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HomeMy WebLinkAbout004 BIG406MOB Engineering Comment Response LetterMONTANA | WASHINGTON | IDAHO | NORTH DAKOTA | PENNSYLVANIA 406.586.0277 tdhengineering.com 234 East Babcock Street Suite 3 Bozeman, MT 59715 January 7, 2022 RE: BIG406LLC MEDICAL OFFICE BUILDING COMMENT RESPONSES - CIVIL TD&H ENGINEERING JOB NO. B20-041 The following responses are being provided to explain how the Engineering Comments received on November 2, 2021 for the Big 406 Medical Office Concept Review Application (21378) are being addressed with this site plan application submittal: DRC Memo – Engineering Comments: General: 1. The applicant must provide a copy of the recorded plat prior to site plan approval in order to clarify easements of proposed development. RESPONSE: The recorded plat is provided with the site plan submittal. Existing easements are shown on page 2 of the plat. The easement for the Equestrian Lane extension south of the project was filed separately and is also included as Gallatin County Document #2675896. 2. The subject property is located within the Baxter Signal Payback. Please contact Marcy Yeykal myeykal@bozeman.net for exact amount determination/payment. RESPONSE: We have contacted Marcy Yeykal. Please see the attached payback amount determination correspondence. Easements: 1. The applicant must provide a ten (10) foot utility easement (power, gas, communication, etc.) along the development’s property frontage. RESPONSE: The 10-foot utility easements are in place around the property street frontages as shown on page 2 of the provided plat. 2. The applicant must provide a thirty (30) foot public utility easement to accommodate both water and sewer. An additional ten (10) feet of width is required for each additional main that occupies the easement. a. The applicant must verify/provide an easement for the 8-inch sewer stub located at the northwest of the subject property. RESPONSE: This sewer stub was originally intended as a future main extension to serve multiple buildings potentially constructed on Lot 4. Now that we know only one building will be constructed on Lot 4, we request to be able to use this stub as the building’s sewer service connection as proposed on the plans. We would abandon the adjacent water main stub that is no longer needed as well. No water/sewer mains should remain at this location requiring new easements. January 7, 2022 PAGE NO. 2 tdhengineering.com 3. No permanent structures shall be placed within a utility easement unless an encroachment permit has been obtained. a. The applicant must make sure the stormwater pond northwest corner of the proposed development is not within any main/main stub easement. RESPONSE: No water/sewer main easement should be required at this location (see response above). The edge of the pond embankment will encroach 1/3 of the distance into the 10’ front setback as allowed by BMC 38.410.080(F). Water Rights: 1. The applicant must contact Griffin Nielsen with the City Engineering Department to obtain a determination of cash-in-lieu of water rights (CILWR). CILWR must be paid prior to site plan approval. RESPONSE: We have sent a CILWR request with project info to Griffin Nielson and a determination is pending. Please see attached determination request correspondence. We understand the CILWR payment is required for final site plan approval. Water & Wastewater: 1. Prior to a determination of adequacy the applicant must provide an estimate of the peak-hour sanitary sewer demand as well as the average and max day demands of domestic water usage for the proposed site development. The estimates must be certified by a professional engineer. a. The applicant must verify sewer allocation in the Sundance Subdivision Sewer Design Report. RESPONSE: Water and sewer demand estimates for this project are provided and certified in the attached engineering design report. We have also verified that the estimated sewer demands for this project are less than the amount allocated for this lot in the most recently approved subdivision design report, which is also attached for refence. 2. A water design report must be prepared by a professional engineer for the proposed project. The water distribution system must be designed to meet the maximum day demand plus fire flow and the peak hour demand. RESPONSE: No water distribution system improvements (main extensions) are proposed with this project that would require this analysis. A standard 8” water main is already available in Galloway Street. Domestic water demand estimates are provided in the attached engineering design report. Domestic water and fire service lines will be sized for the building by the mechanical engineer. 3. The minimum diameter of a service is 4-inch. Services shall connect to the main with in-line gasketed wyes. The service line stub, from the main to the property line or easement line, shall be installed with a maximum slope of 1/2-inch per foot. The minimum slope of a 4-inch service line stub is 1/4-inch per foot. The minimum slope of a 6-inch service line stub is 1/8-inch per foot. Sewer service line stubs will typically be installed 15-feet from the downstream lot line. Services are to be installed perpendicular to the main. RESPONSE: A new 6” sanitary sewer service is designed meeting these requirements. If agreeable to the City, we are proposing to utilize the existing 8” sewer stub as a service connection since that stub is no longer needed for a main extension to this lot (see easement comment 2 response). January 7, 2022 PAGE NO. 3 tdhengineering.com 4. Sewer mains shall have a minimum depth of cover of four (4) feet below final grade. All sewer mains and services with less than five (5) feet of cover will be adequately insulated. a. The proposed sewer service line is running under the proposed stormwater pond. The applicant must make sure bury depths are met. RESPONSE: The proposed sanitary sewer service line is designed with 5’ min. cover below the pond bottom and has been located with adequate separation from proposed pond landscaping trees. 5. The mechanical room will need to be redesigned to allow adequate space for operations. The applicant must coordinate with John Alston, COB Water/Sewer Superintendent regarding this issue. RESPONSE: Acknowledged – The mechanical engineer will be coordinating with the COB Water/Sewer Superintendent to ensure the water room is adequately sized for the proposed domestic and fire service lines. 