2-Special Provisions-Complete.pdf

February 20, 2023

DEPARTMENT OF TRANSPORTATION

STATE OF GEORGIA

SPECIAL PROVISION

PI # 0015023

Fulton County

Section 107—Legal Regulations and Responsibility to the Public

Add the following to Subsection 107.23:

H. Protection of Ecological Resources

The following conditions are intended as a minimum to protect these species and their habitat during any activities that are in close proximity to the known location(s) of these species.

1. All Project personnel shall be advised about the potential presence and appearance of the proposed endangered tri-colored bat (Perimyotis subflavus) and state protected Chattahoochee crayfish (Cambarus howardi) and bluestripe shiner (Cyprinella callitaenia). Suitable habitat for the Chattahoochee crayfish is present within Perennial Stream (PS) 5/Nancy Creek and PS 11. Suitable habitat for the bluestripe shiner is present within PS 5. Pictures and habitat information shall be posted in a conspicuous location in the Project field office until such time that Project construction activities have been completed and time charges have stopped. In addition, the Contractor shall be responsible for maintaining one set of pictures and habitat information on the Project site that is easily accessible at all times. If a Project field office is not present, a copy of the pictures and habitat information shall be supplied to the Project personnel to be kept on the Project during construction activities. All personnel shall be advised that there are civil and criminal penalties for harassing, harming, pursuing, hunting, shooting, wounding, killing, capturing, or collecting of the above species in knowing violation of the Endangered Species act of 1973 and the Georgia Endangered Wildlife Act of 1973.

2. For tri-colored bat, no tree clearing shall occur from May 1 – July 31 or December 1 – February 28.

3. Erodible stockpiled materials and excavation spoil should be placed at least 200 feet away from streams, wetlands, and open waters, if feasible. All disturbed soil located within 200 feet of a stream, wetland, or open water shall be mulched daily or covered with erosion control mats until work in such areas has been completed. If mulch is necessary, mulch with tackifiers or soil stabilizers that are anionic and non-oil based (e.g., granular PAM) shall be used to reduce turbidity and increase longevity. Erosion and sediment control devices (e.g., compost filter socks or silt fence) shall be installed around erodible stockpiles and excavation spoils within 200 feet of a stream, wetland, or open water.

4. Within 200 feet of a stream, wetland, or open water, secondary containment and spill response procedures (e.g., spill kits) shall be provided on site for all heavy equipment to prevent the spread of pollutants during oil changes, refueling, PI No. 0015023, Fulton County

SP 107.23H – Protection of Ecological Resources and equipment maintenance. When feasible, mineral based hydraulic fluids should be replaced with synthetic biodegradable hydraulic fluid.

5. Omit the application of lime and fertilizer within 200 feet of PS 5 and PS 11 (see Environmental Resource Impact

Table [ERIT] for station numbers).

6. In the event any incident occurs that causes injury to the above species along the Project corridor, the Contractor shall report the incident immediately to the Engineer who in turn will notify the State Environmental Administrator, Georgia Department of Transportation, Office of Environmental Services at (404) 631-1100. With the exception of traffic control and erosion control, all activity shall cease pending consultation by the Department with the Fish and Wildlife Service, Georgia Department of Natural Resources Wildlife Resources Division, and the lead Federal Agency.

7. The Contractor shall keep a log detailing any incidents that cause harm or injury to the above species on or adjacent to the Project until such time that Project construction has been completed and time charges have stopped. Following Project completion, the log and a report summarizing any incidents that caused harm to these species shall be submitted by the Contractor to the Engineer, and via email to the GDOT Office of Environmental Services (ecology_submittals@dot.ga.gov) with the PI number in the subject line of the email. GDOT in turn will provide copies of the report to the Fish and Wildlife Service, Georgia Department of Natural Resources Wildlife Resources Division, and the lead Federal Agency.

8. All costs pertaining to any requirement contained herein shall be included in the overall bid submitted unless such requirement is designated as a separate Pay Item in the Proposal.

Updated: 1/6/2017

Bluestripe Shiner (Cyprinella callitaenia)

Description:

• Dusky olive back with silvery sides

• Blueish-black stripe runs from gills to tailfin

• Males develop white spots on fins

• Reaches 3 to 4 inches in length

Habitat:

• Large streams or rivers with swift currents

• Mostly found in areas with small gravel or sandy substrates

Protected By: Georgia Endangered Wildlife Act of 1973 (O.C.G.A § 27-3-130)

Capturing, killing or selling this animal may result in criminal penalties.

See Special Provision 107.23 H.

STATE PROTECTED SPECIES ON THE PROJECT

Fishes of Alabama and the Mobile Basin

Updated: 1/5/2017

Chattahoochee Crayfish

(Cambarus howardi)

• Adults reach a maximum size of 1 ¼ inches

• May appear bronze-green on top with bluish-green claws

• Tail fades from green to yellow-brown

• Orange-brown bands may be present at the joints of appendages including claws, legs, and tail

Habitat:

• Found in clear, free flowing water, especially in shallow riffles with quickly flowing water

• During the day, specimens often seek shelter under rocks

• May be found in a range of stream sizes, from smaller tributary streams to the larger rivers

Protected By: Georgia Endangered Wildlife Act of 1973 (O.C.G.A § 27-3-130)

STATE PROTECTED SPECIES ON THE PROJECT

Capturing, killing or selling this animal may result in criminal penalties.

See Special Provision 107.23 H.

Adults have a body length of 3 to 3.5 inches from head to tail and a wingspan of 8 to 10 inches.

Body has a yellowish-brown appearance due to multicolored fur.

