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57MSP | NORTH CENTRAL
APPENDIX
ENGINEERING REPORT
•
• Engineers and Land Surveyors
851 Bridger Drive, Suite 1, Bozeman, MT 59715 | phone: 406-522-8594
www.seaeng.com
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North Central Master Site Plan Street, Water, Sewer, and Site Preliminary Engineering Report
January 26, Master Site Plan Submittal Prepared for: HomeBase Montana Prepared by: Stahly Engineering and Associates
Engineer of Record: Cordell D. Pool, PE
Quality Control Reviewer: Zach Lowe, PE Attachments
• North Central Phased Civil Plan Sheets C1.0 – C1.4 (Existing Conditions through Phase 4)
• North Central Water Use Estimate by Building and Phase
• Hydrant Flow Test
• North Central Stormwater Calculations
Introduction North Central is an infill redevelopment roughly centered around Bozeman Medical Arts Center property. The property consists of all of Block 3 (Lots 1-24) and Lots 1-10 of Block 4 of Beall’s Third
Addition to Bozeman, Lots 2 and 3 of Block A, and Lots A and B of Block B of Tracy’s Third Addition to Bozeman. The total property size is 4.99 acres. North Central consists of 9 mixed-use buildings with approximately 940,000 sf of building area. North Central includes the existing One 11 building
but impacts from the existing One 11 building have not been considered in this report, since impacts were addressed during its recent development. One 11 2.0 is a large addition to this existing One 11 building and its development is included in this evaluation. The complete North Central building program is provided elsewhere within the Master Site Plan application. North Central envisions minor upgrades to adjacent public streets, and water, sewer, and storm drainage systems. The most extensive upgrades to public spaces include streetscape improvements providing urban streetscapes that are vibrant and welcoming and more subdued residential streetscapes where adjacent to existing neighborhoods. Urban streetscapes include “storefront” sidewalks made up of concrete sidewalks and permeable pavers, on-street parking, furniture, public bike racks, street trees, and pedestrian scale lighting. Additionally, curb bulbs and
mid-block crosswalks are utilized in appropriate locations to emphasize pedestrian travel. Public storm drainage modifications will improve roadway drainage adjacent to the site.
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The site improvements consist of phased demolition and construction of new buildings, service lines, franchise utilities, and site open spaces. All on-site parking is located within building garages. The proposed site improvements will provide inviting pedestrian pathways and open spaces through the site. These open spaces will also provide convenient locations for trash collection, franchise utilities, and on-site stormwater mitigation. Proposed buildings will be served by new services installed on the existing water and sewer network in the adjacent streets. It is anticipated that some buildings will require new fire hydrants located near Fire Department connections to the building fire suppression
systems. Figure 1 – North Central Master Plan Project Vicinity
Figure 1 illustrates the location of the development as well as proposed structures. Proposed phasing of the North Central Master Plan is shown on Plan Sheets C1.0 through C1.4 (existing conditions, and Phase 1 through 4).
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Civil Specifications and Design Standards The civil specifications for the project will be the Montana Public Works Standard Specifications (MPWSS) and the City of Bozeman Modifications to MPWSS (COB Mods). Construction plans will be developed in accordance with the City of Bozeman Design Standards. Street Improvements
Except for the un-improved section of Villard Street and the alley west of Block 4 the existing streets appear to be in adequate condition. Some minor street improvements are proposed to support the
North Central Master Plan. Willson Avenue between Beall and Villard is proposed to be widened from 37’ wide to 39’ wide to better align with the street south of Beall. Beall Street is currently 45’ wide between Willson and Tracy with curb-walks on either side. This plan proposes narrowing Beall
Street to 37’ width to match the street sections to the east and west. The unimproved section of Villard Street adjacent to Block 4 will be improved to a 37’ wide street to match improved sections of this street. Tracy Avenue will remain a 29’-30’ wide street with parking only on the west side.
Lamme Street and Grand Avenue will remain at their existing widths (34’ and 37’ respectively). Streetscape improvements are proposed with respect to the Block Frontage requirements. Storefront streetscapes where buildings are placed near the street are predominant. The proposed storefront streetscape consists of a 6’ wide concrete sidewalk and 6’ wide permeable paver boulevard. Curbed planting beds are proposed around street trees to provide a more appealing landscape than tree grates. Where pedestrian activity is emphasized, benches, bike racks, and pedestrian-scale lighting is incorporated into the streetscape. Additionally, mid-block crosswalks are
proposed on Willson and Beall and curb bulbs are proposed on Beall Street between Willson and Tracy to improve pedestrian mobility around and through the site. Where buildings are setback from the street, a typical sidewalk and planted boulevard streetscape is proposed.
