HomeMy WebLinkAboutStormwater - *COMPILED STORMWATER DETAILS -Erosion Control for Construction on Individual Residential Lots
Scope
The following requirements apply to all single-family residential projects, including;
· New single-family residential construction
· New construction (i.e. additions, etc.) on existing single –family sites
· Idle single family lots both permitted and non-permitted (lots owned by the builder or land developer not yet under
construction).
· Grading, excavating and stockpiling of earth and landscape materials (not specifically limited to new construction) which
results in the transport of any of these materials off site by any means including, but not limited to, wind or water erosion
and vehicular tracking.
Enforcement
The requirements herein are enforced through the requirements of the Fort Collins Stormwater Criteria Manual, and applicable
ordinance. Failure to comply may result in the refusal of inspections, refusal of Certificates of Occupancy, and the suspension,
revocation, or cancellation of Building Permits.
Excavations for basements
When lots are ready for basement excavations and / or additional grading, the BMPs that are protecting the lot shall not be
compromised during the operation. BMPs may be temporarily removed to allow for access and promptly reinstalled at the end of the
basement excavation and/ or grading operations, or at the end of the day- whichever is sooner. At no time shall the lot specific BMPs
be removed over night or during precipitation events.
Basement excavations / grading shall not be performed on a lot(s) if excessive tracking of sediment onto streets will occur. This is
often the case after recent precipitation events, which cause the lot to be “muddy.”
Material from basement excavations shall be contained and protected from sediment transport by surface roughening, watering and
perimeter silt fence or other approved BMPs. The excavated material shall comply with all stock pile criteria outlined in Fort Collins
Stormwater Criteria Manual, specifically, No stockpile shall exceed ten (10) feet in height, and any stockpile remaining after 30 days
shall be seeded and mulched.
If the excavated material is to be moved, and sediment is tracked onto streets, all sediment shall be removed immediately. The streets
shall be scraped and swept periodically throughout the day and at no time shall the material be allowed to remain on the street
overnight. All BMPs shall be reinstalled at the end of each day.
Inlet protection
Following the direction of flow off the site, the nearest inlet is required to have inlet protection, it shall be installed & maintained per
the Fort Collins Stormwater Criteria Manual requirements at all times.
Street/Sidewalk Sweeping
City ordinance prohibits the tracking, dropping or depositing of soils or any other material onto the city streets by or from any vehicle.
Any inadvertent deposited material shall be cleaned immediately by the contractor. Street sweeping shall be performed on a regular
basis. The frequency of sweeping will depend on construction activity, the amount of deliveries, the overall effectiveness /
maintenance of the BMPs, as well as “good housekeeping” practices. City of Fort Collins may request additional sweeping if material
is tracked onto streets. The street sweeping shall be completed within 24 hours of the request.
Maintenance of lot BMPs
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.
*Lots That are in sensitive areas, or conditions are such that the lot(s) cannot be permanently stabilized for an extended period of time,
may require the entire lot to be covered with erosion control blankets. This will be determined on an individual lot basis.
** When all required BMPs are installed and an initial inspection is needed please call the erosion control inspector at (970) 224-6015,
please notify at least 24 hours prior to any construction on this site. If any questions arise about the erosion control needs of a site, this
number should be used.
1.CONTRACTOR SHALL INSTALL BIORETENTION BASINS ACCORDING TO THE APPROVED PLANS AND/OR
CONSTRUCTION SPECIFICATIONS.
2.PRE-CONSTRUCTION
2.1.CONTRACTOR SHALL AVOID COMPACTION OF THE BIORETENTION BASIN AREA TO PRESERVE EXISTING
INFILTRATION RATES.
2.2.CONTRACTOR SHALL CALL FOR CITY INSPECTIONS AT THE INTERVALS STIPULATED IN THE "DURING
CONSTRUCTION INSPECTION CHECKLISTS".
3.DURING CONSTRUCTION:
3.1.CONTRACTOR SHALL PROVIDE CONSTRUCTION OBSERVATION DURING CONSTRUCTION OF THE BIORETENTION
BASIN TO ENSURE COMPLIANCE WITH THE APPROVED PLANS AND DESIGN SPECIFICATIONS.