A key identifying feature is the pinkish forearms that contrast with the black wings.

Habitat:

During summer months, tricolored bats roost among leaf clusters of live or recently dead trees and within features such as barns or bridges. During the winter, this species hibernates in caves and mines; although, where caves are sparse, they will hibernate in culverts, as well as tree cavities and abandoned water wells.

Harming, harassing or killing this animal can lead to fines or jail time.

See Special Provision 107.23 H.

Protected Species On This Project

Tricolored Bat (Perimyotis subflavus) Photo Credit: GA DNR, Center for Biological Diversity

February 8, 2023

STATE OF GEORGIA

SPECIAL PROVISION

P.I. No.: 0015023

COUNTY: FULTON

SECTION 108 - PROSECUTION AND PROGRESS

Retain Sub-Section 108.08 as written and add the following:

108.08. Failure or Delay in Completing Work on Time

D. Restrictive Work Hours

1. Failure to re-open travel lanes as specified in Special Provision Section 150.6.A will result in the assessment of liquidated damages in the amount of $1,000.00, per hour or portion thereof.

The above rates are cumulative and are in addition to any Liquidated Damages which may be assessed for failure to complete the overall project

February 8, 2023

STATE OF GEORGIA

SPECIAL PROVISION

P.I. No.: 0015023

FULTON COUNTY

SECTION 150 – TRAFFIC CONTROL

Delete Subsection 150.6 and add the following:

150.6 Special Conditions:

A. Lane Closures

The Contractor shall not install lane closures, shoulder closures (if applicable), pace traffic or move equipment or materials that interferes with traffic on SR 400 or local side streets between the hours of 6:00 am to 9:00 am and 3:00 pm to 6:00 pm, Monday through Friday.

The Contractor shall coordinate all lane closures and construction access from county, city, and state roads and streets with the City of Sandy Springs, the City of Atlanta, and the Georgia Department of Transportation.

February 7, 2022

P.I. No. 0015023 Fulton County

Section 165— Maintenance of Temporary Erosion and Sedimentation Control Devices

Delete the opening text of Subsection 165.3.05 and replace with the following and retain lettered subsections:

As a minimum, clean sediment from all temporary erosion control devices (except temporary sediment basins) installed on the project when:

One-third the capacity by volume, as measured by depth, has been reached when the erosion control device is within 200 feet of PS 5/Nancy Creek and PS 11 (see Environmental Resource Impact Table [ERIT] for station numbers) for added protection of ecological resources (see Special Provision 107.23H); or

One-half the capacity by volume, as measured by depth, has been reached otherwise for all other erosion control devices (except temporary sediment basins).

Clean sediment from all temporary sediment basins installed on a project when one-third the capacity of the storage volume has been filled.

Handle excavated sediment from any erosion or sediment control device in one of the following ways:

Remove sediment from the immediate area and immediately stabilize it to prevent the material from refilling any erosion or sediment control device.

Place and mix it in the roadway embankment or waste it in an area approved by the Engineer.

Repair or replace at no cost to the Department any erosion or sediment control device that is not functioning properly or is damaged due to negligence or abuse.

Project Special Provision

PI# 0017980

Path 400 Trail Extension

Section 169—Post-Construction Stormwater BMP Items

169.1 General Description

This work includes constructing the following Best Management Practices (BMPs) as shown in the Plans or as directed by the Engineer. This work also consists of providing maintenance on post construction Best Management Practices (BMPs) including but not limited to:

• Bioretention basins

• Bioslopes

• Dry detention basins

• Enhanced dry swales

• Enhanced wet swales

• Infiltration trenches

• Sand filters

• Wet detention ponds

• Other permanent water treatment structures as shown on the Plans or as directed by the Engineer

169.1.01 Definitions

General Provisions 101 through 150.

169.1.02 Related References

A. Standard Specifications

Section 109—Measurement and Payment

Section 161—Control of Soil Erosion and Sedimentation

Section 208—Embankments

Section 500—Concrete Structures

Section 511—Reinforcement Steel

Section 573—Underdrains

Section 574—Edgedrains

Section 603—Rip Rap

Section 643—Fence

PI# 0015023

Section 169—Post Construction Stormwater BMP Items

Section 700—Grassing

Section 702—Vine, Shrub, and Tree Planting

Section 708—Plant Topsoil

Section 711—Turf Reinforcement Matting

Section 800—Coarse Aggregate

Section 801—Fine Aggregate

Section 805—Rip Rap and Curbing Stone

Section 806—Aggregate for Drainage

Section 814—Soil Base Materials

Section 830—Portland Cement

Section 839—Corrugated Polyethylene Underdrain Pipe

Section 846—Polyvinyl Chloride (PVC) Drain Pipe

Section 853—Reinforcement and Tensioning Steel

Section 881—Fabrics

Section 890—Seed and Sod

Section 893—Miscellaneous Planting Materials

Section 894—Fencing

Section 910—Sign Fabrication

Section 911—Sign Posts

Section 914—Sign Paint

B. Referenced Documents

AASHTO M-252

AASHTO M-294

AASHTO M-304

AASHTO T 215

ASTM D-422

ASTM D-698

ASTM D-1784

ASTM D-1785

ASTM D-2434

ASTM D-2466

ASTM D-2564

ASTM D-2665

ASTM D-3786

ASTM D-4491

ASTM D-4533

ASTM D-4632

ASTM D-4751

ASTM D-4833

ASTM F-758

ASTM F-949

169.1.03 Submittals

A. As-Built Documents

Within 45 calendar of completing construction of the post-construction stormwater BMP submit as-built documents that contain the specified information for each post-construction stormwater BMP constructed. Submit BMP as-builts to the Engineer, notify stormreports@dot.ga.gov of the submittal, and use the Department’s electronic submittal process.

