MA1009-PT120405 Bryan W.Shaw,Ph.D.,Chairman �� 04
•
Buddy Garcia,Commissioner ..� . v}•� y
Carlos Rubinstein,Commissioner � +��� a.;l
Mark R.Vickery,P.G.,Executive Director
TEXAS COMMISSION ON ENVIRONMENTAL QUALITY
Protecting Texas by Reducing and Preventing Pollution
April 5, 2012
Ms. Kristi N. McMillan
Galveston District CESWG-PE-RE
U.S.Army Corps of Engineers
P.O. Box 1229
Galveston,Texas 77553-1229
Re: USACE Nationwide Permits
Dear Ms.McMillan:
This letter is in response to your January 23,2012,letter requesting Clean Water Act Section
401 certification of the United States Army Corps of Engineers (Corps)Nationwide Permits
(NWPs). The Final Notice of Reissuance of Nationwide Permits was published in the
Federal Register(Vol.77,No.34,pages 10184-1029o)on February 21,2012. Proposed
regional conditions for NWPs in Texas were proposed in public notices on February 24,2011
and November 14,2011.
The Texas Commission on Environmental Quality(TCEQ)has reviewed the Final Notice of
Reissuance of Nationwide Permits and the proposed regional conditions. On behalf of the
Executive Director and based on our evaluation of the information contained in these
documents,the TCEQ certifies that the activities authorized by NWPs 1,2,4,5, 8,9,to,11,
20,23,24,28,34,35,and 48 should not result in a violation of established Texas Surface
Water Quality Standards as required by Section 401 of the Federal Clean Water Act and
pursuant to Title 3o,Texas Administrative Code,Chapter 279.
The TCEQ conditionally certifies that the activities authorized by NWPs 3,6,7, 12,13,14,15,
17, 18, 19,21, 22,25,27,29,30,31,32,33,36,37,38,39,40,41,42,43,44,45,46,49,50,51
and 52 should not result in a violation of established Texas Surface Water Quality Standards
as required by Section 401 of the Federal Clean Water Act and pursuant to Title 30,Texas
Administrative Code,Chapter 279. Conditions for each NWP are defined in Enclosure 1 and
more detail on specific conditions are discussed below.
The TCEQ understands that a prohibition against the use of NWPs in coastal dune swales
will be included in the 2012 Texas Regional Conditions(Regional Conditions)for all NWPs,
except for NWP 3. Inclusion of a prohibition of using NWPs in coastal dune swales,except
for NWP 3,is a condition of this 401 TCEQ certification.
P.O.Box r3o87 • Austin,Texas 78711-3087 • 512-239-10oo • www.tceq.texas.gov
How is our customer service? www.tceq.texas.gov/goto/customersurvey
Ms. Kristi N.McMillan
U.S.Army Corps of Engineers
USACE Nationwide Permits
Page 2
April 5, 2012
The TCEQ wants to clarify the application of NWP 16 in Texas. NWP 16 should be limited to
the return water from upland contained dredged material disposal areas. It is important to
emphasize the intent for dredged material disposal. The TCEQ understands dredged
material to be associated with navigational dredging activities,not commercial mining
activities. To avoid confusion the TCEQ requests that a regional condition be added that
prohibits the use of NWP 16 for activities that would be regulated under Standard Industrial
Classification(SIC)codes 1412 and 1446(industrial and construction sand and gravel
mining). This condition is also included as part of the 401 certification of NWP 16.
The final NWP 16 states that the quality of the return water is controlled by the state through
the 401 certification procedures. Consistent with previous NWPs certification decisions the
TCEQ is conditionally certifying NWP 16 for the return water from confined upland disposal
not to exceed a 300 mg/L Total Suspended Solids(TSS)concentration and request the
Corps to include this condition in the Regional Conditions. The TCEQ recognizes the
usefulness of having an instantaneous method to determine compliance with the 30o mg/L
TSS limit. However,existing literature and analysis of paired samples of turbidity and TSS
from the Texas Surface Water Quality Data indicate this relationship must be a site specific
characterization of the actual sediments to be dredged. To address this approach we have
continued language in the NWP 16 conditional certification that allows flexibility to use an
instantaneous method in implementing the TSS limit when a site specific correlation curve
for turbidity(nephelometric turbidity units(NTU))versus TSS has been approved by TCEQ.
The TCEQ remains interested in working with the Corps in the development of these curves.
We encourage the Corps to accept the conditional certification of NWP 16 as a Regional
Condition and that we work together to find the best methods to implement this limit.
In evaluating this condition for the Regional Conditions for NWPs,the TCEQ encourages the
Corps to consider that TSS limits are promulgated as effluent limits under Title 40 of the
Code of Federal Regulations. The TCEQ requirement to control return water from confined
upland disposal not to exceed a 300 mg/L TSS has also been included in individual 404
permits. It is also important to note that the TCEQ effectively imposes TSS effluent limits in
thousands of wastewater discharge permits issued in Texas under Section 402 of the federal
Clean Water Act.
The TCEQ is conditionally certifying NWP General Condition#12 Soil Erosion and
Sediment Controls,and General Condition#25 Water Quality. The conditions address
three broad categories of water quality management with specific recommendations for Best
Management Practices(BMPs)for each category. These BMPs are intended to enhance the
water quality protection of these General Conditions. A list of TCEQ-recommended BMPs is
included as Enclosure 2.
Attachment 1
t,
Attachment 1
Conditions of Section 401 Certification for Nationwide Permits and General Conditions
General Condition 12(Soil Erosion and Sediment Controls)
Erosion control and sediment control BMPs described in Attachment 2 are required with the use of this
general condition. If the applicant does not choose one of the BMPs listed in Attachment 2,an
individual 401 certification is required.
General Condition 2S(Water Quality)
Post-construction total suspended solids (TSS)BMPs described in Attachment 2 are required with the
use of this general condition. If the applicant does not choose one of the BMP's listed in Attachment 2,
an individual 401 certification is required. Bridge deck runoff is exempt from this requirement.
General Condition 25(Mitigation)
The U.S.Army Corps of Engineers will copy the TCEQ on all mitigation waivers sent to applicants.
NWPs 15.29.59.40,41,42.43.44.50.51,52
The U.S.Army Corps of Engineers will copy the TCEQ on all written approvals of waivers for impacts to
ephemeral,intermittent or perennial streams.
All NWPs except for NWP
These NWPs are not authorized for use in coastal dune swales in Texas.
NWP 3(Maintenance)
-Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 6(Survey Activities)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 7(Outfall Structures and Associated Intake Structures)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 12(Utility Line Activities)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 15(Bank Stabilization)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 14(Linear Transportation Projects)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
Revised April 5,2012 Page i of 4
Attachment 1
Conditions of Section 401 Certification for Nationwide Permits and General Conditions
NWP 15(U.S.• Coast Guard Approved Bridges)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 16 (Return Water From Upland Contained Disposal Areas)
Activities that would be regulated under Standard Industrial Classification(SIC)codes 1442 and 1446
(industrial and construction sand and gravel mining)are not eligible for this NWP. Effluent from an
upland contained disposal area shall not exceed a TSS concentration of 300 mg/L unless a site-specific
TSS limit,or a site specific correlation curve for turbidity(nephelometric turbidity units(NTU))versus
(TSS)has been approved by TCEQ.
NWP 17(Hydropower Projects)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 1$ (Minor Discharges)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 19(Minor Dredging)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 21(Surface Coal Mining Operations)
Soil Erosion and Sediment Controls under General Condition 12 are required, Post-construction TSS
controls under General Condition 25 are required.
NWP 22(Removal of Vessels)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 25(Structural Discharges)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 27(Aquatic Habitat Restoration, Establishment,and Enhancement Activities)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 29(Residential Developments)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
Revised April 5,2012 Page 2 of 4
Attachment 1
Conditions of Section 401 Certification for Nationwide Permits and General Conditions
NWP 30(Moist Soil Management for Wildlife)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 31(Maintenance of Existing Flood Control Facilities)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 32(Completed Enforcement Actions)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 33(Temporary Construction.Access and Dewatering)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 36(Boat Ramps)
The U.S.Army Corps of Engineers will copy the TCEQ on all written waivers for discharges greater than
the 5o cubic yard limit or boat ramps greater than 20 feet in width. Soil Erosion and Sediment Controls
under General Condition 12 are required. Post-construction TSS controls under General Condition 25
are required.
NWP 37(Emergency Watershed Protection and Rehabilitation)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 38(Cleanup of Hazardous and Toxic Waste)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 39(Commercial and Institutional Developments)
Soil.Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 40(Agricultural Activities)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 41(Reshaping Existing Drainage Ditches)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
Revised April 5,2012 Page 3 of 4
Attachment i
Conditions of Section 401 Certification for Nationwide Permits and General Conditions
NWP 42(Recreational Facilities)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 43 (Stormwater Management Facilities)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 44(Mining Activities)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 45(Repair of Uplands Damaged by Discrete Events)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 46(Discharges in Ditches)
Soil Erosion and Sediment Controls under General Condition 12 are required.
NWP 49 (Coal Remining Activities)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 5o(Underground Coal Mining Activities)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required,
NWP.ri1 (Land-Based Renewal Energy Generation Facilities)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
NWP 52 (Water-Based Renewal Energy Generation Pilot Projects)
Soil Erosion and Sediment Controls under General Condition 12 are required. Post-construction TSS
controls under General Condition 25 are required.
Revised April 5,2012 Page 4 of 4
Attachment 2
Attachment 2
401 Water Quality Certification Best Management Practices(BMPs)for Nationwide
Permits
Below are the 401 water quality certification conditions the Texas Commission on Environmental
Quality(TCEQ)added to the February 21,2012 issuance of Nationwide Permits(NWP),as
described in the Federal Register(Vol. 77,No. 34,pages 10184-10290).
Additional information regarding these conditions,including descriptions of the best
management practices(BMPs),can be obtained from the TCEQ by contacting the 401
Coordinator, MC-15o,P.O. Box 13087,Austin,Texas 78711-3087 or from the appropriate U.S.
Army Corps of Engineers district office.