On-street parking will be maintained as allowed by City code. Parking is not proposed within street vision triangles, within 20’ of mid-block crossings, or in front of trash or maintenance accesses. A new storm drain is proposed in Villard to improve drainage of the unimproved and low-slope portions of this street. A new storm drain is proposed in Tracy to collect storm runoff from Block 3. Street curb and gutter will be replaced along all building frontages, and additional curb inlets are proposed to improve street drainage at intersection crosswalks. The existing unimproved 14’ alley west of Block 4 will be paved and widened to a 16’ paved alley with new alley approaches. Water
City water mains exist in Willson Avenue, Tracy Avenue, Beall Street, Grand Avenue, and Lamme Street. The water mains in Willson Avenue, Tracy Avenue, and Grand Avenue are each 6” cast iron, the water main in Beall Street is 10” cast iron, and the water main in Lamme Street is 8” ductile iron.
The existing buildings on Block 3 are served by a single water and a single fire service from the water main in Beall Street. Block 4 has no building services, but landscape irrigation is provided by a water service from the water main in Willson. The existing buildings in Block A are served by adjacent connections to the main in Beall. Lot A of Block B is currently a parking lot and contains no
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water service connection, and the existing One 11 building is served by connections to the main in Lamme. The capacity of the existing water mains in this portion of town has been shown by the City’s Facility Plan to be adequate to support re-development. North Central, a high-density urban development, has a very efficient water use and there is significant water use currently occurring on the site. Proposed buildings would have new services for water, fire protection and sewer. New fire hydrants are proposed near Fire Department connections to the building fire suppression systems.
Table 1. North Central Estimated Water Use
Total Development Summary
Average Daily Flow Average Annual Flow
New Flows Introduced Area (sf)
#
Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Residential Units 400 50 20,000 22.40
Office 96,000 30 2,880 3.23
Retail 20,210 30 606 0.68
Hotel 66,000 100 90 9,000 10.08
Restaurant 15,000 500 7,500 8.40
Irrigation 3,260 1.00
Total New Flows 43,246 45.79
Existing Flows Removed Area (sf)
#
Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Demolished Structures Data from Meter Readings -9,956 -11.15
Total Net Increase in Flow from Redevelopment Gpd AF/yr
new flows introduced minus existing flows removed 33,290 34.64
Table 1 provides a summary of the water use estimates for new development within North Central. Approximately 25% of the impact of new water demands from the development are offset by the existing water uses removed over the course of the project. A detailed water use estimate by
building and phase is provided at the end of the report. Average domestic water use estimates were made based on proposed building use. Parameters used for these estimates are based on typical City of Bozeman values and data obtained from City meter readings. Office and retail spaces use an estimated 30 gallons per day (gpd) per 1000 sf of floor area. Restaurant spaces use an estimated 500 gpd per 1000 sf of floor area. There currently is not an established water use estimate for this type of urban, high-density residential use, so water meter readings from the recently constructed Black Olive building were used to estimate residential
water use in North Central. The Black Olive mid-rise residential building contains a very similar program of residential units with very similar projected demographic of residents. Metered water demands after the Black Olive building reached 100% occupancy showed a per unit water use of 47.25 gpd/unit. An estimated water use of 50 gpd/unit was used for residential units within North Central in this report. Similarly, hotel use estimates were made based on meter readings from similar recently developed hotels. Specifically, meter readings from the Element hotel demonstrated
a per unit water use of 90 gpd.
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Irrigation water use is very low in response to the urban design. Irrigation lines will provide water to the trees, planters and open spaces on the site. Drought tolerant plants and a drip irrigation system are proposed to conserve water. Drip irrigation lines and tree bubblers will be used for planters and trees. The irrigation system will be “high-efficiency” and use an estimated 1.0 acre-feet per year for the entire North Central project. Average annual water use for new development within North Central is estimated to be 45.79 acre-
feet/year. Approximately 11.15 acre-feet/year of existing water use will be removed by the demolition of existing structures on the development, for a net increase of annual water use of 34.64 acre-feet/year within the development.
