HomeMy WebLinkAboutCENTERPOINT PLAZA - FDP - FDP160027 - SUBMITTAL DOCUMENTS - ROUND 4 - EROSION CONTROL LETTER/REPORT1
EROSIONCONTROLREPORT FOR
CENTERPOINT PLAZA FIRST REPLAT
Job Number 1028
August 11, 2016
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EROSION CONTROL REPORT
FOR
CENTERPOINT PLAZA
PREPARED FOR:
NEXGEN PROPERTIES, LLC
One Denver Tech Center
5251 DTC Parkway, Suite 8000
Greenwood Village, CO 80111
(303) 923-2442
PREPARED BY:
RICK ENGINEERING COMPANY, INC.
4 Inverness Court East #300
Englewood, CO 80112
(303) 537-8020
JN 1028
August 11, 2016
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Table of Contents
1.0 Introduction
1.1 Site Description………………………………………………………………………5
1.2 Stormwater Management Controls: …………………………………………………6
1.3 Disturbed Soils ………... ……………………………………………………………6
1.4 Vehicle Tracking Control……………………………………………………………6
1.5 Location of Contaminated Soils ……………………………………………………6
1.6 Vehicular Traffic………………………………………………………….…………7
1.7 Location of Material Stockpile……………………………………………..………..7
1.8 Batching Plant………………………………………………………………….……7
1.9 Maintenance…………..…………………………………………………,,,,,,,………7
1.10 Portable Toilets, Workers Trash and Onsite Waste Management Practices…,,,.…... 7
1.11 Dewatering………………………………………………………...,...…………..…7
1.12 Soil Characteristics………………………………………………….,……,,………7
1.13 Seeding and Mulching…………………………………………………,,,,,,,………7
1.14 Controls……………...…………………………………………………,,,,,,,………8
2.0 Construction Sequence………………………………………………………………………13
2.1 Erosion Control Plan…………………………………………………………………….…15
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2.2 Erosion Control Security Calculations…………………………………………….…….…15
List of Figures:
Figure, 1 Project Site Location…………………………………………………………………5
List of Tables:
Table 1 Construction Sequence…………………………………………………………………13
Table 2 Estimate of Probable Cost for Erosion Control Escrow Security…………………… 15
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1.0 Introduction
1.1 Site Description
Centerpoint Plaza (project site) is located in the northwest quarter of Section 20,
Township 7 North, Range 68 West of the 6th
Principal Meridian in the City of
Fort Collins, Colorado. More specifically, the project site is bounded by
Timberline Road on the west, Midpoint Drive on the north, Railroad Right of
Way on the north and industrial development to the east as shown on the location
map (Figure 1) below.
The project site is a total of approximately 2.34 acres. Phase 1 development was
completed in May of 2006. The Phase 2 area is approximately 1.57 acres. Soil is in
undisturbed state on the site and consists of native weeds and medium dense grasses.
There are no impervious areas on the site other than a walkway running North South. The
project is going to be a 2.5 story commercial building with other site infrastructure
consisting of paved parking areas with curb, gutter and sidewalk, utility service line and
storm utilities. The Centerpoint Plaza site is within the Spring Creek Drainage Basin, as
identified by the City of Fort Collins Master Drainage Plan, but not within any regulatory
floodplains designated by either the City or FEMA. Spring Creek is a major watercourse
that flows from Spring Canyon Dam at Horsetooth Reservoir to its confluence with the
Poudre River.
Figure 1: Project Location
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1.2 Stormwater Management Controls:
Description of all SWMC:
The project has no SWMP administrator as of now, a SWMP Administrator will be designated to
the project when the project will be awarded to a contractor. The SWMP Administrator shall be
responsible for all SWMP needs including immediate maintenance and correction of BMPs on site.
During the performance of the work required by the plans, the contractor shall carry out proper
measures wherever necessary to reduce dust nuisance. The contractor will be held liable for any
damage resulting from dust originating from his operations under these plans, on right-of-way or
elsewhere.
1.3 Disturbed and Stored Soils
Approximately 1.57 acres will be disturbed during construction and any disturbed soils shall be
stabilized with the appropriate BMPs on site as shown on the erosion control plan and sequencing
chart. Earthwork on site is anticipated to be a balance, and/or any excess shall be hauled off-site.
No large stock piles are anticipated and no stock pile shall exceed 10 feet in height. Minimal stock
piles of utility spoils may occur on site and shall be stabilized to prevent sediment transport by
surface roughing, watering and perimeter silt fencing.
