HomeMy WebLinkAboutASCENT STUDIO CLIMBING & FITNESS - FDP - FDP150023 - SUBMITTAL DOCUMENTS - ROUND 1 - EROSION CONTROL LETTER/REPORTSEDIMENT AND EROSION CONTROL REPORT
FOR
TIMBERLINE CENTER, SECOND FILING, LOT 2
FORT COLLINS, COLORADO
Prepared for:
RB+B Architects, Inc.
325 East Mountain Avenue, Suite 100
Fort Collins, CO 80524
Prepared by:
TJB Consulting Group, LLC
P.O. Box 1348
Longmont, Colorado 80502
July 1, 2015
ENGINEER’S CERTIFICATION
I hereby certify that this Sediment and Erosion Control Report For Timberline Center, Second
Filing, Lot 2 was prepared under my direct supervision in accordance with the general guidelines
set forth by the Colorado Department of Public Health and Environment for Stormwater
Discharges Associated with Construction Activity and Ft. Collins regulations. The signature and
stamp affixed hereon certifies that the Stormwater Management Plan was prepared in accordance
with the required regulations; however, the stamp and signature does not certify or guarantee
future performance of the execution of the plan by the contractor. The contractor is responsible
for executing the construction work according to the specifications set forth in this report and in
accordance with all applicable permit requirements.
Todd J. Borger
Registered Professional Engineer
State of Colorado No. 32993
(Will be Signed & Stamped pending City Approval)
SEDIMENT AND EROSION CONTROL REPORT
FOR
TIMBERLINE CENTER, SECOND FILING, LOT 2
General Intent:
This report is being prepared to comply with City of Ft. Collins regulations governing proposed
site construction. Per City published regulations:
Fundamental Erosion Control Principles
The intent of erosion control design is to protect adjacent properties and downstream
properties from the detrimental effects of land disturbing activity. Water erosion is
always directional, i.e., always down-slope. This directional nature of water erosion can
be used to design resistance to sediment movement near the downstream edge of the
disturbed property. The erosion control design may govern slope placement so that
sediment-laden runoff is not directly tributary to an adjacent property. The slope may
need to be built to accommodate a temporary diversion channel, which keeps water on
the disturbed parcel.
Control measures are necessary for each phase of development (each phase of a
development must have a "stand alone" erosion control plan), and it is understood that
initial grading and construction will require certain control measures, which will change
or be replaced as development progresses. Temporary control measures such as silt
fences or diversion structures may be used during the initial grading and construction
phase and later either removed completely or replaced with grass or permanent sediment
basins.
Erosion control measures can be arranged to perform in sequence so that sediment
reduction caused by one measure releases less sediment to the next. In this manner, series
resistance to sediment movement can be built into a project so that stormwater released to
adjacent properties or streams is carrying the allowable amount of sediment. The
resistance to released sediments can be designed to minimize costs and minimize
interference with on-site construction activities.
The construction and maintenance of erosion control measures is critical to ensure proper
performance. Erosion Control Plans must include construction details and maintenance
guidelines.
1.0 SITE DESCRIPTION
This Report is intended to cover the construction of the improvements associated with the
Ascent Studios building on Timberline Center, Second Filing, Lot 2 [a.k.a. Site]. See
section 1.1 for a description of the Construction Activities and attached Overall Sediment
Management & Erosion Control Plan.
This project is located in the East 1/2 of Section 19, Township 7 North, Range 68
West of the 6
th
Principal Meridian, City of Ft Collins, Larimer County, Colorado. Lot
2 of Seconding filing covers a portion of lots 12 & 13 of the original Timberline
Center, those lots being presently addressed as 2121 & 2127 South Timberline Road.
The project areas is generally bounded on the West by Joseph Alley Drive and by
undeveloped property to the North, East and South. Property to the North and East
does contain some public and private infrastructure improvements associated with
prior construction within Timberline Center. These improvements consist of utilities
for water, sanitary sewer, storm drainage, private access drive, gas, electric and cable
tv. These are represented with the Utility Planset under review on Sheet C2, existing
site conditions survey.
