HomeMy WebLinkAbout556 CAJETAN ST - DUPLEX & CARRIAGE HOUSE - FDP230003 - SUBMITTAL DOCUMENTS - ROUND 2 - EROSION CONTROL LETTER/REPORT
ALLES TAYLOR & DUKE, LLC 3610 35TH AVE. UNIT #6
LICENSED PROFESSIONAL ENGINEERS EVANS, 80620
LICENSED PROFESSIONAL LAND SURVEYORS 970-330-0308
Table of Contents:
• Project Description and Nature of Construction
o Site Location
o Existing Site Conditions
o Proposed Construction Activities
• Potential Pollutant Sources:
o All disturbed and stored soils
o Vehicle tracking of sediments
o Management of contaminated soils
o Loading and unloading operations
o Outdoor storage of construction site materials, building materials, fertilizers, and
chemicals
o Bulk storage of materials
o Vehicle and equipment maintenance and fueling
o Significant dust or particulate generating processes
o Routine maintenance activities involving fertilizers, pesticides, detergents, fuels,
solvents, and oils
o On-site waste management practices
o Concrete truck/equipment washing, including the concrete truck chute and associated
fixtures and equipment
o Dedicated asphalt and concrete batch plants
o Non-industrial waste sources such as worker trash and portable toilets
o Saw cutting and grinding
o Other non-stormwater discharges including construction dewatering not covered under
the Construction Dewatering Discharges general permit and was water that may
contribute pollutants to the MS4
• Construction Control Measures (Installation and Removal)
• Phasing (if applicable)
• Maintenance and inspection requirements
• Final vegetation and stabilization
ALLES TAYLOR & DUKE, LLC 3610 35TH AVE. UNIT #6
LICENSED PROFESSIONAL ENGINEERS EVANS, 80620
LICENSED PROFESSIONAL LAND SURVEYORS 970-330-0308
Project Description and Nature of Construction:
Site Location and Existing Site Conditions:
Erik Haagenson (Owner) is proposing to develop Lot 1 of Old Town North Fourth Filing, recorded with
the Larimer County Clerk & Recorder on December 20, 2018, at Reception No. 20180077798. The
address of the subject property (site) is 556 Cajetan St, Fort Collins, CO 80524, and is located within the
Southwest Quarter (SW 1/4) of Section 1, Township 7 North, Range 69 West of the 6th Principal
Meridian, City of Fort Collins, County of Larimer, State of Colorado. The site, Parcel No. 9701387001, is
bounded on the south by Cajetan Street and is approximately 60’ west of Redwood St. A vicinity map is
included in Figure 1 below with the site outlined for reference.
Figure 1. Vicinity Map
The proposed development of the site includes: a side by side duplex (Unit 1 = 766 ft2 footprint, Unit 2 =
735 ft2 footprint), 3 separate garages (Garage 1 = 230 ft2 footprint, Garage 2 = 240 ft2 footprint, Garage 3
= 288 ft2 footprint) with a stairway adjacent to Garage 1 that leads to the carriage house above the
garages = 80 ft2 footprint, a carriage house above the garages = 769 ft2, drive/parking surface with
concrete and pavers, a concrete walk between the duplex and garages/carriage house, and Landscaping.
The site is approximately 5,990 ft3 (0.138 acres) in size and is currently undeveloped with bare ground
and weeds. Approximately 10-20% of the site is vegetated with weeds. Lot 2 to the west has been
developed with a single-family residence. Tract A to the east is vacant and will eventually be developed
per the Old Town North Fourth Filing Landscaping Plan. Vehicle access to the site will be from the 12’
Alley that is adjacent to the north side of the site.
A topographic survey was performed by Alles Taylor & Duke (ATD) for the site and surrounding features
on September 2, 2022. Elevations provided are based on the National Geodetic Survey (NGS) Benchmark
Designation A 402, PID LL1017, which has an elevation of 4962.47’ (NAVD 88). Existing stormwater
runoff generated onsite flows to the north, east, and south at approximately 1-2 % slopes.
