SEWER LINE MATERIALS
1. Ductile Iron Pipe
All ductile iron pipe shall be in accordance with AWWA C151- latest revision (ANSI A21.51) and shall be in 18 to 20 foot lengths with single rubber gasket (push-on) joints in accordance with AWWA C111-latest revision (ANSI A21.11). All 8-inch pipe will be minimum Class 50 in accordance with AWWA C150-latest revision (ANSI A21.50).
2. Polyvinyl Chloride Gravity Sewer Pipe (PVC)
a. PVC gravity sanitary sewer pipe and related fittings shall be manufactured in accordance with all the requirements of ASTM C3034, SDR 35, Type PSM polyvinyl chloride sewer pipe and fittings. PVC gravity sewer pipe may be used for 8 inch mains and shall be supplied in 12.5 foot lengths with bell-and-spigot joints. All fittings shall use rubber gaskets which conform to the requirements of ASTM F477.
3. 3. Pipe Fittings
DIP and PVC Pipe 4” in Diameter and Larger:
a. All fittings for DIP and PVC pipe shall be compatible with the pipe specified herein (meeting the specifications as included in the above pipe specifications and per ANSI/AWWA Specification A21.10/C110.
b. All fittings shall be cast or ductile iron and shall utilize mechanical joints in accordance with the requirements of ANSI/AWWA A21.11/C111. DIP in buildings, tanks and to a point 5 feet outside these premises shall be flange fitted unless mechanical joints are shown on the Drawings. Gaskets shall be plain rubber, of heavy section and high durometer, single molded. Lubricant used to facilitate assembly of joints shall be non-toxic, tasteless, odorless grease that will not support bacteria.
4. Steel Pipe
a. Steel pipe for aerial creek crossings or boring installations (without encasement and carrier pipe) shall be high strength steel, spiral welded or smooth-wall seamless manufactured in accordance with ASTM A139 and A283 and consisting of grade "B" steel with a minimum yield strength of 35,000 psi. On 8 and 10 inch pipe, the minimum wall thickness shall be 0.375 inches.
b. The outside of the pipe shall have one coat of zinc chromate primer conforming to Federal Specification TT-86a and afterwards painted with a compatible black paint.
c. Pipe ends shall be right-angled and shall be compatible to receive a "dresser style 62" - type I or approved equal mechanical transition coupler.
5. Steel Encasement Pipe
a. Steel encasement pipe shall be spiral welded or smooth-wall seamless, consisting of grade "B" steel with a minimum yield strength of 35,000 psi and manufactured in accordance with ASTM A139 and A283.
b. The pipe thickness shall be as required by the encroachment agreement obtained from the controlling agency, but in no case be less than 0.250 inches and the ends shall be beveled and prepared for field welding at the circumferential joints. Thicker encasement pipe may be required by the North Carolina Department of Transportation, Railroads and other agencies.
c. The pipe shall be coated inside and outside, in accordance with AWWA C203 or the N. C. Department of Transportation or the American Railway Engineering Association's specifications. All encasement pipe must be approved by the appropriate controlling agency (i.e. NCDOT, RR, etc.) prior to ordering the material.
d. If the encasement pipe is used to carry a sewer main, then a vent pipe shall be installed. The vent pipe shall be made from ASTM A139 and A283, grade "B" steel, with a minimum yield strength of 35,000 psi and coated as described above. The vent pipe location shall be approved by the appropriate agency prior to installation.
e. All carrier piping shall be slip joint ductile iron and the minimum inside diameter casing shall be 8 inches greater than the inside dimension of the carrier pipe as follows:
Carrier Pipe Steel Casing Pipe
Inside Diameter Minimum Inside Diameter
4 inch 12 inch
6 inch 14 inch
8 inch 16 inch
12 inch 20 inch
16 inch 24 inch
a. Manholes shall be D.O.T. certified. Manholes shall be manufactured in accordance with ASTM C478-80 and shall be precast with monolithic base and eccentric cone. All manholes will be 4'0" inside diameter with 5 inch walls or 5'0" with 6 inch thick walls and have a 6 inch minimum base.
b. All manholes over 10'0" deep (top rim to lowest point) shall be 5'0" diameter. All manholes with 21 inch or larger pipes will be 5'0". The standard joint shall be sealed with plastic cement putty meeting Federal Specifications SS-C-153. "O" ring joints shall conform to the requirements of ASTM C443. A neoprene rubber flexible boot shall be supplied with the manholes to tie the pipe to the barrel section. These boots and clamps shall meet the requirements of ASTM C923.
c. Manholes deeper than 3'0" shall have steps. Manhole steps will be press set plastic, or approved equal. Steps will also be provided on the outside of raised manholes when the top elevation is greater than 3 feet above the existing ground elevation.
d. All industrial dischargers shall provide a monitoring manhole easily accessible. All discharge from the property must pass through one monitoring manhole before entering the public sewer system.
7. Manhole Rings and Covers
a. Manhole frames and covers shall meet requirements of ASTM A-48 for Class 30 Gray Iron. Shall be Dewey Brothers MHRCR-2001 for all off-street locations and Dewey Brothers MHRCR-2001-EC for all in-street locations or approved equal. All covers will be perforated and marked "SEWER" unless otherwise required by the County or these specifications.
b. Manholes located in off-street locations shall be extended one foot above finished grade. Manholes in flood plains shall extend 2 feet above the 100-year flood elevations or be provided with sealed covers and vented.