This lot consists of approximately 1.43 acres and generally slopes to the North and
East. The project extents extend past the Lot boundary and will disturb an estimated
1.7 acres. Per the prior filing plan and existing infrastructure, the site drainage will
split toward 2 existing inlets. One inlet is North the site, the other is Northeast of the
site.
The latitude near the center of the Site is 40°33’33”N. The longitude near the center
of the site is 105°02’28”W.
1.1 Construction Activity
The Site is a commercial building. The construction activity includes: overlot grading;
installation of services for water & sanitary sewer, storm drainage improvements,
pavement and concrete flatwork construction and landscaping. Please refer to the
separate submittals to the City for Site Plan and Utility Plans. Site plan documents
contain the final landscape plan for the site.
1.2 Proposed Sequence for Major Activities
Construction of the Site will be completed in one phase. Currently, the anticipated
construction schedule includes a start of construction in summer 2015, and completion in
early 2016.
Likely construction operations include the following likely sequence once permits are
obtained, to be finalized by the Contractor, Architect and Project Owner:
1. Call for buried utility locates.
2. Install initial sediment control measures.
3. Perform overlot grading, begin building construction.
4. Install sewer, water, and storm drainage pipe.
5. Install conduits for dry utilities & private irrigation.
6. Install walks, curb/gutter, alley & street pavements.
7. Remove initial ecp measures & install final epc measures.
8. Obtain construction acceptance & c.o. from city.
9. Monitor final ecp measures and repair as warranted.
10. Obtain final construction acceptance of site and close out permits.
A detailed s.e.q. chart will be prepared by contractor to outline Contrator's preferred
methods and actual timing of construction.
1.3 Estimates of the total area of the site and the area of the site expected to undergo
clearing, excavation or grading
The Site is approximately 1.4 acres in size. The area of the Site to undergo clearing,
excavation or grading is approximately 1.7 acres.
1.4 Estimated runoff coefficient of the site before and after construction activities are
completed and any existing data describing the soil, soil erosion potential or the quality
of any discharge from the site
The estimated runoff coefficients for the Site before construction activities commence
are:
Runoff Coefficients, C
2-year 10-year 100-year
Existing 0.05 0.20 0.40
The estimated runoff coefficients for the Eastgate Site after construction of all public
improvements are given in the table below.
Runoff Coefficients, C
2-year 10-year 100-year
Developed 0.74 0.80 0.86
The estimated percent imperviousness for this Filing before construction activities
commence is 2%.
The estimated percent imperviousness for this Filing after construction of all public
improvements is 75%.
1.5 Description of the soil types on the site and /or the potential for soil erosion.
Existing soils are description with the report, with sub-section 3.0 reproduced here:
Geotechnical Engineering Report
Ascent Studio Climbing Gym
2121 and 2127 South Timberline Road
Fort Collins, Colorado
May 7, 2014
Terracon Project No. 20145015
Upon project completion, Site will be fully covered with finished landscaping,
building, pavement and other hardscape, which will control sediment migration.
Areas disturbed outside of the site legal boundary will be paved or re-established
with vegetation per plan documents.
1.6 Description of the existing vegetation at the site and an estimate of the percent
vegetative ground cover
At present the existing vegetative cover for the Eastgate Site consists primarily of open
field containing 90% grasses.
1.7 Location and description of any other potential pollution sources, such as vehicle
fueling, storage of fertilizers or chemicals, etc.
Please see the erosion Control Plan for potential pollution sources. Potential pollution
sources include: material stockpiles and contractor mobilization, staging and equipment
maintenance areas. Soils that will be stockpiled for more than 30 days shall be protected
from wind and water erosion within 14 days of stockpile construction. If chemical storage
is required on-site, a spill prevention and control plan shall be provided--none is
anticipated at this time. The project contractor will update the plan & City staff as
warranted.
1.8 Location and description of any anticipated non-stormwater components of the
discharge, such as springs and landscape irrigation return flow.
No potential for irrigation return flow from this phase of construction has been identified.
