Drainage and Erosion Control Matters

Silverthorne, once proud to have the Blue River designated as “Gold Medal” waters by the Colorado Wildlife Commission, is determined to regain that prestigious status. To restore our waterways to their pristine condition, it is essential to implement responsible construction management techniques on all sites regardless of size. Proper Stormwater management must be prioritized.

Area of Disturbance

Area of disturbance is defined as the total area on any construction site where construction activity is expected to result in disturbance of the ground surface.  This includes, but is not limited to, access, clearing, grading, irrigation installation, landscaping, excavation and demolition activities, as well as haul road and areas used for staging where traffic will result in the disturbance of the ground surface.

What to think about when designing a stormwater plan for a construction site:

• Erosion control devices
• Sediment control devices 
• Area of disturbance 
• Grading – both existing and proposed contours 
• Flowlines 
• Setbacks, building envelope, property line 
• Construction fence 
• Construction parking 
• Material storage 
• Soil storage 
• Construction dumpster(s) 
• Portalet 
• Concrete washout 
• Revegetation plan 

Town of Silverthorne expectations for all construction sites:

• Inspections: Town of Silverthorne staff will conduct random site visits to ensure that all construction projects meet the requirements of this document. 
• Violations: Violators will be subject to fines, or a stop work order. If a stop work order is issued, an inspection will be required to verify that corrections have been made and a fee of $65 will be charged.
• Construction Hours: Acceptable hours of construction, including material and equipment pickup/deliveries are 7 A.M to 7 P.M., Monday through Saturday. No construction is permitted on Sundays and holidays.

• Temporary Address: A temporary address should be posted before any permitted work begins.  Address characters should be a minimum height of 5 inches and should be legible from the roadway.  If the construction project is more than 150 feet from curb or shoulder of street, address must be placed within 10 feet of property line. 

• Construction Parking: No vehicles associated with the construction project will be allowed to park on Town streets or right-of-way without a Construction Parking Permit.  Construction parking permits can be applied for online.  

• ROW Utilization: All deliveries or heavy equipment usage should be on your construction site unless you have obtained a ROW permit from the Public Works Department. Use good traffic control techniques such as flaggers for all deliveries or heavy equipment usage. 

• Site Access: Contractors must maintain emergency access on and around the site, including but not limited to police, fire, and ambulance services. 

• Building Permit Submittals Required: A Construction Management Plan must be submitted with every Building Permit. This plan must include sufficient sediment and erosion control best management practices (BMPs) to control stormwater on the site. BMPs must be installed according to design specifications and maintained at all times. 

• Area of Disturbance: Stake your area of disturbance. If the subject site has a building envelope, then the area of disturbance shall not exceed the building envelope. The area of disturbance must avoid any wetlands or other environmentally sensitive areas on the site, and buffer zones may be imposed on a case-by-case basis (based on Town Code requirements). In any case, the area of disturbance shall not go beyond the property boundaries of the subject site. If the total area of disturbance is equal to or greater than one acre, a Construction Stormwater Discharge Permit is required from the Colorado Department of Public Health and Environment.

• Construction Housekeeping: Before any permitted work is started, adequately sized dumpsters shall be in place. Jobsites are expected to be kept in an orderly fashion.  Loose building materials, papers, wrappers, and other trash capable of being blown by winds shall be secured or removed from the building site to prevent littering of the adjacent properties.  

• Storage: Construction trailer, materials, stockpiles, equipment, portable toilets, or dumpsters must be located entirely within the building envelope on the site being constructed and cannot be stored, stacked, or staged on Town streets or right-of-way (ROW) at any time. 

• Sanitation: After permit issuance and before any approved work is started, temporary toilets (“porta-toilets”) are required at all construction job sites. 

• Be neighborly: Notify the neighbors of ongoing construction on your site. 

• Erosion Control: Prevent erosion to the maximum extent practical using your choice of established BMPs. Dust must be controlled at all times. Lightly watering during the summer is good practice to control dust. 

• Sediment Control: Contain, and properly dispose of, sediment to the maximum extent practical using your choice of established BMPs. Streets must remain free from sediment and tracked soils.  A tracking pad is required. 