Peak hour flows were estimated based on the average daily flow and a peak hour factor of 6, water use occurs during 4 hours of the day. Irrigation peak flows were estimated using a peak hour factor
of 3, irrigation occurs over 8 hours. Total peak hour water demand from the new development within North Central is estimated at 173.4 gpm. Applying the same peaking factors to metered flows of existing buildings on the property, it is estimated that a peak hour demand of 41.5 gpm from existing
structures is being removed from the site through demolition. The net increase to peak hour demand from the existing site conditions to proposed development is estimated to be 131.9 gpm. Planned water and fire service lines are shown on the Civil plan sheets. Buildings 3-1, 3-2, and 3-3, Mountain View West will connect to the existing 10” water main in Beall Street. Buildings 3-4 and Mountain View East will connect to the existing 6” water main in Tracy Avenue. Buildings 3-5 and 4 will connect to the existing 6” water main in Willson Avenue. The One 11 2.0 building will use the existing One 11 building’s water service, with appropriate upsizing of the existing meter. The water
service line sizes will be determined by the plumbing fixture counts in each building and the Uniform Plumbing Code flow rates for each of the fixture counts. The water and fire service lines have not been determined yet, but they are anticipated to be 4” or 6”. The water and fire service lines will be
designed by a PE and submitted for review as required by the building permit. As part of the 2017 Water facility plan, a fire flow test was performed on a hydrant on the northwest corner of Villard St and Tracy Ave adjacent to Block 3, and the test results are included with this report. The static water pressure is approximately 137 psi. Two adjacent hydrants were opened simultaneously at their 2.5” diameter nozzle, one flowed at 1,601 gpm and the other at 1,744 gpm for a total flow of 3,345 gpm. These flows resulted in a 25 psi drop at the residual test hydrant, which had a residual pressure of 112 psi. This test indicates that reasonable urban fire flows can be met in this area. Four new fire hydrants are proposed, one at each intersection, to provide improved fire protection for new buildings. It is anticipated that new hydrants would provide similar fire flows to the existing hydrant tested. Sewer
City sewer mains exist in Willson Ave, Tracy Ave, and Lamme Street. The sewer main in Willson Ave is 10” lined vitrified clay pipe (VCP), the sewer main in Tracy Ave is 8” PVC, and the sewer main in
Lamme Street is 10” PVC. It appears that there are 4 existing sewer services, 2 from Willson Ave and 2 from Tracy Ave serving the existing buildings in Bock 3. Block A appears to currently be served by a single connection to the main in Lamme Street. One 11 is served by a connection to Willson Avenue. The capacity of the sewer mains is not easily identified, and the City is currently
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updating their hydraulic model of these sewer mains. The flow data in this report will allow the City to make capacity determinations of the existing sewer mains. North Central, a high-density urban development, has a very efficient water use and low wastewater generation, and there is significant wastewater generation currently occurring on the site. Proposed new sewer service connections to the existing sewer mains are shown on the Civil plan sheets. As currently planned, Buildings 3-1, 3-2, 3-5, 4 and One 11 2.0 will connect to the existing
10” sewer main in Willson Avenue. Buildings 3-3 and 3-4 will connect to the existing 8” sewer main in Tracy Avenue. The Mountain View Buildings will connect to the existing 10” sewer main in Lamme. Additionally, to accommodate kitchen facilities, grease interceptors are being provided for restaurant
spaces in Building 3-1 and the Mountain View East building. North Central wastewater generation is anticipated to be equal to the water use shown in Table 1
less the irrigation use, or approximately 40,000 gallons per day. Approximately 10,000 gpd of existing sewer flows from structures that will be demolished will be removed from the system, for a net new wastewater generation of 30,000 gpd. Using a peak hour factor of 6, the peak hour flow
discharging to the sewer is estimated to be 166.6 gpm. An estimated 41.5 gpm of peak hour demand will be removed via demolition, for a net increase of peak hour sewer flows of 125.1 gpm. The net new sewer flows will be split between the 3 existing sewer mains as described previously and shown in the Civil plan sheets. Approximately 67.6 gpm will be added to the Willson sewer main at peak hour, approximately 15.5 gpm will be added to the Tracy sewer main at peak hour, and approximately 42.1 gpm will be added to the Lamme sewer main at peak hour.
