Clearing Blocked Internal Storm Drains
- Procedure code:
- Thermal and Moisture Protection
- Iron Roof Drain
- Last Modified:
A. This procedure includes guidance on inspecting for and clearing out blocked internal storm drains. Prevention
of potentially blocking debris from entering the drains
via the roof is an important factor in preventing blocked
drains. See 3.01 A.1. and A.2. below for preventive
B. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
- Safety Precautions
- Historic Structures Precautions
- Quality Assurance
- Delivery, Storage and Handling
- Project/Site Conditions
- Sequencing and Scheduling
- General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
A. Diagnostic Equipment: High performance durable
camera/transmitter system equipped with small black and
white camera head and pipe location transmitter; able to
negotiate multiple 90 degree bends in 2" to 10", such as
“SeeSnake Diagnostic Tools” (RIDGID), or
Note: Complete system includes camera, push cable, 3" &
6" centering guides, cable drum and dolly, interconnect
cable, 9" high resolution B&W monitor with integrated
power supply, light dimmer and sunshade, operator’s
manual, RCA to RCA video cable, BNC to RCA adapter.
B. Drain cleaning equipment such as an auger and/or saw
tooth cutter (Ridgid), or approved equal, as
required for the specific blockage type.
A. Examine the foundation and exterior of the building by
walking around the building during a heavy rain storm.
Look for blocked or broken storm drains, leaking or
overflowing gutters or perforated downspouts. Notice
where water is ponding on the ground around the building.
- Clean gutters and downspouts twice a year—in late
spring and in late fall.
- Provide screen barriers at gutter outlets to
prevent debris from entering into the downspout and
storm drain system.
- Examine interior walls where internal roof drains run
vertically, to identify staining, failed paint, failed
plaster or other signs of water damage near the drains.
3.02 ERECTION, INSTALLATION, APPLICATION
Caution: Do not attemt to flush drains with water to remove debris. Excessive pressure can create internal leaks, causing staining and damage to adjacent building materials. Inspect annually; open and clean-out accessible points periodically.
A. When there is apparent blockage and signs of water damage
inside the building, use “low-tech” attempts such as
routers to clear the drain. If these attempts are not
successful, it is possible to identify the problem via
new video tools.
B. Identify the problem through video inspection and
determine the fault location as accurately as possible
using a high-performance camera/transmitter system.
- Plug in the system and turn on the monitor.
- Push the camera head into the line and continue to
slowly feed it through. Follow manufacturer’s
- Blockages will be evident on the video monitor as
viewed by the camera.
- Once the blockage has been identified, use the
location transmitter to accurately identify its
location. Follow manufacturer’s instructions.
B. Remove blockages using a mechanical auger or tooth cutter
as required for the type of blockage. Follow
manufacturer’s instructions. If necessary, excavate the
section of drain line in question and replace any cracked
or broken pipe.
C. Test drain lines between catch basin and municipal storm
D. Replace any missing drain covers to match existing.