I. Erosion Control
Disturbed areas must be stabilized to prevent the introduction of sediment to adjacent wetlands
or water bodies during wet weather conditions(erosion). At Ieast one of the following BMPs
must be maintained and remain in place until the area has been stabilized for NWPs 3,6,7,12,
13,14,15,17,18, 19,21, 22,25,27, 29,30,31,32,33,36,37,38,39,40,41,42,43,44, 45,46,49,
5o,51,and 52. If the applicant does not choose one of the BMPs listed,an individual 401
certification is required. BMPs for NWP 52 apply only to land-based impacts from attendant
features.
o Temporary Vegetation o Blankets/Matting
o Mulch o Sod
o Interceptor Swale o Diversion Dike
o Erosion Control Compost o Mulch Filter Socks
o Compost Filter Socks
H. Sedimentation Control
Prior to project initiation,the project area must be isolated from adjacent wetlands and water
bodies by the use of BMPs to confine sediment. Dredged material shall be placed in such a
manner that prevents sediment runoff into water in the state,including wetlands. Water bodies
can be isolated by the use of one or more of the required BMPs identified for sedimentation
control. These BMP's must be maintained and remain in place until the dredged material is
stabilized. At least one of the following BMPs must be maintained and remain in place until the
area has been stabilized for NWPs 3, 6,7, 12, 13,14,15,17, 18,19, 21,22,25,27, 29,30,31,32,
33,36,37,38,39,40,41,42,43,44,45,46,49,50,51,and 52.If the applicant does not choose
one of the BMPs listed,an individual 401 certification is required. BMPs for NWP 52 apply only
to land-based impacts from attendant features.
o Sand Bag Berm o Rock Berm
o Silt Fence o Hay Bale Dike
o Triangular Filter Dike o Brush Berms
Revised April 5,2012 Page 1013
Attachment 2
401 Water Quality Certification Best Management Practices(BMPs)for Nationwide
Permits
o Stone Outlet Sediment`Daps o Sediment Basins
o Erosion Control Compost o Mulch Filter Socks
o Compost Filter Socks
III. Post-Construction TSS Control
After construction has been completed and the site is stabilized,total suspended solids(TSS)
loadings shall be controlled by at least one of the following BMPs for NWPs 12, 14, 17,18,21,29,
31, 36,39,40,41,42,44,45,49, 50,.51,and 52. If the applicant does not choose one of the BMPs
listed,an individual 401 certification is required. BMPs for NWP 52 apply only to land-based
impacts from attendant features. Runoff from bridge decks has been exempted from the
requirement for post construction TSS controls.
o Retention/Irrigation Systems o Constructed Wetlands
o Extended Detention Basin o Wet Basins
o Vegetative Filter Strips o Vegetation lined drainage ditches
o Grassy Swales o Sand Filter Systems
o Erosion Control Compost o Mulch Filter Socks
o Compost Filter Socks o Sedimentation Chambers*
*Only to be used when there is no space available for other approved BMPs.
IV.. NWP 16:Return Water from Upland Contained Disposal Areas
Effluent from an upland contained disposal area shall not exceed a TSS concentration of 300
mg/L unless a site-specific TSS limit, or a site specific correlation curve for turbidity
(nephelometric turbidity units(NTU))versus(TSS)has been approved by TCEQ.
V. NWP 29,j9,40,42,43.44.50,51. and 52
The Corps will copy the TCEQ on all authorizations for impacts of greater than 300 linear feet of
intermittent and ephemeral streams:
•
Revised April 3,2012 Page 2 of 3
•
Attachment 2
401 Water Quality Certification Best Management Practices (BMPs)for Nationwide
Permits
VI. NWP in and 41
The Corps will copy the TCEQ on all authorizations for impacts greater than 500 linear feet in
length of ephemeral,intermittent,perennial streams or drainage ditches.
VII. NWP 36
The Corps will copy the TCEQ on all authorizations for discharges greater than the 5o cubic yard
limit or boat ramps greater than 20 feet in width.
VIII. All NWPs except NWP 3
These NWPs are not authorized for use in coastal dune swales in Texas.
Revised April g,2012 Page 3 of 3
Attachment 3
Attachment 3
Reference to Nationwide Permits Best Management Practices Requirements
NWP Permit Description Erosion Sediment Post
Control Control Construction
TSS
1 Aid to Navigation
2 Structures in Artificial Canals
3 Maintenance X X
4 Fish and Wildlife Harvesting,Enhancement
and Attraction Devices and Activities
5 Scientific Measurement Devices
6 Survey Activities benching X X
7 Outfall Structures and Associated Intake X X
Structures
8 Oil and Gas Structures on the Outer
Continental Shelf
9 Structures in Fleeting and Anchorage Areas
10 Mooring Buoys
11 Temporary Recreational Structures
12 Utility Line Activities X X X
13 Bank Stabilization X X
14 Linear Transportation Projects
X X X
15 U.S.Coast Guard Approved Bridges X
16 Return Water From Upland Contained
Disposal Areas
17 Hydropower Projects X X X
18 Minor Discharges X X X
1g Minor Dredging X X
20 Response Operations for Oil and Hazardous
Substances
21 Surface Coal Mining Operations X X X
22 Removal of Vessels X X
23 Approved Categorical Exclusions
Revised April 5,2012 Page 1 of 3
Attachment R
Reference to Nationwide Permits Best Management Practices Requirements
NWP Permit Description Erosion Sediment Post
Control Control Construction
TSS
24 Indian Tribe or State Administered Section
404 Programs
25 Structural Discharges X X
26 [Reserved]
27 Aquatic Habitat Restoration,Establishment, X X
and Enhancement Activities
28 Modifications of Existing Marinas
29 Residential Developments X X X
3o Moist Soil Management for Wildlife X X
31 Maintenance of Existing Flood Control X X X
Facilities
32 Completed Enforcement Actions X X
33 Temporary Construction,Access and X X
Dewatering
34 Cranberry Production Activities
35 Maintenance Dredging of Existing Basins
36 Boat Ramps X X X
37 Emergency Watershed Protection and
X X
Rehabilitation
38 Cleanup of Hazardous and Toxic Waste X X
39 Commercial and Institutional Developments X X X
40 Agricultural Activities X X X
41 Reshaping Existing Drainage Ditches X X X
42 Recreational Facilities X X X
43 Stormwater Management Facilities X X
44 Mining Activities X X X
45. Repair of Uplands Damaged by Discrete X X X
Events
46. Discharges in Ditches X X
Revised April 5,2012 Page 2 of 3
Attachment g
Reference to Nationwide Permits Best Management Practices Requirements
NWP Permit Description Erosion Sediment Post
Control Control Construction
TSS
47. [Reserved]
48. Existing Commercial Shellfish Aquaculture
Activities
49. Coal Remining Activities X X X
5o. Underground Coal Mining Activities X X X
51. Land-Based Renewable Energy Generation X X X
Facilities
52. Water-Based Renewable Energy Generation X X X
Pilot Projects
•
Revised April 5,2012 Page 3 of 3
Attachment 4
Attachment 4
Description of BMPs
EROSION CONTROL BMPs
Temporary Vegetation
Description: Vegetation can be used as a temporary or permanent stabilization technique for
areas disturbed by construction. Vegetation effectively reduces erosion in swales,stockpiles,
berms,mild to medium slopes,and along roadways. Other techniques such as matting,mulches,
and grading may be required to assist in the establishment of vegetation.
Materials:
•The type of temporary vegetation used on a site is a function of the season and the availability
of water for irrigation.
•Temporary vegetation should be selected appropriately for the area.
• County agricultural extension agents are a good source for suggestions for temporary
vegetation.
•All seed should be high quality,U.S. Dept.of Agriculture certified seed.
Installation:
• Grading must be completed prior to seeding.
• Slopes should be minimized.
• Erosion control structures should be installed.
• Seedbeds should be well pulverized,loose,and uniform.
• Fertilizers should be applied at appropriate rates.
• Seeding rates should be applied as recommended by the county agricultural extension agent.
•The seed should be applied uniformly.
• Steep slopes should be covered with appropriate soil stabilization matting.
Blankets and Matting
Description: Blankets and matting material can be used as an aid to control erosion on critical
sites during the establishment period of protective vegetation. The most common uses are in
channels,interceptor swales,diversion dikes,short, steep slopes,and on tidal or stream banks.
Materials:
New types of blankets and matting materials are continuously being developed. The Texas
Revised April 5,2012 Page of 30
•
Attachment 4
Description of BMPs
Department of Transportation(TxDOT)has defined the critical performance factors for these
types of products and has established minimum performance standards which must be met for
any product seeking to be approved for use within any of TxDOT's construction or maintenance
activities. The products that have been approved by TxDOT are also appropriate for general
construction site stabilization. TxDOT maintains a web site at
http://www.txdot.gov/business/doing_business/product_evaluation/erosion_control.htm
which is updated as new products are evaluated.
Installation:
• Install in accordance with the manufacturer's recommendations.
• Proper anchoring of the material.
• Prepare a friable seed bed relatively free from clods and rocks and any foreign material.
• Fertilize and seed in accordance with seeding or other type of planting plan.
• Erosion stops should extend beyond the channel liner to full design cross-section of the
channel.
•A uniform trench perpendicular to line of flow may be dug with a spade or a mechanical
trencher.
• Erosion stops should be deep enough to penetrate solid material or below level of ruling in
sandy soils.
•Erosion stop mats should be wide enough to allow turnover at bottom of trench for stapling,
while maintaining the top edge flush with channel surface.
Mulch
Description: Mulching is the process of applying a material to the exposed soil surface to
protect it from erosive forces and to conserve soil moisture until plants can become established.
When seeding critical sites,sites with adverse soil conditions or seeding on other than optimum
seeding dates,mulch material should be applied immediately after seeding.Seeding during
optimum seeding dates and with favorable soils and site conditions will not need to be mulched.
Materials:
• Mulch may be small grain straw which should be applied uniformly.
• On slopes 15 percent or greater,a binding chemical must be applied to the surface.
• Wood-fiber or paper-fiber mulch may be applied by hydroseeding.
• Mulch nettings may be used.
Revised April 5,2012 Page 2 of 30
Attachment 4
Description of BMPs
•Wood chips may be used where appropriate.
Installation:
Mulch anchoring should be accomplished immediately after mulch placement. This may be done
by one of the following methods:peg and twine,mulch netting,mulch anchoring tool,or liquid
mulch binders.
Sod
Description: Sod is appropriate for disturbed areas which require immediate vegetative
covers,or where sodding is preferred to other means of grass establishment. Locations
particularly suited to stabilization with sod are waterways carrying intermittent flow,areas
around drop inlets or in grassed swales,and residential or commercial lawns where quick use or
aesthetics are factors. Sod is composed of living plants and those plants must receive adequate
care in order to provide vegetative stabilization on a disturbed area.
Materials:
• Sod should be machine cut at a uniform soil thickness.
• Pieces of sod should be cut to the supplier's standard width and length.
•Torn or uneven pads are not acceptable.
• Sections of sod should be strong enough to support their own weight and retain their size and
shape when suspended from a firm grasp.
• Sod should be harvested,delivered,and installed within a period of 36 hours.
Installation:
•Areas to be sodded should be brought to final grade.
•The surface should be cleared of all trash and debris.
• Fertilize according to soil tests.
•Fertilizer should be worked into the soil.
•Sod should not be cut or laid in excessively wet or dry weather.
•Sod should not be laid on soil surfaces that are frozen.
