How Drawing Review Caught 5 Conflicts on an Oklahoma City 911 Center

A 911 Center, EOC, and Fire Station in Oklahoma City's Tornado Zone

An architect was finishing the drawings for a public safety center in Oklahoma City: a 911 call center, an emergency operations center, police space with holding cells, and a fire station apparatus bay.

Every part of that program raises the bar. The building is an essential facility that has to keep working through the disaster it exists to respond to, and Oklahoma City sits in the highest tornado wind zone in the building code. The structure, the shelter, the power, and the security spaces all carry requirements an office building never sees.

The architect wanted the drawings checked against the code analysis, the specs, and the owner's program before the set went out for bid.

Helonic Found Risk Category II Design Criteria on a Risk Category IV Building

The architect uploaded the PDF set, the specifications, and the owner's program. Helonic compared the code analysis and structural notes with each other, and the architectural, MEP, fire protection, and civil drawings with the specs and the program.

The first finding was an unprotected storm shelter envelope. The building code requires 911 call centers, emergency operations centers, and police and fire stations in the highest tornado wind zone, which includes Oklahoma City, to include a storm shelter built to the ICC 500 standard. The code analysis on G-002 designated the dispatch and EOC area as the shelter, and the wall types showed reinforced concrete walls and roof there.

Mechanical ducts, outside air louvers, and exhaust openings penetrated the shelter envelope with no impact-protected assemblies. The door hardware schedule listed standard hollow metal doors and frames at the shelter entrances. The spec required tested storm shelter assemblies, and the drawings did not show them.

Storm shelter assemblies are tested products with lead times, and a shelter with an unprotected opening does not meet code. Found at inspection, the fix is replacing doors and frames and adding protected penetrations through finished concrete. That was priced at $150,000 to $500,000 with 6 to 16 weeks of delay. Fixed before bid, it was $3,000 to $10,000.

The second was a risk category mismatch. The code analysis classified the building as Risk Category IV, the highest, because it is an essential facility. That category drives higher wind loads, higher seismic importance factors, and stricter anchorage for mechanical and electrical equipment. The structural general notes on S-001 listed design wind speeds and importance factors for Risk Category II, a standard office building.

The structure, roof deck attachment, curtain wall, and rooftop equipment anchorage were all designed to a lower standard than the code requires for this building, and the MEP anchorage specs referenced the lower category too. That makes it a design-wide problem: members, connections, roof attachment, and equipment supports may all need revision.

Caught in design, it is a recalculation. Caught after steel is ordered, it is reinforcement and replacement across the building. That was priced at $300,000 to $1.5 million with 6 to 16 weeks of delay. Fixed before bid, the redesign was $10,000 to $40,000.

The third was apparatus bay exhaust clashing with doors and heaters. The apparatus bay on A-102 had 14-foot-wide overhead doors with high-lift tracks. The spec required a source-capture vehicle exhaust system with overhead rails above each bay, so diesel exhaust is captured as trucks start and leave. Mechanical showed gas-fired radiant tube heaters along the bay, and fire protection showed sprinkler mains across it.

The exhaust rails, door tracks, radiant heaters, and sprinkler mains all occupied the same 3 to 4 feet below the roof structure. The radiant heaters also need clearance to combustibles and to the exhaust hoses.

Exhaust capture protects firefighters from diesel exposure, a well-known occupational cancer concern, so it cannot be value-engineered out. Rerouting after installation means rehanging heaters, rails, and sprinkler mains in a bay that is probably already holding trucks. That was priced at $40,000 to $150,000 with 1 to 3 weeks of delay. Fixed before bid, it was $1,000 to $5,000.

The fourth was emergency power short of the program. The spec section 26 32 13 and the owner's program required the 911 center and EOC to run on generator power for 72 to 96 hours, with redundant N+1 generators so one can be serviced or fail without losing power. The electrical one-line on E-601 showed a single generator, and the civil and mechanical drawings showed a fuel tank sized for about 24 hours.

The drawings delivered no redundancy, a third of the required fuel, and no space for a second generator pad or paralleling switchgear. A 911 center that loses power during a tornado outbreak is the failure the building exists to prevent.

Adding a second generator, paralleling gear, and a larger fuel tank after the site and electrical rooms are built means new pads, new switchgear, and new underground work, with long equipment lead times. That was priced at $400,000 to $1.2 million with 16 to 40 weeks of delay. Fixed before bid, it was $5,000 to $15,000.

The fifth was holding cells drawn like ordinary rooms. The detention equipment spec section 11 19 00 required detention-grade doors and hardware, security glazing, stainless steel detention plumbing fixtures, tamper-resistant electrical devices, and ligature-resistant security grilles. Mechanical sheet M-201 showed standard ceiling diffusers and return grilles in the cells, plumbing showed standard fixtures, and electrical showed standard devices.

Every discipline drew the cells like ordinary rooms. Detention-grade items also need different rough-in: secure plumbing chases, different grille mounting, and secure access panels.

Holding areas cannot be used until they meet security and safety standards, and retrofitting means opening finished walls and ceilings in the most secure part of the building. Detention equipment also has long lead times. That was priced at $50,000 to $200,000 with 4 to 10 weeks of delay. Fixed before bid, it was $2,000 to $5,000.

See government and civic drawing review, Oklahoma City plan check, ASCE 7-22 wind and seismic changes, generator and emergency power coordination, ductwork routing conflicts, code compliance checks, and the California K-12 review.

$940,000 to $3.55 Million in Field Rework Fixed for $21,000 to $75,000

Helonic flagged all five before the set was issued for bid, while each fix was still a drawing or calculation revision.

Fixed at that stage, the five came to $21,000 to $75,000. Found in the field, the same five were priced at $940,000 to $3.55 million.

The risk category finding reached the most of the building, and the emergency power finding carried the longest delay. Both go to whether the building can do its job during a storm.

The shelter doors, the generator, and the holding cells each fell short of a spec section or program requirement the drawings never picked up. Across 1,000+ drawing packages Helonic has reviewed, about 6 in 10 sets with specifications had at least one conflict between the drawings and the project manual. See what Helonic found across 1,000+ drawing reviews.

ICC 500 Storm Shelters, Risk Category IV, and Essential Facility Design in Oklahoma City

Oklahoma adopts the International Building Code statewide through the Oklahoma Uniform Building Code Commission, and Oklahoma City enforces it with local amendments.

The IBC requires 911 call stations, emergency operations centers, and fire, rescue, ambulance, and police stations to include a storm shelter where the shelter design wind speed for tornadoes is 250 mph, which covers Oklahoma City. The shelter is built to ICC 500, which requires every opening in the shelter envelope, including doors and ventilation openings, to use assemblies tested for wind pressure and debris impact.

The IBC assigns essential facilities to Risk Category IV. Under ASCE 7, that category uses the highest design wind speeds, a seismic importance factor of 1.5, and stricter design for the anchorage of mechanical and electrical components. A structural general note that lists Risk Category II criteria changes every load downstream of it.

The International Agency for Research on Cancer classifies diesel engine exhaust as carcinogenic to humans, which is why fire stations specify source-capture exhaust in the apparatus bay.

Emergency and standby power is installed under the National Electrical Code. The runtime and N+1 redundancy for a 911 center usually come from the owner's program, so the drawings have to carry them even where the code minimum is lower.

“Our code analysis said Risk Category IV; our structural notes were still using Risk Category II wind speeds. Helonic flagged it before we issued for bid. On an essential facility, that's a mistake that touches every part of the building.”

Oklahoma City Public Safety Center Review: Questions and Answers