The City of Bellingham drainage system is comprised of natural and man-made conveyance and detention systems. Natural conveyance systems are creeks and lakes that receive and channel runoff from rain and other sources to minimize the impacts of the runoff. Man-made conveyance systems consist of a network of open ditches, catchbasins, closed pipes, manholes, water quality and water detention facilities such as ponds, vaults, storm filters, bioswales, etc. These two systems work in concert to control the amount and improve the quality of runoff before it is discharged into major streams, lakes and Bellingham Bay. The system is maintained by the Stormwater Division of Public Works. Work performed on the drainage system generally falls into one of nine categories described below.
Open ditches are inspected each year to ensure that proper flow is maintained. If an inspection identifies a need for maintenance, City crews will schedule time to do the maintenance. This work is scheduled throughout the year as time permits.
Best management practices dictate pumping every catch basin and manhole once each year. To accomplish this, Public Works uses a vactor truck and crew to remove sediment and debris from the system. Material removed from catch basins and manholes is considered a low to moderate risk waste and is disposed of accordingly.
This
is again accomplished using the vactor truck and crew. The task involves
running high pressure water through the storm main lines to remove any
accumulated material. This material is then removed from the system when the
catch basins and manholes are pumped.
Trash
racks are devices that are installed at the entrance to large storm lines to
intercept and trap any trash or organic debris before it enters the enclosed
pipe system. Trash racks are patrolled according to a set schedule as well as
during and after storms. Storm patrol also includes cleaning debris from the
grates on catch basins to ensure that water can freely enter the storm system.
These two activities combine to create an effective means of controlling
overflows and flooding within the system.
Periodically the enclosed storm drainage system fails. These failures are caused by settling trenches, crushed mainlines, failing joints between pipe segments, root invasion and incorrect structures, such as old water tanks, that have been installed as culverts. Minor and emergency repairs are typically made by City crews, while major new construction repairs or replacements are done by private contractors working on behalf of the City.
There
are 4 main streams running through Bellingham; Chuckanut Creek, Padden
Creek, Whatcom Creek and Squalicum Creek. Each creek has smaller streams
(tributaries) draining into it. Maintenance consists of removing debris from
culverts that enable the creek to run under the roadway. Examples of debris
include log jams, beaver dams and buildup of sediment and gravel due to
erosion. If debris is excessive, presenting a flooding hazard to neighboring
areas, City crews may perform creek or channel dredging on a case-by-case
basis. Dredging and other in-stream work must be closely coordinated with
the Department of Ecology, Fish and Wildlife, and other associated local,
state, and federal agencies and is performed by Public Works crews on an
infrequent basis and only with close coordination with these agencies.
Regional detention facilities, and the associated flow control structures, are inspected and maintained yearly. This involves filling in low areas on dams and berms, filling and compacting rodent holes, removing vegetation that has grown within the facility and general inspection of the outfall and associated structures for defects. Over time, sediment can also build-up within detention facilities. City Crews identify affected facilities through the annual inspection process and generate work orders to schedule sediment removal on an as-needed basis.
Water
quality facilities include detention ponds, storm filters, detention pipes
and vaults, bioswales and various types of sand or gravel filters. Ponds and
bioswales require annual vegetation maintenance and inspections similar to
regional detention facilities. Detention vaults and fat pipes are inspected
for sediment accumulation and require periodic cleaning using the vactor
truck. Storm filters require frequent cleaning to remove accumulated
sediment and are inspected to monitor their effectiveness and life span.
Filter replacements are done annually.
Large scale improvements are also done to improve drainage. These improvements are done by private contractors under contracts with the City, with oversight by Public Works Engineering.
Questions or problems with the drainage system should be reported to the Public Works Operations Division.