3.2.LOOSE MATERIALS SHALL NOT BE STORED ON THE BIORETENTION AREA.
3.3.THE CONTRACTOR SHALL, AT ALL TIMES DURING AND AFTER SYSTEM INSTALLATION, PREVENT SEDIMENT,
DEBRIS AND DIRT FROM ANY SOURCE FROM ENTERING THE BIORETENTION SYSTEM.
4.GEOTEXTILE LINERS:
4.1.WHERE USED, GEOTEXTILE LINERS (PERMEABLE OR IMPERMEABLE AS PER PLAN) SHALL BE INSTALLED ALONG
PERIMETER OF CROSS-SECTION OF THE BIORETENTION CELL.
4.2.WHERE USED, GEOTEXTILE LINERS SHALL BE PLACED IN ACCORDANCE WITH MANUFACTURER'S STANDARDS AND
RECOMMENDATIONS. ALL SEAMS AND OPENINGS IN THE LINER SHALL BE SEALED ACCORDING TO
MANUFACTURER'S RECOMMENDATIONS AND SPECIFICATIONS.
4.3.WHERE USED, IMPERMEABLE GEOMEMBRANE SHEET / LINER SHALL BE 40 MIL THICK, HIGH-DENSITY
POLYETHYLENE DESIGNED SPECIFICALLY FOR FLEXIBLE GEOMEMBRANE APPLICATIONS. ADJACENT STRIPS OF
IMPERMEABLE LINER SHALL OVERLAP A MINIMUM OF 18", OR PER MANUFACTURER'S SPECIFICATION.
4.4.WHERE USED, CONTRACTOR TO PLACE LINER IN A WAY THAT ENSURES ENOUGH SLACK IN THE LINER TO ALLOW
FOR BACKFILL AND SETTLING WITHOUT TEARING THE LINER.
5.AGGREGATES AND BSM:
5.1.ALL AGGREGATES SHALL BE ANGULAR, CRUSHED, WASHED ROCK, CLEAN OF DEBRIS AND WITH NO MORE THAN
1% FINES.
5.2.RESERVOIR AGGREGATE SHALL BE GRADATION ASTM #57 OR #67.
5.3.DIAPHRAGM AGGREGATE SHALL BE "PEA GRAVEL", WITH GRADATION ASTM #8, #89 OR #9.
5.4.THE BIORETENTION SOIL SHALL MEET THE CITY BIORETENTION SAND MEDIA ("BSM") SPECIFICATION FOUND
AT:https://www.fcgov.com/utilities/business/builders-and-developers/development-forms-guidelines-regulations/
NOTES:
12" MAX1
MAXIMUM ALLOWABLE
PONDING DEPTH IS 12"
FROM THE TOP OF THE
MULCH
4 MAX
PONDING DEPTH MUST
NOT EXCEED FLOWLINE
ELEVATION OF ADJACENT
GUTTER8" MIN DEPTH THICKENED
CURB ADJACENT TO
VEHICULAR PAVEMENTS
OVERFLOW
RISER OPTION
(AS PER PLAN)
8" MIN DEPTH
THICKENED CURB
ADJACENT TO
VEHICULAR
PAVEMENTS
STANDARD CROSS-SECTION
1
2
WALLED CROSS-SECTION
PONDING DEPTH MUST
NOT EXCEED FLOWLINE
ELEVATION OF ADJACENT
GUTTER
18" MIN
4"
12" MAX
30" MIN
36" MIN
BASIN WIDTH
COVER PLATE
8"
SIDEWALK CHASE
18" MIN
OVERFLOW RISER
OPTION (AS PER PLAN)
REINFORCED
CONCRETE WALLS (AS
PER PLAN)
4" MIN DEPTH OF
DIAPHRAGM AGGREGATE
8" MIN DEPTH OF
RESERVOIR AGGREGATE
18" MIN DEPTH OF
BIORETENTION SAND MEDIA
MAXIMUM ALLOWABLE
PONDING DEPTH IS 12"
FROM THE SURFACE OF
THE MULCH
4" MIN DIAMETER
PERFORATED PVC
UNDERDRAIN
6.UNDERDRAIN:
6.1.UNDERDRAIN PIPE TO BE PERFORATED OR SLOTTED. PERFORATIONS OR SLOTS TO BE SMALLER THAN SURROUNDING AGGREGATE TO ENSURE AGGREGATE DOES NOT FALL INTO OR
CLOG THE OPENINGS.