6. The applicant must prepare plans and specifications for any fire service line in accordance with the City’s Fire Service Line Policy. The plans must be prepared by a Professional Engineer and be provided to and approved by the City Engineer prior to initiation of construction of the fire service or fire protection system. The applicant must also provide Professional Engineering services for construction inspection, post-construction certification and preparation of mylar record drawings. Fire service plans, and domestic services 4” or larger, must be a standalone submittal, separate from the site plan submittal. City of Bozeman applications for service must be completed by the applicant. RESPONSE: Acknowledged – We will submit separate fire service line plans meeting the City requirements. Stormwater: 1. If stormwater runoff generated from the proposed development was accounted for within the Sundance Subdivision Stormwater Management Plan, the applicant must confirm this is the case and verify current standards will be met for the proposed development as part of the formal Site Plan submittal. RESPONSE: Stormwater runoff generated from this lot was not accounted for within the subdivision stormwater management design and will be addressed with on-site facilities. 2. The applicant must include a drainage plan with post-construction stormwater management controls that are designed to infiltrate, evapotranspire, and/or capture for reuse the post- construction runoff generated from the first 0.5 inches of rainfall from a 24-hour storm preceded by 48 hours of no measurable precipitation. For projects that cannot meet 100% of the runoff reduction requirement, the remainder of the runoff from the first 0.5 inches of rainfall must be either: a. Treated onsite using post-construction storm water management control(s) expected to remove 80 percent total suspended solids (TSS); b. Managed offsite within the same sub-watershed using post-construction storm water management control(s) that are designed to infiltrate, evapotranspire, and/or capture for reuse; or c. Treated offsite within the same sub-watershed using post- construction storm water management control(s) expected to remove 80 percent TSS. RESPONSE: Understood – please see attached engineering design report for information on how the fist 0.5 inches of rainfall is being addressed on-site. 3. The applicant must provide on-site detention with release rates limited to predevelopment runoff rates. Retention ponds must be sized based on a 10-year, 2-hour storm intensity. January 7, 2022 PAGE NO. 4 tdhengineering.com RESPONSE: Understood – please see the plans and engineering design report for details of a proposed pond overflow structure designed to limit release rates to predevelopment runoff rates after retaining the first 0.5 inches of rainfall volume. 4. The storm drainage plan must include a description of the ultimate destination of stormwater runoff from the project and an evaluation of its impact on downslope facilities and water quality. RESPONSE: Understood – please see the engineering design report for more info. 5. All open off-street parking areas and drive aisles must have perimeter concrete curb around the entire parking lot, including driving access ways. Continuous concrete curbing must be built according to standards provided by the review authority. Unless otherwise approved, the perimeter curb must be six-inch by six-inch concrete. a. The applicant must provide curbing around Phase I to eliminate stormwater runoff and delineate drive aisles to remove potential future vehicular conflicts. RESPONSE: Curbing has been provided around all phase Phase 1 parking and circulation areas, see site plan drawings for more info. 6. The applicant must identify snow storage areas for the parking area. Snow removal storage areas must be sufficient to store snow accumulation on site. Such areas shall not cause unsafe ingress/egress to the parking areas, shall not cause snow to be deposited on public rights-of-way, shall not include areas provided for required parking access and spaces, and shall not be placed in such a manner as to damage landscaping. RESPONSE: Understood – please see the site plan drawings for proposed snow storage areas which have been coordinated with the landscaping plans. Transportation: 1. Equestrian Ln is classified as a “local” street which requires 60 feet of right-of-way (ROW). Development of the Site requires the improvement of the street along the Site’s frontage to City standards, which includes proper drainage, dedication of ROW, pavement, detached sidewalks, landscaped and irrigated boulevard strip, trees within the boulevard, curb and gutter along with proper access points into the site. RESPONSE: Equestrian Lane was recently constructed to Davis Lane in 2021. This project proposes to complete the Equestrian Lane sidewalk along the property frontage. The 60’ ROW for equestrian lane was recorded as Gallatin County Document #2675896 which is attached for refence. 2. Accesses on local streets must be at least 150 feet from an intersection with an arterial. a. The access on Equestrian Lane with Davis Ln (minor arterial) is currently less than 150 feet. Please address and revise with resubmittal. RESPONSE: The access on Equestrian Lane has been moved further west to meet the access separation requirements. 3. All sidewalks that are to be publicly-maintained and all sidewalks along arterial streets (Davis Lane) shall have a minimum width of six (6) feet and shall be 6-inches thick reinforced concrete. RESPONSE: The sidewalk along Davis will be 6-feet wide and 6-inches thick meeting the City standard for publicly maintained sidewalks. Please see site plan drawings for more info. January 7, 2022 PAGE NO. 5 tdhengineering.com 4. The applicant must submit a peak hour trip generation value to the City to determine whether a traffic impact study is required. RESPONSE: Peak hour trip estimates were submitted and the attached TIS waiver confirmation was received for the Phase 1 site plan. 5. Table 38.400.090-1 provides the minimum distance between public and/or private accesses and intersections. Drive access for the proposed parking lot must align with the drive accesses across the street, or be at least 40 feet apart. RESPONSE: The north drive access to Galloway Street meets the 40’ separation requirement from the exiting driveway access apron to the north. No driveways exist along Equestrian Lane south of the project to coordinate with. Lighting: 1. Provide continuous lighting for all arterial (Davis Lane) as specified in Table B - New Construction Lighting Design Guidance. RESPONSE: We understand new street lighting for Davis lane adjacent to this project is being addressed as part of the overall subdivision development.