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HomeMy WebLinkAbout21029 MSPEngCommentResponses_07142021 MEMORANDUM ------------------------------------------------------------------------------------------------------------ TO: Danielle Garber, Associate Planner FROM: Karl Johnson, Engineer I RE: APPLICATION NO 21029 - North Central MSP DATE: March 19, 2021 ----------------------------------------------------------------------------------------------------------- ENGINEERING COMMENTS: 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. Acknowledged. The applicant is currently coordinating with utility providers to determine appropriate utility and easement configurations for the Block 4 and One 11 2.0 projects. The applicant will continue to coordinate with utility providers to ensure correct utility placement and appropriate access for each individual project. It is anticipated that a number of easements will be required for the project. A new sheet, C1.6, has been included in the civil plans for the project titled “NC Shallow Utility Plan” that provides an overview of planned shallow utility and utility easements for the development. For each project within the North Central Master Plan, finalized written confirmation of required easements will be provided to the City for review during the Site Plan application process. 2. BMC 38.410.060 (C) - The applicant must provide a mutual access easement for all pathways crossing multiple lots a. This would not be required if lots are aggregated into one lot within each respective block. Acknowledged. Two of the blocks within the North Central Master Plan, Block 4 and Block B, will be aggregated such that all lots contained within the project are aggregated into single lots and will not require mutual access easements. Block 3 and Block A will both feature common access easements serving the pathways that cross multiple lots. A new sheet, C1.5 “Lot and Easement Summary Map”, has been included in the civil plans that shows the type and location of planned easements for the development. 3. DSSP V.D - Permanent structures or significant landscaping may not encroach on utility easements or be within 10 feet of utility mains and services. Acknowledged. As planned, all proposed structures or landscaping will not encroach into proposed utility easements. This issue will continue to be addressed with individual Site Plan applications. 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 2018 and 2019 in several locations across the Master Plan area. Results from this monitoring are included with this submittal. Appropriate separation from the bottom of buildings and subsurface stormwater facilities is achieved in all locations. During individual Site Plan applications, detailed design information will be provided for City review showing appropriate separation from seasonally high groundwater. 2. DSSP II.B. Storm Drainage Plan - The existing stormwater flow patterns are being changed from the historic patterns in the area. a. One 11 2.0 Building stormwater is being redirected into Beall Street storm drain that was previously flowing north on Grand. The proposed One 11 2.0 building stormwater design has been revised to direct overflow north on Grand Avenue, preserving the historical runoff pattern. b. Water from Block 4 Lot 1A previously going down North Wilson now being directed into West Villard Street storm sewer. In subsequent discussions with the City it has been determined that the originally proposed storm sewer in Villard is the appropriate choice. While historic runoff patterns are slightly altered in this instance, the overall reduction in stormwater runoff from the site is substantial and the impacts to the Villard storm sewer are insignificant. Furthermore, installation of the storm sewer in Villard reduces construction impacts on Willson Avenue. c. A portion of Block 3 Lot 4A previously draining north on North Tracey is being directed into the West Villard Street storm drain. The stormwater runoff previously draining north in North Tracy from Block 3 was captured in the curb inlets located at the Villard and Tracy. Though the path of entry into Villard Storm sewer will be altered, the overall historic drainage path is preserved. Additional information has been provided to the city confirming the existing flow pattern. d. The applicant has indicated permeable pavers will be used in public road ROW. Stormwater management systems are not allowed within public ROW. In subsequent discussion with the City, the proposed use of permeable pavers in public ROW has been accepted. This acceptance was confirmed during an April 12th meeting between the City and various members of the development team, as recorded in the attached document “Meeting Minutes”. The applicant must provide a detailed analysis evaluating impacts of changing flow patterns in the area to downstream infrastructure and discharge receiving bodies. While the storm sewer in Villard will slightly change historic runoff patterns in that area, all other historic runoff patterns have been maintained. In subsequent correspondence with the City during the Block 4 Site Plan review, the City has deemed this alteration of runoff patterns to be acceptable. Due to the very complex nature of modeling stormwater infrastructure and the significant overall reduction in runoff flows, the City has determined that the applicant is not required to analyze the downstream impacts of this flow alteration. 