstream piping system (by pump, elevation of piping, or steam and/or air pressure) above the supply pressure at the point of consideration which would cause, or tend to cause, a reversal of the normal direction of flow.

4.16 Backsiphonage

The term “Backsiphonage” shall mean a form of backflow due to a reduction in system pressure which causes a subatmospheric pressure to exist at a site in the water system.

4.17 Backflow Prevention Assemblies

Includes the following types of backflow protection: approved air gap separation, approved reduced pressure principle backflow prevention assembly, approved double check valve assembly, approved pressure-type vacuum breaker and atmospheric vacuum breaker.

4.17.1 Approved Air Gap Separation

The unobstructed vertical distance through the free atmosphere between the lowest opening from any pipe or faucet conveying water to a tank, fixture, receptor, sink, or other assembly and the flood level rim of the receptacle. The vertical, physical separation must be at least twice the diameter of the water supply outlet, but never less than 1.0 inch.

4.17.2 Approved Check Valve


The term “approved check valve” shall mean a check valve that is drip-tight in the normal direction of flow when the inlet pressure is at least one (1) psi and the outlet pressure is zero. The check valve shall permit no leakage in a direction reverse to the normal flow. The face of the closure element and valve seat must be of bronze composition or other non-corrodible material which will seat tightly under all prevailing conditions of field use, plastic material will not be accepted. Pins and bushings shall be of bronze or other non-corrodible, non-sticking arterial, machined for easy, dependable operation. The closure element normally referred to as a clapper shall be internally weighted or otherwise internally equipped to promote rapid and positive closure in all sizes where this feature is obtainable.

4.17.3 Approved Reduced Pressure Backflow Prevention Assembly (R/P)

Is an assembly of two independently operating approved check valves with an automatically operating differential relief valve between the two check valves, tightly closing shut-off valves on either side of the check valves, plus four properly located test cocks for the testing of the check and relief valves. The device shall operate to maintain the pressure in the zone between the two check valves at a level two psi less than the pressure on the public water supply side of the device. At cessation of normal flow the pressure between the check valves shall be two psi less than the supply pressure. In case of leakage of either check valve, the differential relief valve shall operate to maintain this reduced pressure by discharging to the atmosphere. When the inlet pressure is two psi or less, the relief valve shall open to the atmosphere. To be approved, the installer must follow all manufactures guidelines, the relief valve must be installed 12” plus the diameter of the supply pipe above ground.

4.17.4 Approved Double Check Valve Assembly (D/C)

Is an assembly composed of two single, independently acting, approved check valves, including tightly closing shut - off valve located at each end of the assembly and fitted with properly located test cocks.

4.17.5 Approved Double Check Detector Assembly (DCDA)

The term “double check-detector backflow prevention assembly” shall mean a specially designed assembly composed of a line-size approved double check valve assembly with a bypass containing a specific water meter and an approved double check valve assembly. The meter shall register accurately for only very low rates of flow up to 3 g.p.m. (gallons per minute) and shall show a registration of all rates of flow. This assembly shall only be used to protect against a non-hazard (i.e. pollutant). All manufactures recommend that a DCDA be used primarily on fire sprinkler systems.

4.17.6 Approved Pressure Type Vacuum Breaker (PVB)

Is an assembly containing a single loaded check valve and an air opening which shall admit air whenever the pressure within the body of the assembly is reduced so that there is a tendency toward backsiphonage. The body of the assembly must be equipped with


two tight closing shutoff valves, one immediately upstream from the body and one immediately downstream of the body, and two properly located test cocks. It is designed to operate under pressure for long periods of time without becoming inoperative, making it possible to isolate a lawn sprinkler line from the potable system. It must be installed such that it could never be subject to backpressure.

4.17.7 Atmospheric Vacuum Breaker

Is a device which prevents back-siphonage by creating an atmospheric vent when there is either a negative pressure or sub-atmospheric pressure in a water system. This is a non-testable device.

4.18 Approved Bypass

Is a connection from the McAllen Public Utility side of an approved device to the customer side of the device for the purpose of diverting the water around the backflow preventer while it is being repaired or replace. Permanent bypasses on backflow prevention devices will themselves include provisions for backflow prevention as described within this program.