• During periods of high temperature,the soil should be lightly irrigated.
Revised April 5,2012 Page 3 of 3o
Attachment 4
Description of BMPs
•The first row of sod should be laid in a straight line with subsequent rows placed parallel to and
butting tightly against each other.
• Lateral joints should be staggered to promote more uniform growth and strength.
• Wherever erosion may be a problem,sod should be laid with staggered joints and secured.
• Sod should be installed with the length perpendicular to the slope(on the contour).
• Sod should be rolled or tamped.
• Sod should be irrigated to a sufficient depth.
•Watering should be performed as often as necessary to maintain soil moisture.
•The first mowing should not be attempted until the sod is firmly rooted.
• Not more than one third of the grass leaf should be removed at any one cutting.
Interceptor Swale
Interceptor swales are used to shorten the length of exposed slope by intercepting runoff,prevent
off-site runoff from entering the disturbed area,and prevent sediment-laden runoff from leaving
a disturbed site. They may have a v-shape or be trapezoidal with a flat bottom and side slopes of
3:1 or flatter. The outflow from a swale should be directed to a stabilized outlet or sediment
trapping device. The swales should remain in place until the disturbed area is permanently
stabilized.
Materials:
• Stabilization should consist of a layer of crushed stone three inches thick,riprap or high
velocity erosion control mats.
• Stone stabilization should be used when grades exceed 2%or velocities exceed 6 feet per
second.
• Stabilization should extend across the bottom of the swale and up both sides of the channel to a
minimum height of three inches above the design water surface elevation based on a 2-year,
24-hour storm.
Installation:
•An interceptor swale should be installed across exposed slopes during construction and should
intercept no more than 5 acres of runoff.
•All earth removed and not needed in construction should be disposed of in an approved spoils
site so that it will not interfere with the functioning of the swale or contribute to siltation in
other areas of the site.
Revised April 5,2012 Page 4 of 3o
Attachment 4
Description of BMPs
•All trees,brush,stumps,obstructions and other material should be removed and disposed of so
as not to interfere with the proper functioning of the swale.
• Swales should have a maximum depth of 1.5 feet with side slopes of 3:1 or flatter.Swales should
have positive drainage for the entire length to an outlet.
•When the slope exceeds 2 percent,or velocities exceed 6 feet per second(regardless of slope),
stabilization is.required.Stabilization should be crushed stone placed in a layer of at least 3
inches thick or may be high velocity erosion control matting.Check dams are also
recommended to reduce velocities in the swales possibly reducing the amount of stabilization
necessary.
• Minimum compaction for the swale should be go%standard proctor density.
Diversion Dikes
A temporary diversion dike is a barrier created by the placement of an earthen embankment to
reroute the flow of runoff to an erosion control device or away from an open,easily erodible area.
A diversion dike intercepts runoff from small upland areas and diverts it away from exposed
slopes to a stabilized outlet,such as a rock berm,sandbag berm,or stone outlet structure.These
controls can be used on the perimeter of the site to prevent runoff from entering the construction
area. Dikes are generally used for the duration of construction to intercept and reroute runoff
from disturbed areas to prevent excessive erosion until permanent drainage features are installed
and/or slopes are stabilized.
Materials:
• Stone stabilization(required for velocities in excess of 6 fps)should consist of riprap placed in
a layer at least 3 inches thick and should extend a minimum height of 3 inches above the design
water surface up the existing slope and the upstream face of the dike.
• Geotextile fabric should be a non-woven polypropylene fabric designed specifically for use as a
soil filtration media with an approximate weight of 6 oz./yd2,a Mullen burst rating of 140 psi,
and having an equivalent opening size(EOS)greater than a *so sieve.
Installation:
• Diversion dikes should be installed prior to and maintained for the duration of construction
and should intercept no more than io acres of runoff.
• Dikes should have a minimum top width of 2 feet and a minimum height of compacted fill of 18
inches measured form the top of the existing ground at the upslope toe to top of the dike and
have side slopes of 3:1 or flatter.
•The soil for the dike should be placed in lifts of 8 inches or less and be compacted to 95%
standard proctor density.
•The channel,which is formed by the dike,must have positive drainage for its entire length to
an outlet.
Revised April 5,2012 Page 5 of 30
Attachment 4
Description of SMPs
• When the slope exceeds 2 percent,or velocities exceed 6 feet per second(regardless of slope),
stabilization is required.In situations where velocities do not exceed 6 feet per second,
vegetation may be used to control erosion.
Erosion Control Compost
Description:Erosion control compost(ECC)can be used as an aid to control erosion on critical
sites during the establishment period of protective vegetation.The most common uses are on
steep slopes,swales,diversion dikes,and on tidal or stream banks.
Materials:
New types of erosion control compost are continuously being developed. The Texas Department
of Transportation(TxDOT)has established minimum performance standards which must be met
for any products seeking to be approved for use within any of TxDOT's construction or
maintenance activities. Material used within any TxDOT construction or maintenance activities
must meet material specifications in accordance with current TxDOT specifications. TxDOT
maintains a website at
http://www.txdot.gov/business/contractors_consultants/recycling/compost.htm that provides
information on compost specification data.
ECC used for projects not related to TxDOT should also be of quality materials by meeting
performance standards and compost specification data. To ensure the quality of compost used as
an ECC,products should meet all applicable state and federal regulations,including but not
limited to the United States Environmental Protection Agency(USEPA)Code of Federal
Regulations(CFR),Title 40, Part 503 Standards for Class A biosolids and Texas Natural
Resource Conservation Commission(now named TCEQ)Health and Safety Regulations as
defined in the Texas Administration Code(TAC), Chapter 332,and all other relevant
requirements for compost products outlined in TAC,Chapter 332. Testing requirements
required by the TCEQ are defined in TAC Chapter 332,including Sections§332.71 Sampling and
Analysis Requirements for Final Products and§332.72 Final Product Grades. Compost
specification data approved by TxDOT are appropriate to use for ensuring the use of quality
compost materials or for guidance..
Testing standards are dependent upon the intended use for the compost and ensures product
safety, and product performance regarding the product's specific use.The appropriate compost
sampling and testing protocols included in the United States Composting Council(USCC)Test
Methods for the Examination of Composting and Compost(TMECC)should be conducted on
compost products used for ECC to ensure that the products used will not impact public health,
safety, and the environment and to promote production and marketing of quality composts that
meet analytical standards.TMECC is a laboratory manual that provides protocols for the
composting industry and test methods for compost analysis.TMECC provides protocols to
sample,monitor,and analyze materials during all stages of the composting process.Numerous
parameters that might be of concern in compost can be tested by following protocols or test
methods listed in TMECC. TMECC information can be found at
http://www.tmecc.org/tmecc/index.html. The USCC Seal of Testing Assurance(STA)program
contains information regarding compost STA certification. STA program information can be
found at http://tmecc.org/sta/STA_program description.html.
Revised April 5,2012 Page 6 of 30
Ms.Kristi N. McMillan
U.S.Army Corps of Engineers
USACE Nationwide Permits
Page 3
April 5, 2012
Enclosure 3 is provided as a quick reference table for all NWPs. A detailed description of the
BMPs is provided in Enclosure 4. Runoff from bridge decks has been exempted from the
requirement for post-construction total suspended solids(TSS)controls under General
Condition 25. As stated in our April 11,2011 and November 30,2011 letters to the Corps,the
TCEQ would like to include these BMPs for the protection of waters in the state specific to
each NWP as part of the regional conditions for Texas.
The TCEQ is conditionally certifying NWPs 13, 29,39,40,41,42,43,44,50,51,and 52 to
require the Corps to copy TCEQ on all written approvals of waivers for impacts to
ephemeral,intermittent or perennial streams. The TCEQ is conditionally certifying NWP 36
to require the Corps to copy TCEQ on all written waivers for discharges greater than the 5o
cubic yard limit or boat ramps greater than 20 feet in width. The TCEQ is also conditionally
certifying General Condition 23 Mitigation to require the Corps to copy TCEQ on any
written notification of a mitigation waiver. The TCEQ is requesting this information to fulfill
its responsibility to ensure water of the state is appropriately protected by understanding the
impact of waivers being granted in Texas.
This certification decision is limited to those activities under the jurisdiction of the TCEQ.
For activities related to the production and exploration of oil and gas,a Texas Railroad
Commission certification is required as provided in the Texas Water Code§26.131.
The TCEQ has reviewed the Notice of Reissuance of Nationwide Permits for consistency with
the Texas Coastal Management Program(CMP)goals and policies in accordance with the
CMP regulations{Title 31,Texas Administrative Code(TAC),Chapter(§)5o5.3o}and has
determined that the action is consistent with the applicable CMP goals and policies.
This certification was reviewed for consistency with the CMP's development in critical areas
policy{31 TAC§5o1.23}and dredging and dredged material disposal and placement policy
{31 TAC§5o1.25}. This certification complies with the CMP goals{31 TAC§501.12(1,2,3,
5)}applicable to these policies.
The TCEQ reserves the right to modify this certification if additional information identifies
specific areas where significant impacts,including cumulative or secondary impacts,are
occurring,and the use of these NWPs would be inappropriate.
No review of property rights,location of property lines,nor the distinction between public
and private ownership has been made,and this certification may not be used in any way with
regard to questions of ownership.
Ms. Kristi N.McMillan
U.S.Army Corps of Engineers
USACE Nationwide Permits
Page 4
April 5, 2012
If you require further assistance,please contact Mr.John Trevino,Water Quality
Assessment Section,Water Quality Division(MC-150),at(512) 239-4600.
Sincerely,
Ch W.Maguire
W ter Quality Division '
Texas Commission on Environmental Quality
CWM/JT/gg
Attachments
ccs: Mr.Stephen Brooks,Branch Chief,U.S.Army Corp of Engineers,Regulatory Branch,
CESWF-PER-R,P.O.Box 17300,Fort Worth,Texas 76102-0300
Ms.Kate Zultner,Secretary,Coastal Coordination Council,P.O. Box 12873,Austin,
Texas 78711-2873
Mr.Allan E.Steinle,Branch Chief,U.S.Army Corps of Engineers,Albuquerque
District,4101 Jefferson Plaza NE,Room 313,Albuquerque,New Mexico 87109-343.5
Regulatory Branch Chief,U.S.Army Corps of Engineers,Regulatory Branch CESWT-
PE-R, 1645 South loist East Avenue,Tulsa,Oklahoma,74128
Regulatory Branch Chief,U.S.Army Corps of Engineers,El Paso Regulatory Office,
CESPA-OD-R-EP,P.O.Box 6096,Fort Bliss,Texas 79906-6096
Attachment 4
Description of BMPs
Installation:
• Install in accordance with current TxDOT specification.
• Use on slopes 3:1 or flatter.
•Apply a 2 inch uniform layer unless otherwise shown on the plans or as directed.
