HomeMy WebLinkAbout06.a. 2013 Collection System Sanitary Sewer Overflow Annual ReportCentral Contra Costa Sanitary District
' 6.a.
BOARD OF DIRECTORS
POSITION PAPER
Board Meeting Date: April 3, 2014
Subject. BOARD ACCEPTANCE OF 2013 COLLECTION SYSTEM SANITARY
SEWER OVERFLOW ANNUAL REPORT
Submitted By.
Paul A. Seitz, Collection System
Operations Division Manager
Initiating Dept /Div.:
Collection System Operations
Department / Field Operations
REVIEWED AND RECOMMENDED FOR BOARD ACTION:
P. Seitz - CSO Division Manager
R. Bailey
General Manager
ISSUE: The Central Contra Costa Sanitary District's (District) Sanitary Sewer Overflow
(SSO) Annual Report has been prepared and presented for the District Board of
Directors' information and acceptance.
RECOMMENDATION: Accept the 2013 Collection System SSO Annual Report.
FINANCIAL IMPACTS: None related to this action.
ALTERNATIVES /CONSIDERATIONS: Not applicable.
BACKGROUND: The 2013 Collection System SSO Annual Report summarizes the
overflows that occurred in the District's sanitary sewer system during the period of
January 1, 2013, through December 31, 2013. This is the eighth SSO Annual Report;
however, it is not required to be submitted pursuant to the RWQCB's revised
requirements. The report summarizes SSOs by the number and size, the volume, the
causes, the locations, and the trends. The collection system experienced 48 overflows
last year.
RECOMMENDED BOARD ACTION: Accept the 2013 Sewer System Overflow Annual
Report.
CSO /C:\ Users \danderson\AppData \Local \Microsoft \Windows \Temporary Internet
Files \Content.Outlook \DVCG8C5G \SSO Annual Rpt- 2013.doc
ANNUAL REPORT OF SANITARY SEWER OVERFLOWS FOR
CALENDAR YEAR 2013
The 2013 Collection System SSO Annual report summarizes the overflows that
occurred in the District's sanitary sewer system during the period of January 1, 2013,
through December 31, 2013.
Number and Size of SSOs
The total number of SSOs for the reporting period was 48. All of the SSOs were
associated with gravity sewers. No overflows were experienced as a result of
surcharging in wet weather conditions. The volumes of the SSOs are summarized as
shown on Table 1.
Table 1. Number of SSOs
Size of SSO (gallons)
Number
Percent of Total by Number
Greater than or equal to 1,000
2
4%
Between 100 and 999
18
38%
Between 10 and 99
22
46%
Less than 10
6
12%
Public portion of lateral
N/A
—
Total
48
100%
The volume of spills contained and returned to the sewer system, as well as the volume
reaching the waters of the State, is shown in Table 2.
Table 2. Volume of SSOs
This report does not include SSOs that occurred from private sewer service laterals that
were caused by conditions in privately owned laterals. The property owners are
responsible for the condition and operation of their sewer service laterals.
Volume (gallons)
Percent of Total by
Volume
Total volume reaching waters
210
0.4%
of the State
Total volume not recovered but
not reaching waters of the
2,202
4.5%
State
Total volume contained and
returned to sewer system for
46,404
95.1%
treatment
Total
48,816
100%
This report does not include SSOs that occurred from private sewer service laterals that
were caused by conditions in privately owned laterals. The property owners are
responsible for the condition and operation of their sewer service laterals.
Cause of SSOs
The predominant cause of SSOs during the period of this report was roots. The
distribution of SSOs by cause is shown on Table 3.
Table 3. Causes of SSOs
Cause of SSO
Number
Percent of Total
Blockage:
Roots
35
73%
Grease
1
2%
Debris (rags, rock, paper)
4
8%
Vandalism
1
2%
Construction debris
—
—
Contractor error
7
15%
Multiple causes
—
—
Subtotal for blockages
48
100%
Infrastructure failure
—
—
Inflow and infiltration
—
—
Flow capacity deficiency
—
—
Cause unknown
—
—
Total
48
100%
Location of SSOs
The District's Engineering department is currently working on multi - phased rehabilitation
projects in the District's service area. The Collection System Operations department is
continuing its "quality cleaning" program as well.
There was one repeat overflow in 2013.
SSO Trends
The following graph shows a comparison of data for the current reporting period, 2013,
with previous reporting periods from years 2010 through 2013.
Figure 1. Total SSOs 2010 — 2013
Updated through January 2013
Year: 2010 2011 2012 2013
Total SSOs by year: 1 431 371 491 48
JAN
5
7
6
2
FEB
6
7
3
4
MAR
3
0
3
3
APR
5
1
3
3
MAY
2
1
2
3
JUN
4
3
2
4
JUL
1
4
3
4
AUG
2
3
5
4
SEP
2
3
0
3
OCT
3
2
6
5
NOV
5
3
4
7
DEC
5
3
12
6
100
90
80
70
60
50
40
30
20
10
0
Comparison of Cumulative Overflows
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