Subsequent revisions to and submissions of the post-construction stormwater BMP as-built documents following the initial submission shall be at no additional cost to the Department.

B. Compost Documentation

For the compost portion of the engineered soil mix submit a notarized certification that includes the following:

• The feedstock by percentage in the final compost product.

• A statement that the compost meets federal and state health and safety regulations.

• A statement that the composting process has met time and temperature requirements.

• A copy of the lab analysis, less than four months old, performed by a Seal of Testing Assurance certified lab verifying that the compost meets the physical requirements specified.

When requested by the Engineer, one Solvita Compost Maturity Test kit shall be provided. The Solvita Compost Maturity Test kit is available from:

Woods End Research Laboratory Inc.

Box 297

Mt. Vernon, Maine 04352

1-800-0451-0337 email: info@woodsend.org or approved equal.

169.2 Materials

Provide materials shown on the Plans, such as pipe, spillways, wood baffles, plants, and other accessories including an anti-seep collar, when necessary. Materials shall be approved by the Engineer before use.

Materials shall meet the following Specifications/Requirements:

Material GDOT Specification/Requirement

Nonwoven geotextile filter fabric ASTM D-3786: Mullen burst strength = 280 psi

ASTM D-4491: permittivity = 1.30 sec-1

ASTM D-4533: Trapezoidal tear strength = 60 lb

ASTM D-4632: Grab tensile strength = 160 lb

ASTM D-4632: Grab tensile elongation = 50%

ASTM D-4751: AOS = 70 US standard sieve

ASTM D-4833: Puncture Resistance = 85 lb

Class A, AA, and B Concrete 500/ASTM C-76-10

Reinforcement Steel 511

Rip Rap 603, 805

Permanent Grass, Sod, and Other Vegetation 700

Turf Reinforcement Matting 711

Coarse Aggregate 800

Fine Aggregate 801

Soil Base Materials 814

Rip Rap and Curbing Stone 805

Portland Cement 830

Corrugated Polyethylene Underdrain Pipe 839/AASHTO M252 or M294

PVC Underdrains 846/ASTM F-758, ASTM F-949

Reinforcement and Tensioning Steel 853

Fabrics 881

Seed 890

Miscellaneous Planting Materials 893

Mulch 893.2.02

Signage 910, 911, 914

Landscape Plantings 702

A. Engineered Soil Mix Requirements

1. Use an engineered soil mix that meets the requirements herein. Do not use a mixture that contains toxic or pathogenic substances. Obtain the materials from sources approved by the Engineer. Ensure that aggregate retained on No. 10 (2 mm ) sieve is of hard, durable particles.

2. Remove particles with a diameter greater than 2 in (50 mm) before placing the engineered soil mix. Remove particles with screens or by hand if few oversized pieces exist. Otherwise, crush the oversized pieces to less than 2 in and use them in the proportions shown by the gradation table below.

3. Use 5-10% by dry weight composted organic matter as soil components. All components shall be free of heavy metals, pathogens, pesticides, and herbicides.

Produce General Use Compost by aerobic (biological) decomposition of organic matter. Compost feedstock may include, but is not limited to, leaves and yard trimmings, Class A biosolids, food scraps, food processing residuals, manure or other agricultural residuals, forest residues, bark, and paper. Compost shall not contain any visible refuse or other physical contaminants, material toxic to plant growth, or over 5% sand, silt, clay or rock material. Mixed municipal solid waste compost and Class B biosolids, as defined in the United States

Environmental Protection Agency Code of Federal Regulations (USEPA, CFR), Title 40, Part 503 are unacceptable. Ensure Compost meets all applicable USEPA, CFR, Title 40, Part 503 Standards for Class A biosolids and the following requirements:

Test Requirements Test Method

Organic Matter Content 25-100% (dry mass) TMECC 05.07-A

Particle Size 100% passing 2 in. (50 mm) sieve

50-70% retained on 3/8 in. (9.5 mm) sieve

TMECC 02.02-B

Soluble Salts 5.0 max. * dS/m TMECC 04.10-A

Fecal Coliform Pass TMECC 07.01-B pH 5.5 – 8.5 pH TMECC 04.11-A

Stability 8 or below TMECC 05.08-B

Maturity greater than 80% TMECC 05.05-A

Heavy Metals Pass TMECC 04.06 and TMECC 04.13-B

*A soluble salt content up to 10.0 dS/m for compost used in Compost Manufactured Topsoil will be acceptable.

NOTE: All physical requirements are in accordance with the United States Department of Agriculture and the United States Composting Council, “Test Methods for the Examination of Composting and Compost” (TMECC). Organic Matter Content and Particle Size requirements are in accordance with

AASHTO R51-13.

4. Use 90-95% by dry weight inorganic soil components with the following properties:

Sieve Size Percent Passing by Weight

Passing 2 in (50 mm) 100

Passing No. 4 (4.75mm) 98-100

Passing No. 8 (2.36 mm) sieve 95-100

Passing No. 10 (2.0 mm) 86-100

Passing No. 16 (1.18 mm) sieve 70-100

Passing No. 30 (600 µm) sieve 40-75

Passing No. 50 (300 µm) sieve 10-35

Passing No. 100 (150 µm) sieve 2-15

Passing No. 200 (75 µm) sieve 0-10

Clay size (< 2 µm) 0-6

5. Ensure that material passing the No. 10 (2 mm) sieve meets the following requirements:

Property Value

Liquid Limit (LL) ≤25

Plasticity Index (PI) ≤10

Volume Change, Maximum Percent 12

Maximum Dry Density, lb/ft³* 105

Permeability (in/hr) 1 – 6

Phosphorous Index (P-index) <25

*by standard Proctor

169.2.01 Fabrication

General Provisions 101 through 150.

