CITY OF ANAHEIM
DEPARTMENT OF PUBLIC WORKS
SUBDIVISION SECTION

SEWER DESIGN MANUAL

TABLE OF CONTENTS

   

1.

ALIGNMENT

2.

GRADE

3.

SIZING

 

DESIGN FLOW

 

ROUGHNESS COEFFICIENT

 

VELOCITY

 

MAXIMUM DEPTH OF FLOW

 

LATERAL SIZE

4.

MATERIALS

5.

BEDDING

6.

MANHOLES

7.

EASEMENTS

 

PRIVATE SEWER

Sanitary sewers are designed primarily to carry to a satisfactory point of treatment and ultimate disposal the spent water supply of a community, industrial wastes and unavoidable amounts of ground water infiltration. All waters not containing impurities which are actually or potentially objectionable should be excluded as far as possible from the sanitary sewer system. The flow rates of sewage for which sewer capacity should be provided must be determined from careful considerations of the present and probable future quantities of domestic sewage and commercial and industrial wastes.

1. ALIGNMENT

Sewer shall be located in the street, not in the parkway. sewer trench shall not extend under edge of gutter.

A minimum radius of 150' shall be used for any horizontal bend. Maximum deflection at any joint shall not exceed two (2) degrees.

Connection:
4" to main line (8" or larger): saddle
6" to main line (8" or larger): snap-in wye
8" to main line (8" or larger): manhole

When jacking is required, details to be shown on plans. 18" minimum diameter C.I.P. with 3/8" wall thickness required for 8" V.C.P. Jacking may be required by the City Engineer when crossing arterial highways.

Minimum horizontal spacing between sewer line and water line is 11'.

Provide lateral for each lot per Standard Detail No's. 222 and 223.

2. GRADE

Sewer shall be normally 7' to 8' deep (to soffit of pipe). Mainline minimum depth at manhole shall be 5.67 ft (5'- 8").

Minimum slope:
D = 8" s = 0.0036
D = 10" s = 0.0030
D = 12" s = 0.0024
D = 15" s = 0.0020
Indicate slope in terms of s = 0.002, not s = 0.2%.

Avoid vertical curves. Straight grade from manhole to manhole. Use of vertical curve to be approved by the Development Services Manager.

Elevation drop thru manhole:
Straight thru: no change in pipe size,
Match soffit: right angle turns and no change in pipe size,
0.10' drop: right angle turns and no change in pipe size,
0.20' drop: right angle turns and change in pipe size.

Avoid drop manholes. Use of drop manholes to be approved by the Development Services Manager.

Encasement is required when clearance between pipe is less than 18" and where required separation with water line can not be maintained per Standard Detail W-130.

Encasement sewer line per Standard Detail No. 225 and when:

Top of bell of sewer is less than 3' from bottom of water line,
Storm drain is within 1.5' (18") above sewer line,
Sewer line is above water line.


Slope anchors and backfill stabilizers are required where pipe slope exceeds 30%. Slope anchors shall be placed at 7' vertical interval per Standard Detail No.  
225.

3. SIZING

Since the quantity of domestic sewage is a function of the population and of water consumption, lateral and submain sewers should be designed for the saturation density of population expected in the areas served. The sewer system should be designed for tributary areas, land use and population estimated to prevail at least 25 to 50 years in the future.

All sewers shall be designed based on the peak flow rate and the following criteria.

A minimum pipe size of 8" shall be used for all public sewers and private sewers within street.

Design flows:

The average daily flow of sewage and ground water is the average 24 hour discharge during a period of a year. The peak flow determines the hydraulic capacity of sewers.

Single family residential:
Average flow: 110 gpcd (gallons per capita per day)
Per capita factor: 3.8 people per household
Peak factor: 2.0

Multiple family:
Average flow: 110 gpcd
Per capita factor: 2.8 people per household for condominiums
2.2 people per household for apartments Maximum for two stories with 900 sf/unit and 50% lot coverage.

Peak factor: 2.0

Commercial:
Zone CL- Limited (shops) : 100g/1,000sf/day
Zone CR- Recreation (hotels): 150g/unit/day
Zone CO- Office : 200g/1,000sf/day Zone
CH- Heavy (Restaurant) : 50g/seat with one seat per 5sf Zone
CG- General : 100g/1,000sf/day

Lot coverage varies from 40 to 70% depending upon location.

