CHAPTER 200 STORM SEWER CONSTRUCTION STANDARDS

Transcription

1 CHAPTER 200 STORM SEWER CONSTRUCTION STANDARDS Storm Sewer System: 1. Detention/retention of stormwater runoff shall be provided in accordance with the requirements of the DuPage County Countywide Stormwater and Floodplain Ordinance and the Village of Lombard Ordinances and requirements. Side slopes of a detention/retention facility shall be no greater than three feet horizontal to one foot vertical (3:1) or four feet horizontal to one foot vertical (4:1) on a residentially zoned lot. If the minimum slope cannot be achieved, than a structurally engineered retaining wall shall be incorporated into the design of the detention/retention facility. Embankments or excavations adjacent to public right-of-way shall comply with 605 ILCS 5/ As a minimum: A. The storm sewer system shall be designed to convey stormwater from a 10- year storm by gravity flow (without any surcharging of the sewer). The Design Engineer shall provide necessary plans and calculations (including hydraulic grade line) to document compliance with this requirement to the satisfaction of the Private Engineering Services Division. B. Where a proposed storm sewer or stormwater drainage system connects to an existing sewer or drainage system, the Design Engineer shall furnish any and all studies and calculations to demonstrate to the satisfaction of the Private Engineering Services Division that the existing system has the capacity to accommodate the additional flows without adversely affecting the existing system or other properties. This requirement may include, but is not limited to, hydraulic and hydrologic studies of the entire tributary watershed, not simply the proposed development. Where a storm sewer system is intended to drain additional areas, the studies and calculations shall include all tributary areas. Future development shall be allowed for in the calculations and a proposed development will not be allowed to use up the remaining capacity of a sewer where other undeveloped tributary areas have no other reasonable stormwater outlet.

2 SECTION LINE AND GRADE A proposed development shall adjust (reduce) the allowable release rate based on the capacity of the receiving sewer available to the development. All storm sewer pipe and structures shall be constructed to the planned line and grade. All storm sewer systems shall be designed and constructed at a minimum cleansing velocity of three (3) feet per second. SECTION MATERIALS All materials and methods shall conform to the applicable minimum standards established by the American Society for Testing Materials. All storm sewers shall be constructed of reinforced concrete culvert pipe (RCCP) and meet the requirements of Section 550 of the IDOT "Standard Specifications for Road and Bridge Construction", latest edition. Polyvinyl Chloride (PVC) pipe may be used in landscaped areas or for roof drain connections (from the building to the nearest available downstream storm structure) when located under a privately maintained paved areas, but only when approved in writing by the Private Engineering Services Division. SECTION PIPE CULVERTS THROUGH DRIVEWAYS Precoated fully-lined galvanized corrugated steel pipe may be used for residential driveway crossings only when a ditch section is present. Reinforced concrete culvert shall be used for commercial and industrial driveway crossings only when a ditch section is present. Pipe culverts shall meet the requirements of Section 542 of the IDOT Standard Specifications for Road and Bridge Construction, latest edition. SECTION TRENCH BACKFILL IN PAVED AREAS All trenches for storm sewers located under or within two feet of proposed or existing paved surfaces, stabilized shoulders, curb, or sidewalks, shall be fully backfilled with select granular material conforming to the requirements of Section 208 of the IDOT Standard Specifications for Road and Bridge Construction, latest edition, except that the gradation of the material shall be CA-7 from the spring line of the pipe to 12 below the bottom of the pavement. From 12 below the bottom of the pavement to the top of the trench it shall be CA-6. No recycled concrete will be allowed. Selected granular backfill shall be placed in uniform layers not exceeding twelve (12) inches (loose measure) and compacted with mechanical equipment to 95% of the standard proctor CHAPTER PAGE 2. 1