ALLES TAYLOR & DUKE, LLC 3610 35TH AVE. UNIT #6
LICENSED PROFESSIONAL ENGINEERS EVANS, 80620
LICENSED PROFESSIONAL LAND SURVEYORS 970-330-0308
Stormwater runoff exiting the site either flows north into the drainage pan along the alley and into the
storm inlet located on the south side of Osiander St, or onto Tract A east of the site, or south into the curb
and gutter along Cajetan St and Redwood St, eventually reaching the same storm inlet on the south side of
Osiander St. The storm inlet on Osiander St is piped to the north into a Detention pond utilized for a
portion of the Old Town North Subdivision. Stormwater in the detention pond drains into the Dry Creek
drainage basin, which is a tributary to the Poudre River. The Poudre River is approximately 0.5 miles
Southwest of the site.
A geotechnical report was not conducted for the site, all soil information is provided by Web Soil Survey.
Per Web Soil Survey, the entire site is comprised of Nunn Clay Loam – Hydrologic Soil Group C. Nunn
Clay Loam has the following characteristics:
• Slope: 0 to 1 percent
• Parent Material: Pleistocene age alluvium and/or eolian deposits
• Depth to restrictive feature: more than 80 inches
• Drainage Class: well drained
• Runoff class: medium
• Depth to water table: more than 80 inches
• Frequency of flooding: none
• Frequency of ponding: none
• Typical Profile:
o Ap – 0 to 6 inches: clay loam
o Bt1 – 6 to 10 inches: clay loam
o Bt2 – 10 to 26 inches: clay loam
o Btk – 26 to 31 inches: clay loam
o Bk1 – 31 to 47 inches: loam
o Bk2 – 47 to 80 inches: loam
The southern half of the site is located in the 500-yr floodplain, floodplain requirements do not apply to
the site.
Proposed Construction Activities:
The existing site is bare ground, so no demolition will occur. The site will be graded to comply with the
grading & drainage plan, which is sheet C-6 of the drawing set. Utilities will be installed per the Utility
Plan shown on sheet C-4 of the drawing set. An existing water service stub is located near the south
property line and an existing sanitary sewer service stub is located near the north property line. Existing
electrical, gas, and communications lines are located near the south property line. Flat work installation
includes the walks leading to the duplex, the garage floors located on the north side of the site, the
walkway between the duplex and garages, and the drive/park surface. The finished floor elevation of the
duplex is 4970’ and the finished floor elevation of the garages varies. The duplex and garages/attached
dwelling unit above the garages will be constructed per the architectural plans provided by Freeman
Architects, in accordance with the Grading & Drainage Plan. Landscaping will be installed on the west,
south, and east sides of the site. The Landscape plan will be designed by a Landscape Architect.
ALLES TAYLOR & DUKE, LLC 3610 35TH AVE. UNIT #6
LICENSED PROFESSIONAL ENGINEERS EVANS, 80620
LICENSED PROFESSIONAL LAND SURVEYORS 970-330-0308
Potential Pollutant Sources:
Disturbed and Stored Soil:
Approximately 100% of the site (5,990 ft2) may be disturbed at any given time with construction
activities since it is a small site. Soil that has been disturbed becomes loose and can lead to
erosion/sediment issues during storm events. The south, east, and northern limits of disturbance lines will
have straw wattles placed to prevent sediment from leaving the site (Straw Wattles). If soil does manage
to leave the site onto hard surfaces, it will be swept or scraped for cleanup (Street Sweeping). Storm
sewer inlets will have rock sock protection to capture sediment that may be washed from the site (Rock
Sock Style Inlet Protection). Soil storage/stockpiles may be anticipated during construction on the subject
property or on Tract A adjacent to the East, which is also owned by Erik Haagenson. Stockpiles are very
susceptible to soil erosion. If stockpiles are necessary, they will be placed away from drainage pathways
and monitored after storm events for erosion issues. The stockpile will be kept loose, not compacted, and
watered as needed to prevent dust issues (site watering). Wattles may be placed around the toe of the
stockpile to prevent sediment from being washed away. The stockpile may also be structurally covered or
if it is going to sit a long while may be reseeded (temporary seeding).
