What to Consider When Designing Green Stormwater Systems, Part 2

Last month’s blog was the first in a series that focuses on maintenance considerations for Green Infrastructure (GI) systems. We touched on how the design of GI systems should be guided by maintenance funding, equipment, material, staff, and frequency. We saw how early consideration of operations and maintenance (O&M) factors can streamline feasibility assessment, refine design, and reduce total cost.

The next step of the GI design process is the establishment and documentation of O&M protocols, typically achieved through the development of an Operations and Maintenance Manual. A GI O&M manual is a document, or series of documents, that define the components and functionality of a GI facility and describe how each of those components are to be maintained. The following is a noncomprehensive list of elements with descriptions that should be included in a GI O&M manual:

Formatting: O&M manuals come in a variety of styles, presentations, and formats and should be developed with the user in mind. A good place to start is to catalog existing established maintenance procedures of the division or group that will be charged with the upkeep of the GI system. How is this information currently conveyed? Electronically? Notebook binder? Calendar? Discuss with maintenance personnel what elements of the existing process work and what elements are problematic. The next step is to verify that the format and presentation of the O&M documents for GI can be logically and systematically integrated with existing protocols.

SPU and King County Green Stormwater Infrastructure Operations & Maintenance Manual (Courtesy of MIG|SvR)

With the advancement of handheld technology like smart phones, it’s possible to create manuals that have touch screen applications where a simple swipe can bring up an array of images, identify problem zones, or track and send a message to a colleague in another office. There is no right or wrong way to present the information, what’s most important is that the information is presented in a format that is useful and helpful to the user.

Photos: GI O&M manuals should use photographs along with narrative instructions to provide clarity in terms of equipment, material, and operational categories. Photos help to define intent and clarify steps associated with maintenance operations. They are particularly useful when working with multilingual crews. By showing photographs of components and conditions, staff can be more confident that they are performing maintenance in the correct zone and using the correct approach. This way, errors are less likely to occur.

Curb Cut Cobbles at Barton Basin (Courtesy if MIG|SvR)

Describe System Functionality: O&M manuals should include a brief description of the GI facility and components, including the purpose or function of each. As an example, finish the sentence “these are cobbles” with “which serve to slow stormwater flows entering the facility to minimize erosion.” By sharing more detailed information about function, the manual empowers crews to make judgment calls in the field, including making suggestions to improve existing or future installations.

Level of Service: O&M manuals should quantitatively describe the anticipated level of maintenance for each element of the GI system and clarify which level of maintenance pertains to aesthetic standards and which pertains to performance needs. Manuals can include phrases such as “in order to properly convey stormwater, the curb cut shall be free of blockages”. Lists can also be employed to provide a hierarchy with operations and safety related maintenance prioritized, if desired, from those that are associated with appearance. Generally, maintenance activities prioritize those related to function and safety over those related to appearance.

Maintenance Testing: Although the manual should have a schedule listing the periodic maintenance requirements for each GI system, it is also helpful if the manual identifies techniques with which field personnel can identify when additional maintenance action is required beyond what is prescribed on a periodic basis. This could include visual inspection, anecdotal complaints, step-by-step testing procedures, and the identification of minimum and maximum compliance thresholds. Common practices include infiltration tests for determination of surface flow rates or visual inspection of curb cuts for blockages.

Silva Cell Equipment List (Courtesy of DeepRoot)

Equipment and Materials: All manuals should include an easy to reference equipment and materials list. The list should identify the tools, materials, user manuals etc., along with a description of the maintenance or repair objective served by each. Examples include a soil probe which allows users to collect a small diameter soil sample to provide a quick soil profile for verification of content depths and moisture contentf or bark mulch, a landscape material placed for plant health.

Without proper maintenance, GI facilities are unlikely to provide the stormwater function for which they were installed. With early and frequent communication, designers and operations staff can create an O&M manual that will serve all personnel for the life of the facility.

Our third and final installation in this three-part series is Staff Education and Training.


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