3 density in accordance with the applicable AASHTO or ASTM requirements. For pipe bedding requirements, See Section (A). SECTION CONSTRUCTION REQUIREMENTS A) PIPE BEDDING Granular pipe bedding material or granular cradle shall be required on all storm sewers. Granular pipe bedding shall be a minimum of six (6) inches thick. The trench shall be backfilled with granular material, CA-7 gradation, to the springline of the pipe. (See Standard Detail STORM 11) B) PIPE COVER All culverts, storm drain, and sewer pipe shall be of proper type and class for the depths intended and shall have a minimum cover of two (2) feet. For additional clarification see IDOT "Standard Specifications for Road and Bridge Construction", latest edition. C) HANDLING OF PIPE Storm sewer pipe shall be handled in a manner that will prevent damage. Damaged or defective material on the job site shall be rejected and replaced to the satisfaction of the Private Engineering Services Division. Methods of construction conducive to the damage of the pipe shall be corrected when called to the attention of the contractor. SECTION STORM SEWER STRUCTURES A) STRUCTURES IN NON-PAVED AREAS Only inlet type structures or structures without sumps shall be permitted in nonpaved areas. (See Standard Detail STORM 1 & 2) During construction, silt boxes or filter baskets shall be staked or installed in place at each structure to prevent debris and foreign material from entering the sewer system. They shall be maintained until vegetation has matured enough to prevent erosion. (See Standard detail STORM 14) B) INVERTS OF STRUCTURES CHAPTER PAGE 2. 2

4 All structures without sumps shall be provided with a precast or cast-in-place concrete fillet to provide a smooth flow between pipe sections. (See Standard Detail STORM 1 & 2) C) SEALING OF STRUCTURES A continuous layer of non-hardening preformed bituminous mastic material (Rub- R-Nek, EZ Stick, or equal as approved by the Private Engineering Services Division) shall be applied to each structure barrel, cone top section and adjusting ring to provide a watertight seal. No hydraulic cement shall be applied above the cone section or flat top and between frame and structure/rings. D) MANHOLE ASSEMBLIES Manholes are to be constructed with steps and a cone or flat top assembly with an opening offset from center. (See Standard Detail STORM 1 & 13) E) PIPE CONNECTIONS All storm sewer pipe to pipe connections shall be sealed with butyl mastic or preformed flexible, gasket type (ASTM C-443) to ensure water tightness. Lifting holes shall be plugged with a preformed polyethylene plug. The plug shall be manufactured by POPIT Inc., Levittown, Pennsylvania. For more details: POPIT Inc., 922 S. Woodbourne Road, PMB #333, Levittown, PA 19057, Phone: , Fax: , Product available through the following area companies: Welch Brothers Inc. Concrete Specialties, Inc Graham Street 900 W. 9 th Street Bartlett, IL Lockport, IL Phone: (847) Phone: (815) Fax: (847) Fax: (815) For new construction, changes in pipe materials between structures shall not be allowed unless approved in writing by the Private Engineering Services Division. At no time shall connections between the storm sewer systems and sanitary sewer systems be allowed. F) MORTAR COLLARS All pipe section connections to storm structures shall be shaped, both inside and outside the storm structure, with additional mortar to provide a three (3) inch collar around the pipe. (See Standard Detail STORM 1, 2, 3, & 4) G) CONNECTION FOR DRAIN AND/OR FIELD TILE CHAPTER PAGE 2. 3