Vehicle Tracking of Sediment:
Vehicle access to the site is through the Alley on the north. If vehicles used during construction are found
to be tracking soil/sediments onto the alley drive surface, the alley will be swept/scraped for cleaning
(Street Sweeping). If sediment is not cleaned in a timely manner, the inlet rock socks will trap and prevent
sediment from entering the storm sewer inlet (Rock Sock Style Inlet Protection).
Management of Contaminated Soils:
No contaminated soils are anticipated for the site and no known contaminants exist. If contaminated soils
are encountered, the material will be disposed of properly per State waste laws (Materials Management
Control).
Loading and Unloading Operations:
Loading and unloading operations will occur during construction. If vehicle tracking of sediments
becomes an issue, it will be resolved per the vehicle tracking of sediment section above (Street
Sweeping). If any spills/contamination occurs during loading and unloading operations, spill prevention
and response procedures will be utilized (Materials Management Control).
Outdoor Storage of Construction Site Materials, Building Materials, Fertilizers, and Chemicals:
Building and Landscaping materials are anticipated to be stored outside onsite. No chemicals shall be
stored outside. Materials stored outside shall be inspected to ensure no negative impacts. Materials that
can be placed on pallets shall be so that they are elevated and won’t be impacted by stormwater runoff
(Site/Materials Management Control).
Bulk Storage of Materials:
Bulk storage of materials is not anticipated. If liquid chemicals are to be stored onsite, they shall be stored
in a drum container and stored away from drainage features (Site/Materials Management Control).
ALLES TAYLOR & DUKE, LLC 3610 35TH AVE. UNIT #6
LICENSED PROFESSIONAL ENGINEERS EVANS, 80620
LICENSED PROFESSIONAL LAND SURVEYORS 970-330-0308
Vehicle and Equipment Maintenance and Fueling:
No vehicle and equipment maintenance and/or fueling is anticipated to occur onsite.
Significant Dust or Particulate Generating Processes:
The construction activities will result in dust or particulate generating processes. The project will follow
all required BMPs articulated in the Fugitive Dust Manual and at least one additional BMP included
during each of the identified activities in accordance with City Ordinance No. 044,2016. A copy of the
Dust Control Manual shall be kept onsite during construction for reference. Such activities will include
but not limited to watering the site, covering equipment, and slow site speeds.
Routine Maintenance Activities (Fertilizers, Pesticides, Detergents, Fuels, Solvents, Oils, Etc.):
Proper application rates and recommended timing of application will be followed when applying
fertilizers and pesticides and will be properly stored out of the elements. Storage of maintenance materials
that may be a possible contaminant shall be kept inside, or outside covered and above the ground, or in
locations such as a connex box, trailers, vehicles (Site/Materials Management Control).
Onsite Waste Management Practices (Waste Piles, Liquid Wastes, Dumpsters, Etc.)
Any waste pile will be kept in a grouped pile for short duration until disposal. Dumpsters will be covered
and will be hauled off when needed. Leakage from dumpsters will be monitored. Dumpsters and waste
piles will be located at least 50 feet from drainage ways (Site/Materials Management Control).
Dedicated Asphalt and Concrete Batch Plants:
Asphalt and concrete batch plants will not be utilized onsite, premixed concrete materials will be
delivered to the site.
Non-industrial Waste Sources (Worker Trash, Portable Toilets):
Trash and sanitary services will be required onsite. Trash generated onsite will be placed in the dumpster.
Portable toilet facilities shall be properly anchored to the ground and placed at least 50 feet from a
drainage way.