6.2.DO NOT WRAP UNDERDRAIN WITH GEOTEXTILE OR SOCK.
6.3.UNDERDRAIN PIPE MUST OUTFALL BY GRAVITY AND MUST TIE INTO A STORMWATER PIPE, INLET OR SYSTEM AND THE LOCATION MUST BE APPROVED BY THE CITY. THE UNDERDRAIN
TIE-IN SHALL MEET ALL REQUIRED PIPE SIZE, TYPES, AND COVER REQUIREMENTS THAT MAY APPLY TO PIPING THAT EXTENDS BEYOND THE LIMITS OF THE BIORETENTION CELL AND
ENCROACHES INTO PUBLIC RIGHT-OF-WAY OR OTHER PROPERTY.
7.OVERFLOW INLET:
7.1.A 100-YEAR OVERFLOW SPILLWAY OR INLET MUST BE PROVIDED.
7.2.ALL OVERFLOW INLETS SHALL BE CAPPED WITH A DOME-SHAPED GRATE, OR PER PLAN.
7.3.IN ALL CASES, AN EMERGENCY OVERFLOW ROUTE SHALL BE PROVIDED AND THE LOCATION SHALL BE IDENTIFIED ON THE PLANS (THIS MAY BE COINCIDENT WITH THE 100-YEAR
OVERFLOW SPILLWAY).
8.CLEANOUTS:
8.1.PROVIDE CLEANOUTS (AS PER PLAN) TO ALLOW INSPECTION (BY CAMERA) OF THE UNDERDRAIN SYSTEM DURING AND AFTER CONSTRUCTION.
8.2.CLEANOUTS SHALL BE PROVIDED AT EACH BEND GREATER THAN OR EQUAL TO 90° AND EVERY 100' ALONG A STRAIGHT RUN. CLEANOUT SHALL BE INSTALLED PER THE APPROVED
PLANS.
8.3.CLEANOUTS SHALL BE A SOLID WALL PVC STRUCTURE FOR ALL VERTICAL SECTIONS WITH FITTINGS TO CONNECT TO DISTRIBUTION AND UNDERDRAIN PIPING MATERIALS, AS
REQUIRED.
9.FOREBAY:
9.1.THE FOREBAY SHALL BE EASILY ACCESSIBLE WITH A HARD SURFACED BOTTOM FOR MAINTENANCE PURPOSES.
9.2.THE FOREBAY SHOULD NOT EXTEND INTO THE SAND MEDIA TO PREVENT ANY SETTLING OF THE FOREBAY.
10.LANDSCAPE MATERIALS
10.1.CONTRACTOR SHALL NOT PLACE WEED BARRIER ANYWHERE WITHIN THE BIORETENTION BASIN. IF MULCH IS PLACED IN THE BIORETENTION BASIN, IT MUST BE NON-FLOATABLE.
10.2.IF MULCH OR COBBLES ARE PLACED IN THE BIORETENTION BASIN, THE MAXIMUM ALLOWABLE WATER DEPTH OF 12" AND REQUIRED BASIN VOLUME MUST BE MEASURED FROM THE
TOP SURFACE OF THE MULCH OR COBBLE.
10.3.ROLLED TURF OR SOD IS NOT AN ALLOWABLE LANDSCAPE MATERIAL FOR BIORETENTION BASINS. LOW WATER CONSUMPTION LANDSCAPE PLANTINGS ARE PREFERRED FOR
BIORETENTION BASINS.
10.4.LANDSCAPE PLANTINGS SHALL NOT BE PLACED TO IMPEDE DRAINAGE INTO OR OUT OF THE BIORETENTION BASIN.
