HomeMy WebLinkAbout27_STORM_WATER_MANAGEMENT_&_EROSION_CONTROL27.1Storm Water Management & Erosion Control
storm water management
& erosion control
section
27
27.2 Bar Slash X Ranch LLC - Annexation and Stage Road PUD/Subdivision: Final Submission
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27.3Storm Water Management & Erosion Control
PRELIMINARY EROSION CONTROL / STORM WATER MANAGEMENT PLAN
(SWMP)
Stage Road Subdivision PUD, Aspen, COLORADO
August 30, 2004
PREPARED FOR:
Contractor not yet determined
OWNER:
Mr. John Lifton
216 West Colorado Ave.
P.O. Box 997
Telluride, CO 81435
ph (970)728-5353
PREPARED BY:
BUCKHORN GEOTECH INC.
222 SOUTH PARK AVE
MONTROSE CO 81401
Contact: Brian Renfrow ph (970) 249-6828
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27.4 Bar Slash X Ranch LLC - Annexation and Stage Road PUD/Subdivision: Final Submission
Existing and Proposed Storm Water Runoff
Typically, peak runoff in the mountain region will occur due to spring snowmelt when saturated
soils limit infiltration. However, the soils related to this site are highly permeable minimizing the
volume of runoff during the spring snowmelt. Rather, developing erosion controls for localized
summer cloud bursts that produce intense, short duration, runoff events are most important.
The pre-developed runoff coefficient is estimated at 0.15 with a developed runoff coefficient
estimated between 0.15 and 0.20. The pre-developed runoff curve number, using the SCS
method, was estimated at 61 for a pasture or range with HSG of B. The total disturbed drainage
basin contributing to the outfall from the site is approximately 96 acres and the developed runoff
curve number is estimated to remain at 61 for the developed area, due to the minimal impact of
the improvements. Drainage for each developed home site is not considered part of this study.
Existing runoff from the contributing water shed is collected by road drainage and irrigation
ditches and ultimately discharges to Maroon Creek and the Roaring Fork River. The proposed
permanent storm water management for the site includes two water storage pond which will
collect storm water from the open meadows and store water for irrigation purposes.
At the time of construction the final storm water management plan will be developed for the
contractor. Because construction may not begin for a few years, this preliminary plan
summarizes the Best Management Practices which will be implemented during construction for
proper erosion control.
Potential Pollutants and Non-Storm Water Discharges
Potential pollutants to the on-site wetlands and storm water runoff include vehicle fluids;
construction finishes such as paints and varnishes; solvents and cleaners; herbicides, pesticides
and fertilizers; blowing waste materials; and other construction or maintenance items. Potential
non-storm water discharges include wash water, water line flushing, and ground water discharge.
Potential pollutants shall be controlled by the following methods:
�Education: All on-site personnel shall be informed of the sensitive nature of the on-site
wetlands and the required protection of the storm water system. All sub-contractors shall
be made aware of the SWMP. Such information shall include instruction on proper
storage, use and disposal of potential pollutants and any required controls to prevent
pollution of the surface and storm water.
�Disposal Facilities: The Contractor shall provide and maintain appropriate on-site
disposal containers. Such containers shall include spill containment controls as needed
and shall be covered to prevent blowing of waste.
�Storage Facilities: The Contractor shall provide and maintain appropriate storage
facilities. All potential pollutants shall be stored in an appropriate, covered, storage
facility with spill containment controls as needed. The Contractor shall check the site
daily for improperly stored materials and correct the problem.
�Proper Use: The Contractor shall ensure all potential pollutants are used in a proper
manner to prevent spills, over flow, excessive use, or over spray that may contaminate
surface soils or storm water. All waste material shall be properly disposed of in a manner
that will not provide potential contamination. When the site use of a potential pollutant is
complete the substance should be removed from the site.
�Waste Concrete: Concrete trucks and equipment shall not be washed out to the storm
water system. Any required wash out shall be contained in an area that will not reach the
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27.5Storm Water Management & Erosion Control
storm water system. Once the area has dried out any residue concrete shall be disposed
of in an appropriate disposal container.
�Vehicle Maintenance: Vehicle maintenance and equipment storage areas should be
paved and surface runoff contained for appropriate disposal.
Potential Non-Storm Water Discharges shall be controlled by the following methods:
�Wash water: No unnecessary vehicle or equipment washing shall occur on-site. If it
becomes necessary to clean equipment or vehicles on site to prevent sedimentation of
adjacent road the wash shall occur in an area with appropriate sediment and wash water
controls.