Saw Cutting and Grinding:
Saw Cutting and grinding is not anticipated onsite.
Ground Water Dewatering:
Ground water issues will need to be field verified. A Geotechnical study was not conducted onsite. If
groundwater encountered, dewatering activities may be required. If material is anticipated to be pumped
to a stormwater conveyance, the proper Construction Dewatering Permit must be pulled from the State of
Colorado.
ALLES TAYLOR & DUKE, LLC 3610 35TH AVE. UNIT #6
LICENSED PROFESSIONAL ENGINEERS EVANS, 80620
LICENSED PROFESSIONAL LAND SURVEYORS 970-330-0308
Control Measures (Installation and Removal):
Sediment Control Log (SCL)
Sediment Control Logs, often referred to as straw wattles, are used as a sediment barrier to intercept sheet
flow runoff from disturbed areas. Straw Wattles will be placed around the entire perimeter of the site
excluding the west property line and the access point on the north. Stormwater runoff does not exit the
site to the west. The straw wattles shall be installed prior to any soil disturbance and will remain intact
until the site has reached final stabilization. Wattles may be used around the toe of any soil stockpiles to
reduce the transport of sediment.
Rock Sock (RS)
A rock sock is constructed of gravel that has been wrapped by wired mesh or a geotextile to form a filter.
Rock socks are typically used as a perimeter control to prevent sediment from entering an inlet.
Stormwater runoff exiting the site either flows north into the drainage pan along the alley and into the
storm inlet located on the south side of Osiander St, or onto Tract A east of the site, or south into the curb
and gutter along Cajetan St and Redwood St, eventually reaching the same storm inlet on the south side of
Osiander St. The inlet does already have rock socks around the perimeter and will need to be field
verified to ensure still functioning properly. If not in place already, the inlet protection shall be installed
prior to any soil disturbance and will remain intact until the site has reached final stabilization.
Riprap (RR)
Riprap is not anticipated onsite.
Temporary and Permanent Seeding (TS/PS)
Permanent seeding should be used to stabilize areas at final grade that will not be otherwise stabilized.
Effective seeding requires proper seedbed preparation, selecting an appropriate seed mixture, using proper
equipment, and protecting seeding areas with mulch or fabric. Temporary seeding may be required to
stabilize disturbed areas that will be inactive for an extended period of time. If the inactive period is two
weeks or less, techniques such as surface roughening may be used. If soil stockpiles are going to sit a long
while, temporary seeding may be used for stabilization.
Phasing:
The project will be completed in one phase.
Maintenance and Inspection Requirements:
Straw wattles will eventually degrade. Accumulated sediment must be removed before the depth is one-
half the height of the wattle. Any damaged wattles must be replaced/repaired in a timely manner. Wattle
may be removed upon final stabilization of the site. Areas disturbed beneath the wattles need to be seeded
and mulched.
Rock socks are susceptible to displacement and breaking due to vehicle traffic. Rock socks must be
inspected for damage frequently. If damaged, repair or replace in a timely manner. Remove sediment
building by sweeping or vacuuming as needed to maintain the functionality of the BMP, typically when
ALLES TAYLOR & DUKE, LLC 3610 35TH AVE. UNIT #6
LICENSED PROFESSIONAL ENGINEERS EVANS, 80620
LICENSED PROFESSIONAL LAND SURVEYORS 970-330-0308
sediment has accumulated behind the rock sock to one-half of the sock’s height. The rock socks may be
removed upon final stabilization of the site.
Monitor and observe seeded areas to identify areas of poor growth or areas that fail to germinate. Reseed
and mulch these areas, as needed. An area that has been permanently seeded should have a good stand of
vegetation within one growing season if irrigated. Seeded areas may require irrigation, particularly during
extended dry periods. Protect seeded areas from construction equipment and vehicle access.
