Business has been slow at the Blonde Tulip, a quaint flower shop in the Mayfair in Coconut Grove, so Pearl Meyer figured she could boost earnings by adding a coffee bar. She was stunned when Miami-Dade County denied her a permit for a new sink.

“It’s frustrating,” said Meyer. “We’ve been dealing with the permit process for six months, and this was just the latest hang up.”

Meyer is not alone. The Blonde Tulip’s was one of 12 permit applications to add a sink, toilet or shower in Coconut Grove that have been denied since August, when the county put a moratorium on any new sewage outflow to the main pump station that serves the neighborhood.With higher-than-average summer rains seeping into the county’s aging pipe system, and more raw sewage flowing through than it was designed to handle, Pump Station #9 has reached capacity. Hence the moratorium, which stands to pinch the pocketbooks of everything from small businesses like Meyer’s to large developments, like a planned overhaul of West Coconut Grove.

The county says work is already under way to repair the aged facility at 2202 SW 26th Lane and will continue for 18 months. The cost could exceed $1 million.

But the moratorium represents the first immediate negative consequence of the county waiting too long to fix its aging sewage system and water treatment plants.

“This is the biggest job killer that will hit our neighborhood for the next 10 years,” said Marc Sarnoff, vice chairman of the Miami City Commission. “Restaurants that could open in CocoWalk are going to go to Midtown or Miami Beach.”

Added Miami-Dade Mayor Carlos Gimenez: “Yes, it has a direct impact on economic activities in Dade County. We’re facing capacity issues; we know that.”

Gimenez stressed that in most of the 12 cases — the county said it could not immediately provide the names of all the businesses affected — the county’s Regulatory and Economic Resources Department is working to help the shop owners. The management of Mayfair, for instance, proved that the center has empty stores, clearing the way for other establishments to add sinks, showers or drains without a net increase in outflow.

The problems stem from a decades-old sewer system with crumbling pipes and water treatment plants badly in need of renovation and replacement. They are in such bad shape that the U.S. Justice Department, Environmental Protection Agency, and Florida Department of Environmental Protection sanctioned the county in May, saying it was not abiding by the federal Clean Water Act.

The parties have been negotiating for a resolution. Immediate repairs for 13,000 miles of piping and six water treatment plants could reach about $1.4 billion, though Water and Sewer Department Director John Renfrow recently said the county needs a 12-year, $12 billion overhaul.

The problem in Coconut Grove is the first anyone can recall from that pump station since the last time the feds visited in 1993, when they mandated that the facility run a maximum of 10 hours a day. The county ultimately signed a consent decree and paid a $2 million fine.

“This reflects atrocious planning on the part of the county,’’ said first-term Miami-Dade Commissioner Xavier Suarez, whose district includes Coconut Grove. He wants repair work to start as soon as possible.