• Site Containment and Security: A construction fence is required to ensure that unauthorized individuals do not access the site, and that all construction debris remains on site. Residential sites must have a perimeter fence at least 4 feet tall and commercial sites must have a perimeter fence at least 6 feet tall.  

General Requirements

• Per Silverthorne Town Code: Construction hours are 7 a.m. to 7 p.m., Monday through Saturday. No construction is permitted on Sundays and federally designated holidays. Violators will be ticketed.
• Plumbing and mechanical permits are issued separately and will need to be obtained from the Town of Silverthorne Building Department located at 601 Center Circle, Silverthorne Colorado, 970-262-7360.
• Electrical permits are issued separately and will need to be obtained from the SummitCounty Building Department located at 37 S.C.R. 1005, Frisco Colorado, 970-668-3170.
• At no time shall any materials or debris be stored or stacked within the Town right-of-ways.
• An ILC (improvement location certificate) must be approved before the foundation wall inspection. Submit one stamped copy to the Planning Department at least 24 hours before requesting the foundation inspection.
• Guaranty of landscaping: In the months of November through April, before the issuance of a certificate of occupancy, the applicant shall provide security for not less than 150% of the then-current written estimated cost of the landscaping improvements (including materials and labor) approved by the Community Development Department. The written estimate shall be obtained from an independent landscaping contractor, and the security shall be in a form acceptable to the Town.
• Before any permitted work is started, dumpsters, adequate in size to handle trash and unwanted materials from the permitted project, shall be in place. All loose building materials, papers, wrappers, etc., capable of being blown by winds shall be secured or removed from the building site to prevent littering of the adjacent streets and properties. (Possible maximum penalties for littering: up to $1,000 fine and/or one year imprisonment).
• All dogs on construction sites shall be leashed or caged at all times (Silverthorne Town Code).
• Provide temporary numbers or addresses using characters with a minimum height of 5" and a contrasting color in such a position as to be plainly visible and legible from the street or road, before any permitted work is started. Permanent address characters are required before a Certificate of Occupancy may be issued. IRC Section 321.1 as amended. If building is more than 150 feet from curb or shoulder of street, address must be within 10 feet of property line.
• Foundation drain, damp-proof/waterproofing and foundation insulation MUST BE inspected separately.

Administrative Requirements

The issuance of a permit shall not be construed to be a permit for, or an approval of, any violation of any of the provisions of this code or of any other ordinance of the Town. The issuance of a permit based on construction documents and other data shall not prevent the building official from requiring the correction of errors in the construction documents and other data. The building official is authorized to suspend or revoke a permit whenever the permit is issued in error or on the basis of incorrect, inaccurate or incomplete information, or in violation of any ordinance or regulation or anyof the provisions of this code. IBC Sections 105.4 and 105.6

Construction or work for which a permit is required shall be subject to inspection by the building official and such construction or work shall remain accessible and exposed for inspection purposes until approved. Approval as a result of an inspection shall not be construed to be an approval of a violation of the provisions of this code or of other ordinances of the jurisdiction. Inspections presuming to give authority to violate or cancel the provisions of this code or of other ordinances of the jurisdiction shall not be valid. It shall be the duty of the permit applicant to cause the work to remain accessible and exposed for inspection purposes. Neither the building official nor the jurisdiction shall be liable for expense entailed in the removal or replacement of any material requiredto allow inspection. IBC Section 109.1 as amended.

It shall be the duty of the holder of the building permit to notify the building official when work is ready for inspection. It shall be the duty of the permit holder to provide access to and means for inspection of such work for any inspections that are required by this code. IBC Section 109.5. Safe access for inspections must be provided. Ladders should be available on-site, when necessary. If work is covered for weather protection, have someone on site to clear coverings before the inspector arrives. Inspectors do not provide snow removal services. Inspections may not be performed and re-inspection fees charged, if safe access is not provided.

A $65 reinspection fee may be assessed for each inspection or reinspection when such portion of work for which inspection is called is not complete or when corrections called for are not made. Reinspection fees may be assessed when the inspection record card or correction notice are not posted or otherwise available on the work site, the approved plans are not readily available to the inspector, for failing to provide access on the date for which the inspection is requested, for deviating from plans requiring the approval of the building official, or failure to maintain premise identification. In instances where reinspection fees have been assessed, no additional inspection requests will be accepted for the project, until the reinspection fees have been paid. IBC Section 109.7 as amended.