10.5.TEMPORARY IRRIGATION MAY BE INSTALLED TO ESTABLISH LANDSCAPING OR SEED IN THE BIORETENTION BASIN.2" MIN
8" MIN
4"
FLAT
FOREBAY IS REQUIRED TO
BE PLACED AT
CONCENTRATED INFLOW
LOCATIONS; PER PLANS
AND SITE SPECIFIC
DETAILS
LANDSCAPING TO BE
INSTALLED PER
APPROVED
LANDSCAPING PLAN
6"-12"
4" MIN DEPTH OF
DIAPHRAGM AGGREGATE
8" MIN DEPTH OF
RESERVOIR AGGREGATE
8" MIN 4" MIN DIAMETER
PERFORATED PVC
UNDERDRAIN
2" MIN
30" MIN
GEOTEXTILE
FABRIC OR LINER
(AS PER PLAN)18" MIN DEPTH OF
BIORETENTION SAND
MEDIA
NATIVE SOIL
ZONE
RUNDOWN OR SCOUR
PROTECTION NEEDED
ON SLOPES
8"
FLAT AREA - SEE DESIGN
PLANS FOR EXTENTS OF
BIORETENTION FLAT
SURFACES
APPROVED:
DRAWN BY:DETAILS
CONSTRUCTION DATE REVISED:
DETAILSTORMWATER
BIORETENTION
JUNE 2023
SAA
D-53
TYPICAL
BIORETENTION
OR SAND FILTER
CROSS-SECTION
UPTURNED
ELBOW
DAYLIGHT ELEVATION
AND THE
UNDERDRAIN MUST
BE BELOW THE
BIOSAND MEDIA OF
THE LID FEATURE
UNDERDRAIN @
0.50% MIN SLOPE
1.CONTRACTOR SHALL INSTALL BIORETENTION BASINS ACCORDING TO THE APPROVED PLANS AND/OR
CONSTRUCTION SPECIFICATIONS.
2.THIS DETAIL SHALL BE USED IN CONJUNCTION WITH DETAIL D-53 OR D-54. PLEASE REFER TO RAIN
GARDEN/SAND FILTER DETAIL FOR THE BIOMEDIA STRUCTURE.
3.THIS OPTION IS ONLY FOR USE WITH SYSTEMS THAT DO NOT HAVE AN IMPERMEABLE LINER.
NOTES:
30" MIN
12" MAX
18" MIN
4"
8" MIN
APPROVED:
DRAWN BY:DETAILS
CONSTRUCTION DATE REVISED:
DETAILSTORMWATER
BIORETENTION - UPTURNED ELBOW OUTFALL
D-53ADECEMBER 2018
HEM
1.CONTRACTOR SHALL INSTALL SAND FILTER BASINS ACCORDING TO THE APPROVED PLANSAND/OR CONSTRUCTION SPECIFICATIONS.2.PRE-CONSTRUCTION2.1.CONTRACTOR SHALL AVOID COMPACTION OF THE SAND FILTER BASIN AREA TO PRESERVEEXISTING INFILTRATION RATES.2.2.CONTRACTOR SHALL CALL FOR CITY INSPECTIONS AT THE INTERVALS STIPULATED IN THE"DURING CONSTRUCTION INSPECTION CHECKLISTS".3.DURING CONSTRUCTION:3.1.CONTRACTOR SHALL PROVIDE CONSTRUCTION OBSERVATION DURING CONSTRUCTION OFTHE SAND FILTER BASIN TO ENSURE COMPLIANCE WITH THE APPROVED PLANS ANDDESIGN SPECIFICATIONS.3.2.LOOSE MATERIALS SHALL NOT BE STORED ON THE SAND FILTER BASIN AREA.3.3.THE CONTRACTOR SHALL, AT ALL TIMES DURING AND AFTER SYSTEM INSTALLATION,PREVENT SEDIMENT, DEBRIS AND DIRT FROM ANY SOURCE FROM ENTERING THE SANDFILTER SYSTEM.4.GEOTEXTILE LINERS:4.1.GEOTEXTILE