5 All storm water drains or field tiles encountered during construction shall be connected to the storm drainage system. The location of known field tiles shall be depicted on the final engineering plans. The connection point of all field tiles to the storm drainage system shall be shown on the As-built record drawings for the storm sewer system. H) MANHOLES Manholes shall be located at the junction of two (2) storm sewer pipes or at any change of grade, alignment or size of pipe. The maximum spacing of manholes shall be three hundred (300) feet for storm sewers. I) MANHOLE APPURTENANCES The following items shall apply to all manhole structures: a. Manhole shall be furnished with a self-sealing frame and solid cover (Neenah Foundry R-1772-C, East Jordan Iron Works , or equal approved by the Private Engineering Services Division) with the word Storm imprinted on the cover in raised letters. b. Both the manhole frame and cover shall have machined horizontal and vertical bearing surfaces. Inverted manhole frames are not allowed. c. Pick holes shall not create openings through the manhole cover. d. Manholes located in areas subject to inundation shall be furnished with waterproof, bolt-down frames and covers (Neenah Foundry R-1916-C East Jordan Iron Works PT or equal approved by the Private Engineering Services Division. e. Manhole frames shall be adjusted to proper grade utilizing rubberized adjusting rings or reinforced, precast concrete rings. Brick, metal shims or concrete blocks shall not be allowed. f. All manhole frames and adjusting rings shall be securely sealed to the cone section or top barrel section of the manhole using resilient, flexible, non-hardening, preformed, Butyl Mastic (Rub R Nek, EZ Stick, or equal as approved by the Private Engineering Services Division). This mastic shall be applied in such a manner that no surface water or ground water inflow can enter the manhole through gaps between the top barrel section or cone section and the first adjusting ring, between adjusting rings, or between the last adjusting ring and the manhole frame. Up to twelve (12) inches of adjusting rings may be installed on a given manhole. Concrete CHAPTER PAGE 2. 4

6 SECTION ADJUSTMENTS rings must be at least 3 thick. No more than three (3) adjusting rings in total shall be used. g. A continuous layer of non-hardening, preformed bituminous mastic material (Rub R Nek, E Z Stick or equal, as approved by the Private Engineering Services Division) shall be applied to each manhole barrel, cone, and top section to provide a watertight seal. h. A non-shrink hydraulic cement or Portland cement mixture shall be used on all manhole interior joints. No mortar shall be applied above the cone section or flat top. i. Only plastic polymer steps shall be used. j. Manhole steps on a maximum sixteen (16) inch center shall be furnished with each manhole, when required and specifically called out, securely anchored in place, and true to vertical alignment, in accordance with the Lombard Standard Detail STORM 13. k. Hydraulic cement, mortar, and concrete must be of strength and water tightness quality per ASTM Standards. l. All manholes shall be thoroughly cleaned of dirt and debris and all visible leakage eliminated before final inspection and acceptance. In no instance shall a structure be constructed entirely of adjusting rings. When adjustments are necessary, a minimum of two tapered rubberized adjusting rings shall be used for final adjustment. Concrete rings must be at least 3 thick. Recycled rubber rings may be used. Maximum height of adjustment is 12 inches. A maximum of 3 rings (all rubber and /or rubber and concrete mix) rings will be allowed. The rings shall be set in a bed of preformed non-hardening mastic (Rub-R-Nek or approved equal). In landscape areas, concrete adjusting rings shall be mortared inside and outside of the joints. In non-landscaped areas, mortaring on the outside of the concrete adjusting rings shall not be required. In all locations non-preformed mastic (for cones, flat tops, or rings) or manufacturer approved adhesive/sealant (for rubber, high density expanded polystyrene with polyuria coating or expanded polypropylene products) shall be used. Under no circumstances shall frames be set to grade using miscellaneous construction material. (See Standard Storm Detail 7 & 8) SECTION CHAPTER PAGE 2. 5

7 OPEN CUTTING OF PAVEMENT Open cutting of pavement is not allowed without a permit from the Private Engineering Services Division. SECTION CONNECTION TO EXISTING FACILITIES Prior approval from the Private Engineering Services Division shall be received before connections are made to any existing storm sewer. SECTION CLEANING Prior to acceptance, the storm sewer system shall be cleaned and operational to the satisfaction of the Private Engineering Services Division. SECTION END SECTIONS Storm sewer outlet structures (i.e. end sections, flared end sections, box inlets) with an opening greater than twelve (12) inches in diameter, shall be covered with a grate whose openings are three (3) inch horizontal by eight (8) inch vertical and which is rakeable. (See Standard Detail STORM 12) All flared-end sections shall have additional hydraulic cement to provide a three (3) inch collar around the connection to the pipe. CHAPTER PAGE 2. 6