Section 5 – Responsibility

5.1 General

The implementation of a program for the effective control of cross connections and backflow prevention requires the full cooperation of all concerned: the state and local health agencies, the water purveyor, the Building Permits & Inspections Department, the licensed backflow prevention assembly tester, and the customer.

5.2 Texas Commission on Environmental Quality

The “Rules & Regulations for Public Water Systems” of the Texas Environmental Quality govern the design, construction, operation and maintenance of Public Water Supplies.

5.3 McAllen Public Utility

To ensure adequate protection in individual cases McAllen Public Utility is required by the Texas Commission on Environmental Quality to determine the degree of health hazard to the public potable water system. When it is determined that a backflow prevention assembly is required for the protection of the public water system, McAllen Public Utility will require the customer, at his expense, to properly install a backflow prevention assembly at each service connection and/or at the hazard point, and to test annually or more often in those instances where successive inspections indicate repeated failure, and to properly repair and maintain said assembly or assemblies.

5.4 McAllen Public Utility General Manager or Assigned Designee


The McAllen Public Utility General Manager or assigned designee will establish a Cross Connection Control and Backflow Prevention Program within McAllen Public Utility and enforce the Cross-Connection Control Regulations in accordance with the guidelines outlined in this ordinance on both new and existing facilities.

5.5 McAllen Public Utility Cross Connection and Backflow Prevention Program

The McAllen Public Utility Cross Connection and Backflow Prevention Program under the direction of the McAllen Public Utility General Manager or assigned designee will be responsible for enforcing the Cross-Connection Control Regulations in accordance with the guidelines outlined in this ordinance on both new and existing facilities.

5.6 Building Permits & Inspections Department

The Plumbing Inspection section of the Building Permits & Inspections Department has the responsibility to assure compliance with all Plumbing Codes pertaining to cross connections, proper installation of the customer’s building plumbing including the connection line to the public potable water supply. It is the responsibility of the Building Permits & Inspections Department to coordinate applicable building permits approvals with Utility Engineer, City Engineer, Fire Chief & Water Purveyor for the total containment.

5.7 Responsibility of Licensed Tester

When directed to test, repair, over haul or maintain backflow prevention assemblies, a licensed backflow prevention assembly tester will have the following responsibilities:

The tester will be responsible for performing accurate field tests and for repairing or overhauling backflow prevention assemblies and making reports of such repair to the consumer and responsible authorities on forms approved by the administrative authority having jurisdiction. The tester shall include the list of materials or replacement parts used. The tester shall be equipped with and be capable of using all the necessary tools, gauges, and other equipment necessary to properly test, repair and maintain backflow prevention assemblies. It will be the tester's responsibility to insure that original manufactured replacement parts are used in the repair of or replacement of parts in a backflow prevention assembly. It will be the tester's further responsibility not to change the design, material or operational characteristics of an assembly during repair or maintenance without prior approval of the approving authority. A licensed tester shall perform the work and be responsible for the accuracy of all tests and reports.

Reports must be submitted to: McAllen Public Utility Att: Backflow Program P.O. Box 220 McAllen, Tx 78505 956-681-1660 [email protected]

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It will be the licensed tester’s responsibility to furnish the serial number of his/her test kit and gauge test certification shall be on record with McAllen Public Utility The gauge must be maintained to a + 2 % accuracy. The tester shall be responsible for the competency and accuracy of all tests and reports prepared by him/her and for the work done by any persons under his/her jurisdiction.

5-8 Customer Responsibility The customer has the primary responsibility of preventing contaminants from entering his potable water system(s) or the public potable water system. The customer’s responsibility starts at the point of delivery from the public potable water system, and includes his/her complete internal water system. The customer, at his own expense, shall install and test upon installation, test annually, and maintain approved backflow prevention assemblies as required by McAllen Public Utility. Following any repair, overhaul, re-piping or relocation of an assembly the customer shall have it tested to insure that it is in good operating condition and will prevent backflow. Tests, maintenance and repairs of backflow prevention assemblies shall be made by a licensed backflow prevention assembly tester. It is the customer’s responsibility to provide the Test and Maintenance Report to McAllen Public Utility upon request. Direct questions to: McAllen Public Utility, Backflow Program at (956) 681-1660 or e-mail: [email protected]

Section 6 – Procedures

6.1 General

The procedure outlined here is based on the aforementioned principle of containment of the potential or actual hazard within the customer’s premises. Proposed deviations or exception may be referred to the McAllen Public Utility General Manager.