The general sequence of major construction activities will be as follows:
• Clearing and grubbing
• Rough grading including grading of water quality basins
• Utility installation – Sewer, storm drain, water and dry utilities
• Building construction
• Roadway fine grading and paving
• Landscaping
Silt fence will be installed before any site disturbance to check erosion. After the site is graded, it
will be protected using wattles laid on contours and the site will be hydroseeded to prevent any
erosion post grading. Inlets shall be protected using rock socks. Silt fences will be removed after
the site has stabilized and there is required amount of vegetation. In addition to stormwater
discharge there are no other sources of non-stormwater discharge through the site.
1.4 Vehicle Tracking Control:
Wherever construction vehicles access routes intersect paved roads, provisions shall be made to
minimize the transport of sediments by runoff or vehicles tracking on the paved surface. A
stabilized Vehicle Tracking Control (VTC) pad shall be installed and maintained throughout
construction, as shown on the drainage and erosion control plan. The contractor shall be
responsible for clearing tracked mud on a daily basis.
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1.5 Location of Contaminated Soils
There are no contaminated soils located on the project site.
1.6 Vehicular Traffic
All the vehicular traffic on site will pass through North East side of the site and over the Vehicle
Tracking pad so that tracking of mud on streets is minimized. Contractors shall take advantage of
parking, loading and unloading on the existing paved areas to the north of the site, where available,
in order to minimize parking on the active construction site.
1.7 Location of Material Stockpile
Location of Material Stockpiles shall be located a minimum 50 feet away from any inlet structure
or watercourse. Material stock piles such as utility piping, construction building materials are
anticipated to be located to the west of the site, in the proposed parking areas, south of the
proposed building. During construction, material stock piles shall be secured and covered during
any storm events.
1.8 Batch Plant
There shall not be any asphalt or concrete batch plants on the site.
1.9 Maintenance
Good housekeeping practices shall be implemented for Porter House Apartments. These
practices include proper maintenance of sediment and structural controls as well as vehicle and
material storage areas. Required aspects of maintenance include proper inspections and required
repairs, record keeping, tracking, and documentation practices.
A contact person(s) responsible for responding to maintenance questions has been identified in
the Field Maintenance Contact Person form in Appendix F of this SWMP. Maintenance
procedures shall follow the Construction General Permit Part C.3-c as well as those BMPs
outlined within this SWMP and Appendices E and H.
1.10 Portable Toilets, Workers Trash and Onsite Waste Management Practices
Portable toilets shall be provided by the contractor. Toilets shall be located a minimum of 50 feet
away from any inlet or water source.
Dumpsters and waste piles shall be located a minimum of 50 feet away from any inlet or water
source and shall be secured appropriately.
1.11 Dewatering
It is anticipated that the project site will not involve groundwater and stormwater dewatering
practice and hence any scope of spills is minimal
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1.12 Soil Characteristics
According to Natural Resources Conservation Services (NRCS) Hydrologic Soil Group of site is C
and the vegetation consists of native weed and grasses.
1.13 Seeding and Mulching
Proposed seeding and mulching shall be per the approved landscape plan.
For evergreen trees, 6 feet diameter mulch shall be provided with a 6” planting rim for trees in
dryland planting beds and in irrigated native seeds areas where irrigation zones are to be shut down
after establishment.
For deciduous trees, 4” depth of mulch is suggested with a 6’ diameter mulch ring. Mulch has to be
kept away from woody trunk. For shrubs 4” mulch depth is suggested
1.14 Controls
Erosion and Sediment Controls
Prior to, during, and after site clearing, the contractor shall install erosion and sediment
control measures at the locations indicated and as determined by his construction
sequencing and/or phasing, and noted in the construction schedule. Wherever possible,
the construction shall be phased to minimize the amount and length of time that soils are
exposed and the contractor shall not disturb an area until it is necessary for construction
to proceed. The SWMP shall be kept current for all phases of construction activity. The
general contractor shall keep an up-to-date record of the type, location, and date of
control measures that have been installed during the various phases of construction by
means of a redlined working drawing, or other method.
Stabilization Practices
As much as possible, existing vegetation shall be preserved in place, especially
around the perimeter of the site where it can act as an effective means to reduce
runoff velocity, thus reducing erosion and allowing sedimentation prior to leaving
the site. Where this is not possible, existing vegetation shall be relocated at
critical locations, such as adjacent to receiving waters or at the top and bottom of
a slope. In addition, utilizing preserved-in-place vegetation within disturbed areas
will provide canopy and root systems to protect and hold soil in place.
All vegetation outside the limits of construction is to remain undisturbed; there is
vegetation within the limits of disturbance that will be preserved, as noted in
Figure 4-2. If dictated by construction progression, temporary stabilization will
also be provided, by means of temporary seeding or mulching, to disturbed areas
where activities have temporarily ceased.
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Interim soil stabilization will be achieved by means of establishing temporary
vegetation, applying a stabilizing agent, and/or other similar measures. The
frequency of applying the agent will be dependent on project weather conditions.