�Water line flushing: If any disinfection chemical is present in water line flush water, the
water shall be directed to an area for containment until such disinfection is dissipated
then a controlled release to the storm water is allowed. Appropriate erosion and
sediment control shall be in place.
�Ground water discharge: Appropriate permitting shall be in place prior to any ground
water discharge. Testing and effluent limitation shall be in accordance with the permit.
Appropriate erosion and sediment control shall be in place.
Best Management Practices for Construction Activities
Construction includes necessary site clearing, earthwork, utility trenching, as required to complete
the road infrastructure and pond. Order of activities for erosion and sediment control compliance
should be as follows. Refer to Appendix A for erosion and sediment control specifications.
Prior to earthwork:
�Stake limits of disturbance and place markers for definition.Note:No disturbance is
allowed outside the staked limits.
�Construct storm water inlet controls for existing drainages and place erosion logs per the
attached drawings.
Preliminary earthwork:
�Install permanent 20’-100’ wide untouched vegetative buffer between all construction and
any wetland, riparian area or natural drainage. No direct piped drainage from developed
areas to wetland or riparian areas shall be permitted; drainage to these areas shall be in
a manner that will prevent point discharge and promote sheet flows
�Irrigation wells and/or ponds constructed for irrigation water supply or as hazards shall
not be located in streams or wetlands.
�Construct stabilized entrances and parking/staging and storage areas.
�Strip topsoil in area of immediate construction. Stockpile topsoil that is to be reused and
cover topsoil pile to prevent erosion, sediment transport and contamination of pile. Cover
with 2 layers of heavy plastic and anchor securely. Any excess material shall be
removed off site.
�Establish job trailer, temporary trash dumpster and toilet facility.
�Leave any disturbed surfaces in a roughened state. If areas are to remain untouched
more than 30 days then implement a temporary surface sediment control (mulching).
Continuing earthwork:
�Complete cut and fills to rough grade contours.
�Rough the surface of the roadways as described in the attached specification.
�Install erosion logs as shown on the drawings.
�Construct storm drain inlets and protect inlet from sediment and other pollutants using
erosion log check dams.
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27.6 Bar Slash X Ranch LLC - Annexation and Stage Road PUD/Subdivision: Final Submission
�Establish inside area for materials storage to prevent storm water contamination.
�Establish orderly staging and storage area, do not store any materials that may
contaminate storm water in outside storage area.
�Establish inside area at garage for materials storage for any materials with potential to
contaminate storm water. Provide spill containment as necessary for stored materials.
Ongoing Maintenance and Inspection:
�Maintain site clean of trash and debris, provide regular service for trash dumpster and
temporary toilet facility.
�Inspect storage area on daily basis to check for any potential for storm water
contamination and correct.
�Inspect all sediment and erosion controls on a minimum of once per week and after any
storm event.Repair as necessary and institute additional controls if necessary. Remove
any sediment at sediment controls when it exceeds ½ the available storage capacity.
During seasonal periods of higher runoff, inspection and maintenance shall be performed
on a daily basis if necessary.
�Inspect all disturbed areas and retrack to roughen and apply additional mulch as
necessary to prevent erosion and sediment transport.
�Educate all on-site personnel regarding the erosion and sediment control plan and the
importance of storm water quality protection. Prohibit any dumping of waste materials
(concrete, paint etc.) on site.
�Implement additional erosion and sediment controls as necessary, based on visual
inspection, as work progresses.
�Maintain daily logs of inspection, maintenance and implementation of SWMP.
Completion of earthwork:
�As areas of the site achieve final subgrade elevations, place topsoil, road base per civil
drawings and vegetation per landscape plan. Leave temporary erosion and sediment
controls in place until vegetation is well established.
�When site work is complete, and final surface is stabilized, remove and reclaim erosion
and sediment controls and construct permanent controls as shown on the plan.
�Review site and remove any trash or construction debris and repair any areas of erosion.
�Continue to inspect and maintain erosion and sediment controls at a minimum of once
per week and after any storm event until vegetation is 100-percent established.
�Any landscaped areas that are not 100-percent established after one-year shall be
replanted or reseeded as necessary to achieve final cover.
Permanent Storm Water Controls
The permanent storm water controls for erosion and sediment include the hard surfaces,
landscaped surfaces, vegetated slopes,paved and rip-rapped drainage channels, and piped
system. Maintaining all surfaces in good condition and removing sediment from the storm water
conveyances on a regular (quarterly as needed) basis should provide for appropriate storm water
management of the site. All areas should be inspected at a minimum of twice annually and after
every significant storm event. Any damaged areas should be repaired and temporary controls
(such as mulch or silt fencing) implemented as needed. Also, the Owner should be aware that no
non-storm water discharges should be allowed on the site, do not dispose of any household
waste, cleaners, paints or other non-storm water items to the ground or drainage structures,
contact local agencies for appropriate disposal methods.