169.2.02 Acceptance

The Contractor is required to submit a minimum of three (3) cubic-foot-sized random engineered soil mix samples per 150 tons of material per each source to the Department’s Physical and Chemical Testing Branch of the Office of Materials and Testing 20 working days before placement for testing to ensure acceptability for use as directed by the Project Engineer. The Department’s Office of Materials and Testing reserves the right to disapprove the engineered soil mix for use if test results show that parameters do not meet the acceptable values specified above. Acceptance must be granted prior to placement.

The Department will test engineered soil mix as follows:

Test Method

Soil Gradation GDT 4

Volume Change GDT 6

Maximum Density GDT 7 or GDT 67

Liquid Limit AASHTO T 89

Plastic Limit and Plasticity Index AASHTO T 90

Permeability AASHTO T 215

169.2.03 Materials Warranty

General Provisions 101 through 150.

169.2.04 Delivery Storage and Handling

General Provisions 101 through 150.

169.3 Construction Requirements

169.3.01 Personnel

General Provisions 101 through 150.

169.3.02 Equipment

General Provisions 101 through 150.

169.3.03 Preparation

General Provisions 101 through 150.

169.3.04 Fabrication

General Provisions 101 through 150.

169.3.05 Construction

A. Bioretention Basins

Construct bioretention basins as shown in the Plans, or as modified by the Engineer, after final grade and stabilization of the area upstream of each bioretention basin are achieved. If this is not feasible, stormwater flow shall be diverted around the bioretention basin and the basin area protected with temporary erosion and sediment control measures. Once the basin has been stabilized, vegetation shall be established within the bioretention basin per the details shown in the Plans.

1. Excavation

Excavation should be limited to the width and length of the bioretention basin per the details shown in the Plans or as directed by the Engineer. Avoid placing excavated material near the open trench so as not to jeopardize the stability of the trench sidewalls. The bottom of the excavated trench should be flat across its width and length, shall not be loaded in a way that causes soil compaction, and should be scarified prior to placement of specified materials. The sides of the trench shall be trimmed of all large roots. The sidewalls should be uniform with no voids and scarified prior to placement of materials for specified engineered drainage layers. Trench sidewalls shall be lined with the specified filter fabric after infiltration testing, if applicable.

2. Infiltration Testing

If the Plans indicate that infiltration testing is not needed, do not cap the underdrain.

If the Plans indicate that infiltration testing is needed the Contractor shall perform the following test after excavating to the bottom elevation of the bioretention basin:

When soil is dry, excavate a single test hole 1-2 feet in diameter and 1-2 feet deep in the bottom of the

BMP if the BMP is less than 1,000 square feet. If the BMP is greater than or equal to 1,000 square feet, excavate two test holes 1-2 feet in diameter in the bottom of the BMP. Holes shall be located in the areas of the bottom of the BMP which visually appear to have the finest-grained soils such as silt or clay. Scarify the walls and bottom of the hole(s).

Fill the hole(s) with 6 inches of water. Measure the depth of the water in the hole(s) every hour for 2 hours or until all water is infiltrated, whichever is less. If all the water has infiltrated in 2 hours, leave the underdrain and upturned orifice capped.

If all the water has not entirely infiltrated, calculate the infiltration rate by dividing the depth of water infiltrated within an hour by the time tested. If the water has not infiltrated within 2 hours, repeat tests until sequential tests are within 20 percent. Convert units to in/hr.

If the infiltration rate is equal to or greater than 1 in/hr leave the underdrain and upturned orifice capped. If the infiltration rate is less than 1 in/hr, leave the underdrain capped but uncap the upturned orifice. If a substantial amount of clay is encountered during excavation, the Engineer may use judgement to determine if the underdrain should be fully uncapped. In the case where two holes are used or multiple tests are conducted, the average of the values may be used to determine underdrain configuration.

3. Underdrain System/Aggregate Layer

Install underdrain system(s) made of perforated polyethylene or perforated PVC pipe at the locations and depth per details shown in the Plans for conveyance of stormwater that has filtered through the media. Perforations shall be 3/8-inch diameter and spaced 6-inches on center with four rows running longitudinally. A removable end cap connected to the underdrain system shall be installed per the details shown in the Plans. If infiltration is feasible, the end cap shall be closed except for emergency drainage or maintenance purposes. The underdrain pipe shall be surrounded by an aggregate layer as defined in the details and a 2-3-inch filter blanket of size No. 89 aggregate (Georgia Department of Transportation Specification Section 800) shall be used to segregate the aggregate layer from the engineered soil mix. Aggregates used in underdrain systems shall be double washed and free of fines and organic materials. Cleanouts shall be provided at the end of each underdrain branch. Cleanouts shall extend to an elevation such that they are accessible once the trench is backfilled with the specified media, and shall have a locking screw top lid, to discourage vandalism and tampering.

4. Engineered Soil Mix

Install the engineered soil mix specified above for a 24-inch-minimum-thickness and nonwoven geotextile filter fabric per the details shown in the Plans. Water the engineered soil mix during installation to ensure gentle consolidation of the material. The engineered soil mix shall be placed in a maximum of 12-inch lifts and shall be protected from contamination by foreign matter during installation. If the engineered soil mix becomes contaminated or the filter fabric is damaged, remove contaminated or damaged materials and replace them at no additional cost to the Department. Avoid using heavy equipment within the basin area during installation to avoid compromising the hydraulic conductivity of the engineered soil mix and to prevent damage to the underdrains.