•When rolling is specified,use a light corrugated drum roller.
Mulch and Compost Filter Socks
Description:Mulch and compost filter socks(erosion control logs)are used to intercept and
detain sediment laden run-off from unprotected areas.When properly used,mulch and compost
filter socks can be highly effective at controlling sediment from disturbed areas. They cause
runoff to pond which allows heavier solids to settle. Mulch and compost filter socks are used
during the period of construction near the perimeter of a disturbed area to intercept sediment
while allowing water to percolate through.The sock should remain in place until the area is
permanently stabilized. Mulch and compost filter socks may be installed in construction areas
and temporarily moved during the day to allow construction activity provided it is replaced and
properly anchored at the end of the day. Mulch and compost filter socks may be seeded to allow
for quick vegetative growth and reduction in run-off velocity.
Materials:
New types of mulch and compost filter socks are continuously being developed. The Texas
Department of Transportation(TxDOT)has established minimum performance standards which
must be met for any products seeking to be approved for use within any of TxDOT's construction
or maintenance activities. Mulch and compost filter socks used within any TxDOT construction
or maintenance activities must meet material specifications in accordance with TxDOT
specification 5049. TxDOT maintains a website at
http://www.txdot.gov/business/contractors_consultants/recycling/compost.htm that provides
information on compost specification data.
Mulch and compost filter socks used for projects not related to TxDOT should also be of quality
materials by meeting performance standards and compost specification data. To ensure the
quality of compost used for mulch and compost filter socks,products should meet all applicable
state and federal regulations,including but not limited to the United States Environmental
Protection Agency(USEPA)Code of Federal Regulations(CFR),Title 4o,Part 503 Standards for
Class A biosolids and Texas Natural Resource Conservation Commission Health and Safety
Regulations as defined in the Texas Administration Code(TAC), Chapter 332,and all other
relevant requirements for compost products outlined in TAC, Chapter 332. Testing requirements
required by the TCEQ are defined in TAC Chapter 332,including Sections§332.71 Sampling and
Analysis Requirements for Final Products and§332.72 Final Product Grades. Compost
specification data approved by TxDOT are appropriate to use for ensuring the use of quality
compost materials or for guidance.
Revised April 5,2012 Page 7 of 3o
Attachment 4
Description of BMPs
Testing standards are dependent upon the intended use for the compost and ensures product
safety,and product performance regarding the product's specific use.The appropriate compost
sampling and testing protocols included in the United States Composting Council(USCC)Test
Methods for the Examination of Composting and Compost(TMECC)should be conducted on
compost products used for mulch and compost filter socks to ensure that the products used will
not impact public health,safety, and the environment and to promote production and marketing
of quality composts that meet analytical standards.TMECC is a laboratory manual that provides
protocols for the composting industry and test methods for compost analysis.TMECC provides
protocols to sample,monitor,and analyze materials during all stages of the composting process.
Numerous parameters that might be of concern in compost can be tested by following protocols
or test methods listed in TMECC. TMECC information can be found at
http://www.tmecc.org/tmecc/index.html. The USCC Seal of Testing Assurance(STA)program
contains information regarding compost STA certification. STA program information can be
found at http://tmec,c.org/sta/STA_program_description.html.
Installation:
• Install in accordance with TxDOT Special Specification 5049.
• Install socks(erosion control logs)near the downstream perimeter of a disturbed area to
intercept sediment from sheet flow.
• Secure socks in a method adequate to prevent displacement as a result of normal rain events
such that flow is not allowed under the socks.
• Inspect and maintain the socks in good condition(including staking,anchoring,etc.).
Maintain the integrity of the control,including keeping the socks free of accumulated silt,
debris,etc.,until the disturbed area has been adequately stabilized.
SEDIMENT CONTROL BMPS
Sand Bag Berm
Description: The purpose of a sandbag berm is to detain sediment carried in runoff from
disturbed areas. This objective is accomplished by intercepting runoff and causing it to pool
behind the sand bag berm. Sediment carried in the runoff is deposited on the upstream side of
the sand bag berm due to the reduced flow velocity. Excess runoff volumes are allowed to flow
over the top of the sand bag berm. Sand bag berms are used only during construction activities
in streambeds when the contributing drainage area is between 5 and io acres and the slope is less
than 15%,i.e.,utility construction in channels,temporary channel crossing for construction
equipment,etc. Plastic facing should be installed on the upstream side and the berm should be
anchored to the streambed by drilling into the rock and driving in"T"posts or rebar(#5 or#6)
spaced appropriately.
Revised April 5,2012 Page 8 of 30
Attachment 4
Description of BMPs
Materials:
• The sand bag material should be polypropylene,polyethylene,polyamide or cotton burlap
woven fabric,minimum unit weight 4 oz/yd 2,mullen burst strength exceeding 300 psi and
ultraviolet stability exceeding 70 percent.
•The bag length should be 24 to 3o inches,width should be 16 to 18 inches and thickness should
be 6 to 8 inches.
• Sandbags should be filled with coarse grade sand and free from deleterious material. All sand
should pass through a No. 10 sieve. The filled bag should have an approximate weight of 40
pounds.
• Outlet pipe should be schedule 40 or stronger polyvinyl chloride(PVC)having a nominal
internal diameter of 4 inches.
Installation:
• The berm should be a minimum height of 18 inches,measured from the top of the existing
ground at the upslope toe to the top of the berm.
•The berm should be sized as shown in the plans but should have a minimum width of 48 inches
measured at the bottom of the berm and 16 inches measured at the top of the berm.
• Runoff water should flow over the tops of the sandbags or through 4-inch diameter PVC pipes
embedded below the top layer of bags.
• When a sandbag is filled with material,the open end of the sandbag should be stapled or tied
with nylon or poly cord.
• Sandbags should be stacked in at least three rows abutting each other,and in staggered
arrangement.
• The base of the berm should have at least 3 sandbags. These can be reduced to 2 and i bag in
the second and third rows respectively.
• For each additional 6 inches of height,an additional sandbag must be added to each row width.
• A bypass pump-around system,or similar alternative,should be used on conjunction with the
berm for effective dewatering of the work area.
Silt Fence
Description: A silt fence is a barrier consisting of geotextile fabric supported by metal posts to
prevent soil and sediment loss from a site. When properly used,silt fences can be highly effective
at controlling sediment from disturbed areas. They cause runoff to pond which allows heavier
solids to settle. If not properly installed,silt fences are not likely to be effective. The purpose of a
silt fence is to intercept and detain water-borne sediment from unprotected areas of a limited
Revised April 5,2012 Page 9 of 30
Attachment 4
Description of BMPs
extent. Silt fence is used during the period of construction near the perimeter of a disturbed area
to intercept sediment while allowing water to percolate through. This fence should remain in
place until the disturbed area is permanently stabilized. Silt fence should not be used where
there is a concentration of water in a channel or drainage way. If concentrated flow occurs after
installation,corrective action must be taken such as placing a rock berm in the areas of
concentrated flow. Silt fencing within the site may be temporarily moved during the day to allow
construction activity provided it is replaced and properly anchored to the ground at the end of
the day. Silt fences on the perimeter of the site or around drainage ways should not be moved at
any time.
Materials:
• Silt fence material should be polypropylene,polyethylene or polyamide woven or nonwoven
fabric.The fabric width should be 36 inches,with a minimum unit weight of 4.5 oz/yd,mullen
burst strength exceeding 190 lb/in 2,ultraviolet stability exceeding 70%,and minimum
apparent opening size of U.S.Sieve No.30.
• Fence posts should be made of hot rolled steel,at least 4 feet long with Tee or Y-bar cross
section,surface painted or galvanized,minimum nominal weight 1.25 lb/ft 2,and Brindell
hardness exceeding 14o.
• Woven wire backing to support the fabric should be galvanized 2"x 4"welded wire, 12 gauge
minimum.
Installation:
• Steel posts,which support the silt fence,should be installed on a slight angle toward the
anticipated runoff source. Post must be embedded a minimum of 1 foot deep and spaced not
more than 8 feet on center. Where water concentrates,the maximum spacing should be 6 feet.
• Lay out fencing down-slope of disturbed area,following the contour as closely as possible.The
fence should be sited so that the maximum drainage area is 1/4 acre/zoo feet of fence.
•The toe of the silt fence should be trenched in with a spade or mechanical trencher,so that the
down-slope face of the trench is flat and perpendicular to the line of flow. Where fence cannot
be trenched in(e.g.,pavement or rock outcrop),weight fabric flap with 3 inches of pea gravel
on uphill side to prevent flow from seeping under fence.
• The trench must be a minimum of 6 inches deep and 6 inches wide to allow for the silt fence
fabric to be laid in the ground and backfilled with compacted material.
• Silt fence should be securely fastened to each steel support post or to woven wire,which is in
turn attached to the steel fence post. There should be a 3-foot overlap,securely fastened where
ends of fabric meet.
Triangular Filter Dike
Description: The purpose of a triangular sediment filter dike is to intercept and detain water-
Revised April 5,2012 Page 10 of 30
Attachment 4
Description of BMPs
borne sediment from unprotected areas of limited extent. The triangular sediment filter dike is
used where there is no concentration of water in a channel or other drainage way above the
barrier and the contributing drainage area is less than one acre, If the uphill slope above the dike
exceeds 10%,the length of the slope above the dike should be less than 5o feet. If concentrated
flow occurs after installation,corrective action should be taken such as placing rock berm in the
areas of concentrated flow. This measure is effective on paved areas where installation of silt
fence is not possible or where vehicle access must be maintained. The advantage of these
controls is the ease with which they can be moved to allow vehicle traffic and then reinstalled to
maintain sediment
Materials:
• Silt fence material should be polypropylene,polyethylene or polyamide woven or nonwoven
fabric.The fabric width should be 36 inches,with a minimum unit weight of 4.5 oz/yd,mullen
burst strength exceeding 190 lb/in 2 ,ultraviolet stability exceeding 70%,and minimum
apparent opening size of U.S.Sieve No. 30.
•The dike structure should be 6 gauge 6"x 6"wire mesh folded into triangular form being
eighteen(18)inches on each side.
Installation:
•The frame of the triangular sediment filter dike should be constructed of 6"x 6",6 gauge
welded wire mesh, 18 inches per side,and wrapped with geotextile fabric the same composition
as that used for silt fences.
• Filter material should lap over ends six(6)inches to cover dike to dike junction;each junction
should be secured by shoat rings.
• Position dike parallel to the contours,with the end of each section closely abutting the adjacent
sections.
•There are several options for fastening the filter dike to the ground.The fabric skirt may be
toed-in with 6 inches of compacted material, or 12 inches of the fabric skirt should extend
uphill and be secured with a minimum of 3 inches of open graded rock,or with staples or nails.
