A. 
Sanitary sewerage refers to waste water derived from domestic, commercial and industrial pretreated waste to which storm, surface, and ground water are not intentionally admitted. Pre-treatment shall follow all the requirements as set forth by Washington State Department of Ecology (DOE) and the Langley Municipal Code.
B. 
Any extension of Langley's sanitary sewer system must be approved by the department of public works and must conform to the city of Langley comprehensive sanitary sewer plan, Department of Ecology (DOE), and Department of Health (DOH) requirements.
C. 
New construction within the corporate city limits is required to connect to the city sewer system as outlined in Title 18 and Ordinance 696 as they currently read or are hereafter amended.
D. 
Anyone who wishes to extend or connect to the city's sewer system should contact the department of public works for a sewer extension/connection fee estimate of the costs due the city for a sewer extension or connection.
E. 
Prior to the release of any water meters, or occupancy, all public works improvements must be completed, approved, as-built drawings submitted to the city and all applicable fees must be paid.
F. 
See Section 15.01.015 for definitions of specific sewers. Maintenance of the side sewer, from the main line tee to the building, shall be the responsibility of the property owner.
(Ord. 743, 1997)
If curbs are present, the location of all side sewers shall be marked on the face or top of the cement concrete curb with an "S" one-quarter inch into concrete.
(Ord. 743, 1997)
A. 
All surveying and staking shall be performed by an engineering or surveying firm capable of performing such work. The engineer or surveyor directing such work shall be licensed as such by the state of Washington.
B. 
A pre-construction meeting shall be held with the city prior to commencing staking. All construction staking shall be inspected by the city prior to construction.
C. 
The minimum staking of sewer lines shall be as directed by the city engineer or as follows:
1. 
Stake location of mainline pipe and laterals every 50 feet with cut to invert of pipe.
2. 
Stake location of all manholes for alignment and grade with cut or fill to rim and invert of pipes.
(Ord. 743, 1997)
Prior to acceptance and approval of construction, the following tests shall apply to each type of construction:
A. 
Gravity Sewer.
1. 
Prior to acceptance of the project, the gravity sewer pipe shall be subject to a low pressure air test per WSDOT/APWA Standards. The contractor shall furnish all equipment and personnel for conducting the test under the observation of the city inspector. The testing equipment shall be subject to the approval of the city.
The contractor shall make an air test for his own purposes prior to notifying the city to witness the test. The acceptance air test shall be made after trench is backfilled and compacted and the roadway section is completed to subgrade. The developer shall be responsible for paying city costs for inspections as set by council resolution.
All wyes, tees, and ends of side sewer stubs shall be plugged with flexible joint caps, or acceptable alternates, securely fastened to withstand the internal test pressures. Such plugs or caps shall be readily removable and their removal shall provide a socket suitable for making a flexible jointed lateral connection or extension. Immediately following the pipe cleaning, the pipe installation shall be tested with low pressure air.
2. 
Testing of the sewer main shall include a television inspection by the contractor. Television inspection shall be done after the air test has passed and before the roadway is paved. Immediately prior to a television inspection, enough water shall be run down the line so it comes out the lower manhole. A copy of the video tape and written report shall be submitted to the city. Acceptance of the line will be made after the tape has been reviewed and approved by the inspector.
3. 
A water test of all manholes may also be required. The water test shall be made by the contractor first by filling the manhole up with water and letting it sit for 24 hours to allow the water to saturate the concrete. After 24 hours the manhole shall be filled to the top of the cone. The water cannot drop more than 0.05 gallons in 15 minutes per foot of head above invert to pass. Upon completion of the water test, the water shall be pumped out of the manhole and not allowed to be released to the system.
4. 
A mandrel test may be required on all mainline sewers as defined in Section 15.01.015.
B. 
Force Main.
1. 
Prior to acceptance of the project, the pressure line and service lines shall be subjected to a hydrostatic pressure test of 200 pounds for four hours and any leaks or imperfections developing under said pressure shall be remedied by the contractor. No air will be allowed in the line. The main shall be tested between valves. Insofar as possible, no hydrostatic pressure shall be placed against the opposite side of the valve being tested. The pressure test shall be maintained while the entire installation is inspected.