The applicant must prepare a chemical (pesticides, fertilizers, and herbicides) control plan that
minimizes chemical use and encourages biological controls when available. The plan should
identify the chemicals that will be used as well as the proper application methods to ensure
protection of water quality and long term monitoring. A chemical safety program; including
storage, handling and application considerations as well as disposal shall be developed and
made available for reference by all employees.
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27.7Storm Water Management & Erosion Control
Responsible Parties
The General Contractor shall be responsible for implementing, maintaining and monitoring
effectiveness of the Storm Water Management Plan during construction. The General Contractor
shall supplement or revise the plan as necessary to control all on-site erosion as site conditions
develop and to ensure all site runoff is treated by the storm water controls. The General
Contractor shall notify the Engineer of any significant revisions or any deletions. The General
Contractor is responsible for actions of all sub-contractors as they relate to the Storm Water
Management Plan and shall ensure all sub-contractors are aware of the plan and the intent of site
controls and maintain such intent.
Consultants Qualifications
Buckhorn Geotech is a full service consulting engineering firm servicing both private and
municipal clients the Western Slope of Colorado for over 20 years. This plan was prepared by
Judy Kittson, P.E. who has over 15-years experience in civil engineering design incorporating
storm water management and has been closely involved in development of erosion and sediment
control Best Management Practices for municipalities and for private development for the past 10
years. Please call for any additional information required.
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27.8 Bar Slash X Ranch LLC - Annexation and Stage Road PUD/Subdivision: Final Submission
Appendix A
TEMPORARY SEEDING
CONSTRUCTION SPECIFICATIONS:
Timing: The proper time to seed is dependent upon the climate of the area.
Seed Mixes: Select plants appropriate to the season and site conditions.
�The seeding rates are based on a minimum acceptable pure live seed (PLS) of 80%. When
PLS is below 80% adjust rates accordingly.
�Legumes should be inoculated with the proper rhizobium bacteria before planting. Pellet
inoculated seed can be purchased or inoculation can be done in the field. Use only fresh, age
dated inoculate specifically labeled for use with the legume you are using.
Site Preparation:
�Grade as needed and feasible to permit the use of equipment for seedbed preparation.
�Install needed erosion control practices, such as sediment basins,diversion dikes and
channels, prior to seeding. Divert concentrated flows away from seeded areas.
�Soil tests should be done to determine the nutrient and pH content of soil. Depending on the
results of soil tests, soil management may be necessary to adjust the pH to between 6.5 and 7.0
(for most conditions). All lime, fertilizer and other soil amendments should be addressed
following sound soil management practices.
�Surface roughening: If the area has been recently loosened or disturbed, no further
roughening is required. When the area is compacted, crusted or hardened the soil shall be
loosened with discing, raking or harrowing. Tracking with bulldozer cleats is very effective on
sandy soils.
�Hydroseeding and hydraulic planting generally require less seedbed prep.
�Generally, slopes steeper than 2:1 that cannot have good seedbed preparations with
equipment, and will sometimes require hydraulic planting techniques.
�Seed to soil contact is the key to good germination. Prepare a 3-5 inch (76-127 mm) deep
seedbed, with the top 3-4 inches (76-102 mm) consisting of topsoil. Note that the earth bed upon
which the topsoil is to be placed should be at the required grade.
�The seedbed should be firm but not compact. The top 3 inches (76 mm) of soil should be
loose, moist and free of large clods and stones.For most applications, all stones larger than 2
inches (51 mm) in diameter, roots, litter and any foreign matter should be raked and removed.
�The topsoil surface should be in reasonably close conformity to the lines, grades and cross
sections shown on the grading plans.
Planting:
�Seed should be applied as soon after seedbed preparation as possible, when the soil is loose
and moist.
�Always apply seed before mulch.
�Apply seed using calibrated spreaders, cyclone seeders, mechanical drills, or hydroseeders
so the seed is applied uniformly on the site.
�Apply fertilizer if required. Seed and fertilizer should be incorporated into the soil by raking or
chain dragging, or otherwise floated, then lightly compacted to provide good seed-soil contact.
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27.9Storm Water Management & Erosion Control
TEMPORARY SEEDING CONT.
�Straw mulch,erosion control blankets or mulch and soil binders should be applied over the
seeded areas.
