Milpitas Municipal Code Art. XI Design Standards

The Standards specified in this section are hereby established as Sanitary Sewer Design Standards for the City. All sewer lines constructed by the City or for dedication to the City shall be designed in accordance with said standards.

(Ord. 208 (part), 6/17/80)

Section 11.02

Said Design Standards are hereby established as follows:

Service capacity of sewer lines and sewer use dependent upon line capacity to sewer will be based on the following criteria:

A. GENERAL DESIGN CRITERIA

1. Vitrified Clay pipe or Acrylonitrile- Butadiene-Styrene pipe

2. Co-efficient of friction "n" = 0.013

3. Minimum velocity = 2 feet per second

4. Maximum velocity = 8 feet per second

B. COLLECTION SYSTEM CAPACITY REQUIRED (Q)

Q = Peak Factor (PF) × Average Daily Flow (SF) + I/I (see Fig. 11.02 for each basin).

Peak Factor: PF = 0.96 × (SF raised to the power of -.21) (SF = Average Daily Flow in MGD) PF shall not be less than 1.6 in any event Average Day Flow Generation Factors: Residential: 75 gpd Per Capita Then multiply by household size for each unit Single Family—3.5 Multiple Family—3.0 Mobile Home—1.6 e.g. 225 gpd per Multiple Family Unit Commercial: 2500 gpd Per Net Acre Industrial: 6000 gpd Per Net Acre

C. CONSTRUCTION STANDARDS

Maximum Distance between manholes: 500 feet

Minimum Cover over pipe: 5 feet.

Design for grid system layout—Cross connect between lines. When not possible, install flushing inlets at dead ends.

Allow a drop around 90° bends in manholes of .2 foot.

All materials to be in accordance with standards and specifications of City.

All construction to be in accordance with standards and specifications of City.

D. All trunk sewers must contain capacity for immediate service area including service area upstream.

Sewer use districts (in acres) shall be determined by dividing pipe capacity in CFS (using given factors) by peak flow factors (using given factors).

(Ord. 208.18, 5/20/86)

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