The contractor shall provide all necessary equipment and shall perform all work connected with the tests. Tests shall be made after all connections have been made. This is to include any and all connections as shown on the plan. The contractor shall perform all tests to assure that the equipment to be used for the test is adequate and in good operating condition and the air in the line has been released before requesting the city to witness the test.
2. 
A water test for all wet wells in accordance with the manhole water test for gravity sewer shall be required.
3. 
A mandrel test in accordance with Section 7-17.3(2)G of the Standard Specifications is required.
4. 
Pump operation, alarms, and electrical inspection of all lift stations is required.
(Ord. 743, 1997)
A. 
The design of any sewer extension/connection shall conform to city standards, Department of Ecology's "Criteria of Sewage Works Design," and any applicable standards as set forth herein and in Sections 15.01.025 and 15.01.040.
B. 
The layout of extensions shall provide for the future continuation of the existing system as determined by the city.
C. 
Sewer systems shall be designed to current Department of Ecology standards.
D. 
The city of Langley general notes on sewer installation shall be included on any plans dealing with sanitary sewer design.
(Ord. 743, 1997)
A1. 
Size. Sewer mains shall be sized for the ultimate development of the tributary area. Nothing shall preclude the city from requiring the installation of a larger sized main if the city determines a larger size is needed to meet the requirements for future service.
The minimum size for submains and mains shall be eight-inch inside diameter. The minimum size for a side sewer in the right-of-way (from the sewer main to the property line) shall be six inches. See definitions in Section 15.01.015.
A2. 
Six-inch diameter lateral is required for all commercial or general business applications or for multifamily connections. The design is subject to all other design requirements as noted in this chapter.
B. 
Material. Sewer main shall be PVC, ASTM D 3034, SDR 35 with joints and rubber gaskets conforming to ASTM D 3212 and ASTM F 477.
C. 
Depth. Gravity sewer will typically have a minimum cover of five feet to provide gravity service to adjoining parcels, adequate head room within manholes for maintenance personnel and vertical clearance between water and sewer lines. Actual depth will be determined by slope, flow, velocity and elevation of existing system.
D. 
All building sewer connections to the main shall be made with a wye connection. All new mains connecting to existing mains shall require the installation of a new manhole if the connection is not made at an existing manhole. If a new connection is made at an existing manhole, the manhole shall be re-channeled per city standards and specifications.
(Ord. 743, 1997)
A. 
At connection to existing system, all new sewer connections shall be physically plugged until all tests have been completed and the city approves the removal of the plug.
B. 
Connection of new pipelines to existing manholes shall be accomplished by using provided knock outs. Where knock outs are not available, the manhole shall be core drilled for connection. The transition of connecting channels shall be constructed so as not to interrupt existing flow patterns.
C. 
Connection of a pipeline to a system where a manhole is not available shall be accomplished by pouring a concrete base and setting manhole sections. The existing pipe shall not be cut into until approval is received from the city.
D. 
Connections to manholes requiring a drop shall follow the criteria as outlined in Section 15.01.190.
E. 
Connections where a new building sewer is the same size as the existing main shall be accomplished by the installation of a new manhole.
F. 
Taps shall not be allowed to protrude into the existing main. A city inspector shall be notified 48 hours prior to any tap of a city sewer. A city inspector shall be present to witness the tap.
(Ord. 743, 1997)
A. 
Precast manholes shall meet the requirements of ASTM C 478 with either a precast base or a cast in place base made from 3,000 psi structural concrete. Manholes shall be Type 1, 48-inch diameter minimum. The minimum clear opening in the manhole frame shall be 24 inches. Joints shall be rubber gasketed conforming to ASTM C 443 and shall be grouted from the inside. Lift holes shall be grouted from the outside and inside of the manhole. Manholes constructed of other materials may be approved by the city engineer, provided they meet the requirements of Section 2.318 of the Department of Ecology's "Criteria for Sewage Works Design." Material specifications need to be submitted for review before an alternate material will be considered.
B. 
Eccentric manhole cone shall be offset so as not to be located in the tire track of a traveled lane.
C. 
Manhole frames and covers shall be cast iron casting marked "Sewer" conforming to the requirements of ASTM A 30, Class 25, and shall be free of porosity, shrink cavities, cold shuts or cracks, or any surface defects which would impair serviceability. Repairs of defects by welding or by the use of smooth on or similar material will not be permitted. Manhole rings and covers shall be machine finished or ground on seating surfaces so as to assure nonrocking fit in any position and interchangeability. Manholes located in areas subject to inflow shall be equipped with a PRECO sewer guard watertight manhole insert or approved equal.