Wherever there are practical difficulties involved in carrying out the provisions of this code, the building official shall have the authority to grant modifications for individual cases, upon application of the owner or owner's representative, provided the building official shall first find that special individual reason makes the strict letter of this code impractical and the modification is in compliance with the intent and purposeof this code and that such modification does not lessen health, accessibility, life and fire safety, or structural requirements. The details of action granting modifications shall be recorded and entered in the files of the department of building safety Section 104.10.

The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, at least the equivalent of that prescribed in this code in quality, strength, effectiveness, fire resistance, durability and safety. Section 104.11.

Additions, alterations, or repairs to any building or structure shall conform to the requirements of the code for new construction. Additions or alterations shall not be made to an existing building or structure which will cause the existing building or structure to be in violation of any provisions of this code. IBC section 3402.1, as amended. As an example, if the basement finish work affects any existing mechanical or combustion air installations, they will be subject to the code requirements for new installations. Final determination of requirements will be made by the building inspector during field inspections

Our goal is to make finding water and sewer construction requirements and the application and inspection process as simple as possible. Email the water department with any questions. 

• Town of Silverthorne Water and Sewer Design Standards
• Calculations of EQRs (Equivalent Residential Units – or “Taps”) required for your project can be found here in the Town Code.
• Costs for water and sewer EQRS (“tap fees”), quarterly fees, and use fees can be found here.

Building Permit Submittal

When construction plans have been submitted to the Town as a building permit, the Utilities Department Staff will review them for conformance with Town Standards. Here’s what we look for:

1. Structure is NOT to be grounded via water line
2. For each metered location, only one water and one sewer connection to the Town mains is permitted.
3. Mechanical room detail and location with water meter and backflow preventer installation and design
   specifications including reduced pressure back-flow equipment for any fire suppression system Pressure and Flow data at water service connection that was used as basis of design for fire sprinkler
   systems, if any. If using pressure booster pumps, specify type.
4. Water meter size specified by the mechanical engineer. A single family residence water meter is usually ¾ inch (15gpm max). Large homes or homes located near the top of a pressure zone may use 1” (25gpm max) Spec Sheets for Badger Meters can be found here.
5. Size, materials, and location of water and sewer service lines, valves, cleanouts, protection of cleanouts and valves, and construction details for connections to TOS mainlines.
6. Individual sewer lift station and low pressure force main design and details if applicable
7. Sewer service line grease and sand trap design if applicable
8. Number of bedrooms and bathrooms, total square footage. For modification of existing residences, let us know if there is a change in Bedroom/Bathroom count.
9. Any change of use such as warehouse to retail etc., so that we can evaluate changes to EQRs and backflow prevention requirements

Inspection Requirements

Once construction has begun, Town inspections are required for the entire length of both water and sewer service lines. Email the water department to request water and sewer inspections. Please give us at least 2 business days’ notice for these inspections so that the lines can then be covered as quickly as possible. Here’s what we’ll be looking for:

Water

Material

• Water service lines are to be K Copper or Plastic Poly Ethylene (PE) only, no copper pipe larger than 1” in diameter is permitted - use PE or Ductile Iron Pipe (DIP) above 1” diameter
• If PE pipe is used, a 12-gauge copper trace wire must run from the curb box cap to the water meter and all PE pipe must have stainless steel stiffener inserts at all compression fittings
• Provide one continuous pipe from curb-stop to water meter location in building
• Service lines are to be all new material without kinks, or any damage
• No services shall have in-line couplings unless approved in advance by inspector
• Only compression type Corporation and Curb-stop valves and fittings are permitted underground, no
  Solder or glue joints are permitted on underground water pipes
• Service valve must have a McDonald type curb box with stem. The cap must be protected and be at or
  above finished grade, provide flat 12” stone or concrete pad under valve, located within 1’ property line.
• Any extension couplings to curb box must be welded. Cap is to be “hand tight”.

