HomeMy WebLinkAboutMARS LANDING - PDP190013 - SUBMITTAL DOCUMENTS - ROUND 3 - VARIANCE REQUESTMarch 3, 2021Wes LamarqueEngineering Development ReviewCity of Fort Collins281 N College AvenueFort Collins, CO 80524RE:Mars Landing - Variance Request to City of Fort Collins Stormwater
Criteria Manual Chapters 1.2.3.5 and 7.4.0Dear Wes,Please find this letter as our formal request for an administrative variance to the requirements set forth in Chapters 1.2.3.5 and
Chapter 7.4 of the City of Fort Collins Stormwater Criteria Manual as they relate to water quality BMPs. The project, Mars Landing, is located at the southwest corner of the intersections
of Mars Drive and Skyway Drive in the City of Fort Collins.The project consists of a 3.79 acre project site of which 3.45 acres of developed project area will be routed through an on-site
detention pond that releases into a public stormwater conveyance system.Chapter 1.2.3.5 of the City of Fort Collins Stormwater Criteria Manual requires water quality treatment for 100%
of developed site area. Of this, 75% of all newly added or modified impervious area must be treated by approved Low Impact Development (LID) techniques. Approximately 90% of the added
impervious area on this site will be routed through an underground stormwater collection chamber system, which is an approved LID technique. Chapter 7.4 of the City of Fort Collins
Stormwater Criteria Manual allows for Water Quality Detention BMPs to achieve the required Water Quality Treatment that is not achieved through LID methods. Due to site constraints,
including shallow outfall depth, restricted detention pond area by developed density requirements, and existing topography, providing water quality through Water Quality Detention for
the remaining developed site area is not feasible. Alternatively, we would like to request a variance to the mentioned Chapters of the City of Fort Collins Stormwater Criteria Manual
and install a “Snout” water quality inside the proposed inlet that conveyes the otherwise untreated runoff to the detention pond. The “Snout” is a vented hood installed inside the inlet
designed to prevent the outflow of debris and oils. The “Snout” would serve as an effective alternative BMP given the relatively small area (0.09 acres) contributing to the inlet in
which it will be installed.Thank you for your consideration of this variance request. Should you have any questions, please do not hesitate to contact me 970.800.3300.Sincerely,GALLOWAYDonald
B. Cecil, P.E.Civil Project Engineer970.800.3300DonaldCecil@GallowayUS.comcc: