Lantzville Foothills Phase 1 Civil Engineering Conceptual Design

Transcription

Lantzville Foothills Phase 1
Civil Engineering Conceptual Design Report
Lantzville, BC
November, 2015
Prepared by:
Herold Engineering Limited
3701 Shenton Road
Nanaimo, BC V9T 2H1
Tel: 250-751-8558
mail@heroldengineering.com
Lantzville Foothills
November, 2015
Page v
Project No. 2684-002
LANTZVILLE FOOTHILLS PHASE 1
CIVIL ENGINEERING CONCEPTUAL DESIGN REPORT
TABLE OF CONTENTS
1.0
Introduction and Background ................................................................................. 1
1.1
2.0
Project Scope – Phase 1 .................................................................................. 1
Roads and Access ..................................................................................................... 2
2.1
Road Design Criteria ........................................................................................ 2
2.2
Phase 1 Collector Road Design (Harwood Drive) ....................................... 2
2.3
Phase 1A, 1B, and 1C Road Design .............................................................. 3
2.3.1 Copley Ridge Drive - Road Design ....................................................... 3
2.3.2 High Bridge Circle and Broad Ridge Pass Road Design ................... 4
3.0
2.4
Strata and Shared Access Road Design ...................................................... 4
2.5
Phase 1 Access Options ................................................................................. 5
Water ............................................................................................................................ 6
3.1
Water Design Criteria ....................................................................................... 6
3.2
Source: Well Location, Quality, Quantity ...................................................... 6
3.2.1 Well Location ............................................................................................ 6
3.2.2 Quality ....................................................................................................... 7
3.2.3 Quantity..................................................................................................... 7
3.3
Phase 1 Domestic and Fire Flow Demands .................................................. 7
3.4
Storage Requirements for Phase 1: Domestic and Fire .............................. 8
3.5
Storage Requirements for DOL: Domestic and Fire .................................... 9
3.6
Reservoir Locations ........................................................................................... 9
3.7
Interconnectivity ............................................................................................... 9
3.8
Pumpstation ..................................................................................................... 10
3.9
Pressure Zones.................................................................................................. 10
Table 1 – PRV Settings..................................................................................... 11
3.10 Phase 1 Distribution ......................................................................................... 11
3.11 Lot Services....................................................................................................... 12
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Table of Contents continued…
4.0
5.0
6.0
7.0
Sanitary Sewers......................................................................................................... 13
4.1
Sanitary Sewer Design Criteria ...................................................................... 13
4.2
Phase 1 Distribution ......................................................................................... 13
4.3
Connection to DOL at Aulds Road .............................................................. 14
4.4
Lot Services....................................................................................................... 14
Stormwater Management ....................................................................................... 15
5.1
Storm Design Criteria ...................................................................................... 16
5.2
Storm Sewer System ........................................................................................ 16
5.3
Downstream Impact and Compliance with Riparian Areas .................. 17
Electrical, Cable, Telephone and Gas ................................................................. 18
6.1
Electrical ........................................................................................................... 18
6.2
Cable and Telephone.................................................................................... 18
6.3
Gas .................................................................................................................... 18
Conclusion ................................................................................................................ 19
Appendices
Appendix A – Drawings C01, C03, SK1
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1.0
Page 1
Introduction and Background
Herold Engineering Limited has been retained by Storm Mountain Development Corp &
Lone Tree Properties Inc. to provide analysis and assessment of the site in support of a
proposed development.
Historically, the existing site was covered in second growth forest, which provided
accessible areas for logging companies to extract quality timber. Today, the site is
being used by the local community for recreational activities such as: mountain biking,
hiking and rock climbing.
The proposed development that makes up the ‘Lantzville Foothills’ is located in the
upper area of the District of Lantzville, BC, largely located between Harwood and
Vipond Roads, and consists of 1838 acres of land as a result of a combination of
multiple parcels.
This Civil Engineering Conceptual Design Report focuses on the proposed servicing and
design strategies used to subdivide and develop 103 lots, thereby creating Phase 1 of
the development.
1.1 Project Scope - Phase 1 Subdivision
Phase 1 is located in parcel Block 471 (156.98 ha), Nanoose District, Except Parts in Plans
27114 and VIP78883. The proposed subdivision Phase 1 focuses solely on 103 single
family lots, with areas dedicated to future District-owned roads, parks and servicing
infrastructure.
The proposed 103 lots which make up Phase 1 are expected to be developed and
constructed over 3 years, and are divided into the following sub-phases as shown on
drawing C01:
Phase 1A ..................................... 34 lots (28 single family lots and 6 Strata lots)
Phase 1B ..................................... 33 lots (25 single family lots and 8 Strata lots)
Phase 1C......................................................................................................... 36 lots
Servicing requirements and rationale for Phase 1 development are examined in the
following servicing sections.
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Roads and Access
2.1 Road Design Criteria
All road and driveway design criteria will be in accordance to ‘District of Lantzville
Subdivision and Development Bylaw No. 55, 2005’. For design criteria outside of the
standards outlined in DOL’s Bylaw 55, the BC MOT Standard and Specifications for
Highway Construction and TAC Geometric Design Guide for Canadian Roads will be
used.
2.2 Phase 1 - Collector Road Design (Harwood Drive)
The main access to Phase 1 will be via a proposed collector road (Harwood Drive) with
an 18m right of way, extending from the Harwood Drive Bridge for approximately 1km
south and accommodating all traffic from Harwood Drive. Future expansion of the site
beyond the scope of Phase 1 may introduce traffic from Vipond Road, south of the
proposed development. The proposed design for Harwood Drive is adequate for all
future expected traffic.
Previous construction efforts have already blasted and cleared a majority of the right of
way swath along Harwood Drive south of the existing bridge. The existing road
alignment has been used previously as a logging road and land access, with existing
maximum grades of 12%.
Harwood Drive will provide direct access to 12 lots in Phase 1C at the south east portion
of the proposed Phase 1 development, and will serve as the main collector for entry
into Phase 1A and 1B via Copley Ridge Drive and into Phase 1C via Broad Ridge Pass.
The design criteria for Harwood Drive will be based on DOL Engineering Specifications
Section 3.7 as follows:
Collector Road Drawing .................
Road Width .......................................
Max Grade ........................................
Min. Centreline Radius ....................
Design Speed....................................
R4SS
8.0m (R.O.W. width 18m)
12.0%
100m
50km/hr.
Cross section drawing R4SS defines the collector road as having: a 2.5m wide multiuse
sidewalk (concrete or asphalt) along the fill section, 2.0m vegetated swales on both
sides, an asphalt thickness of 80mm, base course thickness of 100mm and a subbase
thickness of 250mm. Coordination with the Geotechnical Engineer to determine the
final road structure will occur during the detail design phase.
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Vertical alignment design for crests and sags will be based on the BC Mot and TAC:
K crest value ............................... 6-7
K Sag value............................. 11-12
The southbound traffic lane will be adjacent to the steep slopes of Phase 1A made up
primarily of shallow bedrock. If additional cut is required along this side, a minimum
slope of 0.25H:1V can be safely used as coordinated with the Geotechnical Engineer.
Final details will be confirmed as the design proceeds.
2.3
Phase 1A, 1B, 1C Road Design
2.3.1
Copley Ridge Drive - Road Design
Main access to the 34 Phase 1A lots and the 33 lots that make up Phase 1B will
be via an 800m long, 7.5m wide residential road, extending west from Harwood
Drive. This section of road will provide two access points to Phase 1A’s residential
roads and one access point to Phase 1B’s residential road.
The design criteria for Copley Ridge Dr. will be based on DOL Engineering
Specifications Section 3.7 as follows:
Residential Road Drawing ..............
Road Width.......................................
Max Grade .......................................
Design Speed: .................................
R3SS (R.O.W. width 16m)
7.5m
15.0%
90m
50km/hr.
Cross section drawing R3SS defines the 7.5m wide residential road as having a
1.5m wide multiuse sidewalk along the fill section, a 2.0m vegetated swale on
the cut section side, an asphalt thickness of 50mm, base course thickness of
75mm and a subbase thickness of 230mm. Coordination with the Geotechnical
Engineer to determine the final road structure will occur during the detail design
phase.
Existing vertical profiles along the previously blasted and cleared section of road
have a maximum grade of approximately 15%.
Vertical alignment design for crests and sags will be based on the BC Mot and
TAC:
K crest value ............................... 6-7
K Sag value............................. 11-12
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2.3.2
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High Bridge Circle and Broad Ridge Pass Road Design
Access to Phase 1A lots will be via High Bridge Circle a 408m long, 6.5m wide
residential road that connects to Copley Ridge Dr. at two points serving as
access to Phase 1A’s 34 lots.
Access to Phase 1B Strata, and serving as an alternate access to Phase 1C, will
be via Broad Ridge Pass which will also be based on the same 6.5m residential
road design criteria as High Bridge Circle.
Primary access to Phase 1C from Harwood Drive will be via Broad Ridge Pass, a
6.5m wide residential road based on the R2SS residential road design criteria. This
road will also connect with Copley Ridge Drive from Phase 1B side.
The design criteria for High Bridge Circle and Broad Ridge Pass will be based on
DOL Engineering Specifications Section 3.7 as follows:
Residential Road Drawing ..............
Road Width .......................................
Max Grade ........................................
Design Speed....................................
R2SS (R.O.W. width 15m)
6.5m
15.0%
90m
50km/hr.
Cross section drawing R2SS defines the 6.5m residential road as having a 1.5m
wide multiuse sidewalk along the fill section, a 1.5m vegetated swale on the cut
section side, an asphalt thickness of 50mm, base course thickness of 50mm and
a subbase thickness of 200mm. Coordination with the Geotechnical Engineer to
determine the final road structure will occur during the detail design phase.
Vertical alignment design for crests and sags will be based on the BC Mot and
TAC:
K crest value................................ 6-7
K Sag value ............................. 11-12
2.4 Strata and Shared Access Road Design
Strata Roads in Phase 1A (Lost Bear Glen) and Phase 1B (Stone Gate Heights), private
access lane (Hidden Terrace Lane), and shared driveways shall be built to the same
road structure and width as residential road R2SS.
The strata roads, private access lanes and shared driveways will be designed to DOL’s
standard identifying a maximum common driveway grade of 18%.
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2.5 Phase 1 Access Option
As previously stated, main access to Phase 1 will be via the Harwood Drive/ Aulds Road
intersection consisting of a proposed road realignment made up two radii; a 75m radius
and a 55m radius at 40km/hr design speed configuration from Aulds to Harwood (east
to south). This proposed realignment will be almost entirely located on 6696 Harwood
Drive as shown on drawing C03. This lot has been purchased by the Developer, Storm
Mountain Development Corp, specifically for this road realignment.
Harwood Drive will be reconstructed to suit the proposed realignment, and a proposed
back to back 55m radius at 40km/hr design speed s-curve will accommodate vehicular
traffic over the existing Harwood Drive bridge. The latest traffic impact assessment
conducted by Boulevard Transportation, dated October 28, 2015, anticipates that peak
pm hour vehicular traffic from Aulds to Harwood will increase from 4 to 76 vph, and from
Harwood to Aulds, the peak pm hour vehicular traffic will increase from 1 to 43 vph. The
aforementioned road realignment will accommodate this increase in traffic without
disturbing the existing level of service, by keeping traffic flowing through Aulds
Road/Harwood Drive.
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Water
3.1 Water Design Criteria
All water design criteria will be in accordance to ‘District of Lantzville Subdivision and
Development Bylaw No. 55, 2005’ and MMCD standards. In particular, DOL Bylaw 55
states that:
•
“All new lots shall be provided with a connection to the Municipal water system,
or if not available, confirmation is required from a Professional Engineer that
each new lot has the capability to supply 3400 litres (748 gallons) of drinking
water (that meets the Drinking Water Protection Regulation) per day from a
well.”
•
Minimum residual pressure during peak daily demand = 275 kPa (40psi)
•
Minimum residual pressure at fire flow rate + average daily demand = 138 kPa
(20psi)
•
Maximum working pressure at the main = 1035 kPa (150psi)
Since there is no municipal water connection available for Phase 1 of the project, a
250mm diameter production well has been drilled and completed by GW Solutions
(GWS) in October, 2014. This well will be used as the primary water supply for the 103 lots
that make up Phase 1.
3.2 Source: Well Location, Quality and Quantity
3.2.1
Well Location
The 250mm diameter production well named PW D4-2014 GWS 10” is located
approximately 540m southwest of the proposed Foothills reservoir as shown on
drawing C04 with the following UTM coordinates:
Zone 10
Easting ................................................
Northing .............................................
Ground Elevation Near Well Head
420273.71 m
5453243.50 m
285m
12m west of the production well, is a multilevel monitoring well named MW D32013 GWS 6” (first drilled in February 2013 and completed in October, 2014). Both
wells have been drilled to monitor and obtain water supply from a fractured
bedrock aquifer.
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It should be noted that on November 6, 2015, GWS provided a draft report on a
second production well named PW 2-2015-GWS-10”, located approximately
300m away from PW D4-2014 GWS 10”, with adjacent monitoring well named
Well #2-2015-GWS-6”.
3.2.2
Quality
According to the GW Solutions (GWS) report dated September 18, 2015, quality
from well PW D4-2014 GWS 10” was tested by Maxxam Analytical during a 72
hour pumping test in November, 2014, and the testing results were compared
against the current applicable Guidelines for Canadian Drinking Water Quality –
GCDWQ. The parameters tested included: conductivity, temperature, pH,
oxido-reduction potential, dissolved oxygen, and salinity. Results of these tests
indicate that all analyzed parameters meet the GCDWQ guidelines except for
pH levels, which are slightly higher than recommended (8.8 vs. 6.5-8.5); however,
it was noted in this report that the pH levels are expected to decrease with time.
3.2.3
Quantity
The calculated safe yield for well PW D4-2014 GWS 10” has been extrapolated
(by GWS) using the 100-day straight-line projection method in conjunction with a
72 hour pumping test. The extrapolated drawdown over 100 days is 62m, with
pumping continuously at 110 USgpm. The maximum recommended safe yield of
PW D4-2014 GWS 10” is 67 USgpm or 56 Igpm.
The second possible production well, PW 2-2015-GWS-10”, has a safe pumping
yield of 50 Igpm or 60 USgpm. Further details on this second production well will
be investigated for potential use in the future expansion of Lantzville Foothills,
after Phase 1 has been developed.
3.3 Phase 1 Domestic and Fire Flow Demands
As stated in the DOL Bylaw No. 55, all new subdivisions require confirmation of a well
source that can provide 3400L/day/lot. The proposed Phase 1 lots are broken up as
follows:
Phase 1A, 1B, 1C – 103 Lots @ 3400L/day = 350,200L per day supply required.
Well source PW D4-2014 GWS 10” = 67 USgpm = 96,480 US gallons/day, or 365,217L/day,
which would indicate that the well source is capable of meeting the water demand as
outlined in the DOL Bylaw 55 for the proposed 103 lots.
The DOL Bylaw No 55 does not provide design criteria for domestic flows other than a
total maximum daily demand of 3,400L/day/lot. Therefore, this will be the criteria used
for maximum daily demand and for reservoir sizing.
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For fire protection storage, there are a number of storage computations which can
yield highly varied results based on factors such as building size, separations, firewalls
and occupancy class. For the purposes of this report, Phase 1 development will
comprise solely of single family dwellings. At this time it is assumed that the houses will
be multi-storey buildings with a maximum total floor area of 300m2. The typical fire flow
calculation according to the Water Supply for Public Fire Protection 1999 (FUS) is:
F=220C√A
where:
F= the required fire flow in L/min
C= coefficient for construction type (in this case wood frame @ 1.5)
A= total floor area in m2 (in this case 300 m2)
Resulting calculation: F=5,716 L/min
Additional charges:
Low hazard occupancy (-25%)
= -1,429 L/min
No sprinklers (0%)
= No change
Exposures, assume 2 sides at 3.1m (+40%)= +1715 L/min
= 6,002 L/min
Required Fire Flow = 6,002 L/min (100 L/s)
The Fire Underwriters Survey recommends 2 hour duration at the required fire flow,
which results in a fire flow requirement of: 720,240L.
It has been noted in the District of Lantzville water study presentations that the minimum
recommended fire flow for residential buildings is 75 L/s for a 2 hour flow.
It should also be noted that the total fire volume can be reduced (by up to a 50%
charge) if all buildings are sprinklered. Furthermore, calculations for future demands
have not been accounted for at this time (outside of Phase 1), and future phases will
require new calculations for both fire flow and domestic water supply.
3.4 Storage Requirements for Phase 1: Domestic and Fire
Reservoir storage requirements are obtained from the MMCD Design Guidelines. The
Total Storage Volume = A + B + C
Where:
A = Fire Storage (calculated above)
B = Equalization Storage (25% of Maximum day Demand)
C = Emergency Storage (25% of A + B)
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Therefore the total storage volume requirement for Phase 1:
• A = 720,240L
• B = 350,200L x 0.25 = 87,550L
• C = (720,240L + 87,550L) x 0.25 = 201,948L
Total Storage Volume ...................................................................... 1,009,738L (1,010m3)
It should be mentioned that the emergency storage value (C) may be eliminated
based on several factors approved by the District of Lantzville, which are outlined in the
MMCD.
3.5 Storage Requirements for DOL: Domestic and Fire
The District of Lantzville has requested that Storm Mountain include provisions for the
design, and future supply and installation of a new municipal-owned reservoir with
1,800 m3 storage capacity. This reservoir will be used to supply the future anticipated fire
and domestic water demand of the District of Lantville as projected by the District. It is
expected that this water reservoir will receive its water supply from a future connection
into the City of Nanaimo’s municipal water supply, the details of which are unknown at
this time.
3.6 Reservoir Locations
The Reservoir for Phase 1 of the Lantzville Foothills project is proposed to be located as
shown on plan C01 with a reservoir foundation elevation of approximately 339m (top
water level = 342m). This elevation is not necessarily required to be able to service
Phase 1; however, previous construction efforts have created a level, suitable building
pad at this location. This elevation will also be suitable for future reservoir expansion to
service future Phase 2, located south of Phase 1.
The Reservoir for the District of Lantzville, is proposed to be located as shown off of
Harwood Drive on plan C01 with a reservoir foundation elevation of approximately
159m (TWL = 162m).
Both reservoirs will be equipped with low and high level alarms, with data transmitted to
the District of Lantzville for operation and monitoring purposes.
3.7 Interconnectivity
At this time, it is envisioned that Well PW D4-2014 will be directly connected to the
Lantzville Foothills Phase 1 reservoir via a 100mm DR9 HDPE pipe complete with power
and control cables buried beside it and a submersible well pump adequately sized to
pump at the maximum recommended safe yield. Level monitors in the Lantzville
Foothills reservoir will control the well pump.
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The proposed alignment of the well supply to reservoir connection is shown on drawing
SK1, with the total distance equaling 1,080m.
The proposed 100mm HDPE supply line will have a maximum operating pressure of
160psi, along with a maximum water velocity of 0.73m/s at the maximum safe well
pumping rate. Water treatment and residual chlorination will be further developed as
the design proceeds, but are anticipated to include chlorination of the well water
supply via hypchlorinator located within a pumphouse, in an appropriate location to
ensure proper water treatment and contact time prior to distribution.
The Lantzville Foothills reservoir will serve as the main water supply for Phase 1, with
interconnection via a 200mm diameter PVC line to the proposed DOL reservoir aligned
within Phase 1B’s residential road heading west along Broad Ridge Pass, and east along
Copley Ridge Drive where it will turn north to connect to the proposed DOL reservoir
along Harwood Drive. This proposed 200mm diameter PVC watermain will serve solely
as an emergency reservoir fill supply watermain for the Lantzville Foothills reservoir, and
will be called to fill via level monitoring equipment. The proposed DOL reservoir on
Harwood Drive will be supplied with water through a future connection to the City of
Nanaimo (at an assumed location near Aulds Road/Phillip Road intersection).
It is currently envisioned that the proposed DOL Reservoir will be supplied with water via
a 200mm diameter PVC watermain connecting from the Aulds Road/Philip Road
200mm watermain supply line, through Harwood Drive, south along proposed Harwood
Drive and into the proposed DOL Reservoir. It is assumed that the water supply line to
the proposed DOL reservoir will be sufficiently treated and no further treatment will be
necessary upon filling of the reservoir. DOL plans to connect to City of Nanaimo water
supply in the future, with the details unknown at this time.
3.8 Pumpstation
As the proposed reservoir locations and elevations have not deviated from the original
Core Group Consultants design in 2008, the booster pump station will be located at the
proposed DOL Reservoir location complete with 3 multi-stage Grundfos CR 45-7 pumps
(60 hp motors). Each pump is rated to supply 250 USgpm at 205m head. 2 pumps will be
duty pumps, and one will be a standby pump for supplying the Lantzville Foothills
Reservoir (TWL at this time = 342m) with emergency water should the well supply
become temporarily unavailable. Level monitors in the Lantzville Foothills reservoir will
trigger booster pump operation.
3.9 Pressure Zones
The pressure zones and pressure reducing valve (PRV) locations outlined in the original
Core Group Consultant design in 2008 are appropriate for this design report as the
overall subdivision location of Phase 1 is similar. The exact inlet and outlet pressure
requirements will be determined as the design progresses.
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The proposed pressure zones are as follows (refer to drawing SK1 for additional
information):
Zone
1
2
2
3 (future)
Existing
PRV
Elevation
(m)
Reservoir 342 TWL
1
254
2
237
3
166
4
116
Inlet Pressure
(m,psi)
88m, 125psi
105m, 150psi
107m, 152.6psi
74m, 105psi
Outlet HGL (m)
273
273
190 (future)
148
Table 1 – PRV Settings
The locations, elevations, pressures and hydraulic grade lines at the PRVs may change
once the system has been modeled and as the design proceeds. Also, private land
acquisition adjacent to Harwood Drive through the Tavender’s property will be the
determining factor of how the water supply distribution for the future 18 lots (Lot A) is
finally configured.
3.10
Phase 1 Distribution
All watermain piping and fittings design will be to DOL Bylaw No. 55 and MMCD
standards. The proposed distribution will include a 350mm PVC distribution line from the
highest point at Lantzville Foothills Reservoir and delivered to lower pressure zones,
passing through 3 pressure reducing valves, where the distribution line within Phases 1A,
1B, and 1C will reduce to a 200mm PVC watermain. Due to the general steepness of
Phase 1, water main grades will exceed 10% in a number of areas, and will require
trench water mitigation via trench dam installation.
The distribution main within Harwood Drive will be a 250mm PVC watermain, sized for
future expansion south along Harwood Drive, and will also have provisions for future
connection to a 200mm distribution watermain within the 18 lot subdivision that forms
‘Lot A’.
The existing Harwood Drive bridge was designed and constructed with two watermain
crossings: a 350mm diameter opening for the water distribution main, and a 275mm
diameter opening for the supply line for the proposed DOL reservoir on Harwood Drive.
Construction also included supported, insulated piping installed along the underside of
the bridge.
Fire hydrant spacing shall conform to DOL Bylaw 55, such that the maximum lineal
spacing between hydrants is 150m.
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Additionally, hydrants will be spaced such that every home is within a 120m radius of a
hydrant, with fire flows as calculated in section 3.3 using the FUS guidelines. Fire truck
maneuverability will be a governing factor when designing Phase 1 road networks and
turn arounds.
3.11
Lot Services
At this time, it is anticipated that individual lot service connections will be 25mm
diameter polyethylene service piping, complete with AWWA standard backflow
prevention device and water meter within a box at the property line.
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Sanitary Sewers
4.1 Sanitary Sewer Design Criteria
All sanitary sewer design criteria will be in accordance to ‘District of Lantzville
Subdivision and Development Bylaw No. 55, 2005’ and MMCD.
Since there is an existing 250mm PVC sanitary sewer main in Aulds Road, with a 250mm
PVC stub connection at the Harwood Drive/Aulds Road intersection, the proposed
development will be connected to this system. DOL has confirmed that the sewer main
has sufficient capacity to accommodate the proposed development.
Average daily sewage design flows will be based on 270L/cap/day, with a single family
house population equivalent of 2.5 people per unit. The peaking factor will be
calculated according to the Harmon formula:
PF = 1 + 14/(4+√P)
•
Minimum allowance for groundwater infiltration will be based on
0.13L/second/hectare, or 1,000igal/day/acre.
4.2 Phase 1 Distribution
All sanitary sewer piping and fitting design will be to DOL Bylaw No. 55 and MMCD
standards.
The proposed distribution within Phase 1 will include 200mm PVC gravity collection
mains along the major roadways, with 150mm PVC mains collecting along the strata
roads and common access roads. Due to the general steepness of Phase 1, sanitary
main grades will exceed 10% in a number of areas. These areas will incorporate trench
dams as required to mitigate trench water.
The sanitary main along Harwood Drive will be a 250mm PVC gravity main with a stub
and cap installed south of Phase 1C for future expansion. Lots along Harwood Drive
opposite of Phase 1C access will be at a lower elevation than the gravity sanitary main
and will require pumped sanitary services. The DOL services will be gravity to the
property line and pumped within the property. Out of the 103 proposed lots for Phase 1,
27 lots are envisioned to require individual sanitary pump stations; however, the exact
sanitary sewer configuration will be determined during detail design, and may reduce
the number of lots requiring individual sanitary pump stations.
The existing Harwood Drive bridge was designed and constructed to allow a sanitary
sewer crossing complete with a 350mm diameter opening for the sanitary sewer main.
Construction also included supported, insulated piping installed along the underside of
the bridge.
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4.3 Connection to District of Lantzville at Aulds Road
Existing record drawings for the DOL show a stubbed 250mm connection at SMH 35 at
the intersection of Harwood Drive and Aulds Road. The proposed 250mm trunk sewer
along the proposed Harwood Drive extension and existing Harwood Drive will meet the
250mm stub invert elevation of 113.36m.
4.4 Lot Services
For the total 103 proposed lots, servicing solutions shall be chosen based on one of the
following options:
•
•
•
Gravity service at the lowest side of the lot
Gravity service crossing neighbouring property within easement
Individual sanitary pump station on lot with pressure service connection to gravity
sewer service located at the property line
Per DOL Bylaw No. 55, individual residential service connections shall be no less than
100mm in diameter at a minimum 2.0% grade.
It is envisioned at this time that individual pump stations will be required for lots: 29-34,
39-41, 64, 70, 74, 87, 89-91, and 92-102, while the remaining lots will be serviced via a
gravity connection.
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5.0 Stormwater Management
5.1 Storm Design Criteria
All storm design criteria will be in accordance to ‘District of Lantzville Subdivision and
Development Bylaw No. 55, 2005’ and MMCD. Rain Water Management system
requirements are detailed in Schedule D and in Schedule F (Section 3.5) of the DOL
Bylaw No. 55. Some of these requirements include:
Rain Water Management,
•
The Municipality requires that Low Impact Development (LID) techniques be
incorporated in all developments and that the Developer provide drainage
structures that will:
-
Reduce the rate of post development site runoff to predevelopment levels of
a 10 year rain fall event
Ensure a “zero net increase” in runoff
Improve the quality of site drainage water
Reduce erosion and sediments
Address downstream impacts of peak rain runoffs created by the
development.
•
Rainwater shall be managed using surface structures as much as possible. For this
project, natural wetland areas and ponds/swamps shall be incorporated into the
design.
•
Detention facilities (including natural features and wetlands) require the
following criteria:
a. Live storage volume for minor event (2 year storm) shall be 200 m3/ha of
impervious surface area (roof, driveways, roadways, and other hard
surfaces).
b. Corresponding max release rate shall be 5 L/s of contributory catchment.
c. Normal overflow capability for the peak 10-year design flow.
d. Emergency overflow for the 200-year peak design flow, routed in a way
that does not threaten downstream property with erosion or flooding.
e. Rain water storage volumes may be reduced if used in combination with
an infiltration system design in accordance with good engineering
practice.
f.
Rain water storage may be eliminated if peak minor event post
development discharge downstream from an infiltration system does not
exceed 5L/s per ha of contributory catchment.
2684-002
November 12, 2015
November, 2015
•
Page 16
Any rain water management facility proposed to be located on public park land
shall conform to the `Development Guidelines for Surface Rain Water
Management`.
Schedule D – Standards for Rain Water Management Systems of DOL Bylaw No. 55
states that:
•
All small lot residential developments require a rain water management system
that will:
-
Provide an enhanced storm water system installed by the Owner that will
detain water onsite.
•
Any watercourse flowing through the Subdivision shall be protected as an open
channel and left in a natural state or upgraded using current technology to
enhance the riparian zone and stream channel; and,
•
Any flow of surface water from adjoining land or from the Subdivision land shall
be maintained naturally along the existing ground surface.
•
New lots must have a 30 cm thick organic soil layer maintained or replaced on
surfaces that will be vegetated.
All runoff from Phase 1 will eventually drain into Copley Creek. Rain water management
for Phase 1 will ensure that:
1. Impacts to this stream are minimized.
2. 100 year storm runoff will have overland routes identified.
3. Natural flows are retained overland as long as possible and groundwater
recharge maximized.
The Rational Method shall be used to calculate design flow rates for Phase 1
development:
Q = CiA x 2.78
Where C = coefficient of runoff
i = runoff intensity in mm/hour
A = contributing catchment area in hectares
Q = stormwater flow in L/s
5.2 Storm Sewer System
It is anticipated that the majority of the storm system design will be comprised of
roadside ditches with culverts designed and located at low points in the stormwater
drainage system to distribute and direct flows to the natural onsite detention features.
2684-002
November 12, 2015
November, 2015
Page 17
Once the natural drainage paths and watercourses have been identified, the existing
wetlands and natural detention features shall be incorporated to the greatest extent
possible.
5.3 Downstream Impact and Compliance with Riparian Areas
Under the Riparian Area Regulations, an assessment of areas within 30m of a
watercourse must be conducted by a Qualified Environmental Professional, which will
be conducted by EDI Environmental Dynamics, and will identify areas to be preserved,
protected or enhanced.
The RAR Methods state the following:
Stormwater resulting from development within the assessment area (30 m from
streams) should be returned to natural hydrologic pathways. The key to run off
volume reduction and water quality improvement is capturing the small storm
runoff (less than 50% of the rainfall event that occurs once per year, on average)
from these rooftops and impervious surfaces for the entire development. The
goal is to capture runoff from rooftops, driveways, parking and other impervious
areas for infiltration, vapor-transpiration and/or reuse. The RAR is only able to
address development within the Riparian Assessment Area but stormwater
management is an issue for the entire development site and watershed.
Since the District of Lantzville’s Bylaw No. 55 requires LID techniques be implemented to
ensure a “zero net increase” in runoff, the proposed development will require individual
lot storage be designed and installed (soil permitting) by DOL standards, which in effect
will meet the basic RAR objectives.
It should be noted that in 2007 EBA produced a ‘Rainwater Infiltration Feasibility Study’,
outlining most lots within Phase 1 as having low to moderate soil infiltration capacity,
and with only 2 lots specifically noted as having ‘soils suitable for infiltration’ (equivalent
lots in this subdivision are lots 1,2,3 and 4). As the design proceeds, further investigation
will be required to determine which lots within Phase 1 will be conducive to individual
onsite stormwater detention.
2684-002
November 12, 2015
November, 2015
6.0
Page 18
Electrical, Cable, Telephone and Gas
6.1 Electrical
Phase 1 power supply is proposed to be fed from existing overhead power north of
Harwood bridge. Three phase overhead power will extend along the southbound side
of Harwood Drive for 690m until the entrance to Phase 1a, at Copley Ridge Drive, and
then will dip underground for 3.1km of buried servicing for Phase 1. Servicing will include
power to street lighting. It is anticipated that individual power ducting to homes will be
laid under driveways.
Primary correspondence with BC Hydro has been started, but there have not been any
further discussions other than introductory emails and phone calls. Discussions with the
electrical consultant and BC Hydro for primary and secondary power will be held
during as the design proceeds.
There is a 39.42m wide statutory right of way for gas and hydro that runs east of
proposed Harwood Drive. No works relating to the development of Phase 1 are
expected within this right of way.
6.2
Cable and Telephone
Preliminary discussions with Shaw Cable and Telus have not yet been held. It is
expected that cable and telephone ducts will be laid in common trench with hydro
ducting throughout Phase 1, with adequate duct separation per design standards and
specifications. Common trench duct installation (hydro, cable, and tel) is expected for
individual home services as well.
6.3
Gas
A high pressure transmition gas main (150mm diameter) that serves Vancouver Island is
present within the aforementioned 39.42m wide gas and hydro right of way, located
north of Phase 1, and travels through the north boundary of Galloway Marsh and finally,
heads south east along the border of Phase 1.
Preliminary discussions with Fortis have not yet been held, but detail design of gas
servicing for Phase 1 will be expected once the other utilities have established their
design servicing concepts.
2684-002
November 12, 2015
November, 2015
7.0
Page 19
Conclusion
The design of the civil works associated with this project will be consistent with the
District of Lantzville’s Subdivision and Development Bylaw No. 55, 2005 and other design
standards mentioned in this report, and will align with the overall project goals of
usability and practicality.
Prepared by:
Reviewed by:
HEROLD ENGINEERING LIMITED
Paul A. Perejma, P.Eng.
George Hrabowych, P.Eng
2684-002
November 12, 2015
November, 2015
Page 20
Appendix A
2684-002
November 12, 2015
PARK
PARK
P-1B
E
1A
E
AS
PH
AS
PH
P-1A
STRATA
PARK
PHA
PARK
SE 1
A
SE 1
C
PHASE 1B
PHASE 1C
PHA
PARK
P-1C
PARK
PARK
PHASE 1
PRELIMINARY LOT
ARRANGEMENT
C01
LONE TREE PROPERTIES
PARK
LANTZVILLE, BC
PRELIMINARY LAYOUT REVIEW
LANTZVILLE FOOTHILLS - PHASE 1
1B
STRATA
HARWOOD DRIVE &
AULDS ROAD
C03
LONE TREE PROPERTIES
LANTZVILLE
LANTZVILLE FOOTHILLS - PHASE 1
TO CITY OF NANAIMO
CONNECTION
FUTURE
CONNECTION
ZONE 3
(FUTURE)
PRV 4
ZONE 3
(FUTURE)
ZONE 2
ZONE 2
PROPOSED DISTRICT OF
LANTZVILLE RESERVOIR
AND PUMPHOUSE
ZONE 1
PRV 2
ZONE 1
PRV 3
ZONE 2
PRV 1
WATER SUPPLY
EASEMENT
LANTZVILLE FOOTHILLS
RESERVOIR
LANTZVILLE FOOTHILLS
RESERVOIR ACCESS ROAD
WELL SUPPLY LINE
WELL D-4
LOCATION
LANTZVILLE FOOTHILLS - PH1
WATER SUPPLY &
DISTRIBUTION
SK-1

Lantzville Foothills Phase 1 Civil Engineering Conceptual Design

Transcription

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