Environmental Services is working throughout Portland to repair or replace sections of sewer pipes that are deteriorating or at risk of failure.
Before the actual sewer pipe repair work begins, crews will be in the neighborhood completing various tasks to set up the work zones and prepare for major construction.
Pre-construction activities typically occur over time rather than all at once. These activities may include some or all of the activities listed below.
Site Visits and Evaluation
During the project design process, various project team members will be in the neighborhood collecting information that will help them develop a successful project. You may see engineers inspecting manholes and sewer pipes, survey crews taking various measurements, utility locate crews marking underground utilities, community outreach staff talking to residents and businesses, and other field crews conducting important investigations.
To plan for sewer and stormwater improvements, it is necessary for survey crews to collect information about a proposed construction area. Survey crews take a variety of measurements to determine public right-of-way boundaries, private property lines, public sewer easement boundaries, the presence of utility vaults and other landmarks, and other necessary measurements.
You may see survey crews standing on sidewalks and streets in front of properties in the neighborhood to measure the elevations of the first floors of houses or buildings and see if they have basements. This is necessary to obtain measurements of private sewer depths and will help engineers design a sewer system that will maximize gravity service.
To plan for sewer and stormwater improvements, it is important to know what utilities are underground. To avoid damaging those utilities during construction, it is necessary to locate and mark where they are.
Crews paint markings on the street in different colors. They may also place small flags in the ground, or wooden stakes with ribbons, to indicate the presence of underground utilities.
Each color has meaning and indicates what utility is present:
- White—proposed excavation.
- Pink—temporary survey markings.
- Red—electric power lines, cables, conduit, and lighting cables.
- Yellow—gas, oil, steam, petroleum, or gaseous materials.
- Orange—communication, alarm, or signal lines, cables, or conduit.
- Blue—potable (drinking) water.
- Purple—reclaimed water, irrigation, and slurry lines.
- Green—sewer and drain lines.
When a public utility is in close proximity to a sewer pipe, stormwater pipe, or other critical structure, it may be necessary to dig a hole in the street or ground to locate the utility precisely. This activity is called "potholing." When potholing is complete, crews fill the holes and apply an asphalt patch.
Soil Sampling and Geotechnical Investigations
To plan for sewer and stormwater improvements, it is important to know the conditions that engineers and construction crews will encounter underground—the soil types, soil conditions, water levels, rocks, pavement layers, and whether any contaminated soils are present. This information will help engineers determine the appropriate methods to use in constructing the sewer and stormwater improvements.
Before crews can obtain the samples, they must first locate and mark underground utilities to identify safe drilling locations. To obtain the soil, rock, water, and pavement samples, crews dig small holes in street pavement and collect the samples. When soil sampling is complete, crews fill the holes.
Pipe Cleaning and Inspection
Cleaning and inspecting sewer pipes are essential to maintaining the public sewer system and planning improvements.
To clean sewer pipes of debris, crews flush them with water. It may also be necessary to cut tree roots that are intruding into the sewer pipes. Cleaned pipes are then ready for inspection.
To inspect the pipes, crews insert a closed-circuit television video (CCTV) camera into a pipe from a manhole or a sewer cleanout. Video inspection will determine the condition of the pipe and locate where adjacent properties are connected to the public sewer.
Pre-Existing Conditions Photos
Before construction begins, site inspectors will take extensive photos of the work area to document pre-existing conditions. They will take photos of streets, curbs, sidewalks, driveway aprons, and other features of the public right-of-way and private properties that may be affected by construction.
This photographic documentation may be used to determine whether reported damages were present before construction began or occurred during construction.
Tree Trimming and Protection
To protect trees from damage by large construction equipment, it is necessary to trim tree branches at appropriate clearance levels from the street and curb where construction will occur. A general rule is 15 feet at each curbside and 20 feet in the center of the street. Typically, branches hanging over the sidewalk will not be trimmed.
During the design of a sewer or stormwater project, a certified arborist will tour the project area to determine where trees will need to be trimmed before construction can occur on that street. All tree trimming work will be supervised by a certified arborist and will be done at the city's expense.
Before construction begins on a street, crews will install tree protective fencing where necessary to protect tree trunks, roots, and branches from damage. The orange fencing will remain in place until construction is completed.
Erosion control is important to prevent soil, sediment, and cement from entering the sewer and stormwater drainage systems and our rivers and streams. Erosion control helps prevent sewer blockages, basement sewer backups, damage to properties, and loss of wildlife habitat.
Before construction begins and throughout the project, crews will install various measures to prevent erosion of soil, sediment, and cement. These measures include installing filtration bags inside storm drains and placing bags of wood chips outside storm drains within the project area. Crews may also install fencing to contain sediment and debris on the work site.
Prior to beginning the work to install sewer and stormwater improvements on your street, crews will establish a safe work zone for construction. These activities include the following:
- Set up staging area for equipment and materials, which may be stored on nearby streets overnight.
- Install temporary traffic control signs according to approved traffic control plans.
- Install temporary on-street parking removal areas to create a safe work zone.
- Post signs and fliers to notify properties of upcoming construction.
These activities are indicators that construction will begin soon.