Inspection and Maintenance:
�Newly seeded areas need to be inspected frequently to ensure the grass is growing. Areas
which fail to establish cover adequate to prevent sheet and rill erosion will be reseeded as soon
as such areas are identified. Spot seeding can be done on small areas to fill in bare spots where
grass did not grow properly.
�If the seeded area is damaged due to concentrated runoff, additional practices may be
needed.
�Temporary vegetated areas will be maintained until permanent vegetation or other erosion
control practices can be established
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27.10 Bar Slash X Ranch LLC - Annexation and Stage Road PUD/Subdivision: Final Submission
SURFACE ROUGHENING
CONSTRUCTION SPECIFICATIONS:
Cut Slope Roughening:
�Stair-step grade or groove the cut slopes that are steeper than 3:1.
�Use stair-step grading on any erodible material soft enough to be ripped with a bulldozer.
Slopes consisting of soft rock with some subsoil are particularly suited to stair-step grading.
�Make the vertical cut distance less than the horizontal distance, and slightly slope the
horizontal position of the "step" in toward the vertical wall.
�Do not make individual vertical cuts more than 2 feet (0.6 m) high in soft materials or more
than 3 feet (0.9 m) high in rocky materials.
�Groove the slope using machinery to create a series of ridges and depressions that run
across the slope, on the contour.
Fill Slope Roughening:
�Place fill slopes with a gradient steeper than 3:1 in lifts not to exceed 8 inches (0.2 m), and
make sure each lift is properly compacted.
�Ensure that the face of the slope consists of loose, uncompacted fill 4-6 inches (0.1-0.2 m)
deep.
�Use grooving or tracking to roughen the face of the slopes, if necessary.
�Apply seed, fertilizer and straw mulch then track or punch in the mulch with the bulldozer.
�Do not blade or scrape the final slope face.
Cuts, Fills, and Graded Areas:
�Make mowed slopes no steeper than 3:1.
�Roughen these areas to shallow grooves by normal tilling,disking, harrowing, or use a
cultipacker-seeder. Make the final pass of any such tillage on the contour.
�Make grooves formed by such implements close together (less than 10 inches (0.3 m)), and
not less than 1 inch (25.4 mm) deep.
�Excessive roughness is undesirable where mowing is planned.
Roughening With Tracked Machinery:
�Limit roughening with tracked machinery to soils with a sandy textural component to avoid
undue compaction of the soil surface.
�Operate tracked machinery up and down the slope to leave horizontal depressions in the soil.
Do not back-blade during the final grading operation.
�Immediately seed and mulch roughened areas to obtain optimum seed germination and
growth.
Inspection and Maintenance:Periodically check the seeded slopes for rills and washes. Fill
these areas slightly above the original grade, then reseed and mulch as soon as possible.
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27.11Storm Water Management & Erosion Control
HYDRAULIC PLANTING
CONSTRUCTION SPECIFICATIONS:
Site Preparation:
�Grade as needed and feasible to permit the use of equipment for seedbed preparation.
�Install needed erosion control practices, such as sediment basins,diversion dikes and
channels, prior to seeding. Divert concentrated flows away from hydraulic planted areas. See
Temporary Diversion Dike or Continuous Berm BMPs.
�Conduct soil tests to determine pH. Add amendments as necessary to adjust pH. See
Permanent Seeding BMP.
�The seedbed should be firm but not compact. The top 3 inches (76 mm) of soil should be
loose, moist and free of large clods and stones. See Surface Roughening BMP.
Planting:
�See Permanent Seeding BMP.
�Seed to soil contact is important for successful germination.
�Use permanent seed blends for sites to be left dormant for 1 year or more or if no further
disturbances are planned.
�Use permanent seeding techniques before seasonal rains or freezing weather is anticipated.
�Use dormant seeding techniques for late fall or winter seeding schedules.
�Use seed blends appropriate to the season and site conditions. Consult a local agronomist
or erosion control specialist for seed mix. Use a seed blend to include annuals, perennials and
legumes.
�Use seed rates based on pure live seed (PLS) of 80%. When PLS is below 80%, adjust rates
accordingly.
Apply pellet innoculated legumes immediately after placing them in the tank. If they cannot be
immediately applied, pellet innoculated legumes shall be dry applied followed by the hydraulic
applications.
Hydraulic Mulching:
�See Mulching BMP.
�The mulch shall be mixed with seed, fertilizer and additives as specified and applied at a rate
recommended by the manufacturer in order to achieve uniform, effective coverage and provide
adequate distribution of seed.
�If using paper mulch, use approximately 50 lbs. of mulch per 100 gallons of water (23 kg/380
l) and applied at a rate of 1500-2000 lbs/ac (1700-2200 kg/ha), mixed with seed and fertilizer, at
recommended rates, in order to achieve uniform, effective coverage.