6.2 Type of Protection Required

6.2.1 Principle

It is to be recognized that cross connections vary widely in degree of hazard. The degree of protection and the type of protection deemed necessary to prevent backflow and possible contamination of McAllen Public Utility’s system criteria concerning Cross Connection and Backflow Prevention is further outlined in this section. Backflow may occur under many different pressure differentials, varying from so called vacuum to very high pressures. The protection afforded by an assembly depends upon its type and on its proper installation, testing and maintenance.

6.2.2 Air Gap Separation

An air gap installation separating McAllen Public Utility from the customer’s internal water system is acceptable in all situations listed in these procedures so long as it is properly maintained, twice the diameter of the pipe and not less than one inch. Initial

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installations of this type that were originally made in accordance with this program may subsequently change. As these separations are easily eliminated or bypassed, it shall be the prerogative of the Backflow Technician to perform field surveys and to explicitly specify the additional protection of a mechanical assembly. This would result, for example, in the case of a repeated violator of air gap separation standards. The air gap separation must be located as close as practical to the water meter and all the piping between the meter and the receiving tank shall be entirely visible.

6.3 Criteria

The selection of an appropriate backflow prevention assembly depends upon the degree of hazard involved and will be based on the following general criteria:

A: Whether or not the assembly could ever be subject to back pressure due to the customer’s internal pumping pressures or elevation differentials.

B: The nature of the contaminating material under the most critical circumstances.

C: The extent in which additions may be made to the plumbing system at a later date which would affect the initial selection of the assembly.

D: The frequency with which water supply could be exposed to a hazardous condition.

E: The degree of protection of the water supply as provided by the local plumbing code and as enforced by the local Building Permits & Inspections Department.

The McAllen Public Utility General Manager, in cooperation with Building Permits & Inspections Department field representative, shall retain the final decision in individual cases, in accordance with Texas Commission on Environmental Quality Rules and Regulation for Public Water System, Title 30 Texas Administrative Code Chapter 290 Subchapter D and/or the American Water Works Association Manual of Cross Connection Control (Manual M-14).

6.4 Backflow Protection for Fire Lines

As stated on the University of Southern California Foundation Manual of Cross-Connection Control and Hydraulic Research Ninth Edition (latest edition), Section 7.2.3.14 Fire Systems.

6.5 Backflow Prevention Assemblies

Backflow prevention assemblies shall meet the Texas Commission on Environmental Quality Rules and Regulations for Public Water Systems’ standards.

6.6 Procedures on New Facilities

The requirement for installation of a backflow prevention assembly by a new customer of


McAllen Public Utility shall be issued with his request for water service from the McAllen Public Utility or with his application through the Building Permits & Inspections Department for a building permit. In either case, field inspection of the premises and some discussion with the owner or his representative may be necessary to determine what the actual or potential hazards are and therefore what the assembly requirement will be.

6.7 Building Permit

A representative of said department, to assure compliance with the City’s plumbing code, will review all mechanical layouts or building plans submitted to the Building Permits & Inspections Department. The Building Permits & Inspections Department/McAllen Public Utility will stamp all mechanical layouts or plans to indicate backflow and cross connection protection which may be required. For any questions, please contact Building Permits office at (956) 681-1300.

6.8 Customer Service Inspections

In accordance with Texas Commission on Environmental Quality Rules and Regulations a customer service inspection certification shall be completed prior to providing continuous water service to new construction, on any existing service when the water purveyor has reason to believe that cross connections or other unacceptable plumbing practices exist, or after any material improvement correction, or addition to the private plumbing facilities.

Accordingly, should a customer refuse the right of entry of the McAllen Public Utility representative(s) for the purpose of a water used survey or backflow prevention assembly inspection, the McAllen Public Utility must assume maximum hazard and therefore require the highest degree of protection on such customer’s service line.

6.9 Procedures on Existing Facilities

Unprotected cross-connections or improperly installed assemblies are not “grand fathered” in and should be retrofitted to comply with the guidelines outlined in this ordinance.

The following general procedures will be utilized:

6.9.1 Inspection Procedure - Water Use Survey

After a premise inspection by Building Permits & Inspections Department and or a McAllen Public Utility Backflow Technician, a formal written notice advising of the backflow prevention assembly requirements will be issued to the owner or lessee of an establishment or premise.

