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HomeMy WebLinkAbout21029 N Central MSP Eng Comments Response_10152021 MEMORANDUM ------------------------------------------------------------------------------------------------------------ TO: Danielle Garber, Associate Planner FROM: Karl Johnson, Engineer I RE: APPLICATION NO 21029 - North Central MSP R01 DATE: August 23, 2021 ----------------------------------------------------------------------------------------------------------- ENGINEERING COMMENTS: The following comments must addressed to complete a full review of the application. Water and Wastewater 1. 38.410.070. and DSSP.V.A and B – 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. Based on discussions with City staff, the estimates provided with the North Central Engineering Report dated 7-14-21 have been confirmed to be adequate. a. Wastewater Facility Plan - Residential sewer demand calculations must be based on the following: 65 gallons-per-capita-per-day must be used with 2.17 people per dwelling unit. It’s not clear these parameters were used in the sewer estimates. Please provide a breakdown of how total wastewater flows are calculated. See response above. b. DSSP V.A - Residential water use calculations must be based on the following: The water distribution system shall be designed to meet the maximum demand plus fire flow and the peak hour demand. The design shall be based on a maximum hour to average day ratio of 3: 1 (maximum day to average day ratio of 2.3: 1 for an average daily usage of 170-gallons per day per person), plus fire flow demand as determined by ISO (Insurance Services Office) criteria. See response above. i. Alternatively the potable water demand calculations may use the following parameters from the Water Facility Plan: The average daily demand for potable water, including all indoor and outdoor (irrigation) use, calculated assuming the 135 gallons per day per capita water use rate. With an estimated density of 2.14 people per dwelling. The design shall be based on a maximum hour to average day ratio of 3: 1 (maximum day to average day ratio of 2.3: 1 for an average daily usage plus fire flow demand as determined by ISO (Insurance Services Office) criteria. See response above. Transportation 1. 38.220.080 Site Plan Submittal Requirements – Traffic Impact Study (TIS): a. The TIS must show trip distribution on to adjacent and nearby local streets and analyze the local intersections to determine if additional traffic control devices or other provisions are necessary. The applicant is advised that prior to resubmitting or updating the TIS they need to coordinate with the City’s transportation engineer (Taylor Lonsdale). The applicant’s team met with the City’s transportation engineer on August 31, 2021. That meeting and subsequent communication resulted in a second update to the North Central TIS, dated 9-24-21, included with this submittal. This update addresses the comments below. 1. The provided trip distribution graphic shows Villard and Beall Street connecting to Rouse Avenue but these roads do not connect to Rouse Avenue in reality. The graphic and distribution must be updated to represent possible trip distributions. See response above. 2. The provided trip distribution graphic does not show any trips on to Grand Avenue or Tracy Avenue but the proposed development is proposing a substantial amount of parking access on to these streets. The graphic and distribution must be updated to represent trip distributions from these parking accesses. See response above. 3. The TIS reports a 21 percent increase in volume on North Wilson Street but does not provide an analysis if this road can accommodate the increase in traffic. This street already functions poorly due to limited width and parking on both sides of the street. The TIS must be updated to provide analysis of the capacity of North Wilson. See response above. 4. The provided update to the original TIS does not include updated analysis on the increase in traffic volume on Lamme, Villard, Grand, Tracy, or Beall. The TIS must be updated discussing the capacity of these streets to carry the increase in traffic volume. See response above. 5. The provided update to the original TIS does not include an updated analysis on the increase in traffic volume on the following intersections: Mendenhall St and Grand Ave, Mendenhall St and Wilson Ave, Mendenhall St and Tracy Ave, Grand Ave and Beall St, Grand Ave and Lamme, and Lamme St and Tracy Ave. The TIS must be updated discussing the capacity of these intersections to carry the increase in traffic volume. See response above. b. The TIS must discuss how much daily traffic will be generated on existing local and neighborhood streets, roads and alleys, when the subdivision is fully developed, The following traffic generation is inadequate and must updated with a revised TIS: i. It is not clear if the 2021 traffic counts were compared against the 2017 traffic counts to determine if the traffic counts remain appropriate for use as the background volumes or if the traffic