LINERS (PERMEABLE OR IMPERMEABLE AS PER PLAN) MAY BE INSTALLEDALONG PERIMETER OF CROSS-SECTION OF THE SAND FILTER CELL.4.2.PERMEABLE GEOTEXTILE LINER SHALL BE PLACED BELOW THE SAND LAYER IN THE SANDFILTER CELL UNLESS THE ALTERNATIVE CROSS-SECTION IS PROVIDED.4.3.WHERE USED, GEOTEXTILE LINERS SHALL BE PLACED IN ACCORDANCE WITHMANUFACTURER'S STANDARDS AND RECOMMENDATIONS. ALL SEAMS AND OPENINGS INTHE LINER SHALL BE SEALED ACCORDING TO MANUFACTURER'S RECOMMENDATIONS ANDSPECIFICATIONS.4.4.WHERE USED, IMPERMEABLE GEOMEMBRANE SHEET / LINER SHALL BE 40 MIL THICK,HIGH-DENSITY POLYETHYLENE DESIGNED SPECIFICALLY FOR FLEXIBLE GEOMEMBRANEAPPLICATIONS. ADJACENT STRIPS OF IMPERMEABLE LINER SHALL OVERLAP A MINIMUM OF18", OR PER MANUFACTURER'S SPECIFICATION.4.5.WHERE USED, CONTRACTOR TO PLACE LINER IN A WAY THAT ENSURES ENOUGH SLACK INTHE LINER TO ALLOW FOR BACKFILL AND SETTLING WITHOUT TEARING THE LINER.5.AGGREGATES:5.1.ALL AGGREGATES SHALL BE ANGULAR, CRUSHED, WASHED ROCK, CLEAN OF DEBRIS ANDWITH NO MORE THAN 1% FINES.5.2.RESERVOIR AGGREGATE SHALL BE GRADATION ASTM #57 OR #67.5.3.DIAPHRAGM AGGREGATE SHOWN IN ALTERNATIVE CROSS-SECTION SHALL BE "PEAGRAVEL", WITH GRADATION ASTM #8, #89 OR #9.5.4.SAND FILTER MATERIAL SHALL BE GRADATION ASTM C33 SAND.6.UNDERDRAIN:6.1.UNDERDRAIN PIPE TO BE PERFORATED OR SLOTTED. PERFORATIONS OR SLOTS TO BESMALLER THAN SURROUNDING AGGREGATE TO ENSURE AGGREGATE DOES NOT FALL INTOOR CLOG THE OPENINGS.6.2.DO NOT WRAP UNDERDRAIN WITH GEOTEXTILE OR SOCK.6.3.UNDERDRAIN PIPE MUST OUTFALL BY GRAVITY AND MUST TIE INTO A STORMWATER PIPE,INLET OR SYSTEM AND THE LOCATION MUST BE APPROVED BY THE CITY. THE UNDERDRAINTIE-IN SHALL MEET ALL REQUIRED PIPE SIZE, TYPES, AND COVER REQUIREMENTS THATMAY APPLY TO PIPING THAT EXTENDS BEYOND THE LIMITS OF THE SAND FILTER CELL ANDENCROACHES INTO PUBLIC RIGHT-OF-WAY OR OTHER PROPERTY.7.OVERFLOW INLET:7.1.AN OVERFLOW INLET OR RISER PIPE SHALL BE PROVIDED.7.2.ALL OVERFLOW RISER PIPE SHALL BE CAPPED WITH A DOME-SHAPED GRATE.7.3.AN EMERGENCY OVERFLOW ROUTE SHALL BE PROVIDED AND THE LOCATION SHALL BEIDENTIFIED ON THE PLANS.8.CLEANOUTS:8.1.PROVIDE CLEANOUTS (AS PER PLAN) TO ALLOW INSPECTION (BY CAMERA) OF THEUNDERDRAIN SYSTEM DURING AND AFTER CONSTRUCTION.8.2.CLEANOUTS SHALL BE PROVIDED AT EACH