6.9.2 City of McAllen Building Permits & Inspections Department


Plans submitted to the City of McAllen Building Permits & Inspections Department for approval on plumbing modifications or additions to an existing establishment will be reviewed by the McAllen Building Permits & Inspections Department and/or McAllen Backflow Technician to determine the type of backflow preventer required for the entire establishment. The type of backflow preventer required will be noted on the plans for approval.

6.9.3 McAllen Public Utility General Manager

Any customer request for a change on an existing commercial service or on an existing residential service where the change is due to a lawn sprinkler system installation will be routed to the Building Permits & Inspections Department.

6.9.4 McAllen Public Utility’s Backflow Program

The Building Permits & Inspections Department and/or McAllen Public Backflow Program will review each request for a new commercial service to be placed through an existing service connection to check for compliance with this Cross-Connection and Backflow Prevention Control Program.

6.10 Installation

The backflow prevention assemblies and air gap separations shall be installed in accordance with the Texas Commission on Environmental Quality Rules and Regulations for Public Water Systems’ standards.

6.11 Bypass Policy

If a bypass is installed around the approved backflow prevention assembly, the distribution system must be protected from a backflow through this bypass.

6.12 Random Testing

A McAllen Public Utility Backflow Technician may perform periodic tests on backflow prevention assemblies at random locations to ensure that acceptable test standards are being followed by the Licensed Testers. Additionally, assemblies will be randomly selected and tagged in a manner that will determine if the assembly has been tested as required.

Section 7 - Compliance

7.1 Compliance

A customer shall be in compliance when the customer at his/her own expense installs, operates, tests and maintains approved backflow prevention assemblies as required in this ordinance. McAllen Public Utility will send a notice 30 days before the customer’s backflow assembly(ies) is due for testing.


7.2 McAllen Public Utility Procedures for Non-Compliance

McAllen Public Utility shall deny or discontinue water service to any customer and/or property owner failing to cooperate in the installation, maintenance, testing or inspection of backflow prevention assemblies as required in this ordinance.

(1) When a customer fails to complete required corrective actions or send in the inspection/test report within 30 days and McAllen Public Utility has not approved an extension, McAllen Public Utility will take the following enforcement action:

(a) McAllen Public Utility will send a second notice giving the customer an additional 15 days to comply.

(b) If customer has not complied within 15 days of the due date given in the second notice, McAllen Public Utility will have the backflow tested by a private backflow provider. This service along with all related charges will be paid by McAllen Public Utility and in turn, billed to the customer through the McAllen Public Utility bill.


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APPENDIX VIII – SPECIFICATIONS

DIVISION 2 – SITE WORK 02100 CLEARING 02101 Preparation of Right of Way 02102 Clearing and Grubbing 02238 Concrete Removal 02821 Building Demolition 02200 EARTHWORK 02221 Trench Excavation, Backfill, Compaction 02223 Trench Protection 02224 Pipe Boring Drilling & Jacking 02225 Unclassified Street Excavation 02226 Loading & Hauling 02227 Drilling for Electrical Conduit 02230 Excavation 02234 Borrow 02240 Lime Stabilization 02500 DRAINAGE AND UTILITIES 02556 Water Transmission Lines and/or Pressure Sewer Lines 02558 Water Valves 02570 Sanitary Sewers 02572 Manhole Adjust 02580 Storm Sewer Appurtenances 02585 Irrigation Reinforced Concrete Pipe 02590 Reinforced Concrete Pipe 02595 Concrete Box Culverts and Sewers 02600 PAVING AND SURFACING 02601 Flexible Base 02605 Salvaging and Replacing Existing Base 02610 Prime Coat 02612 HMAC Pavement 02616 Asphalt Recycling 02617 Asphalt Surface Treatment 02620 Concrete Curb and Gutter 02670 Milling 02680 Flat Wheel Rolling 02682 Pneumatic Tire Rolling

02700 SITE IMPROVEMENTS 02712 Wire Fences 02720 Chain Link Fences 03300 CONCRETE 03300 Cast-in-Place Concrete 03310 Supplied Concrete 09100 MISCELLANEOUS 09101 Construction Traffic Control 09102 Filter Fabric

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02686 Proof Rolling

CITY OF McALLEN

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