If these two options are not feasible the dike structure maybe trenched in 4 inches.
•Triangular sediment filter dikes should be installed across exposed slopes during construction
with ends of the dike tied into existing grades to prevent failure and should intercept no more
than one acre of runoff.
•When moved to allow vehicular access,the dikes should be reinstalled as soon as possible,but
always at the end of the workday.
Rock Berm
Description: The purpose of a rock berm is to serve as a check dam in areas of concentrated
flow,to intercept sediment-laden runoff,detain the sediment and release the water in sheet flow.
Revised April 5,2012 Page a of 3o
Attachment 4
Description of BMPs
The rock berm should be used when the contributing drainage area is less than 5 acres. Rock
berms are used in areas where the volume of runoff is too great for a silt fence to contain. They
are less effective for sediment removal than silt fences,particularly for fine particles,but are able
to withstand higher flows than a silt fence. As such,rock berms are often used in areas of
channel flows(ditches,gullies, etc.). Rock berms are most effective at reducing bed load in
channels and should not be substituted for other erosion and sediment control measures further
up the watershed.
Materials:
•The berm structure should be secured with a woven wire sheathing having maximum opening
of 1 inch and a minimum wire diameter of 20 gauge galvanized and should be secured with
shoat rings.
• Clean,open graded 3-to 5-inch diameter rock should be used,except in areas where high
velocities or large volumes of flow are expected,where 5-to 8-inch diameter rocks may be
used.
Installation:
• Lay out the woven wire sheathing perpendicular to the flow line. The sheathing should be 20
gauge woven wire mesh with 1 inch openings.
• Berm should have a top width of 2 feet minimum with side slopes being 2:1(H:V)or flatter.
• Place the rock along the sheathing to a height not less than 18".
• Wrap the wire sheathing around the rock and secure with tie wire so that the ends of the
sheathing overlap at least 2 inches,and the berm retains its shape when walked upon.
• Berm should be built along the contour at zero percent grade or as near as possible.
• The ends of the berm should be tied into existing upslope grade and the berm should be buried
in a trench approximately 3 to 4 inches deep to prevent failure of the control.
Hay Bale Dike
Description: The purpose of a hay or straw bale dike is to intercept and detain small amounts
of sediment-laden runoff from relatively small unprotected areas. Straw bales are to be used
when it is not feasible to install other,more effective measures or when the construction phase is
expected to last less than 3 months. Straw bales should not be used on areas where rock or other
hard surfaces prevent the full and uniform anchoring of the barrier.
Materials:
Straw: The best quality straw mulch comes from wheat,oats or barley and should be free of
weed and grass seed which may not be desired vegetation for the area to be protected. Straw
mulch is light and therefore must be properly anchored to the ground.
Revised April 5,2012 Page 12 of 30
Attachment 4
Description of BMPs
Hay: This is very similar to straw with the exception that it is made of grasses and weeds and
not grain stems. This form of mulch is very inexpensive and is widely available but does
introduce weed and grass seed to the area. Like straw,hay is light and must be anchored.
• Straw bales should weigh a minimum of 5o pounds and should be at least 3o inches long.
• Bales should be composed entirely of vegetable matter and be free of seeds.
• Binding should be either wire or nylon string,jute or cotton binding is unacceptable. Bales
should be used for not more than two months before being replaced.
Installation:
• Bales should be embedded a minimum of 4 inches and securely anchored using 2"X 2"wood
stakes or 3/8"diameter rebar driven through the bales into the ground a minimum of 6 inches.
• Bales are to be placed directly adjacent to one another leaving no gap between them.
•All bales should be placed on the contour.
•The first stake in each bale should be angled toward the previously laid bale to force the bales
together.
Brush Berms
Organic litter and spoil material from site clearing operations is usually burned or hauled away to
be dumped elsewhere.Much of this material can be used effectively on the construction site
itself. The key to constructing an efficient brush berm is in the method used to obtain and place
the brush.It will not be acceptable to simply take a bulldozer and push whole trees into a pile.
This method does not assure continuous ground contact with the berm and will allow
uncontrolled flows under the berm.
Brush berms may be used where there is little or no concentration of water in a channel or other
drainage way above the berm.The size of the drainage area should be no greater than one-fourth
of an acre per 100 feet of barrier length;the maximum slope length behind the barrier should not
exceed ioo feet;and the maximum slope gradient behind the barrier should be less than 5o
percent(2:1).
Materials:
•The brush should consist of woody brush and branches,preferably less than 2 inches in
diameter.
•The filter fabric should conform to the specifications for filter fence fabric.
•The rope should be 1/4 inch polypropylene or nylon rope.
Revised April 5,2012 Page 13 of 3o
Attachment 4
Description of BMPs
•The anchors should be 3/8-inch diameter rebar stakes that are i8-inches long.
Installation:
• Lay out the brush berm following the contour as closely as possible.
•The juniper limbs should be cut and hand placed with the vegetated part of the limb in close
contact with the ground.Each subsequent branch should overlap the previous branch
providing a shingle effect.
• The brush berm should be constructed in lifts with each layer extending the entire length of the
berm before the next layer is started.
•A trench should be excavated 6-inches wide and 4-inches deep along the length of the barrier
and immediately uphill from the barrier.
• The filter fabric should be cut into lengths sufficient to lay across the barrier from its up-slope
base to just beyond its peak.The lengths of filter fabric should be draped across the width of
the barrier with the uphill edge placed in the trench and the edges of adjacent pieces
overlapping each other.Where joints are necessary,the fabric should be spliced together with a
minimum 6-inch overlap and securely sealed.
•The trench should be backfilled and the soil compacted over the filter fabric.
• Set stakes into the ground along the downhill edge of the brush barrier,and anchor the fabric
by tying rope from the fabric to the stakes. Drive the rope anchors into the ground at
approximately a 45-degree angle to the ground on 6-foot centers.
• Fasten the rope to the anchors and tighten berm securely to the ground with a minimum
tension of 5o pounds.
• The height of the brush berm should be a minimum of 24 inches after the securing ropes have
been tightened.
Stone Outlet Sediment Traps
A stone outlet sediment trap is an impoundment created by the placement of an earthen and
stone embankment to prevent soil and sediment loss from a site.The purpose of a sediment trap
is to intercept sediment-laden runoff and trap the sediment in order to protect drainage ways,
properties and rights of way below the sediment trap from sedimentation.A sediment trap is
usually installed at points of discharge from disturbed areas.The drainage area for a sediment
trap is recommended to be less than 5 acres.
Larger areas should be treated using a sediment basin.A sediment trap differs from a sediment
basin mainly in the type of discharge structure.The trap should be located to obtain the
maximum storage benefit from the terrain,for ease of clean out and disposal of the trapped
Revised April 5,2012 Page 14 of 30
Attachment 4
Description of BMPs
sediment and to minimize interference with construction activities.The volume of the trap
should be at least 3600 cubic feet per acre of drainage area.
Materials:
• All aggregate should be at least 3 inches in diameter and should not exceed a volume of 0.5
cubic foot.
• The geotextile fabric specification should be woven polypropylene,polyethylene or polyamide
geotextile,minimum unit weight 014.5 oz/yd 2,mullen burst strength at least 250 Will 2,
ultraviolet stability exceeding 70%, and equivalent opening size exceeding 40.
Installation:
• Earth Embankment:Place fill material in layers not more than 8 inches in loose depth.
Before compaction,moisten or aerate each layer as necessary to provide the optimum
moisture content of the material.Compact each layer to 95 percent standard proctor density.
Do not place material on surfaces that are muddy or frozen. Side slopes for the embankment
are to be 3:1.The minimum width of the embankment should be 3 feet.
• A gap is to be left in the embankment in the location where the natural confluence of runoff
crosses the embankment line.The gap is to have a width in feet equal to 6 times the drainage
area in acres.
• Geotextile Covered Rock Core:A core of filter stone having a minimum height of 1.5 feet and
a minimum width at the base of 3 feet should be placed across the opening of the earth
embankment and should be covered by geotextile fabric which should extend a minimum
distance of 2 feet in either direction from the base of the filter stone core.
• Filter Stone Embankment:Filter stone should be placed over the geotextile and is to have a
side slope which matches that of the earth embankment of 3:1 and should cover the
geotextile/rock core a minimum of 6 inches when installation is complete.The crest of the
outlet should be at least 1 foot below the top of the embankment.
Sediment Basins:
The purpose of a sediment basin is to intercept sediment-laden runoff and trap the sediment in
order to protect drainage ways,properties and rights of way below the sediment basin from
sedimentation.A sediment basin is usually installed at points of discharge from disturbed areas.
The drainage area for a sediment basin is recommended to be less than 100 acres.
Sediment basins are effective for capturing and slowly releasing the runoff from larger disturbed
•
areas thereby allowing sedimentation to take place.A sediment basin can be created where a
permanent pond BMP is being constructed. Guidelines for construction of the permanent BMP
should be followed,but revegetation,placement of underdrain piping, and installation of sand or
other filter media should not be carried out until the site construction phase is complete.
Revised April 5,2012 Page 15 of 3o
Attachment 4
Description of BMPs
Materials:
• Riser should be corrugated metal or reinforced concrete pipe or box and should have
watertight fittings or end to end connections of sections.
• An outlet pipe of corrugated metal or reinforced concrete should be attached to the riser and
should have positive flow to a stabilized outlet on the downstream side of the embankment,
• An anti-vortex device and rubbish screen should be attached to the top of the riser and should
be made of polyvinyl chloride or corrugated metal.
Basin Design and Construction:
• For common drainage locations that serve an area with ten or more acres disturbed at one
time,a sediment basin should provide storage for a volume of runoff from a two-year,24-
hour storm from each disturbed acre drained.
• The basin length to width ratio should be at least 2:1 to improve trapping efficiency.The
shape may be attained by excavation or the use of baffles.The lengths should be measured at
the elevation of the riser de-watering hole.
• Place fill material in layers not more than 8 inches in loose depth. Before compaction,
moisten or aerate each layer as necessary to provide the optimum moisture content of the
material. Compact each layer to 95 percent standard proctor density.Do not place material
on surfaces that are muddy or frozen.Side slopes for the embankment should be 3:1(H:V).
• An emergency spillway should be installed adjacent to the embankment on undisturbed soil
and should be sized to carry the full amount of flow generated by a 10-year, 3-hour storm
with 1 foot of freeboard less the amount which can be carried by the principal outlet control
device.
• The emergency spillway should be lined with riprap as should the swale leading from the
spillway to the normal watercourse at the base of the embankment.
• The principal outlet control device should consist of a rigid vertically oriented pipe or box of
corrugated metal or reinforced concrete.Attached to this structure should be a horizontal
pipe,which should extend through the embankment to the toe of fill to provide a de-watering
outlet for the basin.