Site Improvements
North Central site improvements consist of phased demolition and construction of new buildings, services lines, franchise utilities, and site open spaces. All on-site parking is located within building garages. The proposed site improvements will provide inviting pedestrian pathways and open spaces through the site. These open spaces will also provide convenient locations for trash collection, franchise utilities, and on-site stormwater mitigation. Lots With development the existing lots in North Central will be realigned and/or aggregated so each building will exist on a single lot. One 11 2.0 is an addition to the existing One 11 building, and the
two existing lots on Block B will be aggregated so the combined One 11 building will occupy a single lot. The two existing lots on Block A will be realigned around the new Mountain View buildings. No additional street right-of-way is required or proposed. Easements will be required to support common amenities and infrastructure. It is anticipated that easements will be required for common access, franchise utilities, and stormwater infrastructure. Access Site access is thoughtfully designed to be shared, reducing impacts to the streetscape and on-street parking. Internal pedestrian alleys provide access for trash collection, franchise utilities, and open space maintenance. Trash accesses are combined where possible, limiting impacts to on-street parking, and facilitating easier collection. On-site parking is located within garages in Buildings 3-1,
3-2, 3-3, 3-4, 3-5, 4, and One 11. Buildings 3-4 and 3-5 share a single below grade parking garage
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accessed from Tracy Avenue. Buildings 3-1,3-2, and 3-3 also share a common below grade garage with access from Tracy Avenue. Building 4 contains 3 levels of parking accessed from the alley and Villard Street. One 11 2.0 has ground level parking accessed from the existing One 11 garage from Willson, with an exit onto Grand Avenue. Franchise Utilities
Franchise utility routing (power, communications, and gas) within North Central have been shaped by historical development. Existing franchise utilities exist in the alley in Block 4, the alley north of Block 3 and within Beall Street right-of-way. Existing buildings within North Central are mostly
supplied by franchise utilities running within Beall Street. The historical utility location will largely be maintained with new points of service accommodated. The presence of utilities within Beall Street may impact the ability to place boulevard street trees along this street.
Planned improvements are to place the existing overhead power and communication lines in the Block 4 alley and Beall Street underground. Building 4 and One 11 2.0 will be served from the new
underground lines. Buildings 3-1, 3-2, 3-3 and Mountain View buildings will be served from the existing underground utilities in Beall Street. Buildings 3-4 and 3-5 will be served by new underground utilities extending from the alley north of Block 3. To the extent practical, utility meters are proposed along the sides of buildings or in building alcoves, leaving the street frontage and Beall’s Alley frontages free of utilities. Site Storm Drainage
Existing site drainage within North Central is by surface drainage onto adjacent streets or by direct connection of roof drains into storm drain mains in streets. Currently the site is approximately 79%
impervious (building, pavement, or sidewalk) without mitigation. City storm drains exist in portions of Beall Street, Villard Street and Grand Avenue. This drainage condition has not resulted in any noticeable deficiencies, so the down-stream stormwater system can be considered adequate.
Proposed North Central street improvements will add new storm drains in Villard and Tracy and curb inlets at intersections. The service area of the storm drains will not be changed, the added storm drainage infrastructure will serve to reduce surface flow and its impacts to pedestrian travel. As currently planned the site improvements will result in 81% impervious area, so relatively little increase from existing conditions. Site storm water mitigation is based on the redevelopment low impact design (LID) requirement in the City Design Standards to “infiltrate, evapotranspire, or capture for reuse the runoff generated from the first 0.5” of rainfall from a 24-hour storm. Additionally, to maintain capacity within the existing storm drainage infrastructure, the storm water mitigation will reduce peak flows from larger storm events to below the existing storm runoff flows.
Site stormwater mitigation consists of underground chamber/gravel infiltration systems for building roof runoff and permeable pavers for added site hardscape areas. These systems are planned to completely retain storm runoff from the most common storm events (approximately 1” storms,
accounting for 97% of storm events in Bozeman), and larger events will overflow (at a reduced rate) to City storm drains. A total of 4 infiltration systems are planned for: Block 3 buildings, Block 4, Block A buildings, and One 11 2.0. Table 2 shows the summary of the planned retention and runoff
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reduction. This table shows the significantly reduced storm water flows achieved by these LID systems. Detailed stormwater calculations are provided at the end of this report. Table 2. North Central Site Stormwater Mitigation System Retention Volume (cf)
% Reduction of Storm Runoff from Existing 0.5” 10-year 25-year 50-year 100-year
Block 3 6200 100% 52% 44% 40% 36% Block 4 2233 100% 50% 42% 37% 33% Block A 2985 100% 52% 44% 39% 35% One 11 2.0 1490 100% 60% 51% 45% 41% Storm Water Maintenance: General Information The proposed storm water conveyance and infiltration facilities will be operated and maintained by the property manager. Storm Water Facilities Maintenance Schedule
1. Site Housekeeping. (Continuously as needed)
The main cause of storm water facility damage is poor site housekeeping. Sediment tracked onto pavement can be washed into storm water appurtenances and damage these facilities. Trash can clog conveyance structures, potentially causing property damage.
• Keep sidewalk, permeable pavers, and parking areas clean.
• Pick up trash.
• Restore damaged landscaping in order to prevent sediment runoff. 2. Curb, Sidewalk Chase, and Infiltration System Maintenance. (Quarterly) All storm water conveyance structures can acquire sediment and debris buildup. If this sediment and debris is not periodically removed, it can cause undesired ponding and clogging. These conveyance structures need to be inspected and cleaned if required.
• Inspect for sediment or debris in the structures and remove if present.
• Inspect infiltration system through inspection ports for sediment accumulation. Sediment depth less than 3” is acceptable.
• Check for damage, repair as needed. 3. Curb, Sidewalk Chase, and Infiltration System Maintenance. (Long-term) If regular housekeeping and maintenance is not performed adequately, sediment and debris can accumulate in the storm water conveyance structures and infiltration system and clog
them beyond repair.
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• If greater than 3” of sediment is present in infiltration system, hire a contractor with a
Jet-Vac chamber cleaning system to remove the sediment from the infiltration system.
• If original system performance can be achieved through maintenance, hire a
contractor to repair and return conveyance structures and infiltration system to the initial design condition found on City engineering plans.
4. System Monitoring. (Quarterly, except in winter) The storm water facilities shall be inspected quarterly to quickly identify small issues before expensive damage can occur. In addition to regular monitoring, the best time to inspect the performance of storm water facilities is during runoff events.
• Observe system during runoff. Look for ponding on permeable pavers or inlet structures. This can indicate a clogged paver infiltration and/or clogged conveyance structure.
• Open infiltration system inspection ports within 24-hours of a storm event and look for ponded water in the infiltration system. This can indicate clogged infiltration system. If clogged hire a contractor with a Jet-Vac chamber cleaning system to remove the sediment from the infiltration system. 5. Permeable Interlocking Concrete Pavement (PICP) Inspection & Maintenance Guidelines. Service inspection and maintenance shall include the following activities:
• Winter Maintenance:
o Ensure snow is not stockpiled on permeable pavement surface. o Ensure only joint aggregate stone (typically # 8, #89 or #9 washed chip stone) is used for traction as needed. Sand should not be used for winter traction.
• Normal Maintenance:
o Inspect surface for ponding after large rain events. If ponding is observed, identify areas with severe sediment loading and vacuum to remove and
replace with new washed joint aggregate (typically # 8, #89, or # 9 washed chip stone). o Note any sediment laden run-off from adjacent areas onto permeable
pavement. If needed, correct with erosion control measures.
• Annual inspection and maintenance shall include the following activities:
o Replenish paver joints with additional aggregate if level is more than ½ in. below chamfer bottoms.
o Inspect vegetation around PICP perimeter for cover & soil stability, repair/replant as needed. o Inspect and repair all paver surface deformations (depressions/settlement) exceeding 1/2 in. o Repair paver heights offset by more than 1/4 in. above or below adjacent units, or offset by more than 1/8” lippage from paver-to-paver.
o Replace cracked paver units impairing surface structural integrity. o Check drains and outfalls (if existing) for free flow of water. Remove any
obstructions.
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o Check observation wells (if existing) to confirm reservoir is draining (based on size of last rain event).
o Vacuum surface (typically spring), adjust vacuuming schedule per sediment loading. Once a year sweeping is normal unless excessive silts and fines are present in joints.
o Test surface infiltration rate using ASTM C1781. If pavement infiltration rate is < 100 in/hr. employ remedial maintenance procedure utilizing a vacuum
sweeper/method to extract affected clogged joints/voids and replace joint/void areas with #8, #89 or #9 washed chip aggregates and retest infiltration rate to confirm reinstated areas exceed 100 in/hr. flow rate. Repeat remedial process
as needed to exceed the 100 in/hr. criteria.