counts need to be adjusted. The applicant must confirm the 2017 traffic counts are appropriate for use and the 2021 traffic counts support this. See response above. ii. The provided TIS reports trips for the existing Medical Arts building which are based on total net square footage. The Medical Arts building is likely not fully occupied making this an overestimate of traffic reduction in the North Central Master Site Plan. The applicant must confirm the building is fully occupied to justify counting the total square footage in traffic reduction. See response above. iii. Internal Trip capture and alternate mode reductions were both calculated using the total trips generated. It appears this would over estimate total trip reductions. The applicant must provide justification for the accuracy of this practice or remove the reductions of one before applying the other. See response above. 2. BMC 38.400.060.B.4 - All arterial and collector streets and intersections with arterial and collector streets must operate at a minimum level of service "C" unless specifically exempted by this section. The review authority may approve a development only if the LOS requirements are met in the design year. Intersections must have a minimum acceptable LOS of "C" for the intersection as a whole. The provided TIS has identified the following intersections at a LOS below C: N 7th Ave and Durston Rd, S 8th Ave and Babcock St, S Rouse Ave and Babcock St. See response above. The TIS must be updated to provide what mitigation improvements would be required to provide adequate LOS at the intersection (i.e. signalization timing, turning lane configuration, through lane configuration, etc.). See response above. ENGINEERING RECOMMENDED CONDITONS OF APPROVAL: Easements 1. BMC 38.410.060 Easements - 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. Front setback utility easements must be provided or written confirmation is submitted to the community development department from all utility companies providing service indicating that front setback easements are not needed prior to respective site plan approvals. Acknowledged. a. New shallow utilities are not allowed to run parallel in the public right of way as shown on the north side of the “One 11 2.0 Building”. A 3.5 foot utility easement is provided in this location but dry utilities are not shown inside the easement. The new shallow utilities must be located within an approved front setback utility easement. All new shallow utilities are located within planned utility easements. Existing utilities, which are assumed to be legally located within City right-of-way, are not envisioned to be relocated unless the utility service provider desires to relocate them. The utility boxes located on the north of the One 11 2.0 building within the right-of-way are where new utilities connect to existing utilities. Utility occupancy permits have been obtained for the new structures in the right-of-way. ENGINEERING ADVISORY COMMENTS: The following comments are to be addressed with future submittals. General 1. DSSP Plans and Specification Review Policy – Plans, specifications, and submittals for public infrastructure improvements (street improvements (including street lighting), new fire hydrants, and storm mains) must be submitted to the City Engineering Department (engsubmittals@bozeman.net) for infrastructure review. Acknowledged. All required public infrastructure will be submitted to the City Engineering Department for review. 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 fire service lines will be submitted to the City Engineering Department for review. Stormwater 1. Montana Post-Construction Storm Water BMP Design Guidance Manual The applicant must demonstrate that seasonal high groundwater will not impact the function or maintenance of the proposed facilities. Industry guidance recommends a three-foot minimum separation from the bottom of the proposed facility to the underlying groundwater table. The applicant must provide local seasonal high groundwater elevations to support the proposed design. Groundwater monitoring for seasonal high groundwater was performed in 2019 and 2020 in several locations across the Master Plan area. Results from this monitoring are included with this submittal. During individual Site Plan applications, detailed design information will be provided for City review showing appropriate separation from seasonally high groundwater. 