5. Mulch Layer

The mulch layer of the bioretention basin shall be a minimum thickness of 3 inches and shall consist of double shredded hardwood mulch resistant to floating (Georgia Department of Transportation Specification Subsection 893.2.02). The mulch layer should be well aged (stockpiled or stored for at least six months), uniform in color, and free of other materials, such as weed seeds, soil, roots, etc. Grass clippings or pine straw shall not be used as mulch material.

6. Plantings

Plant species used in bioretention basins shall be installed per the details shown in the Plans and meet the requirements outlined in Georgia Department of Transportation Specification Section 702. Plants shall be selected on the basis of a specified hydric tolerance zone and shall be capable of surviving both wet and dry conditions. All plants used shall be well grown and healthy and free from disease and infestation by invasive species. Trees shall not be planted in bioretention basins. Plant substitutions can be made as outlined in Georgia Department of Transportation Specification 702 if the specified plant is not locally available.

7. Pretreatment

Install rip rap forebays, filter strips, level spreaders and other pretreatment devices per the details and at the locations specified in the Plans. Rip rap used in pretreatment devices shall meet the requirements outlined in Georgia Department of Transportation Specification Sections 603 and 805 and woven filter fabric shall meet the requirements outlined in Georgia Department of Transportation Specification Section 881.2.05. Grasses used in filter strips shall be tolerant of both wet and dry conditions and meet the requirements outlined in Georgia Department of Transportation Specification Section 700. Aggregates used in pretreatment shall be double washed and free of fines and organic materials.

8. Signage

Install signage per the details and locations specified in the Plans.

9. Bioretention Basin Maintenance

Contractor shall maintain the bioretention basin as outlined in the GDOT Stormwater System Inspection and Maintenance Manual until maintenance acceptance (paying particular attention to removing sediment, preventing erosion, preventing ponding after rain events, and the maintenance of vegetation).

Inspect the BMP 12 hours after rain events of 1 inch or greater in 24 hours. If the underdrain is capped and ponding is still present, uncap the underdrain and upturned orifice. If the underdrain is uncapped and ponding is still present, follow procedures prescribed in the GDOT Stormwater System Inspection and Maintenance Manual.

At least one occurrence of maintenance to be performed per bioretention basin just prior to maintenance acceptance.

B. Bioslopes

Complete bioslopes as shown in the construction Plans, or as modified by the Engineer, after final grade and stabilization of the area upstream of each bioslope are reached. If this is not feasible, stormwater flow shall be diverted around the bioslope and the bioslope protected with temporary erosion and sediment control measures.

1. Excavation

Excavation should be limited to the width and length of bioslope per the details shown in the Plans or as directed by the Engineer. Avoid placing excavated material near the open trench so as not to jeopardize the stability of the trench sidewalls. The bottom of the excavated trench should be flat across its width and length, shall not be loaded in a way that causes soil compaction, and should be scarified prior to placement of specified materials. The sides of the trench shall be trimmed of all large roots. Sidewalls should be uniform with no voids and scarified prior to placement of materials for specified engineered drainage layers. Trench sidewalls shall be lined with the specified filter fabric.

2. Underdrain System/Aggregate Layer

Install underdrain system(s) made of perforated polyethylene or perforated PVC pipe at the locations and depth per details shown in the Plans for conveyance of stormwater that has filtered through the media. Perforations shall be 3/8-inch diameter and spaced 6-inches on center with four rows running longitudinally. The underdrain pipe shall be surrounded by an aggregate layer of size No. 57 aggregate. Nonwoven geotextile filter fabric shall be used to protect the aggregate layer from the bioslope media mix. Aggregates used in underdrain systems shall be double washed and free of fines and organic materials. Cleanouts shall be provided at the end of each underdrain branch. Cleanouts shall extend to an elevation such that they are accessible once the trench is backfilled with the specified media and shall have a locking screw top lid to discourage vandalism and tampering.

3. Bioslope Media Mix

The bioslope media mix shall contain aggregate, dolomite, gypsum, and perlite and shall be mixed as follows:

Material Quantity

Aggregate:

GDOT size No. 89 stone

No recycled material

Non-limestone material mineral aggregate

3 yd3

(3 yd3 used as a baseline for other mixture components:

adjust total quantity based on bioslope dimensions)

Perlite:

Horticultural grade, free of toxic materials

99-100% passing US No. 4 Sieve

0-30% passing US No. 18 Sieve

0-10% passing US No. 30 Sieve

1 yd3 per 3 yd3 of mineral aggregate

Dolomite: calcium magnesium carbonate, CaMg(CO3)2

Agricultural grade, free of toxic materials

100% passing US No. 8 Sieve

0% passing US No. 16 Sieve

40 pounds per yd3 of perlite

Gypsum: Non-calcined, agricultural gypsum CaSO4•2H2O

(hydrated calcium sulfate)

Agricultural grade, free of toxic materials

100% passing US No. 8 Sieve

0% passing US No. 16 Sieve

12 pounds per yd3 of perlite

Install the bioslope media mix specified above for the 12-inch-minimum-thickness bioslope media mix layer and nonwoven geotextile filter fabric per the details shown in the Plans. Water the media during installation to ensure gentle consolidation of the material. Protect the bioslope media mix from contamination by foreign matter during installation. If the bioslope media mix becomes contaminated or the filter fabric is damaged, remove contaminated or damaged materials and replace them at no additional cost to the Department.