3. 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. 4. 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. 5. Sand/oil separators must be utilized in all parking structures. Sand/oil separators are no longer required to be utilized in all structures, based on subsequent conversations with the City as documented in the attached “Meeting Minutes”. 6. Overflow paths for stormwater must be shown 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. West Villard between Wilson and Tracy appears to be cross sloped from south to north with potential flat spots on the curb. Spot elevations shall be provided to verify that there isn’t a drainage issue. The existing grading on West Villard in this location is relatively flat and is not up to current COB road design standards. However, Villard in this location does appear to be functional. Per the April 12th discussion with City engineering personnel, no improvements to this stretch of Villard are required as part of this development. 8. DSSP V.D.1 - Provide at least 10 feet of separation between storm drain and underground utilities. Acknowledged. 9. BMC 38.410.080 (D) Grading and drainage - Stormwater ponds serving multiple lots in separate ownership must not be located in dedicated open space lots. 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. 10. BMC 38.540.020 – Snowmelt must not drain offsite. Confirm snow storage runoff will be retained and treated onsite. Snowmelt will not drain off-site. Snow storage on the periphery of each site utilizes permeable pavers for snow storage, which allows snowmelt to infiltrate as the stored snow melts. No snow melt runoff will leave the site. Water and Wastewater 1. 38.410.070. and DSSP.V.A and B – 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. • 65 gallons-per-capita-per-day must be used with 2.17 people per dwelling unit which equals 141.85 gpd/dwelling unit. Development is using an estimated 50gpd/unit based on Black Olive development which does not follow COB design standards. An estimate has been provided with the engineering report included in this submittal. 2. DSSP V.A.6.h Services - Existing water services or stubs that are not utilized for service upon development of the lot must be properly abandoned at the water main. Acknowledged. There are a number of existing services that will be abandoned at the main during the course of this project. This requirement will be included in any necessary individual Site Plan’s demolition notes. Abandonment will be performed in accordance with COB requirements. 3. DSSP V.A.8 Hydrants - Two fire hydrants are shown on the intersections of Beal and Wilson and Tracy and Villard. Only one hydrant is required at each intersection. Confirm if existing hydrants are to be abandoned. Though only one fire hydrant is required by the DSSP at each intersection, the COB Fire Department has required a fire hydrant within 100’ of each FDC within the project. After coordination with the fire department, it has been deemed that the proposed new hydrant at the intersection of Tracy and Villard is not necessary, as the existing hydrant at this intersection provides adequate protection. The proposed fire hydrant at the intersection of Willson and Beall has been moved to the north side of the proposed mid-block crosswalk in Beall, to better achieve the required 100’ proximity to the FDCs of served buildings. Transportation 1. Streets improvements: The applicant must coordinate with the city engineering department (Taylor Lonsdale, tlonsdale@bozeman.net) to achieve proper curb to curb width. • North Tracy Avenue must be widened to accommodate on street parking. Coordination with the City Engineering Department has led to the determination that widening of North Tracy Avenue will not be required. Documentation of this determination is provided in the attached minutes from the April 12th meeting with City engineering staff. • West Lamme Street must be widened to match Lamme east of the subject property and improve the intersection with North Tracy Avenue. Coordination with the City Engineering Department has led to the determination that widening of West Lamme Street will not be required. Documentation of this determination is provided in the attached minutes from the April 12th meeting with City engineering staff. 