Bedding and Cover

• 4” minimum bedding under pipe, 6” over top - ¾” minus screened aggregate, back fill with 6” minus
  structural fill or 6” minus pit run.
• Minimum 8’ depth below finish grade without insulation. 10’ maximum bury
• If approved by the Town, insulation must be at least 2” thick x 24” wide, 60psi if water line is less than 8’ below finish grade in areas without vehicular traffic, 100psi insulation is required under driven surfaces, if less than 7’ below finished pavement grade, the water line must be box insulated

Installation and Separation

• Water lines must be at least 10’ from sewer lines. See sewer materials required for crossings.
• Service taps to Town Water Mains must be performed with TOS inspector on site
• Tapping saddles 2” and less are to be all stainless steel or all brass “lead free” (no epoxy or iron)
• Tapping saddles larger than 2”, where permitted, must be Ford or Romac All Stainless Steel material – 250 Psi minimum (no epoxy or iron)
• Contractor must provide as-built drawing of all new private service lines

Sewer

Material

• 4” SDR-26 (strongly recommended) or SDR-35 or C-900, Push-On Gasket Joint, PVC Pipe Only
• No glue together Pipe joints underground outside foundation beyond first cleanout

Bedding and Cover

•  4” minimum bedding under pipe, 6” over top - ¾” minus screened aggregate, back fill with 6” minus
  structural fill or 6” minus pit run.
• Minimum 8’ depth below finish grade without insulation. 12’ maximum bury
• If approved by the Town, insulation must be 2” thick x 4’ wide, 60psi if sewer line is less than 8’ below
  finish grade in areas without vehicular traffic, 100psi insulation is required under driven surfaces, if less than 7’ below finished pavement grade, the sewer line must be box insulated

Installation

• Sewer tapping saddles must be GENCO brand, appropriately sized
• Bell ends must face up-hill, all joints fully inserted
• Use food grade lubricant “duck butter” at all slip joints
• Sewer lines must be at least 10’ from water lines
• If crossing water lines center a 20’ stick of C-900 or SDR26 of sewer service pipe at the crossing
• If approved by the Town, insulation must be at least 2” thick x 24’ wide, 60psi if sewer line is less than 8’ below finish grade in areas without vehicular traffic, 100psi insulation is required under driven surfaces, if less than 7’ below finished pavement grade, the sewer line must be box insulated
• Slope must be greater than 2%
• Maximum of 12’ of depth unless approved in advance by TOS
• No 90 Degree fittings.
• Minimum of 8’ of straight continuous pipe between 45’s
• Clean out with “Y” every 100’ of pipe run or every 180 degrees of bends.
• Clean out with “Y” within 5’ of outside building foundation wall
• Flat 12” stone or concrete pad under each clean out “Y” for support.
• Access to clean out will be at 4” (+/-1”) above finish grade, capped and marked with wood lathe. Access
  within paved areas will req. street box
• Contractor will provide as-built drawing of all new private service lines

Construction Water

 If needed, must be metered and paid for per the Town Bulk water program. Once the
permanent heated and protected location for the water meter and backflow prevention is built, construction water may be taken through this meter, and will show up on the first water bill. Please call us 2 business days in advance to schedule pick up of the water meter at the Town Shop at 264 Brian Ave., Silverthorne.

Final Water and Sewer Inspections

 When you email the permit technician to request a final inspection, the water meter Automatic Meter Reading Device will be programmed and installed. We will also verify location(s) and operation of the water service valve (“curb stop”) and sewer cleanout(s).

Silverthorne Recommended Plant List

Common Name/Scientific Name

Conifer/Evergreen Trees

• Bristlecone Pine/Pinus aristata
• Colorado Blue Spruce/Picea pungens
• Englemann Spruce/Picea engelmannii
• Limber Pine/Pinus flexilis
• Lodgepole Pine/Pinus contorta var. latifolia
• Subalpine Fir/Abies lasiocarpa

Deciduous Trees

• Chokecherry, Shubert/Prunus Virginiana ‘Shubert’
• Quaking Aspen/Populus tremuloides
• Thinleaf Alder/Alnus incana subsp. tenuifolia
• Western Native Birch/Betula occidentalis