2. BMC 404.04.500 Requirement To Control and Reduce Stormwater Pollutants – Provide a stormwater drainage/treatment grading plan and maintenance plan for a system designed to treat the first 0.5 inch of stormwater to remove solids, silt, oils, grease, and other pollutants must be provided to and approved when the Site Plan application are submitted. The plan must demonstrate adequate site drainage (including sufficient spot elevations), storm water detention/retention basin details (including basin sizing and discharge calculations, and discharge structure details), storm water discharge destination, and a storm water maintenance plan. The approved stormwater maintenance plan must be incorporated into the Owners Association Documents and a copy must be submitted prior to Site Plan approval. Detailed stormwater drainage and grading plans will be provided with individual site plans for the projects within the North Central Master Plan. The engineering report included with the master plan submittal includes stormwater calculations for each block of the project, and planned treatment basin sizing based on the planned improvements shown in Master Plan. Each of the stormwater management systems will retain significantly more runoff than minimum requirements and will substantially reduce stormwater runoff flows from the project area. The Engineering Reports submitted with each Site Plan will contain a stormwater maintenance plan for City review. Upon approval, stormwater maintenance plans will be incorporated in the Owner’s Association Documents for each project. More detailed stormwater calculations will be provided with individual Site Plan applications that reflect true design conditions for each project. 3. BMC 38.540.020 - The applicant must identify snow storage areas on the Site Plan 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. Detailed snow storage plans will be provided with individual Site Plan applications. However, projects included in the North Central Master Plan will follow a similar approach to snow storage. The majority of the snow storage required is from public streets and sidewalks. The snow storage areas for this public areas are located within a 6’ wide permeable paver strip between the sidewalk and the curb. The permeable pavers will allow snow melt to infiltrate and not run-off into adjacent streets. This design performs better than typical vegetated boulevards and also provides enhanced pedestrian use during summer months. On-site snow storage will primarily be facilitated by use of the building roofs, which occupy the majority of the overall footprint of each site. Snow storage locations for on-site sidewalks, pathways, alleys, etc. will be specified in accordance with above requirements at the project Site Plan level. 4. A cleanout in the landscaped right-of-way shall be provided to allow proper maintenance for storm lines with bends. Acknowledged. This design element will be included and addressed on the individual Site Plan level. 5. The inlet on corner of Villard and Tracy must be replaced to connect directly north into new manhole. Existing inlet pipe must be properly abandoned. This must be addressed with an infrastructure submittal. Acknowledged. This issue has already been addressed in the individual Block 4 “The Ives” and Block 3.4 “The Henry” project applications currently under the COB development review process. 6. Individual site plans must identify overflow paths that demonstrates that no structures will be flooded during a 100-year storm event. Each stormwater management system installed within the North Central Master Plan, including the temporary stormwater management system installed in Block 3, employ the same design approach for managing overflow. The interior piping includes a roof drain conveyance pipe entering the stormwater management system manhole to direct building runoff into the system. Once the stormwater system reaches capacity, and overflow pipe is located in the manhole that directs this overflow runoff to City of Bozeman storm sewer. Both the roof drain conveyance pipe and the overflow pipe are sized to convey the 100- year storm. Additionally, the stormwater systems themselves are designed with ample capacity to entirely retain the vast majority of storms in Bozeman, typically the 98th percentile. Based on this design, no structures will be flooded during the 100-year storm event. Individual Site Plan applications will provide further information on the stormwater overflow management design. 7. DSSP II.C.3 - Basins serving multiple lots shall be located in common open space owned by a Homeowners or Property Owners Association. Locating a basin within an easement on a lot will not be permitted unless approved by the governing body. Acknowledged. Drainage easements for the multi-user stormwater management systems have been provided and can be seen on the Lot and Easement Summary Map included with this submittal. The Engineering Report specifies who is responsible for each of the different classifications of stormwater mitigation system ownership. The appropriate language providing approval for location of a subsurface retention system will be provided as required during the individual project review process. a. As shown on the provided plans, the City is in general agreement on the overall location of the proposed stormwater facilities and that a separate drainage easement will need to be provided where facilities serve multiple lots Acknowledged. As stated above, the appropriate legal documentation will be provided during the individual project application process. Water Rights 1. BMC 38.410.130 (A) (1) Water rights - 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 