656MULCHING FOR VEGETATION ESTABLISHMENT

550

MULCHING FOR VEGETATION ESTABLISHMENT

656.01Description

This Section shall cover the work of furnishing and placing mulching materials over the soil surface to provide protection from soil erosion and to aid in retention of soil moisture for vegetation establishment.

656.02Materials

Mulch materials shall be furnished in compliance with the requirements given in Article 860.03. A list of acceptable Hydraulic Mulch products, Mulch Control Netting and Tackifiers (List II-20, “TACKIFIERS, MULCH CONTROL NETTING, AND HYDRAULIC MULCH PRODUCTS”) is given in the ALDOT’s MSDSAR manual.

656.03Construction Requirements

Seeded areas shall be covered with mulch within 48 hours after seeding. Mulch shall be applied at the rates required below for the type of mulch used. Mulch shall be furnished to effectively control erosion and promote the establishment of vegetation. Dry blown mulch shall be stabilized by crimping, by the application of a tackifier adhesive, or by anchoring with a mulch control netting, with the following exceptions: crimping shall only be allowed on slopes 3:1 or flatter, and tackifier adhesive shall be required for applications within 10 feet {3 meters} of traffic. During crimping operations, care shall be taken to follow as closely as possible to the contours of the mulched surface. Crimping shall result in the mulch being securely lodged into the soil providing both erosion protection and promotion of vegetation establishment. Tackifier adhesive shall be applied at the rate recommended by the manufacturer. Hydraulic Mulch products shall be applied in accordance with manufacturer recommendations, typically in opposing directions to provide a solid blanket of mulch product. Hydraulic Mulches may be used within 10 feet {3 meters} of traffic as an alternate to dry blown mulch with tackifier adhesive. Hydraulic Mulches and tackifiers shall not be installed in areas subject to channelized flow or areas having a potential to flood during a local 2 year, 24 hour storm event.

Dry blown mulch shall be applied at a rate of not less than 2 tons per acre {4500 kg/ha}. Proof of material weight shall be provided to the Engineer by the Contractor upon delivery of the materials to the project site. The weight ticket shall contain all items required in Item 109.01(h)2. with the exception of the name of the producer and the truck number. Hydraulic Mulch products shall be applied at the rate designated by the manufacturer for the specific slope where they are being applied to provide a solid blanket of the mulch product with no soil showing. In no case shall the applied rate be less than 1 ton per acre {2250 kg/ha} for hydraulically applied mulches. The application rate will be verified by using the air dry weight {mass} per pound {kilogram} and dividing by the surface dimensions of the area covered.

Dry blown mulch shall be applied with a mechanical mulch spreader designed to break up balls or clusters of mulch. If a tackifier adhesive is used to secure the mulch, the mulch spreader shall be equipped to apply the adhesive effectively to the mulch to form a uniform, porous and stable mulch blanket held in place by the adhesive. The adhesive may also be applied hydraulically after mulch application. Crimpers shall be roller-type devices equipped with flat, uncupped, dull edged disks. The disks shall have a minimum width of 1/4 of an inch {6 mm} and shall be placed a maximum of 8 inches {200 mm} apart along the axle or shaft. Crimpers shall be specially designed so that by adding weight {mass} or using hydraulic force from the tractor the mulch will be imbedded a minimum of 2 inches {50 mm} into the ground. The diameter of the disks shall be large enough to prevent the axle or shaft from dragging or in any way disturbing the mulch or soil. Under no circumstances shall a disc harrow be used to perform the crimping operation. Hydraulic mulch application shall be performed using equipment designed for this purpose and that is in compliance with the recommendations of the mulch product manufacturer. ROLLED AND HYDRAULIC EROSION CONTROL PRODUCTS 551

656.04Method of Measurement

Mulch will be measured by the acre {hectare} of the finished surface dimensions of the area ordered treated.

656.05Basis of Payment

Mulch will be paid for at the contract unit price which shall be payment in full for materials, including tackifiers or mulch control netting (if used), equipment, tools and labor necessary to furnish, place and maintain the mulch. Payment for this work will be made upon satisfactory application of the mulching.

656-A Mulching - per acre {hectare} ROLLED AND HYDRAULIC EROSION CONTROL PRODUCTS

659.01Description

This Section shall cover the work of furnishing, installing, and maintaining Rolled Erosion Control Products (RECPs) and Hydraulic Erosion Control Products (HECPs). RECPs and HECPs will be referred to as “erosion control products” in this section. Areas to be covered by erosion control products (ECPs) will be shown on the plans or will be designated by the Engineer.

