October Storm Flows City of Worcester DPW & Parks
Department, Sewer Operations Division January 26,2006 Slide 2
Today's Discussion We are going to talk about Worcester Sewer
System, and how it is interconnected to our local waterways. We
will review some of the cities large scale Flood Control systems
What DPW does to control street and limit flooding We will talk
about the heavy October Rains and some of Worcesters geographic
characteristics What effect did the storm have on Worcester Slide 3
Basic Statistics on Worcesters System 371 miles of sanitary sewer
340 miles of surface sewers 56 miles of combined sewers 27,000
manholes 15,000 + catch basins 329 outfalls 93 major outfalls 31
pump stations Slide 4 Interceptor Sewers City of Worcester
-Topographic Layout of the City -Interceptor Sewers Shown In Red
Slide 5 Worcester, Interconnected Waterways; Culverted Waterways on
this map were constructed for Flood Control, Development, and the
overall protection of the city. Culverting of waterways and related
improvements go back over 80 years. The waterways include; Beaver
Brook, Mill Brook Fitzgerald Brook and Kettle Brook Tributaries.
Slide 6 Worcester, Large Scale Flood Control; The first major flood
control construction was the Beaver Brook Channel around 1914,
followed ditching culverting streams in Tatnuck Brook, Broad Meadow
Brook, Fitzgerald Brook, Kettle Brook, and Coal Mine Brook in the
1930s. Beaver Brook was also culverted extensively through the
1940s. Slide 7 Combined Sewer Area City of Worcester -Topographic
Layout of the City -Combined Sewer Area Shaded Slide 8 Worcester
Combined Sewer System Slide 9 Major Flood Control Projects The
Worcester Diversion,1955 effectively shuts off Kettle Brook form
entering the city through a 16 foot diameter tunnel that runs under
Pakachoag Hill in Auburn Massachusetts. The Chandler Hill Flood
Control Project, 1955, which takes flows from East Park and
includes a 96 inch pipe which runs down most of Shrewsbury Street
to carry flood waters. Slide 10 Major Flood Control Projects
(continued) Through the mid to late sixties three ponds were
eliminated in the West Boylston Street, Gold Star Blvd. Area. Twin
Box Culverts eleven by seven feet were installed to carry flows
from the Weasel Brook area and Indian Lake to Salisbury Pond.
Around this time the Ararat Brook Flood Control project was also
complete north of Indian Lake Slide 11 Major Flood Control Projects
(continued) Through the seventies and eighties storm flows were
removed from the old Mill Brook Conduit, which is basically the
covered over Blackstone Canal, by constructing a series of large
concrete culverts that take flows from Salisbury Pond to the
Blackstone River. There are now two underground rivers running
through the center of the city, one for storm flows and one
combined sewer flows. Slide 12 Major Flood Control Projects
(continued) There are many more major drainage programs that have
been completed to mitigate localized flooding. Most recently the
Mill Brook sewer was extended to outfall further down stream to
reduce flooding in the Green Island Area. Slide 13 Storm Drain
System Maintenance We clean all city catch basins over a two year
period, but if a basin is not working we will make every effort to
get that basin to work. We clean flush and TV inspect many portions
of the stormwater system daily. We sweep streets to keep sand,
leaves and debris from blocking city storm drains. Slide 14 Storm
Drain System Maintenance (continued) The Storm drainage systems in
the city are monitored in dry and wet weather hoping to find
problems before they happen. We have over 50 choke points or stream
crossings that we check bi-monthly in dry and wet weather in hopes
of limiting the chances of flooding. Slide 15 The October Storm
Nine days of rain Slide 16 The October Storm Over 12 inches of rain
Slide 17 DPW Received Over 200 Complaints 17 % were street flooding
11 % were blown off or missing man hole covers 36 % were sewer
backing up into house 36 % were water backing up into cellar We
estimate there were many more problem areas that simply were not
reported. Slide 18 Inflow & Infiltration II The nine days of
rain coupled with the heavy rain, of October 15,2005 caused extreme
snow melt like conditions in the sanitary sewer system. High ground
water conditions surcharged the soil and consequentially the sewer
system. The rain and ground water conditions filled the sewer
system with excess ground water, just like a leaky basement. Slide
19 Inflow & Infiltration II (continued) The excess storm flow
that entered the sanitary sewer system, blew off manhole covers,
backed up into peoples homes, caused sanitary sewer overflows
(SSOs), and Pump Stations to by-pass. Slide 20 Where are we headed
Continuing the I/I program development and implementation.
Development of the cities backflow prevention program. Continue the
cities storm drain system maintenance Slide 21 Slide 22 Slide 23
Questions