1.9 Name of the receiving waters and the size, type and location of any outfall or, if the
discharge is to a municipal separate storm sewer, the name of that system, the location
of the storm sewer discharge, and the ultimate waters
The storm sewer discharge for the site will be collected in curb and gutter and a storm
sewer system and conveyed to the existing water quality / detention pond. Discharge
from the pond is controlled release and eventually discharges to Cache La Poudre River.
2.0 SITE MAP
See the attached Erosion Control Plan for:
Site Layout
Existing Contours
Proposed Contours
Water Quality / Detention Pond
Areas used for construction mobilization and materials stockpile
Construction BMPs
3.0 BMPS FOR STORMWATER POLLUTION PREVENTION
The contractor will utilize any of the following Best Management Practices (BMPs) to
minimize or eliminate the transportation of sediment off-site.
Erosion Controls
Temporary or permanent seeding
o Temporary seeding will occur only in areas expected to remain
undeveloped for extended periods.
o Permanent landscaping / seeding will occur concurrent with construction
activities or after construction activities are completed
o
Concrete Washout
o Concrete and equipment for placing concrete shall only be washed in
designated areas. The concrete washout area shall be graded such that
drainage will not directly enter any onsite or offsite stormwater systems.
After washing, concrete spoils shall be disposed of offsite in a proper
manner.
Sediment Controls
Filter (silt) fence and/or Sediment Control Logs (SCL)
o Silt fence and/or SCL will be installed around the edge of the site prior to
construction activities.
o Silt fence and/or SCL will be installed on all lots per BMP for single lots
erosion control in Urban Storm Drainage Criteria Manual, Vol. 3
Vehicle Tracking Control
o Vehicle tracking controls shall be placed at all construction accesses to
public right-of-way prior to construction.
Storm drain inlet protection
o Inlet protection will be installed at existing storm inlets and at proposed
inlets as storm sewer piping is installed.
Temporary Sediment Basin
o Temporary Sediment Basins will be constructed, if necessary. If deemed
necessary, then sizing calculations and details will be provided to the City
of Longmont at that time.
Materials & Stock pile management
o Will be used at contractor's staging area, to be updated by contractor as
warranted.
Traditional stormwater management practices
Vegetated swale / detention pond
o This site discharges into an existing stormwater detention and water
quality facility via existing storm drainage inlets & pipes.
Good housekeeping
Routine trash/debris removal
o The contractor will remove trash and debris from the site during
construction activities on a weekly basis at a minimum.
Cleaning storm drains, grates and inlets
o The contractor shall clean storm drains, grates and inlets during
construction activities after major storm events or if debris is noted during
self-inspections. Inlet protection will be cleaned when accumulated debris
and/or sediment fills 50% of applied BMP.
Material Storage
o All material storage shall be located within the contractor mobilization
area.
o Storage or disposal of building materials; equipment , solid, sanitary and
toxic wastes (including dumpster areas); compounds such as fertilizers,
lime, asphalt or concrete and fuel shall be restricted to the material
stockpile and contractor mobilization area.
o Fuel, chemical storage and storage of petroleum, toxic or hazardous waste
requires a spill prevention plan to be prepared by the contractor.
o In the event of a minor spill, less than 25 gallons, all contaminated soils
must be treated and/or disposed of in approved solid or hazardous waste
management facilities.
o No toxic or hazardous wastes shall be disposed into storm drains, septic
tanks, or by burying, burning, or mixing the wastes.
o Toxic or hazardous waste shall be disposed of or recycled offsite in
accordance with the current Colorado Department of Public Health and
Environment regulations.
For Emergencies:
Always dial 911
For Non-Emergencies, nights and weekends:
Call Dispatch 303-651-8501
For Non-Emergencies, during regular business hours:
Fire Department HAZARDOUS MATERIALS 303-651-8833, 303-591-9002
For Discharge from Construction Sites:
Call City Inspector 303-651-8416
Temporary Erosion Control
o Should the project become inactive for a period of longer than 30 days, the
contractor shall place all construction materials within the mobilization
area and protect disturbed soil from erosion. Punched straw, mulching or
appropriate geotextiles are acceptable means of soil protection.