The Contractor shall continuously monitor the site conditions and apply
stabilizing agent as necessary to conform to the requirements of the Air Quality
Permit, as well as to minimize dust generated by wind and construction activities.
Water crusting may be used for dust control, but will not qualify as soil
stabilization. Chemicals associated with interim soil stabilization shall be
minimized in discharges by appropriate BMPs and discharges shall be directed to
sediment control measures.
Permanent soil stabilization of all surfaces shall be per the approved Grading and
Improvement Plans. This includes placing riprap on slopes steeper than 3:1 up to
2:1, at culverts and scuppers, and elsewhere as indicated on the Plans. All
culverts shall additionally be protected at the inlets and outlets by grouted rip-rap
for a minimum of 5’ around the culverts on the slope to prevent erosion and
penetration around the pipes. Slopes 3:1 and flatter will be re-vegetated as shown
on the approved Landscape Plans. Slopes that will be re-vegetated shall be
roughened perpendicular to the direction of runoff, by means of slope tracking, or
other method, in order to facilitate the establishment of vegetation, and to modify
flow velocities over the exposed slope. Stone paving will stabilize roadway and
parking areas.
Final stabilization practices for obtaining vegetative cover shall include: seed mix
and application rates: soil preparation and amendments; soil stabilization practices
(e.g. crimped straw, hydro mulch or rolled erosion control products) and
appropriate sediment control BMPs as needed until final stabilization is achieved.
Final stabilization is reached when all ground surface disturbing activities at the
site have been completed, and uniform vegetative cover has been established with
an individual plant density of at least 70% of pre-disturbance levels, or equivalent
permanent, physical erosion reduction methods have been employed
The operator must initiate stabilization measures on disturbed areas as soon as
practicable, but no more than 14 days after construction activity has temporarily
or permanently ceased, except for the following conditions:
Where earth-disturbing activity will resume within fourteen days from
cessation.
Where stabilization by the 14th day is precluded by snow cover or frozen
ground conditions, stabilization measures will be initiated as soon as
practicable.
When vegetative measures are used and it is during seasonally arid or drought
conditions (see General Permit for definitions), stabilization measures shall be
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initiated as soon as practicable.
Where undisturbed areas are awaiting vegetative stabilization for periods
greater than 14 calendar days after the most recent disturbance, non-vegetative
methods of stabilization shall be employed and described in the SWMP.
Note: The operator is not expected to apply temporary or permanent stabilization
measures to areas that are in intended to remain un-vegetated following
construction (e.g., dirt access roads, utility pole pads, areas being used for storage
of vehicles, equipment, or materials).
The general contractor shall keep an up-to-date record of:
The dates and locations where major grading activities occur
When construction activities temporarily or permanently cease
Dates when stabilization measures are initiated and completed and reasons for
delay, if applicable under Part 3.1.2. of the General Permit.
Structural Practices
Structural sediment control measures may include but are not limited to the use
of: filter socks, silt fences, gravel berms, straw bales, gravel-filled bags, sand
bags, and compacted, vegetated berms. Filter socks, V-ditches, gravel bags, and
silt fence will be used unless the SWMP is modified. These measures are to be
installed at the time appropriate with the related construction activity, as
designated on the construction schedule in Appendix D
The operator shall use silt fences, vegetative buffer strips, sediment traps, V-
ditches, or equivalent sediment control BMPs at all down slope boundaries of the
disturbed area. Soil stockpiles shall not be placed in or near stormwater
conveyances or streets leading to stormwater conveyances and must also have
perimeter sediment control BMPs. Sediment control BMPs (Filter socks or
equivalent) are to be used on the perimeter of soil stockpiles when stockpiles are
not actively being worked (i.e. evenings, weekends, and other down times).
During periods of inactivity, all stockpiles shall be covered or stabilized by means
of chemical soil binders with perimeter controls to prevent runoff pollutants from
contaminating other portions of the site.
For inlets that discharge, or could discharge to the waters of the US or to a local
MS4, the operator shall provide effective sediment control BMPs (gravel bags or
equivalent control that allows flow while retaining sediment) at all operational
inlets at all times during construction until all sources with potential for discharge
to the inlet are stabilized.
The contractor and subcontractors shall take all necessary and proper precautions
to protect the construction site and adjacent properties from any erosion and
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siltation that results from construction activities.
Once final stabilization, as defined in Part C.4-c of the General Permit, has been
achieved and all construction activities have ended, temporary structural controls
must be removed.
