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HomeMy WebLinkAbout23_SPREngineeringCommentsWithResponses-Application21231_08172021 MEMORANDUM ------------------------------------------------------------------------------------------------------------ TO: Susana Montana, Senior Planner FROM: Karl Johnson, Engineer I RE: APPLICATION NO 21139 - North Central Block 3.4 Site Plan DATE: July 22, 2021 ----------------------------------------------------------------------------------------------------------- ENGINEERING COMMENTS: Easements 1. BMC 38.410.060 Easements – All Easements indicated below must be provided on city standard easements templates. Drafts must be prepared for review and approval by the city with site plan submittal. Signed hard copies of the easements must be submitted to the city prior to site plan approval. The applicant may contact the review engineer to receive standard templates. a. Front setback utility easements must be ten feet wide, and must always be provided unless written confirmation is submitted to the community development department from all utility companies providing service indicating that front setback easements are not needed. Acknowledged. The applicant is working to obtain utility providers’ approvals of the proposed easements. b. Stormwater ponds must be provided in a drainage easement and must be maintained by a property owners’ association. Acknowledged. Proposed easements are shown on Sheet C1.3 “Lot and Easement Plan”. This plan shows a proposed stormwater easement for the stormwater facility. The applicant is working on Property Owners’ Association documents and easement documents. Stormwater 1. DSSP II.B.6 Storm Drainage Plan - Details and specifications (including invert and other pertinent elevation information) for all storm drainage improvements. a. Provide invert elevations for the proposed stormwater detention facility. The invert elevations have been provided and can be seen on both Sheet C4.0 “Grading and Drainage Plan” as well as Sheet C4.2 “Drainage Details”. b. The stormwater section of the Civil Engineering Report indicates that seasonal high groundwater will be 8.5’ below the bottom of the stormwater retention systems. The provided groundwater monitoring in the provided geotechnical report shows high ground water at 7.6’ and 9.8’ below grade for relative monitoring wells. It appears reporting ground water 8.5’ below the chambers is erroneous. The applicant must confirm the separation between the bottom of the chambers and high groundwater. The stormwater system elevations have been updated based on design refinement. This resulted in minor changes to the stormwater system grades of 1 foot or less. In order to determine groundwater elevation and separation, the groundwater monitoring wells were surveyed to obtain an elevation datum for each monitoring well. The two nearest monitoring wells are Borehole #2 at the NE corner of Block 3 and Borehole #3 at the SE corner of Block 3. The seasonal high groundwater data from 2020 was used since it appeared to be more representative of actual conditions. Borehole Elevation Depth to High GW High GW Elevation BH 2 4796.11 10.83 4785.28 BH 3 4799.89 12.00 4787.89 The stormwater system is located halfway between these two boreholes, resulting in a high groundwater elevation beneath the stormwater system of 4786.58. The stormwater system invert is 4794.53, roughly 8 feet above the seasonal high groundwater. The updated elevations are shown on Sheet C4.2 “Drainage Details”. Water and Wastewater 1. DSSP V.A.6.h Services – It appears the exiting sewer service for the “Same Day Surgery” building will be abandoned with the demolition of the project. The applicant must describe how sewer service will be provided to the building until its redevelopment as defined the North Central Master Site Plan. Acknowledged. It appears that there is some confusion on the building nomenclature. The Same Day Surgery Center is a small addition to the Medical Arts Building that is proposed to be removed prior to The Henry construction. The Medical Arts Building was constructed in multiple phases with each phase having an individual sewer service. The entire building is served by four sewer services, two from Tracy and two from Willson. The phased demolition of the Medical Arts Building proposed in the North Central Master Plan corresponds to the building construction phases and service lines. Removal of the Same Day Surgery Center building addition and its individual sewer service will not impact the remainder of existing Medical Arts Building sewer services. Water/fire service to the Same Day Surgery Center is from the Medical Arts Building plumbing and water/fire lines serving the Same Day Surgery Center will be capped inside the Medical Arts Building. 2. The applicant is advised that the downstream sewer main located within Tracy Ave from W Peach St to W Cottonwood St is a 6-inch Vitrified Clay Pipe (Facility ID: F0310_F0311). This sewer does not meet current city standards. The sewer main must be improved to an 8 inch sewer main meeting current city standards. a. The applicant must coordinate the off-site improvement with the City’s engineering and legal departments regarding the timing requirements of the improvements. Acknowledged. Coordination with the COB Engineering Department regarding this sewer is currently underway. Concurrent construction of this sewer main replacement is proposed, and a Concurrent Construction Request is provided with this resubmittal. b. The applicant is advised the improvements to the sewer main must be submitted to the city for infrastructure review. Acknowledged. General 1. It appears the solid waste pick up for the “Same Day Surgery” building will not be possible during and after construction of the proposed Block 3.4 building due to its current location. The applicant must coordinate with the Same Day Surgery owner to continue solid waste service elsewhere prior to commencement of construction activities. A change in solid waste pick up location and any temporary storage of trash containers on public property will require approval of a temporary use permit for the Same Day Surgery. With the next submittal, please indicate the new location of the Same Day Surgery trash enclosures. Acknowledged. The solid waste pickup noted is for the entire Medical Arts Building and will remain in service until the entire Medical Arts building is demolished. During construction of The Henry, the Medical Arts Building dumpster will be temporarily relocated just to the north so it can be accessed by Villard Street from the west, outside of the construction site fencing. When construction is complete the dumpster will be replaced to its original location, and utilize the same shared, heated access as The Henry’s solid waste pickup. Keeping access to this existing trash pickup and sharing it with The Henry is an essential design component of this plan and the North Central Master Plan. The Construction Management Plan has been updated to show this temporary dumpster relocation. 2. BMC 38.410.130 (A) (1) Water rights - CILWR must be paid prior to site plan approval. Acknowledged. The applicant has been in correspondence with Griffin Nielsen to determine the CILWR fee. ENGINEERING ADVISORY COMMENTS: 1. DSSP Plans and Specification Review Policy – Plans, specifications, and submittals for public infrastructure improvements (storm mains and public street improvements) must be submitted to the City Engineering Department (engsubmittals@bozeman.net) for infrastructure review. Acknowledged. All required infrastructure submittals will be provided to the COB Engineering Department. 2. DSSP Fire Service Line Standard – Plans for all fire service lines must be submitted to the City Engineering Department (engsubmittals@bozeman.net) for review. Acknowledged. All required water and fire service line submittals will be provided to the COB Engineering Department.