BEND GREATER THAN OR EQUAL TO 90° ANDEVERY 100' ALONG A STRAIGHT RUN. CLEANOUT SHALL BE INSTALLED PER THE APPROVEDPLANS.8.3.CLEANOUTS SHALL BE A SOLID WALL PVC STRUCTURE FOR ALL VERTICAL SECTIONS WITHFITTINGS TO CONNECT TO DISTRIBUTION AND UNDERDRAIN PIPING MATERIALS, ASREQUIRED.9.FOREBAY:9.1.THE FOREBAY SHALL BE EASILY ACCESSIBLE WITH A HARD SURFACED BOTTOM FORMAINTENANCE PURPOSES.10.LANDSCAPE MATERIALS10.1.CONTRACTOR SHALL NOT PLACE WEED BARRIER ANYWHERE WITHIN THE SAND FILTERBASIN. IF MULCH IS PLACED IN THE SAND FILTER BASIN, IT MUST BE NON-FLOATABLE.10.2.IF MULCH OR COBBLES ARE PLACED IN THE SAND FILTER BASIN, THE MAXIMUMALLOWABLE WATER DEPTH OF 36" AND REQUIRED BASIN VOLUME MUST BE MEASUREDFROM THE TOP SURFACE OF THE MULCH OR COBBLE.10.3.ROLLED TURF OR SOD IS NOT AN ALLOWABLE LANDSCAPE MATERIAL FOR SAND FILTERBASINS.10.4.LANDSCAPE MATERIALS ARE GENERALLY NOT ENCOURAGED TO BE PLACED ON THEBOTTOM OF THE SAND FILTER BASIN. LANDSCAPE PLANTINGS SHALL NOT BE PLACED TOIMPEDE DRAINAGE INTO OR OUT OF THE SAND FILTER BASIN.10.5.TEMPORARY IRRIGATION MAY BE INSTALLED TO ESTABLISH LANDSCAPING OR SEED INTHE SAND FILTER BASIN.NOTES:8" MIN4" MIN DIAMETERPERFORATED PVCUNDERDRAIN1MAXIMUM ALLOWABLEPONDING DEPTH IS 36"FROM THE TOP OF THEMULCH4 MAXNON-FLOATABLEMULCH (AS PERPLAN)3"PONDING DEPTH MUSTNOT EXCEED FLOWLINEELEVATION OF ADJACENTGUTTERFOREBAY IS REQUIRED TOBE PLACED AT ALL INFLOWLOCATIONS; WITH AMINIMUM 3" DROP FROMGUTTER FLOWLINE TOFOREBAY8" MIN DEPTH OFRESERVOIR AGGREGATE18" MIN DEPTH OFSAND FILTER MATERIAL8" MIN DEPTH THICKENEDCURB ADJACENT TOVEHICULAR PAVEMENTSSTANDARD CROSS-SECTION8"PERMEABLE GEOTEXTILETO BE PLACED BETWEENAGGREGATE LAYERSOVERFLOWRISER OPTION(AS PER PLAN)36" MAX18"8"4"30" MINPONDING DEPTHALTERNATIVE CROSS-SECTION8" MIN DEPTH OFRESERVOIR AGGREGATE18" MIN DEPTH OFSAND FILTER MATERIAL4" MIN DEPTH OFDIAPHRAGM AGGREGATENOTE:THE ALTERNATIVE CROSS-SECTIONS SHOWS A 4"DIAPHRAGM AGGREGATE LAYER INSTEAD OF THEGEOTEXTILE FABRIC, WHICH IS THE ONLY DIFFERENCE FROMTHE STANDARD CROSS-SECTION. ALL OTHER REQUIREMENTSOF THE STANDARD CROSS-SECTION ARE REQUIRED.18" MINFLAT2" MINGEOTEXTILE LINEROPTION (AS PER PLAN)26" MINNATIVE SOILZONEAPPROVED:DRAWN BY:DETAILSCONSTRUCTIONDATE REVISED:DETAILSTORMWATERSAND FILTERDECEMBER 2018HEMD-55