659.02Materials

Erosion control products shall be furnished in compliance with the requirements given in Article

860.11. A list of acceptable erosion control products (LIST II-11 "ROLLED AND HYDRAULIC EROSION

CONTROL PRODUCTS") is given in the ALDOT manual titled "Materials, Sources, and Devices with Special Acceptance Requirements". Information concerning the list and manual is given in Subarticle 106.01(f) and ALDOT-355 "General Information Concerning Materials, Sources, and Devices with Special Acceptance Requirements".

Erosion control products shall utilized as the final stabilization layer in conjunction with the required permanent vegetation.

Degradable ECP's shall be furnished to effectively control erosion and enhance the establishment of vegetation during a defined minimum period of time called "functional longevity". The Contractor shall be responsible for selecting approved ECPs with a functional longevity of sufficient duration to allow establishment of permanent vegetation prior to product degradation or as shown on the plans or as designated by the Engineer.

Permanent ECPs shall be furnished to effectively control erosion, enhance the establishment of vegetation, and permanently reinforce vegetation for applications where permanent vegetation alone will not provide sufficient protection against anticipated erosive forces.

ECPs will be specified based on the characteristics of the intended application site. The maximum slope or the maximum anticipated channel shear stress from the flow of water is given in the following table for each type of erosion control product. ROLLED AND HYDRAULIC EROSION CONTROL PRODUCTS 552

EROSION CONTROL PRODUCTS Product Application ECP Type Maximum Slope (H:V) Maximum Anticipated Channel Shear Stress1 (Pounds per Square Foot) Slope S4 4:1 - S3 3:1 - S2 2:1 - S1 1:1 - Channel C2 - 2.0 C4 - 4.0 C6 - 6.0 C8 - 8.0 C10 - 10.0 NOTE 1 (in the table of ECPs) : The approximate shear stress that an ECP would be exposed to in a channel may be calculated from the formula:  Approximate Shear Stress = g X D X S b  g = Unit weight of water: 62.4 pounds per cubic foot;  D = maximum expected depth of water in the channel (feet);  Sb = slope of bed in (feet per foot).

659.03Construction Requirements

The Contractor shall furnish the Type of ECP shown on the plans or designated by the Engineer. Unless shown otherwise on the plans, RECPs and HECPs may be used interchangeably if equivalent RECPs and HECPs are approved for use. The required Type of ECP shall not be changed without the written approval of the Engineer. Areas requiring rapidly degrading or no-net products will be shown on the plans. If the required Type of ECP is not available to be selected from List II-11, the Contractor shall furnish a more substantial ECP from List II-11 without additional compensation. (For example, if a Type S3 ECP is shown to be required on the plans, and there are no Type S3 products shown in List II-11, Type S2 or Type S1 will be an acceptable substitute. Similarly, if a Type C4 ECP is shown to be required on the plans, and there are no Type C4 products shown in List II-11, Types C6, C8 or C10 will be an acceptable substitute.)

Prior to placement of the ECP, the area shall have been prepared in accordance with the required ground preparation, fertilizing, seeding or other required treatment. It is important that the soil surface is smooth to ensure maximum surface area contact with the ECP.

The Contractor shall submit the ECP manufacturer's installation requirements, including staple patterns for rolled ECPs, to the Engineer before beginning the installation. The ECP shall be installed in accordance with the manufacturer's requirements unless directed otherwise by the Engineer. Rolled ECP typical installation shall be parallel to the direction of flow. There shall be an anchor trench at the top of the installation. Upstream RECPs shall overlap any downstream RECPs. Adjacent RECPS shall also be overlapped. Staples shall be placed on overlaps, at the toe of the RECP, and throughout the RECP installation to ensure the RECP is in contact with the underlying soil. Rolled ECPs that are soil-filled permanent turf reinforcement mats will require either a temporary rolled erosion control product or sod installed on the soil surface to prevent erosion until permanent vegetation is established. Hydraulic ECP typical installation shall be in opposing directions to provide a solid blanket of product. HECPs shall be applied by equipment that meets the recommendations of the product manufacturer. HECPs shall be applied at the rate designated by the manufacturer specific to the slope. The application rate will be verified by measuring the air dry weight {mass} per pound {kilogram} and