2. BMC 38.400.060 Street Improvements Standards – The applicant must demonstrate two cars can pass each other in the alley particularly on garbage day when receptacles will be out in the alley. Per the April 12th meeting with City engineering staff, the proposed alley adjacent to Block 4 has been deemed acceptable as proposed. Documentation of this decision has been provided with the “Meeting Minutes” included with this submittal. a. The applicant must submit a hold harmless agreement with the city if the city is to accept two way access in the alley not meeting standards in BMC 38.400.090. The alley meets City standards and a “hold harmless” agreement should not be required. b. The applicant must demonstrate how snow management will be provided in the alley. Snow storage will be addressed during Site Plan reviews for each building. The Site Plan for Block 4 has been submitted to the City showing that the snow storage for the alley is located between the building and the alley, along the east side of the alley. 3. 38.400.100 Street Vision Triangle – The building is encroaching on the vision triangle on buildings 3-3, 3-4, and 3-5. Specific building footprints will be determined during the Site Plan preparation for each building. The site plans have been updated to show that encroachment into the vision triangle is not a planned element. 4. 38.400.090 Access - The intersection of the access onto North Tracy is within 40’ of Lamme and does not meet the requirements of Table 38.400.090-1. Acknowledged. The location of this access has shifted from North Tracy onto Lamme Street and is further than 40’ from the Tracy Street intersection. 5. 38.220.080 Site Plan Submittal Requirements – Traffic Impact Study (TIS): a. The TIS must provide pedestrian access data to justify the proposed midblock crossings. Mid-block crossings have been deferred to later phases of the North Central Master Plan. The proposed mid-block crossings will be justified at the time of Site Plan applications when pedestrian data can be more accurately estimated. If there is insufficient justification at that time any mid-block crossing can be removed from the project without detrimental impacts to pedestrian circulation. b. The TIS must analyze the existing condition and future impacts on the North Wilson Avenue corridor. An update is provided to the TIS addressing impacts on the Willson Avenue corridor. The update shows that Willson is only minorly impacted with very small added delay. All intersections along the Willson corridor operate at Level of Service “B” or better. c. 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 will be necessary. An update is provided to the TIS addressing impacts on the adjacent local street intersections. The update shows that adjacent streets are not significantly impacted. All intersections along the adjacent streets operate at Level of Service “B” or better. 6. Dry utilities are not allowed in the public right of way boulevard. The applicant must work with the city engineering department and Northwest Energy to achieve proper location of dry utilities. In some portions of the North Central Master Plan, dry utilities currently exist within the public ROW. The applicant is currently working with Northwestern Energy and the City to determine the final location of the relocated existing dry utilities for the One 11 2.0 project. These existing utilities are currently located in the public ROW within Beall. All new utilities required to serve the One 11 2.0 addition are located outside of the public ROW in a proposed utility easement. Where required, the applicant will pursue similar coordination to resolve the issue. Lighting 1. 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. Installation of mid-block crosswalks will not be completed until the necessary lighting improvements can be made on both sides of the crossing. This has resulted in mid-block crosswalks being deferred until improvements are made to both sides of the street. ENGINEERING ADVISORY COMMENTS: Stormwater 1. 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 prior to infrastructure submittal. Acknowledged. The existing curb inlet will be replaced. The appropriate specifications will be included at the individual Site Plan/Infrastructure submittals. 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 corresponded with Griffin Nielsen about CILWR for the initial projects that comprise the Master Plan. CILWR will be paid prior to individual project’s Site Plan approval. Water and Wastewater 1. DSSP V.A.6.H- The applicant must abandon any unused water service stub at the main. Acknowledged. There are a number of existing services that will be abandoned at the main during the course of this project. This requirement will be included in any necessary individual Site Plan’s demolition notes. Abandonment will be performed in accordance with COB requirements. 