• Additional Normal Maintenance Notes: o A dry mechanical or regenerative air type sweeper may be used during dry
periods to remove encrusted sediment, leaves, grass clippings, etc. Vacuum or sweeper settings may require adjustments to prevent uptake of aggregate from the paver voids or joints. Leaf blowers or other standard onsite manual
methods that are used for standard pavement maintenance may be employed to remove this surface debris. o It is not recommended to utilize a pressure washer to clean joints.
o Remove snow with standard plow/snow blowing equipment. o Deicing salt may be used on permeable pavers (proper application and appropriate salt type), but consult property owner or project engineer before usage. In some regions deicing salt use is restricted. Salt use can affect water quality and have environmental impact.
North Central Master Plan Water Use Estimate
Existing Conditions
Buildings Annual Use
Medical Arts Building Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
"Tower" Building Data from Meter Readings 1611 1.81
Existing 1 Story Building 196 0.22
Medical Arts Building 1773 1.99
Total 3581 4.01
Mountain View Building Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Mountain View Building Data from Meter Readings 3657 4.10
Deaconess Building 2718 3.04
Total 6375 7.14
Existing Conditions Total Water Total (gpd) Annual Total (AF/yr)
11.15
Phase 1
Phase 1 Construction
Average Daily Flow Annual Use
Building 4-1 Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Residential Unit 99 50 4,950 5.55
Retail 5710 30 171 0.19
Irrigation 544 0.17
Subtotal 5,665 5.90
One11 2.0 Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Residential Unit 67 50 3,350 3.75
Retail 2500 30 75 0.08
Irrigation 176 0.05
Subtotal 3,601 3.89
Phase 1 Summary Water Total (gpd) Annual Total (AF/yr)
9266 9.79
0 0.00
9266 9.79
Phase 2
Phase 2 Construction
Average Daily Flow Annual Use
Building 3-4 Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Residential Unit 48 50 2,400 2.69
Irrigation 369 0.11
Subtotal 2,769 2.80
Mountain View East Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Restaurant 9000 500 4,500 5.04
Retail 3000 30 90 0.10
Office 96000 30 2,880 3.23
Irrigation 472 0.14
Subtotal 7,942 8.51
Phase 2 Demolition
Buildings Average Daily Flow Annual Use
Existing Structures Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Existing 1 Story Building Data from Meter Readings -196 -0.22
Mountain View Building Data from Meter Readings -3657 -4.10
Phase 2 Summary Water Total (gpd) Annual Total (AF/yr)
10711 11.31
-3854 -4.32
6857 7.00
Phase 3
Phase 3 Construction
Average Daily Flow Annual Use
Building 3-1 Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Residential Unit 30 50 1,500 1.68
Retail 3000 30 90 0.10
Restaurant 6000 500 3,000 3.36
Irrigation 195 0.06
Subtotal 4,785 5.20
Building 3-2 Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Residential Unit 40 50 2,000 2.24
Retail 3000 30 90 0.10
Irrigation 289 0.09
Subtotal 2,379 2.43
Building 3-3 Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Residential Unit 46 50 2,300 2.58
Retail 3000 30 90 0.10
Irrigation 391 0.12
Subtotal 2,781 2.80
Mountain View West Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Retail 0 30 0 0.00
Hotel 66000 100 90 9,000 10.08
Irrigation 319 0.10
Subtotal 9,319 10.18
Phase 3 Demolition
Buildings Average Daily Flow Annual Use
Existing Structures Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Medical Arts Building Data from Meter Readings -1773 -1.99
Deaconess Building Data from Meter Readings -2718 -3.04
