HomeMy WebLinkAbout21129 Gallatin Park Mixed Use SP-ENG 070721
MEMORANDUM
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TO: Danielle Garber
FROM: Mikaela Schultz, Engineer I
RE: Gallatin Park Mixed Use SP Rev 01
APPLICATION NO #21129
DATE: June 7, 2021
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These comments are provided in reference to the above noted Site Plan Revision 01
submittal.
CONDITIONS OF APPROVAL
1. The applicant included (2) easement drafts for review. The easements define the snow storage
easement and a refuse easement agreement between the adjacent property owners. Site plan
approval is conditional of both easements being submitted to the County Clerk and Recorder's
office and filed.
2. The applicant provided a draft of the SID waiver that is acceptable. The applicant must file the
executed Waivers of Right to Protest Creation of Special Improvement Districts (SID’s) with the
County Clerk and Recorder's office.
Stormwater
1. Original Stormwater Design Report BMC 38.410.080 -Engineering Storm Water Design
a. The applicant must demonstrate that storm water runoff discharged off-site is equal to
or less than the design capacity reserved in the subdivision ponds for the subject parcel
in the subdivision's storm water design report. The applicant must also demonstrate how
the first 0.5 inch runoff reduction requirement is being met.
Bio retention Pond: The existing regional storm pond is being utilized for storm
water retention. The pond was designed to handle the runoff from the subject
property given a runoff coefficient of 0.70. The coefficient was updated to 0.73
to match current conditions and the applicant has proposed a small bio retention
pond on site to handle the additional runoff. Please provide updated, certified
calculations to reflect these changes prior to site plan approval.
DSSP Section (II) (D) (3) (c) Discharge Structures –please update the stormwater
report to indicate how long the proposed retention systems (the bioretention
pond and the hydrodynamic separator) will take to infiltrate. The systems need
to be designed to infiltrate standing water and avoid long-term retention in case
of a back-to-back storm event. Provide a calculation on how long it will take to
infiltrate given 6-inch bedding material, seperation fabric, etc.
A portion of Building 3 and the lawn out front is shown as part of Basin B which
drains to the HOA retention pond. This property actually drains out to the street
and does not make it into the retention pond. Please address. The calculations in
the drainage report do not include all of the developed or regraded contributing
area. The applicant must address all lot areas in the calculations prior to site plan
approval.
The applicant must submit the updated storm water design report for review certified by a
professional engineer.