• An anti-vortex device should be attached to the inlet portion of the principal outlet control
device to serve as a rubbish screen.
• A concrete base should be used to anchor the principal outlet control device and should be
sized to provide a safety factor of 1.5(downward forces=1.5 buoyant forces).
• The basin should include a permanent stake to indicate the sediment level in the pool and
marked to indicate when the sediment occupies 50%of the basin volume(not the top of the
Revised April 5,2012 Page 16 of 3o
Attachment 4
Description of BMPs
stake).
• The top of the riser pipe should remain open and be guarded with a trash rack and anti-
vortex device.The top of the riser should be 12 inches below the elevation of the emergency
spillway.The riser should be sized to convey the runoff from the 2-year, 3-hour storm when
the water surface is at the emergency spillway elevation. For basins with no spillway the riser
must be sized to convey the runoff from the 1U-yr,3-hour storm.
• Anti-seep collars should be included when soil conditions or length of service make piping
through the backfill a possibility.
• The 48-hour drawdown time will be achieved by using a riser pipe perforated at the point
measured from the bottom of the riser pipe equal to 1/2 the volume of the basin.This is the
maximum sediment storage elevation.The size of the perforation may be calculated as
follows:
A As x
o= 2h
Cd x 980,000
Where:
Ao=Area of the de-watering hole,ft 2
As=Surface area of the basin,ft 2
Cd=Coefficient of contraction,approximately 0.6
h =head of water above the hole,ft
Perforating the riser with multiple holes with a combined surface area
equal to As is acceptable.
Erosion Control Compost
Description::Erosion control compost(ECC)can be used as an aid to control erosion on critical
sites during the establishment period of protective vegetation.The most common uses are on
steep slopes,swales,diversion dikes,and on tidal or stream banks.
Materials:
New types of erosion control compost are continuously being developed. The Texas Department
of Transportation(TxDOT)has established minimum performance standards which must be met
for any products seeking to be approved for use within any of TxDOT's construction or
maintenance activities, Material used within any TxDOT construction or maintenance activities
must meet material specifications in accordance with current TxDOT specifications. TxDOT
maintains a website at
http://www.txdot.gov/business/contractors_consultants/recycling/compost.htm that provides
information on compost specification data.
Revised April g,2012 Page 17 of 3o
Attachment 4
Description of BMPs
ECC used for projects not related to TxDOT should also be of quality materials by meeting
performance standards and compost specification data. To ensure the quality of compost used as
an ECC,products should meet all applicable state and federal regulations,including but not
limited to the United States Environmental Protection Agency(USEPA) Code of Federal
Regulations(CFR),Title 4o,Part 503 Standards for Class A biosolids and Texas Natural
Resource Conservation Commission(now named TCEQ)Health and Safety Regulations as
defined in the Texas Administration Code(TAC),Chapter 332,and all other relevant
requirements for compost products outlined in TAC,Chapter 332. Testing requirements
required by the TCEQ are defined in TAC Chapter 332,including Sections§332.71 Sampling and
Analysis Requirements for Final Products and§332.72 Final Product Grades. Compost
specification data approved by TxDOT are appropriate to use for ensuring the use of quality
compost materials or for guidance.
Testing standards are dependent upon the intended use for the compost and ensures product
safety, and product performance regarding the product's specific use.The appropriate compost
sampling and testing protocols included in the United States Composting Council(USCC)Test
Methods for the Examination of Composting and Compost(TMECC)should be conducted on
compost products used for ECC to ensure that the products used will not impact public health,
safety, and the environment and to promote production and marketing of quality composts that
meet analytical standards.TMECC is a laboratory manual that provides protocols for the
composting industry and test methods for compost analysis.TMECC provides protocols to
sample,monitor,and analyze materials during all stages of the composting process.Numerous
parameters that might be of concern in compost can be tested by following protocols or test
methods listed in TMECC. TMECC information can be found at
http://www.tmecc.org/tmecc/index.html. The USCC Seal of Testing Assurance(STA)program
contains information regarding compost STA certification. STA program information can be
found at http://tmecc.org/sta/STA_program_description.html.
Installation:
• Install in accordance with current TxDOT specification.
• Use on slopes 3:1 or flatter.
• Apply a 2 inch uniform layer unless otherwise shown on the plans or as directed.
• When rolling is specified,use a light corrugated drum roller.
Mulch and Compost Filter Socks
Description: Mulch and compost filter socks(erosion control logs)are used to intercept and
detain sediment laden run-off from unprotected areas.When properly used,mulch and compost
filter socks can be highly effective at controlling sediment from disturbed areas. They cause
runoff to pond which allows heavier solids to settle. Mulch and compost filter socks are used
during the period of construction near the perimeter of a disturbed area to intercept sediment
while allowing water to percolate through.The sock should remain in place until the area is
permanently stabilized. Mulch and compost filter socks may be installed in construction areas
Revised April 5,2012 Page 18 of 3o
Attachment 4
Description of BMPs
and temporarily moved during the day to allow construction activity provided it is replaced and
properly anchored at the end of the day. Mulch and compost filter socks may be seeded to allow
for quick vegetative growth and reduction in run-off velocity.
Materials:
New types of mulch and compost filter socks are continuously being developed. The Texas
Department of Transportation(TxDOT)has established minimum performance standards which
must be met for any products seeking to be approved for use within any of TxDOT's construction
or maintenance activities. Mulch and compost filter socks used within any TxDOT construction
or maintenance activities must meet material specifications in accordance with TxDOT
specification 5049. TxDOT maintains a website at
http://www.txdot.gov/business/contractors_consultants/recycling/compost.htm that provides
information on compost specification data.
Mulch and compost filter socks used for projects not related to TxDOT should also be of quality
materials by meeting performance standards and compost specification data. To ensure the
quality of compost used for mulch and compost filter socks,products should meet all applicable
state and federal regulations,including but not limited to the United States Environmental
Protection Agency(USEPA)Code of Federal Regulations(CFR),Title 40,Part 503 Standards for
Class A biosolids and Texas Natural Resource Conservation Commission Health and Safety
Regulations as defined in the Texas Administration Code(TAC),Chapter 332,and all other
relevant requirements for compost products outlined in TAC,Chapter.332. Testing requirements
required by the TCEQ are defined in TAC Chapter 332,including Sections§332.71 Sampling and
Analysis Requirements for Final Products and§332.72 Final Product Grades. Compost
specification data approved by TxDOT are appropriate to use for ensuring the use of quality
compost materials or for guidance.
Testing standards are dependent upon the intended use for the compost and ensures product
safety,and product performance regarding the product's specific use.The appropriate compost
sampling and testing protocols included in the United States Composting Council (USCC)Test
Methods for the Examination of Composting and Compost(TMECC)should be conducted on
compost products used for mulch and compost filter socks to ensure that the products used will
not impact public health,safety,and the environment and to promote production and marketing
of quality composts that meet analytical standards.TMECC is a laboratory manual that provides
protocols for the composting industry and test methods for compost analysis.TMECC provides
protocols to sample,monitor,and analyze materials during all stages of the composting process.
Numerous parameters that might be of concern in compost can be tested by following protocols
or test methods listed in TMECC. TMECC information can be found at
http://www.tmecc.org/tmece/index.html. The USCC Seal of Testing Assurance(STA)program
contains information regarding compost STA certification. STA program information can be
found at http://tmecc.org/sta/STA program_description.html.
Installation:
• Install in accordance with TxDOT Special Specification 5049.
Revised April 5,2012 Page 19 of 3o
Attachment 4
Description of BMPs
• Install socks(erosion control logs)near the downstream perimeter of a disturbed area to
intercept sediment from sheet flow.
• Secure socks in a method adequate to prevent displacement as a result of normal rain events
such that flow is not allowed under the socks.
• Inspect and maintain the socks in good condition(including staking,anchoring,etc.).
Maintain the integrity of the control,including keeping the socks free of accumulated silt,
debris,etc.,until the disturbed area has been adequately stabilized.
POST-CONSTRUCTION TSS CONTROLS
Retention/Irrigation Systems
Description: Retention/irrigation systems refer to the capture of runoff in a holding pond,
then use of the captured water for irrigation of appropriate landscape areas. Retention/irrigation
systems are characterized by the capture and disposal of runoff without direct release of captured
flow to receiving streams. Retention systems exhibit excellent pollutant removal but can require
regular,proper maintenance. Collection of roof runoff for subsequent use(rainwater harvesting)
also qualifies as a retention/irrigation practice,but should be operated and sized to provide
adequate volume. This technology,which emphasizes beneficial use of stormwater runoff,is
particularly appropriate for arid regions because of increasing demands on water supplies for
agricultural irrigation and urban water supply.
Design Considerations: Retention/irrigation practices achieve l00%removal efficiency of
total suspended solids contained within the volume of water captured. Design elements of
retention/irrigation systems include runoff storage facility configuration and sizing,pump and
wet well system components,basin lining,basin detention time,and physical and operational
components of the irrigation system. Retention/irrigation systems are appropriate for large
drainage areas with low to moderate slopes. The retention capacity should be sufficient
considering the average rainfall event for the area.
Maintenance Requirements: Maintenance requirements for retention/irrigation systems
include routine inspections,sediment removal,mowing,debris and litter removal,erosion
control, and nuisance control.
Extended Detention Basin
Description: Extended detention facilities are basins that temporarily store a portion of
stormwater runoff following a storm event. Extended detention basins are normally used to
remove particulate pollutants and to reduce maximum runoff rates associated with development
to their pre-development levels. The water quality benefits are the removal of sediment and
buoyant materials. Furthermore,nutrients,heavy metals,toxic materials,and oxygen-
demanding materials associated with the particles also are removed. The control of the
maximum runoff rates serves to protect drainage channels below the device from erosion and to
reduce downstream flooding. Although detention facilities designed for flood control have
different design requirements than those used for water quality enhancement,it is possible to
Revised April 5,2012 Page 20 of 3o
Attachment 4
Description of BMPs
achieve these two objectives in a single facility.
Design Considerations: Extended detention basins can remove approximately 75%of the
total suspended solids contained within the volume of runoff captured in the basin. Design
elements of extended detention basins include basin sizing,basin configuration,basin side
slopes,basin lining,inlet/outlet structures,and erosion controls. Extended detention basins are
appropriate for large drainage areas with low to moderate slopes. The retention capacity should
be sufficient considering the average rainfall event for the area.
Maintenance Requirements: Maintenance requirements for extended detention basins
include routine inspections,mowing,debris and litter removal,erosion control, structural
repairs,nuisance control,and sediment removal.
Vegetative Filter Strips
Description: Filter strips, also known as vegetated buffer strips,are vegetated sections of land
similar to grassy swales except they are essentially flat with low slopes,and are designed only to
accept runoff as overland sheet flow. They may appear in any vegetated form from grassland to.
forest, and are designed to intercept upstream flow,lower flow velocity,and spread water out as
sheet flow.The dense vegetative cover facilitates conventional pollutant removal through
detention,filtration by vegetation,and infiltration.
