City of Morgan Hill Sewer System Master Plan 2017

August 2017

7-4

City of Morgan Hill

Sewer System Master Plan

that, while not deficient, may be approaching full capacity. Deficient pipelines are highlighted in

red on the figure and discussed as follows:

Vineyard Boulevard from La Cross Drive to Monterey Road. This segment experiences

d/D ratios above 0.9.

Hale Avenue from Longview Drive to Main Avenue. This segment experiences d/D ratios

under 0.5 excepting one portion experiencing a d/D ratio above 0.9.

7.2.2

Existing Peak Wet Weather Flows Capacity Evaluation

The wet weather flow analysis is intended to document the impact of rainfall events on the existing

system, and to identify the improvements necessary to limit sanitary sewer overflows. The design

criteria for wet weather events allows pipeline surcharging in the manhole to within three feet of

the rim elevation. The hydraulic analysis indicates two areas of deficiencies, as shown on

Figure

7.2

, and documented in the following:

Monterey Road from Main Avenue to approximately Cosmo Avenue. This segment

experiences surcharging conditions where the hydraulic grade line raises within 3 feet of

the rim elevation.

La Cross Drive from La Grande Drive to Monterey Road. This segment experiences

surcharging conditions within 3 feet of the rim elevation until it reaches Vineyard

Boulevard. From Vineyard Boulevard, the segment of pipeline experiences d/D ratios

above 0.9.

7.3 ULTIMATE BUILDOUT CAPACITY IMPROVEMENTS

The system performance and design criteria summarized on

Table 3.1

, was used as a basis to

evaluate the capacity adequacy of the existing sanitary sewer system. The design flows

simulated in the hydraulic model for the General Plan buildout were summarized on

Table 5.4

and

are documented as follows:

Buildout PDWF = 8.0 mgd

Buildout PWWF = 10.5 mgd

Sewer pipelines are recommended to serve future growth inside the City and increase

the reliability of the sewer collection system as well. The proposed capacity

improvements for the sanitary sewer system are listed on

Table 7.1

. This table lists the

master plan assigned improvement number (e.g,HM-P1), along with other relevant

information including alignment description, pipe size, and pipe length. The improvement

number is further defined in the Capital Improvement Program chapter (Chapter 8). The

improvements are described in detail on the following pages and shown on

Figure 7.3