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PEI IMA Grade 9 study materials
PEI IMA Grade 9 study resources

PEI IMA Grade 9: Building and Structure Design

PEI IMA Grade 9 · Work through your exam, one topic at a time.

All guide sections

Building and Structure Design

Building and Structure Design (Domain 1) tests the physical envelope around the fuel system: island and canopy layout, tank foundations and anchorage, secondary containment structures, and the separation distances that keep dispensers away from buildings, property lines and ignition sources. Expect plan-view and section-view questions that require you to turn NFPA 30, NFPA 30A and PEI RP100/RP200 provisions into dimensions, elevations and details.

Site layout and separation

  • Dispensers sit on raised concrete islands, typically 6–8 in above paving, protected by bollards or a raised curb; bollards must sit outside the hose swing so a hose cannot snag.
  • Distances from dispensers to important buildings, property lines and public ways come from the NFPA 30A tables plus local amendments; the site-specific table on the approved plan governs the field condition.
  • Canopy drainage and dispenser-sump drainage must be directed to a controlled point, never to a storm sewer without an oil/water separator.

Tank support and anchorage

  • USTs bed on at least 12 in of pea gravel or sand, free of rock; backfill is placed and compacted in lifts so the shell is uniformly supported. Point loads crack steel and deform FRP.
  • An empty tank floats. Where the water table can rise above the tank bottom, hold-down straps, deadmen or ballast are designed for the empty condition, not the full one.
  • ASTs sit on ringwalls, saddles or engineered pads; steel saddles use wear pads so the shell can expand.

Dikes and containment structures

  • Dike capacity equals the volume of the largest tank plus freeboard for precipitation.
  • Walls and liners must be liquid-tight and compatible with the product; penetrations need sealed sleeves, and a dike must not be drained by a valve that can be left open.

Worked example

A vertical AST holds 20,000 gal inside a 40 ft × 30 ft dike. Tank volume = 20,000 ÷ 7.48 = 2,674 ft³. Dike area = 1,200 ft², so product depth = 2,674 ÷ 1,200 = 2.23 ft. Add 0.5 ft freeboard → 2.73 ft, so specify a 2 ft 9 in wall. Size for one tank even when the dike holds two, but confirm no piping can carry product out of the diked area.

Traps

  • Omitting freeboard, or using a building wall as a dike (it is not liquid-tight).
  • Checking buoyancy against a full tank instead of an empty one.
  • Placing bollards inside the hose path, or letting a canopy downspout discharge onto the island.