�Paper mulch used to tack and bind straw mulch can be specified at 750 lbs/ac (850 kg/ha).
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27.12 Bar Slash X Ranch LLC - Annexation and Stage Road PUD/Subdivision: Final Submission
HYDRAULIC PLANTING CONT.
�If using wood fiber mulch, use approximately 30-35 lbs. of mulch per 100 gallons of water
(14-16 kg/380 l) applied at a rate of 1500-2000 lbs/ac (1700-2200 kg/ha), mixed with seed and
fertilizer, at recommended rates, in order to achieve uniform, effective coverage.
�Minimum application rates for hydraulic matrices are 500 lbs/ac (561 kg/ha) wood fiber
mulch, 1000 lbs/ac (1121 kg/ha) recycled paper mulch combined with 55 gallons per acre (208
liters per 0.4 ha) acrylic copolymer with minimum 55% solids content.
�For bonded fiber matrix, the BFM shall be applied at rates from 3000-4000 lbs/ac (3363-4484
kg/ha).
�Bonded fiber matrix shall not be applied before, during or immediately after rainfall such that
the matrix will have 24 hours to cure and dry after installation.
�When tacking or anchoring straw with paper fiber mulch, apply at a rate of 750 lbs/ac (840
kg/ha).
�Polymer tackifiers are to be applied at rates of 40-60 lbs/ac (44-67 kg/ha) depending on
manufacturers recommendations.
�Plant muselage or guar tackifiers are to be applied at rates of 80-120 lbs/ac (90-135 kg/ha)
depending on manufacturer’s recommendations.
�Apply liquid straw mulch binders heavier at the edges, in valleys and at the crest of banks.
Inspection and Maintenance:
�Hydraulically treated areas shall be inspected and monitored after installation and periodically
thereafter.
�Hydraulic mulches and tackifiers shall provide the necessary erosion protection until
permanent erosion-resistant cover is established. If sheet or rill erosion is evident then
re-application of treatments shall be necessary.
�Necessary repairs shall be made promptly.
�If the hydraulic mulch or tackifiers were applied as stand alone (without vegetation)
treatments for erosion and dust control, the products longevity must match the length of time that
the soil will remain bare or until revegetation occurs. Periodic inspections will assure the intended
purposes will be met.
�Areas which fail to establish cover adequate to prevent erosion shall be reseeded and
re-mulched as soon as such areas are identified.
�If hydraulically planted areas are damaged by concentrated runoff, the prompt
implementation of additional practices and BMPs may be necessary.
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27.13Storm Water Management & Erosion Control
STRAW ROLLS
CONSTRUCTION SPECIFICATIONS:
�Prepare the slope before the wattling procedure is started.
�Shallow gullies should be smoothed as work progresses.
�Dig small trenches across the slope on contour, to place rolls in. The trench should be deep
enough to accommodate half the thickness of the roll. When the soil is loose and uncompacted,
the trench should be deep enough to bury the roll 2/3 of its thickness because the ground will
settle.
�It is critical that rolls are installed perpendicular to water movement, parallel to the slope
contour.
�Start building trenches and install rolls from the bottom of the slope and work up.
�Construct trenches and install rolls from the bottom of the slope and work up.
�Construct trenches at contour intervals of 3-12 feet apart depending on steepness of slope.
The steeper slope, the closer together the trenches.
�Lay the roll along the trenches fitting it snugly against the soil. Make sure no gaps exist
between the soil and the straw wattle.
�Use a straight bar to drive holes through the wattle and into the soil for the willow or wooden
stakes.
�Drive the stake through prepared hole into soil. Leave only 1 or 2 inches of stake exposed
above roll.
�Install stakes at least every 4 feet apart through the wattle. Additional stakes may be driven
on the downslope side of the trenches on highly erosive or very steep slopes.
Inspection and Maintenance:
�Inspect the straw rolls and the slopes after significant storms. Make sure the rolls are in
contact with the soil.
�Repair any rills or gullies promptly.
�Reseed or replant vegetation if necessary until the slope is stabilized.
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27.14 Bar Slash X Ranch LLC - Annexation and Stage Road PUD/Subdivision: Final Submission
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27.15Storm Water Management & Erosion Control
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27.16 Bar Slash X Ranch LLC - Annexation and Stage Road PUD/Subdivision: Final Submission
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27.17Storm Water Management & Erosion Control
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27.18 Bar Slash X Ranch LLC - Annexation and Stage Road PUD/Subdivision: Final Submission
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