Phase 3 Summary Water Total (gpd) Annual Total (AF/yr)
19264 20.61
-4491 -5.03
14773 15.58
Phase 4
Phase 4 Construction
Average Daily Flow Annual Use
Building 3-5 Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Residential Unit 70 50 3,500 3.92
Irrigation 502 0.15
Subtotal 4,002 4.07
Phase 4 Demolition
Average Daily Flow Annual Use
Existing Structures Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
"Tower" Building Data from Meter Readings -1611 -1.81
Phase 4 Summary Water Total (gpd) Annual Total (AF/yr)
4002 4.07
-1611 -1.81
2391 2.27
Average Annual Flow
New Flows Introduced Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Residential Units 400 50 20,000 22.40
Office 96,000 30 2,880 3.23
Retail 20,210 30 606 0.68
Hotel 66,000 100 90 9,000 10.08
Restaurant 15,000 500 7,500 8.40
Irrigation 3,257 1.00
Total New Flows 43,243 45.79
Existing Flows Removed Area (sf)# Units gpd/1000 sf Gpd/Unit Gpd AF/yr
Demolished Structures Data from Meter Readings -9,956 -11.15
Total Net Increase in Flow from Redevelopment Gpd AF/yr
33,287 34.64
Average Daily Flow
9956.20
Construction
Demolition
Phase Total Net Change
Construction
Demolition
Phase Total Net Change
new flows introduced minus existing flows removed
Construction
Demolition
Phase Total Net Change
Construction
Demolition
Phase Total Net Change
Total Development Summary
Average Daily Flow
North Central Master Plan - Stormwater Calculations
Land Classification C
Rooftops 0.9
Pavement 0.9
Sidewalk 0.9
Permeable Pavers 0.3
Landscape 0.2
Total
Weighted Runoff Coeff. (C )
Design Storm 0.5-Inch 10-Year 25-Year 50-Year 100-Year
Drainage Area (acres) 2.203 2.203 2.203 2.203 2.203
Drainage Area (sf) 95983 95983 95983 95983 95983
Slope (%) 2 2 2 2 2
Time of Concentration (min) 5.0 5.0 5.0 5.0 5.0
24 Hour Precipitation Volumes (in) 0.50 1.84 2.16 2.42 2.67
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Intensity at Tc (Figure I-2 pg. 29) (in/hr) NA 3.22 3.83 4.74 5.34
Peak Runoff Rate at Tc (Q = CIA) (cfs) NA 5.61 6.67 8.27 9.31
Runoff Volume (cf) 3166 11650 13676 15322 16905
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Intensity at Tc (Figure I-2 pg. 29) (in/hr) NA 3.22 3.83 4.74 5.34
Peak Runoff Rate at Tc (Q = CIA) (cfs) NA 5.67 6.74 8.35 9.40
Runoff Volume (cf) 3196 11763 13809 15471 17069
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Runoff Volume Increase (cf) 0 113 133 149 164
Retention Volume (cf) 6200 6200 6200 6200 6200
Net Runoff Volume Post Mitigation (cf) 0.00 5563 7609 9271 10869
% Decrease in Runoff from Existing 100.00 52.2 44.4 39.5 35.7
Rain Event Captured (in.) 0.97
Land Classification C
Rooftops 0.9
Pavement 0.9
Sidewalk 0.9
Permeable Pavers 0.3
Landscape 0.2
Total
Weighted Runoff Coeff. (C )
Design Storm 0.5-Inch 10-Year 25-Year 50-Year 100-Year
Drainage Area (acres) 0.749 0.749 0.749 0.749 0.749
Drainage Area (sf) 32645 32645 32645 32645 32645
Slope (%) 2 2 2 2 2
Time of Concentration (min) 5.0 5.0 5.0 5.0 5.0
24 Hour Precipitation Volumes (in) 0.50 1.84 2.16 2.42 2.67
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Intensity at Tc (Figure I-2 pg. 29) (in/hr) NA 3.22 3.83 4.74 5.34
Peak Runoff Rate at Tc (Q = CIA) (cfs) NA 2.00 2.38 2.95 3.32
Runoff Volume (cf) 1128 4153 4875 5462 6026
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Intensity at Tc (Figure I-2 pg. 29) (in/hr) NA 3.22 3.83 4.74 5.34
Peak Runoff Rate at Tc (Q = CIA) (cfs) NA 2.09 2.48 3.08 3.46
Runoff Volume (cf) 1177 4331 5084 5696 6284
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Runoff Volume Increase (cf) 48 178 209 234 258
