12 Va. Admin. Code § 5-590-875

Current through Register Vol. 40, No. 22, June 17, 2024

Section 12VAC5-590-875 - Direct filtration

A. Direct filtration is defined as a series of treatment processes, including coagulation and filtration but excluding sedimentation. Direct filtration shall be considered only for treatment of high quality and seasonally consistent surface water sources or GUDI sources.

B. An in-plant demonstration study or pilot study shall be required to demonstrate acceptable performance of direct filtration. The study shall be conducted over a sufficient time to treat all expected source water conditions throughout the year. The pilot plant filter shall be of a similar type and operated in the same manner as proposed for full-scale operation.

C. The department may require presedimentation meeting the requirements of 12VAC5-590-865 C to be provided (in the treatment sequence) to direct filtration treatment plants.

D. Rapid mix coagulation and flocculation shall be provided, meeting the requirements of 12VAC5-590-871.

E. Filters shall be dual media or multimedia gravity filters. Design of filtration units shall meet requirements for rapid rate or high rate gravity filters in 12VAC5-590-874, including filter structure, filter media, support gravel, backwash provisions, rate-of-flow control, surface wash, or air scour. Alternative designs may be considered by the department.

F. Turbidity monitoring.

1. Indicating and recording turbidimeters meeting the requirements of 12VAC5-590-770 B shall be provided for:

a. The source water;

b. The filter effluent from each filter; and

c. The CFE.

2. Finished water indicating and recording turbidimeters shall be considered if chemical softening occurs following filtration.

G. Where automatic unit process control is provided, manual override of all automatic features shall be provided.

1. Automatic start-up of treatment plant unit processes is prohibited.

2. Valve actuators shall be provided with manual override capability.

H. The plant design should allow for the future installation of sedimentation basins.

12 Va. Admin. Code § 5-590-875

Derived from Virginia Register Volume 37, Issue 20, eff. 6/23/2021.

Statutory Authority: §§ 32.1-12 and 32.1-170 of the Code of Virginia.