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HomeMy WebLinkAbout19021 - Engineering Comments 2021-05-24 May 3, 2021 Danielle Garber, Associate Planner City of Bozeman Department of Planning and Community Development P.O. Box 1230 Bozeman, MT 59771-1230 Re: Boulder Creek Apartments Site Plan Review COB#: 19021 MMI#: 4192.025 Dear Sarah: This letter is to provide written responses to the comments stated in the engineering review memo dated March 29, 2021. Below are our responses associated with each comment. ENGINEERING COMMENTS: 1. DSSP XII Mid-Block Crosswalks – The applicant must submit the proposed lighting design criteria for the mid-block crosswalk to be reviewed as separate infrastructure submittal. a. BMC Section 38.400.070 – The crossing light must be adopted into and SILD prior to any occupancy on the site Understood the applicant has applied for an SILD modification with Laurae at the City 2. BMC Section 38.410.060 – The provided draft easements exhibits must be stamped by professional engineer or land surveyor. The document must be signed, and filed with the Clerk and Recorder’s Office prior to site plan approval. a. The provided Drainage Easement must be adjusted to encompass the entire storm retention system. The revised drainage easement (EX3a & EX3b) have been included in this resubmittal. Once the draft easement is approved, it will be filed at the Clerk and Recorder’s office. An additional draft drainage easement has been included for Retention Pond #2 at the Northwest corner of Lot 4. 3. Design Standard and Specification Policy (DSSP) Section II Drainage Policy – It is unclear how runoff from drainage area 2 will be retained and treated. A drainage swale is shown grading offsite. The drainage report must identify how this drainage will reach the intended destination of retention pond #2. The report must clearly demonstrate runoff is being treated and post development runoff is kept to predevelopment conditions. A supplemental memo has been included with the drainage report to provide more detail in regard to runoff from Drainage Area 2. 4. BMC Section 38.410.080 – Sidewalk chases are discouraged in public sidewalks. The applicant is encouraged to provide surface flow from the overflow of the proposed retention pond. Understood, the site plan has been revised to eliminate the sidewalk chase. The overflow pipe has been relocated to provide surface flow out. 5. DSSP Utility Design Criteria – Section D.5.b: At no time will the utility line in question be less than nine (9) feet from the edge of the easement or less than ten (10) feet from a parallel utility line. Utility easements will also be required for all fire hydrants maintained by the City of Bozeman. a. Sewer manhole is less than 9 feet from eastern edge of utility easement line. The fire hydrant is less than 9 feet from the edge of the easement. b. The provided utility easement must be revised to reflect this change. The utility easement (EX 2) has been widened to allow 9’ from the sewer manhole and fire hydrant. The revised easement has been included in this resubmittal. 6. BMC 38.410.070. Municipal Water, Sanitary Sewer, and Storm Sewer Systems - The applicant is advised that the proposed project is located within the wastewater drainage basin currently serviced by the Laurel Glenn Lift Station (LGLS). Currently, there is inadequate capacity at the LGLS to support the proposed project. The applicant is advised that a third party (Rosa Apartments) has proposed constructing a sanitary sewer diversion (Cottonwood Sanitary Sewer Diversion) upstream of the development that would divert wastewater flow from the LGLS into the future Norton Ranch East Interceptor/ Davis Lane Lift Station City identified capital improvements, ultimately freeing up enough capacity at the LGLS to support the proposed sanitary loading from the Boulder Creek Development. Currently, both the Norton Ranch East Interceptor and Davis Lane Lift Station are under construction. The applicant is advised that the City has reviewed the Cottonwood Sanitary Sewer Diversion design and associated design reports for the LGLS and is in agreement with the diversion. The applicant is advised that off-site infrastructure improvements must be installed and formally accepted by the City prior to site plan approval BMC 38.270.030 (B)(1)(a). The applicant is advised this site is not eligible for concurrent construction because of the required off-site improvements (BMC 38.270.030). The applicant is advised that horizontal construction work could occur, such as hardscape (i.e. parking lots, permeable pavers, utilities, stormwater improvements, etc.). However, the applicant would need formal approval from the City prior to site plan resubmittal as well as provide a detailed phasing plan accompanied with exhibits that clearly shows how the proposed development intends to build out. Again, engineering recommends the applicant contact the City to discuss the exact requirements prior to resubmittal. This issue has been discussed in a meeting with the city with communication with Karl Johnson attached. Per his email correspondence, a sanitary sewer demand report has been included in this resubmittal illustrating that the proposed project will not exceed the allotted capacity. If you should have any questions regarding these comments, revisions and corrections for the Boulders Apartment Site Plan Application Resubmittal don’t hesitate to contact me, Celine Saucier, PE Project Engineer