D. 
Where lock type castings are called for, the casting device shall be such that the cover may be readily released from the ring and all movable parts shall be made of noncorrosive materials and otherwise arranged to avoid possible binding.
E. 
All castings shall be coated with a bituminous coating prior to delivery to the job site.
F. 
Safety steps shall be fabricated of polypropylene conforming to an ASTM D 4101 specification, injection molded around a one-half inch ASTM A 615 grade 60 steel reinforcing bar with anti-slip tread. Steps shall project uniformly from the inside wall of the manhole. Steps shall be installed to form a continuous vertical ladder with rungs equally spaced on 12-inch centers.
G. 
Gravity sewers shall be designed with straight alignment between manholes.
H. 
Manholes shall be provided at a maximum of 300-foot intervals where six-inch sewer is allowed, 400-foot intervals for eight-inch to 15-inch sewers, 500-foot intervals for 18-inch to 30-inch sewers, at intersections, and at changes in direction, grade or pipe size. (See also Section 15.01.180.) Greater spacing may be permitted in larger sewers.
I. 
Minimum slope through the manhole shall be one-tenth of one foot from invert in to invert out.
J. 
Manhole sizing shall be determined by the following criteria:
1. 
Forty-Eight-Inch Manhole.
a. 
Two connecting pipes, eight-inch to 12-inch diameter.
b. 
Three connecting pipes, eight-inch to 10-inch diameter, perpendicular.
c. 
Four connecting pipes, eight-inch diameter, perpendicular.
2. 
Fifty-Four-Inch Manhole.
a. 
Two connecting pipes, eight-inch to 12-inch with more than 45 degrees deflection.
b. 
Three connecting pipes, 10-inch to 12-inch diameter, perpendicular.
c. 
Four connecting pipes, 10-inch to 12-inch diameter, perpendicular.
3. 
Seventy-Two-Inch Manhole.
a. 
Two connecting pipes, 15-inch to 18-inch diameter with less than 45 degrees deflection.
b. 
Three connecting pipes, 15-inch diameter, perpendicular.
c. 
Four connecting pipes, 15-inch diameter, perpendicular.
4. 
In the above criteria "deflection" refers to the angle between any two pipe channels in the manhole. For other pipe configurations, the size of the manhole shall be approved by the city. The above configurations will provide adequate shelves and room for maintenance and performing TV inspections.
(Ord. 743, 1997)
A. 
All sewers shall be designed and constructed to give mean velocities, when flowing full, of not less than 2.0 feet per second based on Manning's formula using an "n" value of 0.013. Use of other practical "n" values may be permitted by the city if deemed justifiable on the basis of research or field data submitted. The following minimum slopes should be provided; however, slopes greater than these are desirable.
Sewer Size (Inches)
Minimum % Slope
% (Feet per 100')
6
1.00 (0.0100 Ft/Ft)
8
0.40 (0.0040 Ft/Ft)
10
0.28 (0.0028 Ft/Ft)
12
0.22 (0.0022 Ft/Ft)
14
0.17 (0.0017 Ft/Ft)
15
0.15 (0.0015 Ft/Ft)
16
0.14 (0.0014 Ft/Ft)
18
0.12 (0.0012 Ft/Ft)
21
0.10 (0.0010 Ft/Ft)
24
0.08 (0.0008 Ft/Ft)
27
0.07 (0.0007 Ft/Ft)
30
0.06 (0.0006 Ft/Ft)
36
0.05 (0.0005 Ft/Ft)
B. 
Under special conditions, slopes slightly less than those required for the 2.0 feet per second velocity may be permitted by the city engineer. Such decreased slopes will only be considered where the depth of flow will be 0.3 of the diameter or greater for design average flow. Whenever such decreased slopes are proposed, the design engineer shall furnish with the plans his computations of the depths of flow in such pipes at minimum, average, and daily or hourly rates of flow. Larger pipe size shall not be allowed to achieve lesser slopes.
C. 
Sewers shall be laid straight and true with uniform slope between manholes.
(Ord. 743, 1997)
A. 
Manholes shall be provided where pipe size changes occur.
B. 