Peak factor: 2.0

Industrial:
Zone ML and MH: 3,880g/acre/day
Peak factor: 2.0

Roughness coefficient (n):

R.C.P., A.C.P., V.C.P., A.B.S., D.I.P. 0.013
P.V.C. 0.010

Velocity (Average flow):

Minimum 2 fps
Maximum 10 fps

Maximum depth of flow:

From 8" to 12" 1/2 D
15" and larger 3/4 D

Lateral sizes:

Minimum lateral pipe size is 4".

4. MATERIALS

Main line sewer pipe shall be V.C.P.

Sewer pipe under median to be D.I.P. epoxy lined, polylined D.I.P. or V.C.P. encased.

A.B.S. and PVC solid wall pipe and A.B.S. composite pipe may be used as an alternate to V.C.P. as approved by the City Engineer. Use shall be limited to local interior streets and private streets tributary to residential flows only. Sizes shall not exceed 10" in diameter. Pipe characteristics and installation shall be per the Standard Specifications for Public Works Construction
.

V.C.P. joints shall be mechanical compression or Bandseal type.

 5. BEDDING

V.C.P. And D.I.P. - Use City Standard Detail No. 319 for cover between 3' and 15', for cover less than 3' and greater than 15' special bedding is required. Calculations and supporting soils reports to be provided by the Design Engineer. Use a soil weight of 130 lbs/cf (unless soils reports state otherwise) and a safety factor of 1.5. Details of bedding shall be shown on plan.

A.B.S. And PVC - Bedding detail(s) to be shown on plan. Supporting calculations are required.

6. MANHOLES

Manholes to be constructed at intersecting mains, B.C., E.C., angle points and change in pipe size or grade. Only one manhole at BC or EC is acceptable if a short length curve with central angle less than 45 degrees (Maximum length is ).

Maximum manhole spacing is 300'.

When necessary to construct sewer line at depth of less than 4.5', use 5' diameter manhole with 3' diameter manhole cover A.F.C. A- 1251.

Manhole shall be constructed at the end of construction with 4' stub out for future connection. Stub shall be plugged with brick and mortar.

In unpaved areas where there is a danger of the manhole becoming lost, set the top of cover elevation so as not to be less than 1' above existing ground.

7. EASEMENTS

When sewer can not be located within the street, it shall be located in an approved easement.

Easements parallel to lot line shall be on one lot only.

Sewer easement shall be a minimum 15 ft. in width. For deep pipe the easement shall be 2 x depth - O.D. to a maximum 25 ft.

Easement parallel to lot line shall be on one lot only.

Access for maintenance to be 12' wide and must be paved with 0.25' of A.C. over 0.35' of B.M.. Location of access to be approved by the Maintenance Department.

Easement for public sewers shall be dedicated to the City on a recorded map or by a separate deed with the approved easement sketch and the legal description (including closure calculations).

PRIVATE SEWER

Sewers may be drawn in plan view only, however they must show rates of grade, direction of flow, size of pipe, invert and finish surface elevations at cleanouts, manholes and grade breaks, location and elevation of all adjacent or crossing underground facilities, sufficient horizontal controls to permit the system to be located in the field, and any other information which may be required to adequately check, construct and inspect the system.

A. The size of all sewers shall be designed based on the following desirable engineering
    considerations, peak rate of flow with a minimum velocity of 2 fps, a minimum depth of flow
    of 1 inch and a maximum ratio of depth of flow to the diameter of pipe of 0.75. In addition,
    the minimum sizes shall be used:

a. Residential development: 6" min.

b. Industrial development : 4" min.

c. Laterals:

4" min. when serving 1 thru 6 living units in a single building,
6" min. when serving more than 6 living units in a single building or more than one (1) building.

B. Cleanouts may be provided in lieu of manholes at a maximum spacing of 100 feet.
    They shall also be provided at vertical grade break of more than one-half percent (
0.5%)
    or for horizontal deflection angle of more than forty five (45) degrees. All cleanouts shall
    be brought to finished grade.

Standard manholes may be required when deemed necessary by the City Engineer.

C. Add note to each sheet:

           APPROVED ONLY FOR INSPECTION OF WORKMANSHIP AND MATERIALS

            ON PRIVATE PROPERTY


D. Private sewers designed to meet the Plumbing Code may be reviewed and inspected
    by the Building Division. These plans will not be reviewed by the Engineering Department,
    but must meet all requirements of the Uniform Plumbing Code and the Building Division.