Cover the bioslope media mix with turf reinforcement matting 1 (TRM 1), or as directed by the Engineer.

4. Engineered Soil Application

The top 3 inches of the bioslope should consist of engineered soil. Water the engineered soil during installation to ensure gentle consolidation of the material. Do not use a mixture that contains toxic or pathogenic substances. Obtain the materials from sources approved by the Engineer. Ensure that aggregate retained on No. 10 (2 mm ) sieve is of hard, durable particles.

Stabilize the disturbed area adjacent to the bioslope per the Plans immediately after the bioslope is installed. Permanent vegetation using grass cover shall be established within the bioslope surface area using sod.

5. Sod Layer

The sod layer must be grown in primarily sand/sandy-loam soils with less than 6% clay content. Sod shall be half cut or thin cut to promote infiltration. Sod shall consist of at least 75% of the designated grass species specified in the Plans.

6. Pretreatment

Install filter strips per the details and locations specified in the Plans. Grasses used in filter strips shall be tolerant of both wet and dry conditions and meet the requirements outlined in Georgia Department of Transportation Specification Section 700.

7. Signage

Install signage per the details and locations specified in the Plans.

8. Bioslope Maintenance

Contractor shall maintain the bioslope as outlined in the GDOT Stormwater System Inspection and Maintenance Manual until maintenance acceptance (paying particular attention to prevent erosion, preventing the accumulation of sediment, and maintenance of vegetation). At least one occurrence of maintenance to be performed per bioslope just prior to maintenance acceptance.

C. Dry Detention Basins

Construct dry detention basins per the Plans at the required locations, or as modified by the Engineer.

Construct the basins as shown, including but not limited to: grading, drainage, accessories to complete the dry detention basins and temporary mulching and permanent grassing on external slopes. The Contractor may propose alternate construction staging for review and approval. Alternate construction submittals for review shall be provided a minimum of 30 days prior to the construction of a dry detention basin.

1. Excavation

Excavation should be limited to the width and length of the dry detention basin per the details shown in the Plans or as directed by the Engineer. Embankments shall be constructed using the materials and methods specified in Section 208 and shall be compacted to at least 95 percent of the maximum laboratory dry density.

Stabilize the disturbed areas adjacent to dry detention basins per the Plans immediately after each dry detention basin is installed.

2. Pretreatment

Install rip rap forebays per the details and at the locations specified in the Plans. Rip rap used in forebays shall meet the requirements outlined in Georgia Department of Transportation Specification Sections 603 and 805 and woven filter fabric shall meet the requirements outlined in Georgia Department of Transportation Specification Section 881.2.05. Aggregates used in pretreatment shall be double washed and free of fines and organic materials.

3. Dry Detention Basin Maintenance

Contractor shall maintain the dry detention basin as outlined in the GDOT Stormwater System Inspection and Maintenance Manual until maintenance acceptance (paying particular attention to prevention of sedimentation, preventing erosion, maintenance of vegetation, and preventing ponding after rain events). At least one occurrence of maintenance to be performed per dry detention basin just prior to maintenance acceptance.

D. Enhanced Dry Swales

Construct enhanced dry swales as shown in the Plans, or as modified by the Engineer, after final grade and stabilization of the area upstream of each enhanced dry swale are reached. If this is not feasible, stormwater flow shall be diverted around the swale and the swale protected with temporary erosion and sediment control measures.

1. Excavation

Excavation should be limited to the width and length of the enhanced dry swale per the details shown in the Plans or as directed by the Engineer. Avoid placing excavated material near the open trench so as not to jeopardize the stability of the trench sidewalls. The bottom of the excavated trench shall not be loaded in a way that causes soil compaction, and should be scarified prior to placement of specified materials. The sides of the trench shall be trimmed of all large roots. Sidewalls should be uniform with no voids and scarified prior to placement of materials for specified engineered drainage layers. Trench sidewalls shall be lined with the specified filter fabric.

2. Underdrain System/Aggregate Layer

Install underdrain system(s) made of perforated polyethylene or perforated PVC pipe at the locations and depth per details shown in the Plans for conveyance of stormwater that has filtered through the media. Perforations shall be 3/8-inch diameter and spaced 6-inches on center with four rows running longitudinally. A removable end cap connected to the underdrain system shall be installed per the details shown in the Plans. The underdrain pipe shall be surrounded by an aggregate layer as defined in the details and a 2-3-inch filter blanket of size No. 89 aggregate (Georgia Department of Transportation Specification Section 800) shall be used to segregate the aggregate layer from the engineered soil mix. Aggregates used in underdrain systems shall be double washed and free of fines and organic materials. Cleanouts shall be provided at the end of each underdrain branch. Cleanouts shall extend to an elevation such that they are accessible once the trench is backfilled with the specified media and shall have a locking screw top lid, to discourage vandalism and tampering.

3. Engineered Soil Mix

Install the engineered soil mix specified above for the 30-inch thick engineered soil mix and nonwoven geotextile filter fabric per the details shown in the Plans. Water the engineered soil mix during installation to ensure gentle consolidation of the material. The engineered soil mix shall be placed in a maximum of 12-inch lifts and shall be protected from contamination by foreign matter during installation. If the engineered soil mix becomes contaminated or the filter fabric is damaged, remove contaminated or damaged materials and replace them. Avoid using heavy equipment on the basin area during installation to maintain hydraulic conductivity of the engineered soil mix and to prevent damage to the underdrains.

4. Sod Layer

The sod layer must be grown in primarily sand/sandy-loam soils with a clay content of 10% or less. Sod shall be half cut or thin cut to promote infiltration. Sod shall consist of at least 75% of the designated grass species specified in the Plans.

