Storm Water Mitigation System Inspections

If you live in the City of Santa Monica and have an urban mitigation pit as part of your drainage system, you may be required to have an annual inspection for Best Management Practice (BMP) on an infiltration pit or depression basin. You might receive a letter from the City of Santa Monica that starts out like this:

"Your property has participated in the City's Urban Runoff Management Program through the installation of a Best Management Practice (BMP) device, such as an Infiltration Pit or Depression Basin, when construction work was performed in the recent past (since 1999.) The City's Urban Runoff Pollution Ordinance, SMMC 7.10, requires that most major development or construction projects install a physical structure within the property, in the landscape or under the garage (some commercial and multi-family buildings) or driveway, to capture precipitation from roofs and other hardscapes for infiltration or treatment and release to the street. This program seeks to keep small background levels of pollution found in urban runoff off City streets, where it flows untreated into the Santa Monica Bay, and can cause beach postings and closures. This program also seeks to harvest a local water resource and infiltrate it into the ground for groundwater recharge and potential future extraction as a local water supply, reducing dependence on expensive imported water or to harvest into a cistern for reuse."

What does this mean for you, the property owner? You may be required to have an annual visual inspection of your urban runoff mitigation or infiltration system, and turn in paperwork stating that you have done so. We can perform this visual inspection for you.


Our minimum Stormwater Mitigation System Inspection typically consists of:

1. Visual inspection of first-story gutters and any gutters visible from stair-case accessible upper story rooms or stair-case accessible flat roof. This inspection does not include putting our men on a slopping roof, or on a ladder extending beyond one story. If you want gutters inspected that exceed these limitations, we recommend contacting a gutter-cleaning company with appropriate workers compensation coverage for that work.

2. Where practical and accessible as provided in #1 above, hose-water test first-story downspouts to see if water flows through the spouts.

3. Visual inspection of deck and yard drain-inlets so see if they are clear of debris and silt.




4. Hose-water test of main drain from an accessible clean-out or drain inlet to see if water backs up. Basic inspection is based on one line only. If additional lines are needed and authorized, there would be additional cost. Note: A hose produces only a fraction of the flow of a rain-storm and does not detect less than full obstruction. For a more complete evaluation of drain condition the line would need to be snaked and/or videoed, neither of which is provided for in this basic inspection.




5. Visual inspection and quick clearing of pre-pit screen box (up to 12 X 12 by 18 inches deep. Larger or multiple filtration boxes will require additional time and cost.

6. Hose test of drain pipe from pre-pit screen box to pit. This is to verify that water does not back up into the pre-pit screen box.

7. Open inspection-hole cover at the pit and check for standing water. If the inspection hole access is buried, additional costs will be necessary to locate and access the inspection hole.

8. If overflow pipe inlet is accessible, hose-water test overflow pipe to see that it is clear to the street. Other wise run a tape or snake from the street outlet to see if the pipe is open from the street to the pit. Note: A hose produces only a fraction of the flow of a rain-storm and does not detect less than full obstruction. For a more complete evaluation of drain condition the line would need to be snaked and/or videoed, neither of which is provided for in this basic inspection.

Many single family residences, and some larger properties that are regularly inspected will fall within the minimum fee. The minimum fee covers 2 men for up to one hour. If problems are observed, we will report such problems together with recommendations, and where appropriate, estimate costs for treatment. If in-line filters are used on the site, the minimum charge does not include cleaning or replacing the filters. Depending on site conditions, we usually recommend eliminating multiple in-line filters and small pre-pit filter boxes and replacing them with one, large, serviceable filter and inlet box at the pit itself. Our minimum inspection does not include the cleaning of gutters or drains.

Some infiltration pits have been built with overflow drain pipes at the pit higher than inlet pipes. We do not recommend or approve such designs. Usually, we cannot determine whether or not the overflow pipe is lower than the inlet pipe without conducting a separate video inspection, which we do not include in our basic inspection, and is not typically required by the city.

Please take note that infiltration systems retain water on the site that normally would be conducted off the site. This can introduce unintended consequences of unpredicted proportions, especially where there are below-grade structural components such as basements and footings. Also, this type of inspection typically cannot tell us anything about the condition and capacity of the pit itself, or how effectively it is allowing infiltration into the soil. Also, because of the typical pit design, we cannot tell whether the pit will allow overflow water loads to actually reach the overflow pipe without backing up into the main system. In order to confirm this we would need to run a very large amount of water into the pit and observe its performance, which is not included in this minimal inspection. In inspecting the stormwater mitigation system we only report readily observable conditions and problems. We do not thereby approve or certify the overall suitability of the system for the site.

To order an inspection, please call and schedule it with our dispatcher. Please provide us with any information you may have regarding the location of the pit (or pits), the location of the inspection hole (not all pits have inspection holes), and access to a copy of any available plans or drawings used for construction of the pit. If you wish to have your drain lines snaked, hydro-jetted, or repaired during the process of the inspection, or filters and/or basins cleaned at the time of inspection, or sump-pits cleaned and pumps tested, please indicate so when you order the inspection and increase the budget to provide for additional work that will be charged on a time and material basis with the 2-man crew being billed at $170 per hour. The amount of time it takes to clean drain components can vary widely. Therefore we recommend a minimum of a $500 budget for combined visual inspection and minimal cleaning. If more extensive cleaning and or repair is needed, labor and incidental material for a full day on a job-site typically cost between $1,800 and $2,300. If you anticipate extensive problems with a large or old drain system, you may want to consider authorizing a budget of up to one day at a time for the most efficient use of the crew.