Where a smaller sewer joins a larger one, the invert of the larger sewer should be lowered sufficiently to maintain the same energy gradient. An approximate method for securing these results is to place the 0.8 depth point of both sewers at the same elevation.
(Ord. 743, 1997)
Where velocities greater than 15 feet per second are expected, special provisions such as thrust blocking and piping materials shall be made to protect against displacement by erosion and shock.
(Ord. 743, 1997)
A. 
Straight grades between invert out of last manhole and connection to existing are preferred over drops whenever possible. Care must be taken when designing steep grades or sweeps so as not to create a situation of excessive velocity. Grade changes associated with "sweeps" shall not be allowed unless otherwise approved by the city engineer.
B. 
An outside drop connection shall be provided for a sewer entering a manhole at an elevation of 24 inches or more above the manhole invert. Where the difference in elevation between the incoming sewer and the manhole invert is less than 24 inches, the invert shall be filleted to prevent solids deposition. Outside drop structures shall be constructed per city of Langley standard drawings.
C. 
Inside drop connections will not be allowed.
(Ord. 743, 1997)
A. 
Cleanouts are not an acceptable substitute for manholes. A manhole shall be installed at the end of any public sewer extension.
B. 
Location of cleanout for building sewer is governed by the Uniform Plumbing Code as adopted by the Langley Municipal Code.
C. 
All cleanouts in city right-of-way shall be extended to grade and have a cast iron ring and cover. A three-foot-square by four-inch concrete pad shall be installed around all cleanouts that are not in a pavement area. The concrete pad shall be sloped to drain away from the cleanout.
(Ord. 743, 1997)
A side sewer refers to the extension from a building sewer beginning two feet outside the outer foundation wall at the structure to the sanitary sewer main. Side sewers from the sewer main to the right-of-way line shall be minimum six-inch diameter on single-family residences, multifamily and commercial buildings. Side sewers from the right-of-way line to the building shall be minimum four-inch for single-family residential and six-inch for multifamily and commercial buildings. Minimum slope shall be two percent on four-inch side sewers and one percent on six-inch side sewers. Maintenance of the side sewer is the responsibility of the property owner. Prior to connection of a side sewer to the public sewer a side sewer permit must be obtained from the city. Materials and design criteria for a side sewer are covered by the Uniform Plumbing Code (UPC) as adopted by the city of Langley. Inspection of the side sewer installation and test will be done by the public works department inspector. Testing shall be performed by the contractor. The side sewer test shall consist of either a water or air test at four psi for 15 minutes. It is the contractor's responsibility to contact the city 24 hours in advance of test.
(Ord. 743, 1997)
A. 
The design of any lift station shall conform to city standards, the Department of Ecology's "Criteria of Sewage Works Design" and applicable standards as set forth herein and in Sections 15.01.025 and 15.01.040. In addition, the plans shall include the following:
1. 
An overall site drawing of the lift station showing the location of all components including elevations;
2. 
Service size, voltage and enclosure type and location in relation to the pump station;
3. 
A list of specific materials used including quantity, description and manufacturer name;
4. 
A schematic and line diagram of the service and motor control center and lift station;
5. 
The electrical shall be designed to meet state and local electrical code requirements;
6. 
All applicable telemetry installation with schematics; and
7. 
An operation and maintenance manual from the lift station manufacturer shall be supplied.
8. 
A lift station emergency bypass connection shall be installed.
B. 
A design report shall be submitted with each lift station demonstrating conformance with the standards as outlined above and shall address the following items:
1. 
Pump Data.
a. 
Size and type (no variable speed pumps allowed);
b. 
Horsepower;
c. 
Pump curves;
d. 
Head capacity;
e. 
Velocity.
2. 
Motor.
a. 
Size and type;
b. 
Cycle length;
c. 
Type of mount.
3. 
Controls: type.
4. 
Telemetry: alarm system (must be compatible with city system).
5. 
Housing.
a. 
Size and type;
b. 
Ventilation;
c. 
Humidity control;
d. 
Interior lighting;
e. 
Access.
6. 
Auxiliary power: provision for connection required of all lift stations and may be required to furnish auxiliary generator at the direction of the city.
7. 
Well Sizing.
a. 
Type;
b. 
Storage capacity.
8. 
Maintenance.
a. 
Warranty;
b. 
Tools and equipment required.
9. 
Electrical Service.
a. 
Size and type;
b. 
Source.
10. 
Corrosion Protection.
a. 
