Virginia Law

A. The following factors shall be considered in providing adequate separation of water mains and sanitary sewers:

1. Materials and types of joints for water and sanitary sewer mains;

2. Soil conditions;

3. Service branch connections into the water main and sanitary sewer mains;

4. Compensating variations in the horizontal and vertical separations;

5. Space for repairs and alterations of water and sanitary sewer mains;

6. Offsetting of pipes around manholes; and

7. Identification of the physical restraints preventing normal separation.

B. Parallel installation of water mains and sanitary sewers.

1. Under normal conditions, water mains shall be laid at least 10 feet horizontally from a sanitary sewer or sewer manhole. The distance shall be measured edge-to-edge.

2. Under unusual situations when local conditions prevent a horizontal separation of 10 feet, the water main may be laid closer to a sanitary sewer or sewer manhole provided that:

a. The bottom (invert) of the water main shall be at least 18 inches above the top (crown) of the sanitary sewer;

b. Where this vertical separation cannot be obtained, the sanitary sewer shall be constructed of water distribution pipe and pressure tested in place in accordance with 12VAC5-590-1110 and 12VAC5-590-1140;

c. The department may approve concrete encasement of the water main or other physical barrier;

d. The sewer manhole shall be of watertight construction and tested in place; and

e. No water pipes shall pass through or come into contact with any part of a sewer manhole.

C. Crossing of water mains and sanitary sewers.

1. Under normal conditions, water mains crossing sanitary sewers shall be laid to provide a separation of at least 18 inches between the bottom of the water main and the top of the sanitary sewer whenever possible.

2. Under unusual situations when local conditions prevent a vertical separation described in subdivision C 1 of this section, the following construction shall be used:

a. Sanitary sewers passing over or under water mains shall be constructed of the materials described in subsection B of this section and shall be constructed to a point 10 feet beyond and on each side of the crossing; and

b. Water mains passing under sanitary sewers shall, in addition, be protected by providing:

(1) A vertical separation of at least 18 inches between the bottom of the sanitary sewer and the top of the water main;

(2) Adequate structural support for the sanitary sewers to prevent excessive deflection of the joints and the settling on and breaking of the water main; and

(3) That the length of the water main be centered at the point of the crossing so that joints shall be equidistant and as far as possible from the sanitary sewer.

D. The minimum horizontal separation distance between water mains and septic tanks and drainfields, measured edge-to-edge, shall be 10 feet. Greater separation distances shall be provided wherever practical.

E. Water mains shall be located a safe horizontal distance from sources of contamination not already mentioned in this section, such as sewage treatment works and industrial complexes. The owner's engineer shall contact the department to determine the safe separation distances.