Non-Structural Practices
Non-Structural Practices provided include disconnection from impervious areas
minimizing impervious areas and providing source control. Disconnection from
impervious areas are provide by allowing roof drains to drain over pervious area
prior to entering storm drain as well as draining impervious roadways into
pervious area by the use of curb openings prior to entering existing drainage
conveyance or proposed storm drain. Minimizing roadway widths and providing
pervious amenities are in place to reduce impervious areas. Source control by the
use of inlet stenciling has been provided.
Storm Water Management
The contractor and subcontractors shall take all necessary and proper precautions
to protect adjacent property owners and natural washes from any and all damage
that may occur as a result of storm water runoff and/or deposition of debris
resulting from any or all work associated with their construction activities. Any
off-site accumulations of sediment or debris must be removed, in a timely manner
as not to adversely affect downstream water quality, and disposed of as
construction debris as outlined in sub-section 4.3.1 of this SWMP. Good
housekeeping practices will also be implemented. These practices include the
controlled application of carefully selected fertilizers and pesticides and a general
onsite maintenance and disposal program to keep the site free of litter and debris.
Velocity dissipation for concentrated flows will be provided by means of rip-rap
aprons, which will slow the discharge to a non-erosive velocity. These measures
will remain permanently in place at locations noted in the approved grading plans.
Rip-rap is to be installed as soon as aprons are graded so erosion is minimized.
Other storm water management practices may include vegetated swales and
natural depressions to achieve flow attenuation. If the contractor chooses to
deviate from practices recommended herein, this SWMP shall be amended to
reflect the chosen technique(s). These amendment(s) shall include an explanation
of the technical basis used to select the control practice(s).
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Other Controls
Waste Disposal
Except as authorized by a Section 404 Permit, no solid materials of any kind,
including building material, are to be discharged offsite. Waste receptacles are to
be provided at convenient locations, with regular collection schedules. All debris
and waste shall be properly disposed of according to applicable federal, state and
local laws. Receptacles are to be covered and not subjected to storm water run-on
or runoff. No material, liquid or otherwise, is to be discharged through the storm
drain system.
Dust Control
Dust control measures are to conform to the Air Pollution Control Permit and any
measures that may be specified by the Geotechnical Engineer. The geotechnical
engineering evaluation shall be reviewed by the contractor and subcontractors as
it relates to this SWMP. The nature of fill material shall be as described within
the above-referenced evaluation.
The tracking of sediment onto public streets is normally attributed to vehicles
driving through unpaved areas and onto said streets. For the time period just prior
to the start of earth disturbing activity, to prior to site paving, the construction site
entrance shall be protected by a Vehicle Tracking Control. The gravel apron is to
be inspected regularly and maintained as necessary. Any public street shall be
inspected and cleaned as necessary by means of sweeping by the contractor, shall
tracking occur. Street cleaning debris shall be disposed of in the same manner as
all other construction waste as herein described.
The gravel apron may be salvaged for use elsewhere or thoroughly mixed into the
subgrade immediately prior to paving activities. The contractor shall consult with
the Geotechnical Engineer for this project for further recommendations should
this option is used.
Concrete Washout Area
Concrete washouts are an allowable non-stormwater discharge under the
Construction General Permit. The General Permit allows the discharge of
wastewater resulting from washing concrete from trucks, pumps, and ancillary
equipment to an impoundment if the conditions listed in General permit are met.
Dedicated Concrete or asphalt batch plants are not an anticipated use for this
project.
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2.0 Construction Sequence:
A construction schedule has not yet been completed due to the project being in the entitlement
stage. A construction sequencing chart for construction activities is provided in Table 1 below and
on the drainage and erosion control plan.
Table 1: Sequencing Chart
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2.1 Erosion Control Plan: Please see next page.
LOT 3
LOT 2
08-11-2016
PER LANDSCAPE PLANS & POND GUIDELINES
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2.2 Erosion Control Security Calculations:
Table 2 Estimate of Probable Cost for Erosion Control Escrow Security
Engineer’s Estimate of Probable Cost for Erosion Control Escrow Security
Project: Center Point Plaza First Replat
Project No: 1028
Calculations By: Rick Engineering Company Date: 11‐11‐15
Itemized Costs:
Item Unit Quantity Unit Cost Total
Silt Fence LF 880 $ 2.00 $ 1,760.00
Inlet
Protection LF 35 $ 4.00 $ 140.00
Sed. Bas. EA 1 $ 2,500.00 $ 2,500.00
VTC EA 1 $ 2,000.00 $ 2,000.00
Subtotal $ 6,400.00
Multiplier 1.5
Total $ 9,600.00
Formula Based:
Unit Quantity Unit Cost Total
Revegetation AC 1.57 $ 1,500.00 $ 2,355.00
Multiplier 1.5
Total $ 3,532.50
Escrow Security (greater of two estimates, $ 3000.00 min.) $ 9,600.00