871SEDIMENT TRAP - RISER

871.1DESCRIPTION—This work is the construction, maintenance, and removal and/or conversion of riser

type sediment trap to a permanent stormwater management facility.

871.2MATERIAL—

other approved material of adequate size and length.

• Rock. Section 850.2(a)

• Geotextile. Class 4, Type A. Section 735

871.3CONSTRUCTION—As shown on the Standard Drawings, at the location indicated or directed, and

as follows: As specified in Section 201.3, clear and grub the storage area and embankment foundation area site. Excavate the key trench for the full length of the embankment (when located in permanent stormwater management facility) . Install the outlet protection, outlet pipe with the anti -seep collar attached (where indicated), and outlet structure at the location indicated. When indicated, construct the temporary riser pipe assembly, as specified in Section 874.3. When a concrete anti -seep color is specified, construct collar as specified in the applicable parts of Section 1001.3. When the sediment trap is located in a permanent stormwater management facility and a concrete outlet structure is indicated, construct concrete outlet structure as specified in Section 875.3. Construction of the embankment before placing the pipe is not required. Do not use coarse aggregate as backfill material around the pipe. Backfill the pipe with suitable embankment material to prevent embankment leakage along the pipe. Construct outlet protection of the type indicated at outlet end of pipe, as specified in Section 851.3. Place the embankment material, as specified in Section 206.3. When required, obtain borrow excavation for the formation of the embankment, as specified in Section 205. Apply seeding and soil supplements, as specified in Section 804.3. Mulch, if required, as specified in Section 805.3. Install and maintain cleanout stake as required, as indicated, or as directed. Inspect sediment trap after each runoff event to assure that it continues to function properly. Remove accumulated sediment as specified in Section 861.3 and repair as required or as directed. When the tributary area to the sediment trap is stabilized or the sediment trap is no longer required, or if otherwise directed, satisfactorily recondition the site as follows:

• Temporary Sediment Trap: Fill in excavated areas, removing embankments, riser pipe assemblies, outlet pipe, and anti -seep collars, or as directed . Restore the areas as specified in Section 105.14. Satisfactorily dispose of removed materials.

• Sediment Trap located in a Permanent Stormwater Management Basin area: Remove accumulated sediment and restore sediment trap to final basin contouring as indicated, stabilize disturbed areas as indicated, remove temporary orifice covers, temporary stand pipes, affix permanent stormwater management features as specified in Section 875.3, as indicated, or as directed. Satisfactorily dispose of removed materials.

871.4MEASUREMENT AND PAYMENT—

For the type indicated.

For the type indicated.

Section 205.4

For the type indicated.

For the type indicated.

For the type indicated.

Section 850.4

Section 212.4