8. Service Connections to Sewer System
a. Where sewer lines are already in place, the County will tap the sewer line. Where taps are made at the time of installation of the sewer, the following shall apply.
a.1 Where feasible, service connections shall be made into the nearest manhole. Connections into manholes shall be by cored holes into the manhole and the lateral shall be grouted watertight.
a.2 Where making a service connection directly to the main line, the following shall apply:
(a) On PVC, cut hole in pipe using appropriate saw, glue and clamp service saddle over hole.
a.3 The lateral shall be installed from the main line to the edge of the right-of-way or beyond the limits of pavement. The location of the end of the lateral shall be marked with a steel post painted yellow for easy identification. A clean out shall be installed as shown in Standard 22.
a.4 The service connection shall be located by distances from manhole to manhole. The distances shall be recorded on a reproducible medium and submitted to the County for their records or PVC.
a.5 Sewer laterals shall be a minimum of 4" diameter cast iron or PVC. Service grade bell and spigot.
a.6 Service saddles shall be cast iron. Service saddles shall be "Romac" catalog #CB 4.63 UN or approved equal.
B. SANITARY SEWER DESIGN CRITERIA
1. Sanitary sewer plans and specifications shall be sealed by a Professional Engineer, licensed to practice in North Carolina.
2. Minimum manhole depth shall be 4 feet.
3. Minimum pipe size shall be 8 inch diameter.
4. Minimum slope on an 8 inch pipe shall be 0.5%. Maximum slope shall be 15.0% on 8" pipe.
5. Minimum velocity shall be 2 fps.
6. Minimum cover shall be 3.0 feet, unless ductile iron pipe is used.
7. Maximum cover shall be 18 feet, unless ductile iron pipe is used.
8. Manholes in off-street locations shall be extended 1 foot (minimum) above finished grade.
9. Manholes shall extend 2 feet above the 100-year flood elevation or be sealed cover and vented 2 feet above the 100-year flood elevation. If the 100-year flood elevation cannot be readily established, the County shall establish the elevations to which the manhole rims or stack shall be extended.
10. Horizontal and vertical alignment between manholes shall be straight.
11. Provide .02 drop through each manhole.
12. Maximum distance between manholes shall be 400 feet.
13. Use drop manhole where difference between incoming and outgoing pipe inverts is 24" or greater.
14. Provide wye with lateral to the property line and plug for each lot in a subdivision. Provide metal post painted yellow extending at least 3 feet above ground to mark end of lateral.
15. Separate water lines 10 feet horizontal distance from sewer lines (existing or proposed) or keep water line 18 inches clear above sewer line. Where 18 inches clear vertically cannot be maintained below or above the sewer line, both lines shall be mechanical joint ductile iron a minimum of 10 feet on either side of the crossing. Center the crossing at the center of the pipe, both lines.
16. Sewer lines shall have a 25' permanent easement (12.5' each side of center line) in the County's name. A 50' construction easement (25' each side of center line, unless directed otherwise) shall be provided.
SANITARY SEWER PLANS CHECKLIST
Sanitary sewer plans shall contain the following minimum information:
1. Plan and profile on 24" x 36" page.
2. Vertical sea level elevation scale on left of profile and station numbers along bottom of profile.
3. North arrow, all sheets.
4. Plan and profile both run left to right.
5. Centerline intersections of line crossings with sewer noted on profile.
6. Street names above or below corresponding profile, when more than one street is on a page.
7. Identify location of drop manholes in both plan and profile.
8. Invert elevations of all proposed and all existing pipes and pipe sizes entering and leaving all manholes to 0.01' on profile.
9. Rim elevation and vent elevation to 0.1' on profile; existing and proposed grades.
10. Pipe grade to 0.01% and size and type of pipe between manholes.
11. Size and type of existing pipe and direction of flow between each manhole on plan.
12. Station numbers and designation of "Existing" or "New" on each manhole on plan and profile.
13. Indication of "identical" manholes where profile is broken.
14. Location and size of all existing and proposed street and sewer rights of way.
15. Existing pavement on plan, indicate width, and any portion to be cut.
16. Where a line is to be bored indicate location and length of casing and type of pipe on plan and profile.
17. All existing underground utilities in the area.
18. Where ductile iron is to be used, indicate limits on plan and profile. Show shaded on profile.
19. Use ductile iron where storm drain and sewer have less than 2 feet vertical clearance.
20. On aerial crossings, use concrete piers at 18' intervals, indicate on plans and profile, include details of design for the piers and anchorage.
21. Total distance between existing manholes or proposed manholes on the plan and the bearing if the line is not within the street right of way.
22. All lot lines.
23. All street names on plan.
24. Flood plain elevation in all flood plain areas.
25. Creek flow line.
26. All Railroad crossings must be accompanied by a separate encroachment map showing plan and profile and all other information required by the railroad in accordance with their standards.
27. Registered Engineer's seal and signature.
28. Vicinity map showing the location of lines and a visual index of plan sheets.