Shrubs

• Boulder Raspberry/Rubus (Oreobatus) deliciosus
• Chokecherry, Native/Prunus virginiana
• Currant, Alpine/Ribes alpinum
• Currant, Golden/Ribes aureum
• Currant, Wax/Ribes cereum
• Mountain Spray/Holodiscus dumosus
• Peking Cotoneaster/Cotoneaster acutifolius
• Potentilla (ex. Shrubby Cinquefoil)/Potentilla Varieties (ex. Potentilla fruticosa)
• Rabbitbrush/Chrysothamnus nauseosus
• Redtwig Dogwood/Cornus sericea
• Siberian Peashrub/Caragana orborescens
• Twinberry Honeysuckle/Lonicera involucrata
• Western Serviceberry/Amelanchier alnifolia
• Woods Rose/Western Wild Rose/Rosa woodsii

Perennials

• Achillea (ex. Common Yarrow)/Achillea Species (ex. Achillea millefolium (lantana))
• Aquilegia (ex. Rocky Mountain Columbine)/Aquilegia Species (ex. Aquilegia caerulea)
• Bee Balm/Horsemint/Monarda fistulosa
• Black-Eyed Susan/Rudbeckia hirta
• Blue Flax/Linum lewisii
• Campanula (ex. Harebell)/Campanula Species (ex. Campanula rotundifolia)
• Catmint/Nepeta × faassenii
• Chives/Allium schoenoprasum L. var. sibiricum (L.) Hartm.
• Creeping Thyme/Thymus Species
• Fleabane/Erigeron speciosus
• Gaillardia (aka Blanketflower)/Gaillardia aristata
• Geranium, Richardson’s/Geranium richardsonii
• Geranium, Sticky/Geranium viscosissimum
• Golden Banner/Thermopsis divaricarpa
• Hens and Chicks/Sempervivum Species
• Jacob’s Ladder/Polemonium viscosissimum
• Kinnikinnick/Arctostaphylos uva-ursi
• Oriental Poppy/Papaver oriental
• Pasque Flower/Pulsatilla (Anemone) patens
• Pearly Everlasting/Anaphalis margaritacea
• Penstemon, Blue Mist/Penstemon virens
• Penstemon, Rocky Mountain/Penstemon strictus
• Penstemon, Whipple’s/Penstemon whippleanus
• Potentilla, Creeping/Potentilla neumanniana
• Prairie Smoke/Geum triflorum
• Pussytoes/Antennaria spp.
• Rocky Mountain Bee Plant (Annual)/Cleome (Peritoma) serrulata
• Scarlet Gilia/Ipomopsis aggregata
• Scott’s Sugarbowls/Clematis scottii (hirsuitissima var. scottii)
• Sedum/Sedum Species
• Showy Goldeneye/Heliomeris (Viguera) multiflora
• Showy Locoweed/Oxytropis lambertii
• Silky Phacelia/Phacelia sericea
• Silvery Lupine/Lupinus argenteus
• Sneezeweed/Helenium (Hymonoxys) hoopesii
• Snow in Summer/Cerastium tomentosum
• Sulphur Flower/Sulphur Buckwheat/Eriogonum umbellatum
• Bluebunch WheatgrassWallflower/Erysimum capitatum
• Woodland Sage/Salvia nemorosa

Bunch Grasses 

• Indian Ricegrass/Achnatherum (Oryzopsis) hymenoides
• Junegrass/Koeleria macrantha

 Grass Seed (Often Comes in Mixes)

• Blue Wildrye/Elymus glaucus Buckley
• Bluebunch Wheatgrass/Pseudoroegneria spicata (Pursh) Á. Löve
• Canada Bluegrass, Reubens/Poa compressa
• Canby Bluegrass/Poa secunda (ssp. canbyi)
• Creeping Red Fescue/Festuca rubra
• Hard Fescue, Rhino/Festuca brevipila
• Idaho Fescue/Festuca idahoensis
• Indian Ricegrass/Achnatherum (Oryzopsis) hymenoides
• Rocky Mountain Fescue/Festuca saximontana Rydb.
• Sandberg Bluegrass/Poa secunda J. Pres
• Sheep Fescue Varieties/Festuca ovina Varieties
• Slender Wheatgrass/Elymus trachycaulus (Link) Gould ex Shinners
• Tufted Hairgrass/Deschampsia cespitosa (L.) P. Beauv.
• Western Wheatgrass/Pascopyrum smithii (Rydb.) Á. Löve