San Francisco County Municipal Code Ch. 10 Traps and Interceptors

The building sewer or building drain shall have a building trap placed as near as

possible to the curb line or immediately inside any subsidewalk basement wall under the sidewalk. Trap size shall be a minimum of 4 inches (101.6 mm). SECTION 1008.0 – BUILDING TRAPS

Building traps shall not be installed except where required by the Authority Having Jurisdiction. Each building trap where

installed shall be provided with a cleanout and with a relieving vent or fresh-air intake on the inlet side of the trap. [ ← ] Such trap shall have a fresh air inlet of not less than 4 inch (101.6 mm) diameter pipe. The inlet shall be covered by an approved perforated plate not less than 16 square inches (10,323 mm2). Perforations shall be not more than 3/8 inch (9.6 mm) diameter and provide an aggregate open area of not less than one-half the cross-sectional area of the sewer trap. The air inlet shall be connected to the building side of the trap and shall lead to the open air, terminating at a point not less than 10 feet (3.05 m) from any window or door. SECTION 1016.0 – SAND INTERCEPTORS

1016.3.1 When drains are provided for planter boxes, such drains shall enter into the sanitary or storm drainage plumbing system by discharging into an approved sump, receiving tank or sand settling tank. No trap shall be installed between the planter box and any approved receptor. Sizes of drains shall conform to Table 703.2. Catch basins or sumps to drain surface water or collect subsoil drainage shall meet the following requirements: (1) The catch basin or sump shall be poured in place, and all sides and bottom shall be watertight. (2) A removable metal grill approved for applied design loads shall be placed on top with a screen to prevent mosquito breeding. (3) Each catch basin shall be served with its own trap and cleanout, and shall connect to the storm or sanitary system independently. (4) If inlet is located below the building sewer or drain, a sump pump minimum of 1-1/2" (38.1 mm) outlet may be used. The bottom of sump shall maintain a 1' - 0" (304.8 mm) distance from the inlet, creating a 1' - 0" (304.8 mm) sand trap. (5) If the depth of the sump is over 5' - 0" (1.52 m) a larger catch basin shall be required with a permanent ladder securely bolted to the interior to provide access for maintenance. A minimum clear space of 30" × 30" (762 mm × 762 mm) shall be provided. (6) A listed and approved plastic catch basin may be installed in areas of residential buildings that are not subjected to any vehicular traffic and shall be installed on a concrete base to prevent settling, provided all other code requirements of this section and the listing and installation requirements of such catch basin are met. Chapter 11

STORM DRAINAGE SECTION 1101.0 – GENERAL 1101.2.1 Add the following section: 1101.2.1 Leaders, Connection to Drain. All storm water or casual water from roof areas, balconies, lightwells, courtyards or similar areas which total more than 200 square feet (18.4 square meters) aggregate shall drain or be conveyed directly to the building drain, or building sewer, or to an approved alternate location based on approved geotechnical and engineering designs. Such drainage shall not be directed to flow onto adjacent property or over public way, including sidewalks. The opening of the leader shall meet the same requirements asSection 1103.0 of the California Plumbing Code. 1101.2.2 Add the following section: 1101.2.2 Temporary Provisions. When the stormwater sewer is not yet installed, the building stormwater drainage system may discharge into the sewer on the street side of the main trap as near to the curbline as possible. 1101.2.3 Add the following section: 1101.2.3 Temporary Provisions Drain Trap. When, under the provisions of Section 1101.2.2 the building stormwater drainage system discharges to the sewer, a trap shall be placed in that drain at a point near where it branches into the sewer. The trap shall be supplied with clean water by an approved means such as a hose bibb or trap primer.