City of Morgan Hill Sewer System Master Plan 2017

City of Morgan Hill Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study

Basin Inflow and Infiltration Analysis Results Due to potential cross-connections between basins, the I/I results for Basins 7 and 8 are shown together, labelled “Basin 7/8”. The individual results for Basin 7 and 8 are presented as sub-headers and for informational purposes only to be used at the reader’s discretion. Table 2 summarizes the flow monitoring and I/I results for the nine flow monitoring basins that were isolated during this study. Infiltration and inflow rankings are shown such that 1 represents the highest infiltration or inflow contribution and 9 represents the least. Basins that ranked 1, 2 or 3 in a category are color coded red. Please refer to the I/I Methods section for more information on inflow and infiltration analysis methods and ranking methods.

Table 2. I/I Analysis Summary

Peak I/I Rate (mgd)

Evidence of High GWI?

Combined I/I Ranking

Metering Basin

ADWF (mgd)

Combined I/I (gallons)

Inflow Ranking

RDI Ranking

Basin 1 Basin 2 Basin 3 Basin 4 Basin 5 Basin 6

0.19 0.17 0.18 0.21 0.27 0.35 0.40

0.23 0.13 0.46 0.41 0.18 0.57 0.67

56,400 47,200 166,200 114,100 90,900 136,300 230,300 177,700

7 9 1 2 6 5 3

4

No No No No No No No No No No

7 8 1 4 5 6 2

T7

3 5 2

T7 T7

Yes

Basin 7/8

Basin 7 Basin 8

0.24 0.16

0.57 0.21

52,000

Basin 9 Basin 10 System

0.13 0.12 2.65

0.34 0.11 2.97

133,300 16,400

4 8

1 6

3 9

1,135,500

The following inflow/infiltration analysis results are noted:  Inflow: Basins 3, 4, 7/8 and 9 ranked highest for normalized inflow contribution. ♦ If isolated, Basin 7 ranks highly within the Basin 7/8 basin and highly within the collection system.  Rainfall-Dependent Infiltration: Basins 3, 5 and 9 ranked highest for normalized RDI contribution.  Groundwater Infiltration: Basin 6 had GWI rates that were above the WEF typical low-to- average ratio, indicating excessive groundwater infiltration.  Combined I/I: Basins 3, 7/8, 9 and 4 ranked highest for normalized combined I/I contribution. ♦ If isolated, Basin 7 ranks highly within the Basin 7/8 basin and highly within the collection system.

12-0248 AEG CofMorganHill FM Rpt.docx

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