5. Pretreatment

Install rip rap forebays per the details and at the locations specified in the Plans. Rip rap used in forebays shall meet the requirements outlined in Georgia Department of Transportation Specification Sections 603 and 805 and woven filter fabric shall meet the requirements outlined in Georgia Department of Transportation Specification Section 881.2.05. Rip rap forebays shall be located at major inflow locations and energy dissipation shall be provided at all concentrated inflow locations. Maintenance access shall be provided to the forebay. Aggregates used in pretreatment shall be double washed and free of fines and organic materials.

6. Signage

Install signage per the details and locations specified in the Plans.

7. Enhanced Dry Swale Maintenance

Contractor shall maintain the enhanced dry swale as outlined in the GDOT Stormwater System Inspection and Maintenance Manual until maintenance acceptance (paying particular attention to removing sediment, preventing erosion, preventing ponding after rain events, and maintenance of vegetation).

Inspect the BMP 12 hours after rain events of 1 inch or greater in 24 hours. If the underdrain is capped and ponding is still after a rain event uncap the underdrain. If ponding still is still present, follow procedures prescribed in the GDOT Stormwater System Inspection and Maintenance Manual.

At least one occurrence of maintenance to be performed per enhanced dry swale just prior to maintenance acceptance.

E. Enhanced Wet Swales

Construct enhanced wet swales as shown in the Plans, or as modified by the Engineer, after final grade and stabilization of the area upstream of each enhanced wet swale are reached. If this is not feasible, stormwater flow shall be diverted around the swale and the swale protected with temporary erosion and sediment control measures.

1. Excavation

Excavation should be limited to the width and length of enhanced wet swale per the details shown in the Plans or as directed by the Engineer. Avoid placing excavated material near the open trench so as not to jeopardize the stability of the trench sidewalls. The bottom of the excavated trench shall not be loaded in a way that causes soil compaction, and should be scarified. The sides of the trench shall be trimmed of all large roots, uniform with no voids, and scarified during normal stage construction. Install matted permanent grass slopes adjacent to enhanced wet swales immediately after each enhanced wet swale is installed. Once the basin has been stabilized, vegetation shall be established within the enhanced wet swale per the details shown in the Plans.

2. Plantings

Plant species used in enhanced wet swale shall be installed per the details shown in the Plans and meet the requirements outlined in Georgia Department of Transportation Specification Section 702. Plants shall be selected on the basis of a specified hydric tolerance zone and shall be capable of surviving wetland conditions.

All plants used shall be well grown and healthy and free from disease and infestation by invasive species. Plant substitutions can be made as outlined in Georgia Department of Transportation Specification 702 if the specified plant is not locally available.

3. Pretreatment

Install rip rap forebays per the details and at the locations specified in the Plans. Rip rap used in forebays shall meet the requirements outlined in Georgia Department of Transportation Specification Sections 603 and 805 and woven filter fabric shall meet the requirements outlined in Georgia Department of Transportation Specification Section 881.2.05. Aggregates used in pretreatment shall be double washed and free of fines and organic materials.

4. Signage

Install signage per the details and locations specified in the Plans.

5. Enhanced Wet Swale Maintenance

Contractor shall maintain the enhanced wet swale as outlined in the GDOT Stormwater System Inspection and Maintenance Manual until maintenance acceptance (paying particular attention to removing sediment, preventing erosion, and maintenance of vegetation). At least one occurrence of maintenance to be performed per enhanced wet swale just prior to maintenance acceptance.

F. Infiltration Trenches

Construct infiltration trenches as shown in the Plans, or as modified by the Engineer, only after final grade and stabilization of drainage areas upstream of the infiltration trenches are completed to prevent contamination. If this is not feasible, stormwater flow shall be diverted around the trench and the trench area protected with temporary erosion and sediment control measures.

1. Excavation

Excavation should be limited to the width and length of infiltration trench per the details shown in the Plans or as directed by the Engineer. Avoid placing excavated material near the open trench so as not to jeopardize the stability of the trench sidewalls. The bottom of the excavated trench should be flat across its width and length, shall not be loaded in a way that causes soil compaction, and should be scarified prior to placement of specified materials. The sides of the trench shall be trimmed of all large roots. The sidewalls should be uniform with no voids and scarified prior to placement of materials for specified engineered drainage layers. Trench sidewalls shall be lined with specified filter fabric. Infiltration testing is required before excavation and prior to placement of the drainage layer to ensure that infiltration rates were not impacted during excavation and that the in-situ soils have a minimum infiltration rate of 0.7 in/hr (5.0x10-4 cm/s)

2. Observation Wells

Install observation wells made of 2-inch diameter, 0.01-inch-slotted, threaded, schedule 40 PVC pipe at the locations and depth per details shown in the Plans for percolation monitoring. Observation wells shall have a threaded or slip-on top cap and shall have a locking steel sleeve to discourage vandalism and tampering.

3. Drainage Layer

Install the specified materials for drainage layers and filter fabric per the details shown in the Plans. The bottom 6 inches of the drainage layer shall consist of size 10 NS sand (Georgia Department of Transportation Specification Section 801). The drainage layer shall consist of size No. 3 drainage aggregate to the depth specified in the Plans and filter fabric shall be used to segregate the aggregate layer from the sod layer. All aggregates used in drainage layers shall be double washed and free of fines and organic materials. Protect drainage layers from contamination by foreign matter during installation. If drainage layers become contaminated or filter fabric is damaged, remove contaminated or damaged materials.