Filter strips cannot treat high velocity flows, and do not provide enough storage or infiltration to
effectively reduce peak discharges to predevelopment levels for design storms.This lack of
quantity control favors use in rural or low-density development;however,they can provide water
quality benefits even where the impervious cover is as high as 50%.The primary highway
application for vegetative filter strips is along rural roadways where runoff that would otherwise
discharge directly to a receiving water passes through the filter strip before entering a
conveyance system.Properly designed roadway medians and shoulders make effective buffer
strips.These devices also can be used on other types of development where land is available and
hydraulic conditions are appropriate.
Flat slopes and low to fair permeability of natural subsoil are required for effective performance
of filter strips.Although an inexpensive control measure,they are most useful in contributing
watershed areas where peak runoff velocities are low as they are unable to treat the high flow
velocities typically associated with high impervious cover.
Successful performance of filter strips relies heavily on maintaining shallow unconcentrated
flow.To avoid flow channelization and maintain performance,a filter strip should:
• Be equipped with a level spreading device for even distribution of runoff
• Contain dense vegetation with a mix of erosion resistant,soil binding species
• Be graded to a uniform,even and relatively low slope
• Laterally traverse the contributing runoff area
Revised April 5,2012 Page e 21 of 30
Attachment 4
Description of BMPs
Filter strips can be used upgradient from watercourses,wetlands,or other water bodies along
toes and tops of slopes and at outlets of other stormwater management structures.They should
be incorporated into street drainage and master drainage planning.The most important criteria
for selection and use of this BMP are soils,space, and slope.
Design Considerations: Vegetative filter strips can remove approximately 85%of the total
suspended solids contained within the volume of runoff captured. Design elements of vegetative
filter strips include uniform, shallow overland flow across the entire filter strip area,hydraulic
loading rate,inlet structures,slope,and vegetative cover. The area should be free of gullies or
rills which can concentrate flow. Vegetative filter strips are appropriate for small drainage areas
with moderate slopes. Other design elements include the following:
• Soils and moisture are adequate to grow relatively dense vegetative stands
• Sufficient space is available
• Slope is less than 12%
• Comparable performance to more expensive structural controls
Maintenance Requirements: Maintenance requirements for vegetative filter strips include
pest management,seasonal mowing and lawn care,routine inspections,debris and litter
removal,sediment removal,and grass reseeding and mulching.
Constructed Wetlands
Description: Constructed wetlands provide physical,chemical,and biological water quality
treatment of stormwater runoff. Physical treatment occurs as a result of decreasing flow
velocities in the wetland,and is present in the form of evaporation,sedimentation,adsorption,
and/or filtration. Chemical processes include chelation,precipitation,and chemical adsorption.
Biological processes include decomposition,plant uptake and removal of nutrients,plus
biological transformation and degradation. Hydrology is one of the most influential factors in
pollutant removal due to its effects on sedimentation,aeration,biological transformation,and
adsorption onto bottom sediments.
The wetland should be designed such that a minimum amount of maintenance is required. The
natural surroundings,including such things as the potential energy of a stream or flooding river,
should be utilized as much as possible. The wetland should approximate a natural situation and
unnatural attributes,such as rectangular shape or rigid channel,should be avoided.
Site considerations should include the water table depth,soil/substrate,and space requirements.
Because the wetland must have a source of flow,it is desirable that the water table is at or near
the surface. If runoff is the only source of inflow for the wetland,the water level often fluctuates
and establishment of vegetation may be difficult. The soil or substrate of an artificial wetland
should be loose loam to clay. A perennial baseflow must be present to sustain the artificial
wetland. The presence of organic material is often helpful in increasing pollutant removal and
retention. A greater amount of space is required for a wetland system than is required for a
detention facility treating the same amount of area.
Revised April 5,2012 Page 22 of 30
Attachment 4
Description of BMPs
Design Considerations: Constructed wetlands can remove over 90%of the total suspended
solids contained within the volume of runoff captured in the wetland. Design elements of
constructed wetlands include wetland sizing,wetland configuration,sediment forebay,
vegetation,outflow structure,depth of inundation during storm events,depth of micropools,and
aeration. Constructed wetlands are appropriate for large drainage areas with low to moderate
slopes.
Maintenance Requirements: Maintenance requirements for constructed wetlands include
mowing,routine inspections,debris and litter removal,erosion control,nuisance control,
structural repairs,sediment removal,harvesting,and maintenance of water levels.
Wet Basins
Description: Wet basins are runoff control facilities that maintain a permanent wet pool and a
standing crop of emergent littoral vegetation. These facilities may vary in appearance from
natural ponds to enlarged,bermed(manmade)sections of drainage systems and may function as
online or offline facilities,although offline configuration is preferable. Offline designs can
prevent scour and other damage to the wet pond and minimize costly outflow structure elements
needed to accommodate extreme runoff events.
During storm events,runoff inflows displace part or all of the existing basin volume and are
retained and treated in the facility until the next storm event. The pollutant removal
mechanisms are settling of solids,wetland plant uptake,and microbial degradation. When the
wet basin is adequately sized,pollutant removal performance can be excellent,especially for the
dissolved fraction. Wet basins also help provide erosion protection for the receiving channel by
limiting peak flows during larger storm events. Wet basins are often perceived as a positive
aesthetic element in a community and offer significant opportunity for creative pond
configuration and landscape design. Participation of an experienced wetland designer is
suggested. A significant potential drawback for wet ponds in arid climates is that the
contributing watershed for these facilities is often incapable of providing an adequate water
supply to maintain the permanent pool,especially during the summer months. Makeup water
(i.e.,well water or municipal drinking water)is sometimes used to supplement the
rainfall/runoff process,especially for wet basin facilities treating watersheds that generate
insufficient runoff.
Design Considerations: Wet basins can remove over 90%of the total suspended solids
contained within the volume of runoff captured in the basin. Design elements of wet basins
include basin sizing,basin configuration,basin side slopes,sediment forebay,inflow and outflow
structures,vegetation,depth of permanent pool,aeration,and erosion control. Wet basins are
appropriate for large drainage areas with low to moderate slopes.
Maintenance Requirements: Maintenance requirements for wet basins include mowing,
routine inspections,debris and litter removal,erosion control,nuisance control,structural
repairs, sediment removal,and harvesting.
Revised April 5,2012 Page 23 of 30
Attachment 4
Description of BMPs
Grassy Swales
Grassy swales are vegetated channels that convey stormwater and remove pollutants by filtration
through grass and infiltration through soil.They require shallow slopes and soils that drain well.
Pollutant removal capability is related to channel dimensions,longitudinal slope,and type of
vegetation. Optimum design of these components will increase contact time of runoff through the
swale and improve pollutant removal rates.
Grassy swales are primarily stormwater conveyance systems.They can provide sufficient control
under light to moderate runoff conditions,but their ability to control large storms is limited.
Therefore,they are most applicable in low to moderate sloped areas or along highway medians as
an alternative to ditches and curb and gutter drainage.Their performance diminishes sharply in
highly urbanized settings,and they are generally not effective enough to receive construction
stage runoff where high sediment loads can overwhelm the system. Grassy swales can be used as
a pretreatment measure for other downstream BMPs,such as extended detention basins.
Enhanced grassy swales utilize check dams and wide depressions to increase runoff storage and
promote greater settling of pollutants.
Grassy swales can be more aesthetically pleasing than concrete or rock-lined drainage systems
and are generally less expensive to construct and maintain.Swales can slightly reduce
impervious area and reduce the pollutant accumulation and delivery associated with curbs and
gutters.The disadvantages of this technique include the possibility of erosion and channelization
over time,and the need for more right-of-way as compared to a storm drain system.When
properly constructed,inspected,and maintained,the life
expectancy of a swale is estimated to be 20 years.
Design Considerations:
• Comparable performance to wet basins
• Limited to treating a few acres
• Availability of water during dry periods to maintain vegetation
• Sufficient available land area
The suitability of a swale at a site will depend on land use,size of the area serviced,soil type,
slope,imperviousness of the contributing watershed,and dimensions and slope of the swale
system. In general, swales can be used to serve areas of less than 10 acres,with slopes no greater
than 5%.The seasonal high water table should be at least 4 feet below the surface.Use of natural
topographic lows is encouraged,and natural drainage courses should be regarded as significant
local resources to be kept in use.
Maintenance Requirements:
Research in the Austin area indicates that vegetated controls are effective at removing pollutants
even when dormant.Therefore,irrigation is not required to maintain growth during dry periods,
but may be necessary only to prevent the vegetation from dying.
Revised April 5,2012 Page 24 of 30
Attachment 4
Description of BMPs
Vegetation Lined Drainage Ditches
Vegetation lined drainage ditches are similar to grassy swales. These drainage ditches are
vegetated channels that convey storm water and remove pollutants by filtration through grass
and infiltration through soil. They require soils that drain well. Pollutant removal capability is
related to channel dimensions,longitudinal slope,and type of vegetation. Optimum design of
these components will increase contact time of runoff through the ditch and improve pollutant
removal rates. Vegetation lined drainage ditches are primarily storm water conveyance systems.
They have vegetation Iined in the low flow channel and may include vegetated shelves.
Vegetation in drainage ditches reduces erosion and removes pollutants by lowering water velocity
over the soil surface,binding soil particles with roots,and by filtration through grass and
infiltration through soil. Vegetation lined drainage ditches can be used where:
•A vegetative lining can provide sufficient stability for the channel grade by increasing
maximum permissible velocity
• Slopes are generally less than 5%,with protection from sheer stress as needed through the use
of BMPs,such as erosion control blankets
• Site conditions required to establish vegetation,i.e.climate,soils,topography,are present
Design Criteria: The suitability of a vegetation lined drainage ditch at a site will depend on
land use,size of the area serviced,soil type, slope,imperviousness of the contributing watershed,
and dimensions and slope of the ditch system. The hydraulic capacity of the drainage ditch and
other elements such as erosion,siltation,and pollutant removal capability,must be taken into
consideration. Use of natural topographic lows is encouraged,and natural drainage courses
should be regarded as significant local resources to be kept in use. Other items to consider
include the following:
• Capacity,cross-section shape,side slopes,and grade
• Select appropriate native vegetation
• Construct in stable,low areas to conform with the natural drainage system. To reduce erosion
potential,design the channel to avoid sharp bends and steep grades.
• Design and build drainage ditches with appropriate scour and erosion protection. Surface
water should be able to enter over the vegetated banks without erosion occurring.
• BMPs,such as erosion control blankets,may need to be installed at the time of seeding to
provide stability until the vegetation is fully established. It may also be necessary to divert water
from the channel until vegetation is established or to line the channel with sod.