respective site plan approvals. Acknowledged. The applicant has already been coordinating with Griffin Nielsen regarding CILWR fees for some of the initial projects included in the North Central Master Plan. Water and Wastewater 1. BMC 38.270.030.C – Whenever any building lots or building sites are created inside the city limits, municipal water distribution systems, municipal sanitary sewer collection systems, streets, and stormwater collection, treatment, and detention or retention systems must be provided to the lot or site. Each building site must utilize and be connected to both the municipal water distribution and municipal sanitary sewer collection systems. Subject to the provisions of subsection C.1 of this section, these improvements must be designed, constructed, and installed according to the standards and criteria as adopted by the city and approved by the review authority prior to the issuance of any building permits, except when concurrent construction is an identified purpose of the initial project review and approved pursuant to the criteria established in subsection D of this section. The applicant is advised that site plans within the development are shown requiring improvements. Given the complexities associated with each site plan the applicant is advised to understand the completion of improvements. The possibilities of satisfying the completion of improvements section will vary depending on which site is being constructed. The applicant must request, if applicable, which concurrent construction route with each individual site plan application. Acknowledged. 2. BMC 38.270.030 – As shown buildings 3-4 and 3-3 sewer will contribute to a downstream sewer constriction. 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. Acknowledged. It is anticipated that this sewer project will be a portion of the “The Henry (AKA Building 3-4)” project, the first of these two buildings to be constructed. The proposed sewer replaces will be submitted to the COB Engineering Department with the infrastructure submittal for “The Henry”. a. The improvements must be in place prior to building permit approval unless concurrent construction (BMC 38.270.030.D) is approved. Concurrent construction must be requested with respective site plan applications. Please submit a concurrent construction plan in accordance with subsection 14 addressing all the requirements of section D. Acknowledged. A concurrent construction application has been submitted as part of the “The Henry (AKA Building 3-4)” individual project. 3. DSSP V.A.6.H- The applicant must abandon any unused water service stubs at the main. Acknowledged. This general note has been included in the demo specifications for the individual projects. The applicant will continue to specify this requirement at the Site Plan level. 4. The sanitary sewer service to Block A, Lot 2A is shown running through Block A, Lot 3A. This must be moved to run straight into the right of way or an easement must be provided were it is located in the adjacent property. A planned 10’ sewer easement has been included for this proposed sewer service. The proposed location of the sewer service for the Mountain View West Building is to allow the existing trees in the boulevard south of the MVW Building to remain. The planned easement is shown on C1.5 “Lot and Easement Summary Map”. 5. Existing water wells are shown in the existing plan. If wells are to be abandoned they must be abandoned in accordance with DEQ requirements. Acknowledged. This general note has been included in the specifications for the individual projects. The applicant will continue to specify this requirement at the Site Plan level. 6. Change of street widths may require adjustment of location of manholes, inlets, curb stops, hydrants and valve boxes. Acknowledged. Transportation 1. BMC 38.400.090 - Table 38.400.090-1 provides the minimum distance between public and/or private accesses and intersections. The proposed access on to West Villard St for Building 4 is less than 40 feet from the alley access to the west of this building. The building access must be relocated or modification of this standard must be requested in accordance with subsection H of this section prior to Block 4 site plan approval. Acknowledged. A deviation request has been submitted and is currently under review as part of the Block 4 “The Ives” individual project review. 2. 38.220.080 Site Plan Submittal Requirements – Traffic Impact Study (TIS): a. The applicant is advised that engineering is in general agreement with the proposed pedestrian mid-block crossings as shown in Phase 3 of the master site plan. However, the TIS must be updated prior to site plan approvals within Phase 3 to justify the proposed mid-block crossings. Acknowledged. 3. DSSP XII Mid-Block Crosswalks - A streetlight shall be located one half to 1 mounting height in front of the crosswalk on both sides of the street for all mid-block crossings. Acknowledged. This light placement requirement will be incorporated into the individual projects’ infrastructure design.