4. Sod Layer

The top layer of the trenches shall consist of sod as specified in the Plans. Sod must be washed or grown in primarily sand/sandy-loam soils with 10% or less clay content. Stabilize the disturbed areas adjacent to infiltration trenches per the Plans immediately after each infiltration trench is installed.

5. Pretreatment

Install rip rap forebays, filter strips, level spreaders and other pretreatment devices per the details and at the locations specified in the Plans. Rip rap used in pretreatment devices shall meet the requirements outlined in Georgia Department of Transportation Specification Sections 603 and 805 and woven filter fabric shall meet the requirements outlined in Georgia Department of Transportation Specification Section 881.2.05. Grasses used in filter strips shall be tolerant of both wet and dry conditions and meet the requirements outlined in Georgia Department of Transportation Specification Section 700. Aggregates used in pretreatment shall be double washed and free of fines and organic materials.

6. Signage

Install signage per the details and locations specified in the Plans.

7. Infiltration Trenches Maintenance

Contractor shall maintain the infiltration trench as outlined in the GDOT Stormwater System Inspection and Maintenance Manual until maintenance acceptance (paying particular attention to removing sediment, preventing erosion, preventing ponding after rain events, and maintenance of vegetation). At least one occurrence of maintenance to be performed per infiltration trench just prior to maintenance acceptance.

G. Sand Filters

Construct sand filters as shown in the Plans or as modified by the Engineer, after final grade and stabilization of the area upstream of each sand filter are reached. If this is not feasible, stormwater flow shall be diverted around the sand filter and the area shall be protected with temporary erosion and sediment control measures.

1. Excavation

Excavation should be limited to the width and length of the sand filter per the details shown in the Plans or as directed by the Engineer. Avoid placing excavated material near the open trench so as not to jeopardize the stability of the trench sidewalls. The bottom of the excavated trench should be flat across its width and length, shall not be loaded in a way that causes soil compaction, and should be scarified prior to placement of specified materials. The sides of the trench shall be trimmed of all large roots. The sidewalls should be uniform with no voids and scarified prior to placement of materials for specified engineered drainage layers. Trench sidewalls shall be lined with the specified filter fabric.

2. Underdrain System/ Aggregate Layer

Install underdrain system(s) made of perforated polyethylene or perforated PVC pipe at the locations and depth per details shown in the Plans for conveyance of stormwater that has filtered through the media. Perforations shall be 3/8-inch diameter and spaced 6-inches on center with four rows running longitudinally. The underdrain pipe shall be surrounded by an aggregate layer as defined in the details. Nonwoven geotextile filter fabric shall be used to segregate the aggregate layer from the sand filter bed. Aggregates used in underdrain systems shall be double washed and free of fines and organic materials. Cleanouts shall be provided at the end of each underdrain branch. Cleanouts shall extend to an elevation such that they are accessible once the trench is backfilled with the specified media and shall have a locking and threaded top lid to discourage vandalism and tampering.

3. Sand Filter Bed

Install the sand filter bed consisting of size 10 NS sand (Georgia Department of Transportation Specification Section 801) for the 18-inch-minimum-thickness sand filter bed layer and nonwoven geotextile filter fabric per the details shown in Plans. The sand filter bed shall be placed in 6-inch lifts and shall be protected from contamination by foreign matter during installation. Water the sand during installation to ensure gentle consolidation of the material. If the sand filter bed becomes contaminated or the filter fabric is damaged, remove contaminated or damaged materials and replace. Avoid using heavy equipment on the filter bed to maintain hydraulic conductivity of the soil media and avoid damaging the underdrains.

4. Engineered Soil Requirements

a. The top 3 inches of the sand filter should consist of engineered soil. Water the engineered soil during installation to ensure gentle consolidation of the material. Do not use a mixture that contains toxic or pathogenic substances. Obtain the materials from sources approved by the Engineer. Ensure that aggregate retained on No. 10 (2 mm ) sieve is of hard, durable particles.

b. Nonwoven geotextile filter fabric shall be installed between the engineered soil and sand filter bed and shall be readily separable for maintenance. Stabilize the disturbed area adjacent to the sand filter per the

Plans immediately after the sand filter is installed. Permanent vegetation using grass cover shall be established within the sand filter using seeding once the basin has been stabilized. Grass used within the sand filter should be capable of withstanding frequent periods of wet and dry conditions.

5. Pretreatment-Sediment Chamber

Rip rap used in sediment chambers shall meet the requirements outlined in Georgia Department of Transportation Specification Sections 603 and 805 and woven filter fabric shall meet the requirements outlined in Georgia Department of Transportation Specification Section 881.2.05. Aggregates used in pretreatment shall be double washed and free of fines and organic materials.

6. Signage

Install signage per the details and locations specified in the Plans.

7. Sand Filters Maintenance

Contractor shall maintain the sand filter as outlined in the GDOT Stormwater System Inspection and Maintenance Manual until maintenance acceptance (paying particular attention to removing sediment, preventing erosion, preventing ponding after rain events, and maintenance of vegetation). At least one occurrence of maintenance to be performed per sand filter just prior to maintenance acceptance.

H. Wet Detention Ponds

Construct wet detention ponds per the Plans at the required locations or as modified by the Engineer.

Construct the ponds as shown, including but not limited to: grading, drainage, accessories to complete the wet detention ponds and temporary mulching and permanent grassing on external slopes. The Contractor may propose alternate construction staging for review and approval. Alternate construction submittals for review shall be provided a minimum of 30 days prior to construction of a wet detention pond.

1. Excavation

Excavation should be limited to the width and length of the wet detention pond per the details shown in the Plans or as directed…