PennDOT Pub 408 Section 851: Outlet Protection: Rock

851.1DESCRIPTION—This work is construction of a rock outlet protection of the type indicated. This work

includes the maintenance and removal of temporary outlet protection as indicated.

851.2MATERIAL—

(a)Rock, Class as required. Section 850.2(a)

(b)Geotextiles, Class 4, Type A, for the type required. Section 735

(c)Grout. Section 601.2(c)

851.3CONSTRUCTION—As shown on Standard Drawings, as specified in Section 850.3, and as follows:

(a)Rock Basin. Control flow of surface water runoff as needed. Excavate below final grade as required,

install geotextile, and backfill with rock of the class indicated. If required, after rock is in place, saturate the rock with water, then completely fill the voids between pieces with grout, for at least the top 6 inches, and sweep the surface with a stiff broom. Do not place grout if the air temperature is below freezing. In hot, dry weather, protect grouted rock from excessive heat and keep moist for at least 3 days after grouting, using saturated burlap.

(b)Rock Energy Dissipator. Control flow of surface water runoff as needed. Excavate below final grade as

required, install geotextile, and backfill with rock of the class indicated. Make appropriate connection to downstream receiving watercourse as indicated. If required, after rock is in place, saturate the rock with water, then completely fill the voids between pieces with grout, for at least the top 6 inches, and sweep the surface with a stiff broom. Do not plac e grout if the air temperature is below freezing. In hot, dry weather, protect grouted rock from excessive heat and keep moist for at least 3 days after grouting, using saturated burlap.

(c)Rock Apron. Control flow of surface water runoff as needed. Excavate below final grade as required,

install geotextile, and backfill with rock of the class indicated. If required, make appropriate connection to downstream receiving watercourse as indicated.

(d)Riprap Basin. Control flow of surface water runoff as needed. Excavate below final grade as required,

install geotextile, and backfill with rock of the class indicated. Make appropriate connection to downstream receiving watercourse as indicated.

(e)Temporary Installations. Remove rock and geotextile from temporary outlet protection as indicated.

Stockpile rock used in temporary installations on site if necessary before permanent installations. Reuse rock for permanent outlet protection as indicated.

(f)Maintenance. Maintain outlet protection until the project has been completed. Remove excessive

sediment and repair or replace washed out areas to restore outlet protection functionality.

851.4MEASUREMENT AND PAYMENT—

(a)Rock Basin. Each

(b)Rock Energy Dissipator. Each

(c)Rock Apron. Square Yard

(d)Riprap Basin. Square Yard

(e)Temporary Installations. Each

Referenced in this section

Sections that cite this one

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Source: Publication 408 Highway Construction Specifications, 2026 Edition. Pages 778–0 of 1,522. View official source ↗

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850 ROCK LINING

852 PAVED ENERGY DISSIPATOR

851OUTLET PROTECTION: ROCK

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