HomeMy Public PortalAbout2018-10-09 Triton GUL
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October 9, 2018
Triton Stormwater Solutions
Attn: James Maier, Triton Chief Engineer
RE: Triton Stormwater Solution Chambers and Triton Main Header Row
Dear Mr. Maier:
MSD grants approval of the Triton Stormwater Solution M6, C10, and S29 chamber systems and Main
Header Row for use as a standalone post construction stormwater Best Management Practice. These
chambers may be used on new development, redevelopment and highway/roadway improvement
projects of any size under the following conditions:
Properly sized sediment row chambers are provided as a measure of pretreatment at each location
where flow is injected into the Triton system. The sizing of the sediment rows shall be based upon the
Peak Discharge for the Water Quality Storm (Appendix D.10 of the 2000 Maryland Stormwater Design
Manual) tributary to each point of injection, and Table 1:
Chamber Model Max Allowable Peak Discharge for the Water
Quality Storm (cfs) per Chamber
M6 0.030 cfs
C10 0.037 cfs
S29 0.061 cfs
Table 1: Main Header Row – Flow Rates per Chamber
At a minimum, an equal number of non-sediment row chambers are required for each installation.
The Triton outlet shall be perched a minimum 6” and the infiltration bed area sized in accordance with
Figure 1 noted in an approval letter granted to a similar product dated September 20, 2016. With a
perched outlet, and when sized in accordance with Table 1 and the referenced Figure 1, the Main
Header Row and Triton Chambers provide sufficient water quality treatment for its tributary area. A
runoff volume reduction credit of 0.45 may be entered into “11. Site Specific BMP” in the MSD MEP
spreadsheets.
It is noted that Figure 1 was derived using an assumed underlying subgrade saturated hydraulic
conductivity of 0.05 in/hr. This may be the default assumption for all sites utilizing a 6” perched outlet.
When configured with a greater than 6” but less than 18” perched outlet height, MSD will require the
following from a Professional Geotechnical Engineer licensed in Missouri: a) Onsite geotechnical
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investigation to determine the actual saturated hydraulic conductivity of the underlying soils beneath
the Triton/Main Header Row system, b) assessment and recommendation for pavement structural
stability, c) assessment of possible impacts to adjacent structures due to seepage, including
recommended setback distances between those features and the Triton/Main Header Row system.
In all instances, a minimum 2 feet separation is required between the bottom of the infiltration bed and
the seasonal high water table.
Integration with Channel Protection and Detention Design
Channel Protection storage, 2yr-24 hour and 100yr-24 hour detention storage may be managed within
the same system, with a properly configured, sized, maintenance-accessible, reinforced concrete control
structure. The footprint of the infiltration bed/chamber system shall be sized at a minimum to manage
Water Quality, and expanded as necessary to manage these additional volumes as required on sites.
MSD reserves the ability to withdraw or modify this approval based on subsequent information,
including information indicating that the Triton Stormwater Solutions Chambers and Main Header Row
do not satisfy MSD rules, requirements, or construction and material specifications.
Sincerely,
Kaleena Menke, PE
BMP Committee Chair
Engineering / Development Review