After all storm events, the entire site shall be inspected to ensure that all BMPs are functioning properly
(i.e. sediment being trapped, no erosion damage), any problems shall be dealt with promptly.
Final Vegetation and Stabilization:
Exposed dirt in areas that contain hardscapes and buildings will be considered to be stabilized
immediately upon installation. The landscape areas of the sight will contain either permanent seeding or
sod. Any areas where sod will be located will require soil amending in accordance with §12-132 and
irrigated as a permanent feature to the project. Areas where sod will be placed will be considered
stabilized upon installation and would be under warranty. All seeded areas will be seeded based upon the
specs called out in the landscape plan. All seeded areas will be crimped and mulched same day or next
day after seeding in accordance with the temporary and permanent seeding details associated with this
project and in accordance with the City of Fort Collins Erosion Control Criteria. All seeding will be
monitored until the site has reached a vegetative cover (density) of 70%. Once the vegetation has reached
70% density, and confirmed by the City of Fort Collins, the warranty period for Erosion Control will
begin, all stormwater infrastructure will bed cleaned and removed of any sediment deposits and any
remaining temporary control measure will be removed. Maintenance shall be performed on all lot BMPs
on a routine basis and after all precipitation events that cause surface erosion. Reference the Fort Collins
Stormwater Criteria Manual for proper specifications, installation, and maintenance requirements.
Area
(ft2)
Percent Soil Type Depth to Ground
Water (ft)
Number of
Phases
Volume
(yd3)
H:V
Ratio
Distance
(ft)
Total Area of Disturbance for the Project 5,990 - - - - - - -
Total “Onsite” Area of Disturbance within the
property boundary
5,990 - - - - - - -
Total “Offsite” Area of Disturbance beyond the
property boundary
0 - - - - - - -
Total storage/staging areas not incorporated into
the onsite and offsite calculations
0
- - - - - - -
Total area of new or improved haul roads (offsite) 0 - - - - - - -
Heavy construction vehicle traffic areas offsite (haul
roads and heavy vehicle crossings as a result of
Construction Activities)
0 - - - - - - -
Approximate percent of the project that will be
disturbed at any one time
- 100 - - - - - -
Estimated pre-existing percent vegetative density or
percent vegetative cover (plant density or how thick
the grass is) before the project was disturbed
- 10 - - - - - -
Existing Soil Type - - C - - - - -
Depth to Groundwater (data shall be determined
from data taken during high groundwater months to
determine if dewatering activities are anticipated)
- - - Unknown,
Assumed > 6’
- - - -
Number of Phases associated with project - - - - 1 - - -
Total volume of material imported to (+), or
exported from (-), the project
- - - - - 270 - -
Total area of offsite stockpiling of fill from the
project or borrow from stripping the offsite area
0 - - - - - - -
Steepest slope (in a ratio of Horizontal to Vertical,
H:V)
- - - - - - 12.5:1 -
Distance from a riparian area or sensitive area (if
larger than 75 feet mark the field N/A)
- - - - - - - N/A
Mobilization Demolition Grading
Utilities
Installation
Flat work
Installation
Vertical
Installation Landscape Demobilization
Best Management Practices (BMPs)
Structural "Installation"
Silt Fence Barriers*
Contour Furrows (Ripping / Disking)
Sediment Trap / Filter
Vehicle Tracking Pad*
Flow Barriers (Wattles)*x x x x x x
Inlet Filter Bags*x x x x x x
Rock Bags*
Terracing
Stream Flow Diversion*
Rip Rap x x x x x x
Collecting Asphalt / Concrete Saw Cutting Waste
*All BMPs to be Removed once Construction is Complete.
Vegetative
Temporary Seeding Planting Any time the site will sit dorment longer than 30 Days.
Mulching/Sealant Any time the site will sit dorment longer than 30 Days.
Permanent Seeding Planting x x
Sod Installation x x
Rolled Products : Netting/Blankets/Mats
Other:
X = Will be used