2. The applicant may be required to televise the sewer main pipe to verify the condition prior to connection. Engineering is currently following up on maintenance activity performed due to the age and material (vitrified clay) of the existing pipe. Acknowledged. A sewer service similar to those proposed in the Master Plan was recently installed on the VC line in Willson to serve the existing One 11 building. Nothing unusual was encountered. 4. Existing water wells are shown in existing plan. If wells are to be abandoned they must be abandoned in accordance with DEQ requirements. Acknowledged. There are a number of existing wells currently providing heating/cooling of existing structures. Demolition notes for individual Site Plans will include the requirement to abandon in accordance with State requirements. 5. A cleanout in the landscaped right-of-way shall be provided to allow proper maintenance for storm lines with bends. Acknowledged. The Site Plan for One 11 2.0 has been updated to show a clean-out on the stormwater service just outside of the building per this comment. Any further stormwater piping in the North Central development featuring bends will include appropriate cleanouts in the design. This issue will continue to be addressed at the individual Site Plan level. 6. Change of street widths may require adjustment of location of manholes, inlets, curb stops, hydrants and valve boxes. Acknowledged. The proposed change of street widths will not impact rights-of-way, center lines, or main line utilities. Most of the width changes are proposed to correct past deficiencies where streets where not built symmetrically within the rights-of-way. Changing the curb lines will require relocation of curb inlets as shown on the North Central Master Plan drawings. Street and drainage improvements will be submitted for infrastructure review with the appropriate Site Plan. MEETING MINUTES April 12th 2021 The following is meeting minutes for meeting held on 4-12-21 to discuss engineering concerns for the North Central Master Site Plan. Attendees: Cordell Pool, Andy Holloran, Charley Franklin, Andrew Gault, Shawn Kohtz, Ross Knapper, and Karl Johnson 1. Transportation comment #1 requires the widening of North Tracy and West Lamme. Clarify requirements? a. The city will talk to Taylor Lonsdale and follow up b. City Follow-up: Widening of North Tracy and West Lamme will not be required for the project. 2. Transportation Impact Study will address mid-block crossing warrant analysis with respective site plan application. 3. The mid-block crossing on Wilson is discouraged and the mid-block crossing on Beall is encouraged. 4. Transportation comment #5 - Provide clarity on what additional information is needed to respond to this comment. a. The city will talk to Taylor Lonsdale and follow up. 5. Stormwater comment #2 – Provide clarity of what is required to respond to this comment a. City Response: Changing the flow path of stormwater will impact current stormwater system. Stormwater load cannot be increased to specific stormwater pipe segments. 6. Stormwater comment #2.c – Cordell believes this comment may be an error. a. City will look into this and follow up. 7. Boulevard permeable pavers systems will be utilized to infiltrate snow melt and provide walkway for pedestrians. a. The city accepts this use of permeable pavers in the boulevard as proposed. 8. There are no engineering concerns were voiced with utilizing the proposed planter beds for the street trees. 9. Stormwater Comment #9 – Will the proposed stormwater retention systems be required to be in common open space if easements were provided for the systems? a. The city will not require these retention systems to be in open space lots. Stormwater easements must be located over the retention systems (not to include laterals) and must provide access to remove sediments and otherwise maintain the systems. 10. Stormwater Comment #7 – Villard has existing inconsistent slopes, the whole street would have to be replaced to correct the slopes. Improvements proposed with the project will improve the drainage on Villard. a. The city will not require repairs on Villard beyond what was proposed with the master site plan submittal. 11. Wastewater Comment #1 – 65 gallons per capita per day must be utilized to determine sewer demand from the project. 12. Will offsite sewer upgrades be required for the project? a. The city will check the existing sewer capacity once the updated sewer report is received. 13. Alley west of building #4 a. The city will accept a 19 foot alley as proposed with the master site plan but recommends to maintain 2 feet from the residential lot lines to the west edge of alley asphalt. Further City review and comment will be provided with the upcoming submittal of the building 4 site plan. 14. The city did not review the proposed master site plan lighting and will look at it and provide comment with upcoming site plan reviews. Please let me know if I have made any errors or left anything out of the conversation. Thanks, Karl Johnson Engineer I