Retention Volume (cf) 2233 2233 2233 2233 2233
Net Runoff Volume Post Mitigation (cf) 0.00 2098 2851 3463 4051
% Decrease in Runoff from Existing 100.00 49.5 41.5 36.6 32.8
Rain Event Captured (in.) 0.95
0.83
29321
875
825
0
1624
32,645
0.87
0
29,364
0
0
3,281
32,645
0.79
77,204
0
4,274
4,841
9,664
95,983
0.80
Block 3
Existing Area (sf) Post Dev Area (sf)
28,554
7,235
0
14,869
95,983
Design Storm Information
Existing Peak Flow Calculations
Post Dev Peak Flow Calculations
Mitigation Calculations
Site Statistics
Design Storm Information
Existing Peak Flow Calculations
Post Dev Peak Flow Calculations
Mitigation Calculations
Site Statistics
Block 4
Existing Area (sf) Post Dev Area (sf)
45,325
Land Classification C
Rooftops 0.9
Pavement 0.9
Sidewalk 0.9
Permeable Pavers 0.3
Landscape 0.2
Total
Weighted Runoff Coeff. (C )
Design Storm 0.5-Inch 10-Year 25-Year 50-Year 100-Year
Drainage Area (acres) 1.090 1.090 1.090 1.090 1.090
Drainage Area (sf) 47468 47468 47468 47468 47468
Slope (%) 2 2 2 2 2
Time of Concentration (min) 5.0 5.0 5.0 5.0 5.0
24 Hour Precipitation Volumes (in) 0.50 1.84 2.16 2.42 2.67
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Intensity at Tc (Figure I-2 pg. 29) (in/hr) NA 3.22 3.83 4.74 5.34
Peak Runoff Rate at Tc (Q = CIA) (cfs) NA 2.54 3.02 3.74 4.21
Runoff Volume (cf) 1431 5265 6181 6925 7641
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Intensity at Tc (Figure I-2 pg. 29) (in/hr) NA 3.22 3.83 4.74 5.34
Peak Runoff Rate at Tc (Q = CIA) (cfs) NA 2.65 3.15 3.90 4.39
Runoff Volume (cf) 1494 5499 6456 7233 7980
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Runoff Volume Increase (cf) 64 234 274 307 339
Retention Volume (cf) 2985 2985 2985 2985 2985
Net Runoff Volume Post Mitigation (cf) 0.00 2514 3471 4248 4995
% Decrease in Runoff from Existing 100.00 52.3 43.9 38.7 34.6
Rain Event Captured (in.) 1.00
Land Classification C
Rooftops 0.9
Pavement 0.9
Sidewalk 0.9
Permeable Pavers 0.3
Landscape 0.2
Total
Weighted Runoff Coeff. (C )
Design Storm 0.5-Inch 10-Year 25-Year 50-Year 100-Year
Drainage Area (acres) 0.420 0.420 0.420 0.420 0.420
Drainage Area (sf) 18296 18296 18296 18296 18296
Slope (%) 2 2 2 2 2
Time of Concentration (min) 5.0 5.0 5.0 5.0 5.0
24 Hour Precipitation Volumes (in) 0.50 1.84 2.16 2.42 2.67
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Intensity at Tc (Figure I-2 pg. 29) (in/hr) NA 3.22 3.83 4.74 5.34
Peak Runoff Rate at Tc (Q = CIA) (cfs) NA 1.16 1.38 1.71 1.92
Runoff Volume (cf) 653 2401 2819 3158 3484
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Intensity at Tc (Figure I-2 pg. 29) (in/hr) NA 3.22 3.83 4.74 5.34
Peak Runoff Rate at Tc (Q = CIA) (cfs) NA 1.18 1.41 1.74 1.96
Runoff Volume (cf) 668 2457 2884 3231 3565
Design Storm 0.5 Inch 10-Year 25-Year 50-Year 100-Year
Runoff Volume Increase (cf) 15 55 65 73 80
Retention Volume (cf) 1490 1490 1490 1490 1490
Net Runoff Volume Post Mitigation (cf) 0.00 967 1394 1741 2075
% Decrease in Runoff from Existing 100.00 59.7 50.6 44.9 40.5
Rain Event Captured (in.) 1.12
1,152
18,296
32634
0
4,358
4,763
5,713
47,46847,468
0.72
16944
0
716
0
0.76
17,144
0
0
Post Dev Peak Flow Calculations
Mitigation Calculations
Existing Peak Flow Calculations
Post Dev Peak Flow Calculations
Mitigation Calculations
Site Statistics
Design Storm Information
Existing Peak Flow Calculations
Block B - One11 2.0
Existing Area (sf) Post Dev Area (sf)
0
0.86
636
18,296
0.88
Site Statistics
Design Storm Information
Block A - Mountainview
Existing Area (sf) Post Dev Area (sf)
21,664
3,540
10,290
0
11,974