Type of materials;
b. 
Coatings;
c. 
Linings;
d. 
Maintenance.
11. 
Site layout: location of lift station on property, right-of-way or easement.
12. 
Testing.
a. 
Operational;
b. 
Pressure.
13. 
Piping and Valves.
a. 
Size and type;
b. 
Bypass.
See Sections 15.01.215 through 15.01.250, Pressure Sewer, for additional information regarding force mains.
(Ord. 743, 1997)
A. 
The design of any sewer extension/connection shall conform to city standards, the Department of Ecology's "Criteria of Sewage Works Design," and any applicable standards as set forth herein and in Sections 15.01.025 and 15.01.040.
B. 
The layout of extensions shall provide for the future continuation of the existing system as determined by the city. In addition, main extensions shall be extended through the side of the affected property fronting the main.
C. 
The system shall be designed at full depth of flow on the basis of an average daily per capita flow. A friction factor of 0.013 shall be used for Manning's "n" value.
D. 
New sewer systems shall be designed by methods in conjunction with the basis of per capita flow rates. Methods shall include the use of peaking factors for the contributing area, allowances for future commercial areas, and modification of per capita flow rates based on specific data. Documentation of the alternative method used shall be provided along with plans.
E. 
The applicable general notes shall be included on any plans dealing with pressure sanitary sewer design.
(Ord. 743, 1997)
A. 
Material. Force mains for sizes up to 12 inches shall be ductile iron AWWA C151 Class 50 or PVC C900 with ductile iron fittings and gasketed joints. For 14- to 24-inch mains, pipe shall be ductile iron AWWA C151 Class 50 or PVC C905 with ductile iron fittings and gasketed joints. A more rigid pipe may be required where unlimited trench widths occur. All ductile iron pipe and fittings shall be epoxy coated or PE lined and designed for use with corrosive materials.
B. 
Depth. Force mains shall have a minimum 36 inches of cover to top of pipe. See Section 15.01.370 for sanitary sewer/water main separation requirements.
C. 
Velocity. The minimum velocity allowed is two feet per second (fps) at average dry weather flow. Two fps is required to maintain solids in suspension although three fps is desired to scour settled solids. Maximum velocity allowed shall be eight fps.
(Ord. 743, 1997)
PVC is subject to fatigue failure due to cyclic surge pressures. Systems utilizing PVC pipe materials shall be constructed to minimize rapid changes in velocities and a properly sized surge tank provided.
(Ord. 743, 1997)
Air release valves and air/vacuum valves shall be located at the high points of the line within a standard 48-inch manhole or a comparable sized, approved vault. Air release valves shall be fitted with an activated carbon canister to absorb compounds with disagreeable odors prior to releasing the air to the surrounding area. Grades shall be designed to minimize the need for air/vacuum valves when practical. Vehicular access to valve is required for maintenance.
(Ord. 743, 1997)
Provisions to drain a force main to facilitate repairs or to temporarily remove force main from service shall be provided. This may be accomplished through the use of a valved tee connected to a drain line at the low point of the line. A manhole shall be set over the force main at the valved tee.
(Ord. 743, 1997)
A. 
Location of thrust blocking shall be shown on plans. Thrust block concrete shall be poured against undisturbed earth. A plastic barrier shall be placed between all thrust blocks and fittings.
B. 
Designed and approved restraining joint systems may be allowed in lieu of thrust blocking. Restraining joint brand, type, and size shall be specified on the plans.
(Ord. 743, 1997)
Hydrogen sulfide odors (H2S) and the buildup of sulfuric acid (H2SO4) occur in the operation of a force main. To mitigate these conditions some type of control method(s) shall be used. This may include chemical addition at the pump station and/or the re-aeration of the waste water at or near the terminus. Re-aeration may include the following:
A. 
Construction of a vault housing an aspiration assembly.
B. 
The use of hydraulic fall (vertical siphon) within the terminal manhole.
C. 
High velocity discharge with smooth transition so as to not cause splashing of force main into the down stream gravity sewer.
These methods all require an adequate source of fresh air at the vault or manhole. At a minimum, the manhole at the terminus and the first manhole downstream of the terminus shall be coated with Tnemic 120 vinyl ester, Quantum polymorphic resin or approved equal which is resistant to sulfuric acid and hydrogen sulfide.
(Ord. 743, 1997)