• Vegetated ditches must not be subject to sedimentation from disturbed areas.
Revised April 5,2012 Page 25 of 3o
Attachment 4
Description of BMPs
• Sediment traps may be needed at channel inlets to prevent entry of muddy runoff and channel
sedimentation.
• Availability of water during dry periods to maintain vegetation
• Sufficient available land area
Maintenance:
During establishment,vegetation lined drainage ditches should be inspected,repaired,and
vegetation reestablished if necessary. After the vegetation has become established,the ditch
should be checked periodically to determine if the channel is withstanding flow velocities without
damage. Check the ditch for debris,scour,or erosion and immediately make repairs if needed.
Check the channel outlet and all road crossings for bank stability and evidence of piping or scour
holes and make repairs immediately.Remove all significant sediment accumulations to maintain
the designed carrying capacity. Keep the vegetation in a healthy condition at all times,since it is
the primary erosion protection for the channel. Vegetation lined drainage ditches should be
seasonally maintained by mowing or irrigating,depending on the vegetation selected. The long-
term management of ditches as stable,vegetated,"natural"drainage systems with native
vegetation buffers is highly recommended due to the inherent stability offered by grasses,shrubs,
trees,and other vegetation.
Research in the Austin area indicates that vegetated controls are effective at removing pollutants
even when dormant.Therefore,irrigation is not required to maintain growth during dry periods,
but may be necessary only to prevent the vegetation from dying.
Sand Filter Systems
The objective of sand filters is to remove sediment and the pollutants from the first flush of
pavement and impervious area runoff.The filtration of nutrients,organics,and coliform bacteria
is enhanced by a mat of bacterial slime that develops during normal operations. One of the main
advantages of sand filters is their adaptability;they can be used on areas with thin soils,high
evaporation rates,low-soil infiltration rates,in limited-space areas,and where groundwater is to
be protected.
Since their original inception in Austin,Texas,hundreds of intermittent sand filters have been
implemented to treat stormwater runoff.There have been numerous alterations or variations in
the original design as engineers in other jurisdictions have improved and adapted the technology
to meet their specific requirements.Major types include the Austin Sand Filter,the District of
Columbia Underground Sand Filter,the Alexandria Dry Vault Sand Filter,the Delaware Sand
Filter, and peat-sand filters which are adapted to provide a sorption layer and vegetative cover to
various sand filter designs.
Design Considerations:
• Appropriate for space-limited areas
Revised April 5,2012 Page 26 of 30
Attachment 4
Description of BMPs
• Applicable in arid climates where wet basins and constructed wetlands are not appropriate
• High TSS removal efficiency
Cost Considerations:
Filtration Systems may require less land than some other BMPs,reducing the land acquisition
cost; however the structure itself is one of the more expensive BMPs. In addition,maintenance
cost can be substantial.
Erosion Control Compost
Description: Erosion control compost(ECC)can be used as an aid to control erosion on critical
sites during the establishment period of protective vegetation.The most common uses are on
steep slopes,swales,diversion dikes,and on tidal or stream banks.
Materials:
New types of erosion control compost are continuously being developed. The Texas Department
of Transportation(TxDOT)has established minimum performance standards which must be met
for any products seeking to be approved for use within any of TxDOT's construction or
maintenance activities. Material used within any TxDOT construction or maintenance activities
must meet material specifications in accordance with current TxDOT specifications. TxDOT
maintains a website at
http://www.txdot.gov/business/contractors_consultants/recycling/compost.htm that provides
information on compost specification data.
ECC used for projects not related to TxDOT should also be of quality materials by meeting
performance standards and compost specification data. To ensure the quality of compost used as
an ECC,products should meet all applicable state and federal regulations,including but not
limited to the United States Environmental Protection Agency(USEPA)Code of Federal
Regulations(CFR),Title 40,Part 503 Standards for Class A biosolids and Texas Natural
Resource Conservation Commission(now named TCEQ)Health and Safety Regulations as
defined in the Texas Administration Code(TAC),Chapter 332,and all other relevant
requirements for compost products outlined in TAC,Chapter 332. Testing requirements
required by the TCEQ are defined in TAC Chapter 332,including Sections§332.71 Sampling and
Analysis Requirements for Final Products and§332.72 Final Product Grades. Compost
specification data approved by TxDOT are appropriate to use for ensuring the use of quality
compost materials or for guidance.
Testing standards are dependent upon the intended use for the compost and ensures product
safety,and product performance regarding the product's specific use.The appropriate compost
sampling and testing protocols included in the United States Composting Council(USCC)Test
Methods for the Examination of Composting and Compost(TMECC)should be conducted on
compost products used for ECC to ensure that the products used will not impact public health,
safety, and the environment and to promote production and marketing of quality composts that
meet analytical standards.TMECC is a laboratory manual that provides protocols for the
composting industry and test methods for compost analysis.TMECC provides protocols to
sample,monitor, and analyze materials during all stages of the composting process. Numerous
Revised April 5,2012 Page 27 of 30
Attachment 4
Description of BMPs
parameters that might be of concern in compost can be tested by following protocols or test
methods listed in TMECC. TMECC information can be found at
http://www.tmecc.org/tmecc/index.html. The USCC Seal of Testing Assurance(STA)program
contains information regarding compost STA certification. STA program information can be
found at http://tmecc.org/sta/STA_program_description.html.
Installation:
• Install in accordance with current TxDOT specification.
• Use on slopes 3:x or flatter.
• Apply a 2 inch uniform layer unless otherwise shown on the plans or as directed.
• When rolling is specified,use a light corrugated drum roller.
Mulch and Compost Filter Socks
Description: Mulch and compost filter socks(erosion control logs)are used to intercept and
detain sediment laden run-off from unprotected areas.When properly used,mulch and compost
filter socks can be highly effective at controlling sediment from disturbed areas. They cause
runoff to pond which allows heavier solids to settle. Mulch and compost filter socks are used
during the period of construction near the perimeter of a disturbed area to intercept sediment
while allowing water to percolate through.The sock should remain in place until the area is
permanently stabilized. Mulch and compost filter socks maybe installed in construction areas
and temporarily moved during the day to allow construction activity provided it is replaced and
properly anchored at the end of the day. Mulch and compost filter socks may be seeded to allow
for quick vegetative growth and reduction in run-off velocity.
Materials:
New types of mulch and compost filter socks are continuously being developed. The Texas
Department of Transportation(TxDOT)has established minimum performance standards which
must be met for any products seeking to be approved for use within any of TxDOT's construction
or maintenance activities. Mulch and compost filter socks used within any TxDOT construction
or maintenance activities must meet material specifications in accordance with TxDOT
specification 5049. TxDOT maintains a website at
http://www.txdot.gov/business/contractors_consultants/recycling/compost.htm that provides
information on compost specification data.
Mulch and compost filter socks used for projects not related to TxDOT should also be of quality
materials by meeting performance standards and compost specification data. To ensure the
quality of compost used for mulch and compost filter socks,products should meet all applicable
state and federal regulations,including but not limited to the United States Environmental
Protection Agency(USEPA)Code of Federal Regulations (CFR),Title 40, Part 503 Standards for
Class A biosolids and Texas Natural Resource Conservation Commission Health and Safety
Regulations as defined in the Texas Administration Code(TAC), Chapter 332, and all other
Revised April 5,2012 Page 28 of
Attachment 4
Description of BMPs
relevant requirements for compost products outlined in TAC,Chapter 332. Testing requirements
required by the TCEQ are defined in TAC Chapter 332,including Sections§332.71 Sampling and
Analysis Requirements for Final Products and§332.72 Final Product Grades. Compost
specification data approved by TxDOT are appropriate to use for ensuring the use of quality
compost materials or for guidance.
Testing standards are dependent upon the intended use for the compost and ensures product
safety,and product performance regarding the product's specific use.The appropriate compost
sampling and testing protocols included in the United States Composting Council (USCC)Test
Methods for the Examination of Composting and Compost CTMECC)should be conducted on
compost products used for mulch and compost filter socks to ensure that the products used will
not impact public health,safety,and the environment and to promote production and marketing
of quality composts that meet analytical standards.TMECC is a laboratory manual that provides
protocols for the composting industry and test methods for compost analysis.TMECC provides
protocols to sample,monitor,and analyze materials during all stages of the composting process.
Numerous parameters that might be of concern in compost can be tested by following protocols
or test methods listed in TMECC. TMECC information can be found at
http://www.tmecc.org/tmecc/index.html. The USCC Seal of Testing Assurance(STA)program
contains information regarding compost STA certification. STA program information can be
• found at http://tmecc.org/sta/STA_program_description.html.
Installation:
• Install in accordance with TxDOT Special Specification 5049.
• Install socks(erosion control logs)near the downstream perimeter of a disturbed area to
intercept sediment from sheet flow.
• Secure socks in a method adequate to prevent displacement as a result of normal rain events
such that flow is not allowed under the socks.
• • Inspect and maintain the socks in good condition(including staking,anchoring,etc.).
Maintain the integrity of the control,including keeping the socks free of accumulated silt,
debris,etc.,until the disturbed area has been adequately stabilized.
Sedimentation Chambers(only to be used when there is no space available for
other approved BMP's)
Description:Sedimentation chambers are stormwater treatment structures that can be used
when space is limited such as urban settings. These structures are often tied into stormwater
drainage systems for treatment of stormwater prior to entering state waters. The water quality
benefits are the removal of sediment and buoyant materials. These structures are not designed
as a catch basin or detention basin and not typically used for floodwater attenuation.
Design Considerations:Average rainfall and surface area should be considered when
following manufacturer's recommendations for chamber sizing and/or number of units needed
to achieve effective TSS removal. If properly sized,50-80%removal of TSS can be expected.
Revised April 5,2012 Page 29 of 30
Attachment 4
Description of BMPs
Maintenance Requirements: Maintenance requirements include routine inspections,
sediment,debris and litter removal,erosion control and nuisance control.
•
Revised April 5,2012 Page 3o of 3o
PERMIT COMPLIANCE CERTIFICATION
U.S.Army Corps of Engineers Project Number:
Permit Number:
Name of Permittee:
Date of Issuance:
Upon completion of the activity authorized by this permit and any mitigation required by the
permit, sign this certification and return it to the following address:
Regulatory Branch
CESWF-PER-R
U.S. Army Corps of Engineers
P.O. Box 17300
Fort Worth, Texas 76102-0300
Please note that your permitted activity is subject to a compliance inspection by a U.S. Army
Corps of Engineers representative. If you fail to comply with this permit you are subject to
permit suspension,modification, or revocation.
I hereby certify that the work authorized by the above referenced permit was completed in
accordance with the terms and conditions of the said permit,and required mitigation was
completed in accordance with the permit conditions.
Signature of Permittee Date