Dust Control
o Contractor to use water truck to suppress the dust form the project.
o Used oil may not be used as a dust suppressant.
Visual inspection
Regular site inspections
o The contractor will conduct site inspections at least every 14 days and
after every major precipitation event during construction activities. After
construction activities are completed, the property owners will conduct
inspections of the site every 30 days and after every major precipitation or
snow melt event until final stabilization is attained.
Recordkeeping and Reporting
Inspections
o The contractor will maintain a log of their inspections during construction
activities and submit a copy to the city.
o The property owners will maintain a log of their inspections after
construction activities have ceased and submit a copy to the city.
Maintenance
o When maintenance is required, the contractor will make note of it in the
inspection log during construction activities. Maintenance will be
completed within 5 days or as recommended by the City Inspector or
Project Manager.
o After construction activities are complete, when maintenance is required,
the property owners will make note of it in the inspection log.
Maintenance will be completed within 5 days or as recommended by the
City Inspector or Project Manager.
4.0 FINAL STABILIZATION AND LONG-TERM STORMWATER MANAGEMENT
Disturbed areas that will not receive permanent landscaping will be re-vegetated. This
and permanent landscaping will act as effective long-term erosion control for the site.
Sediment that collects in the drainage system and permanent water quality controls shall
be removed prior to the site being considered finally stabilized.
5.0 OTHER CONTROLS
In order to minimize pollutant migration from the site, the contractor will incorporate
material management practices, frequent waste disposal, and an emphasis of vehicle
tracking control to prevent off-site soil tracking.
All fills and subgrades require scarification to 8" minimum depth, moisture conditioning
to with in -1% to +3% of optimum and 95% minimum compaction per geotechnical
reports.
Any fill material imported to the site is subject to approval by the geotechnical engineer
prior to placement on-site.
Fill materials must be free from contaminants which may leach to waters of the state.
6.0 INSPECTION AND MAINTENANCE
The contractor will maintain the site during construction. The contractor will conduct the
site inspections at least every 14 days and after every major precipitation event. These
inspections will be logged. Any repair work required or deficiencies in the existing
BMPs that are noted in the inspection log will be corrected within 5 days.
The property owners will maintain the site after phased construction is complete. The
property owners will continue site inspections for the site every 30 days and after every
major precipitation or snowmelt runoff event until final stabilization is achieved. These
inspections will be logged. Any repair work required or deficiencies in the existing
BMPs that are noted in the inspection log will be corrected within 5 days or as
recommended by the City Inspector or Project Manager.
In addition to the above, Site and Contractor operations will comply with published city
standards:
3.2.1 Inspection Frequency
Documented inspections are required on a biweekly basis and within twenty four
(24) hours of a storm event, with some limited, temporary exceptions for inactive
sites. The City recommends spot-checking BMPs every workday. This is typically
reasonable to achieve and can help to ensure that the BMPs remain in good
working condition. For example, vehicle tracking of sediment onto the roadway is
a common problem that often requires maintenance more frequently than weekly.
Curb socks, inlet protection and silt fence are other BMPs that are prone to
damage and displacement, also benefiting from more frequent inspections.
When the site or portions of the site are awaiting final stabilization (e.g.,
vegetative cover), where construction is essentially complete, the recommended
frequency of inspection is at least once every week. Be sure that this change is
documented and in accordance with relevant permit requirements prior to
reducing the inspection schedule. When snow cover exists over the entire site for
an extended period, inspections are not always feasible. Document this condition,
including date of snowfall and date of melting conditions, and be aware of and
prepare for areas where melting conditions may pose a risk of surface erosion.
Inspections of disturbed sites must be done by the responsible party, at the
minimum, on a bi-weekly basis. Records of inspections including date and time of
inspection, corrective action(s) taken and future planned maintenance activities
must be kept at the construction site by the responsible party and submitted to the
Erosion Control Inspector upon request.
7.0 ADDITIONAL ITEMS
Designated Representative & SWMP Administrator:
At this time, point of contact will be:
RB+B Architects, Inc.
c/o Ms. Kate Penning
325 East Mountain Ave., Suite 100
Ft. Collins, CO, 80524
970.484.0117
At such time the contractor is authorized to proceed, the designated representative &
administrator contact will be updated.
