859SEDIMENTATION POND

859.1DESCRIPTION—This work is construction of a dam to impound water in a storage area.

859.2MATERIAL—

• Embankment. Section 206.2(a)

• Seeding and Soil Supplements. Section 804.2

• Mulch. Section 805.2

• Class A Cement Concrete. Section 704

• Corrugated Metal Pipe. Section 601.2(a)4.b or (a)4.c

• Reinforcement. Section 709.1

• Steel Plate. Section 1105.02

• Welding Material. Section 1105.02(t)

859.3CONSTRUCTION—As shown on the Standard Drawings 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 dam. Excavate the emergency spillway in natural ground. Install the pipe spillway, with the anti-seep collar attached, at the location indicated. Construct the concrete footing for the riser pipe, as specified in the applicable parts of Section 1001.3. Construction of the embankment and trench 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 dam leakage along the pipe. Construct rock basin at outlet end of pipe, as specified in Section 851.3(a). Place the embankment material, as specified in Section 206.3. If required, obtain borrow excavation for the formation of the embankment, as specified in Section 205. Apply seeding and soil supplements, as specified in Section

804.3Mulch, if required, as specified in Section 805.3

When the sedimentation dam is no longer required, or if otherwise directed, satisfactorily recondition the site by filling in excavated areas, and by removing embankments, riser pipe assemblies, corrugated metal pipe, and anti -seep collars. Restore the are as as specified in Section 105.14. Satisfactorily dispose of removed materials.

859.4MEASUREMENT AND PAYMENT—

Section 203.4

Section 601.4(a).

Section 205.4.