Erosion Control Security (ESCROW) Calculations:
As stated above, upon project completion, Site will be fully covered with finished
landscaping, building, pavement and other hardscape, which will control sediment
migration. Areas disturbed outside of the site legal boundary will be paved or re-
established with vegetation per plan documents. It is estimated that the additional
disturbed area may be less than 200 SF. Given this small area, it appears the Site will be
subject to the City's minimum security requirements.
City's current policies are restated below:
1.4 Security for Erosion Control
No land disturbing activity subject to this Stormwater Criteria Manual can begin
until an Erosion Control Plan has been approved and the Owner has submitted
proof of security to ensure rehabilitation of the disturbed land. A performance
bond, irrevocable letter of credit, or cash escrow, acceptable to the Utilities
Executive Director, and naming the City as the protected party, is required. Such
performance bond, irrevocable letter of credit, or cash escrow shall further
guarantee the continued maintenance and replacement of any installed erosion
control measures shown on the approved plan.
The amount of the security is based on one and one-half times the cost to
revegetate the disturbed land to dryland grasses (soil preparation, seed, and
mulch) based upon unit cost determined by the City Stormwater Department's
Annual Revegetation and Stabilization Bid. In no instance, shall the amount of
security be less than one thousand five hundred dollars ($1,500) for residential
and three thousand dollars ($3,000) for commercial projects.
Should the Owner be out of compliance with provisions of the approved Erosion
Control Plan, the City may exercise its rights under the security provided. In the
event that the City exercises such rights, it is not the City's intention to routinely
administer the construction of the measures shown on the erosion control plans,
however, the City reserves the right to enter upon the land and take whatever
actions are necessary to stabilize and revegetate all disturbed areas, or to have the
plan constructed and make repairs as necessary.
The erosion control security will normally be retained by the City until the project
has been completed and there is no further possibility of erosion or sediment
transport from the site. This includes the time for two full growing seasons for the
establishment of grasses on any revegetated areas. At that time, the security will
be released. However, if a part or phase of the site has been completed (including
any revegetated areas which are established but have not yet reached the two
growing season warranty limit), and if it can be determined by the City that there
is no further erosion or sediment transport risk from that part or phase as it relates
to the entire project, then the portion of the erosion control security that would
apply to that part or phase can be released, whether or not the entire project has
been completed. Any partial release of the erosion control security must be
requested by the responsible party.
(5) A new Section 1.5 is added, to read as follows:
1.5 Warranty
The Owner must warrant that the measures shown on the approved erosion and
sediment control plan are properly constructed, installed, and are free from
defective materials and/or workmanship, with said warranty to continue for the
terms set forth below.
The Owner shall warrant and maintain all structural measures for such period of
time as construction on the site continues and/or said measures are necessary to
protect against erosion and sediment transport. The Owner must warrant and
maintain all vegetative measures for two growing seasons after installation. Any
acceptance of installed measures shall not be construed to relieve the Owner of
the duty to warrant and maintain as aforesaid.
(6) A new Section 1.6 is added, to read as follows:
1.6 Enforcement
No land disturbing activity subject to this Stormwater Criteria Manual can begin
on any project unless it is associated with an approved Erosion Control Plan, a
signed Development Agreement, and a submitted erosion control security. All
erosion control measures must be installed when they are necessary as indicated
by the approved Erosion Control Plan and Report, and maintained in accordance
with these Criteria. In order to ensure that all required measures have been
correctly installed and are in proper order and repair, no building permit will be
issued on any project until an inspection of the site and its required erosion
control measures has been made and deemed acceptable by the City.
If, at any time during construction activities, the Owner fails to adhere to the
approved Erosion Control Plan and Report, the construction phase sequence, or
any of the erosion control criteria, the City may employ any or all of the
following:
• Stop all or any part of the work on the project.
• Withhold building permits.
• Withhold certificates of occupancy.
• Exercise the City's rights under the security provided.
• Issue summons and or fines.
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