The Interstate Commerce Commission ordered a Dallas warehouse yesterday to pay nearly $4.5 million in penalties for what the commission said was an illegal rebate scheme that victimized both trucking companies and owner-operators.

According to Peter Shannon, director of the ICC's Bureau of Investigations and Enforcement, the T&N Lone Star Warehouse Co., of Lone Star, Tex., demanded illegal rebates from truckers who came to pickup steel pipe stored in the warehouse for delivery elsewhere.

The warehouse, Shannon said, would demand a $20 to $25 fee for loading the steel pipe with forklift. But that charge was never approved by the ICC.

Shannon said 22 trucking companies were victimized by the scheme, and 15 of them passed on the extra charges to owner-operators who they had contracted to do the work for them. Those trucking firms deducted the charge from the salaries they paid the drivers.

If, as expected, the warehouse refuses to pay, the case will be ahnded over to the Dallas U.S. Attorney for prosecution. Meanwhile, the ICC has asked the U.S. District Court in Tyler, Tex., to order the warehouse and trucking companies to stop the rebating practice.

In a separate announcement, the ICC said it has filed suit in U.S. District Courts in New York and New Jersey charging four interestate truckers and two freight forwarders with illegally withholding $2.5 million in overpayments from both shippers and receivers.The payments was part of a double-billing scheme, which involved billing a company twice and failing to return the second payment.

According to Shannon, the firms would hide the overpayments in various categories on their books, such as "unmatched cash," "unresolved items," and "unapplied revenue."

Among the companies apparently victimized by the double-billing practice were Chase Manhattan Bank, General Tire & Rubber and Whirlpool Corp.

The actions were filed against Acme Fast Freight, Inc., of Lake Success, N.Y.; A-P-A Transport Corp. of North Bergen, N.J.: Universal Carloading and Distributing Co. of New York City; Inland Express Inc. of Syracuse, N.Y.; Gilbert Carrier Copr. of Secaucus, N.J., and Cooper-Jarrett Inc., Morristown, N.J.

The ICC is asking restitution to customer-shippers who were overcharged.

In a third announcement, the ICC said it had, under the direction of Chairman Dan O'Neal, developed a new code of ethics for employes. The proposed Canons of Conduct cover everything from prohibited financial interests to misuse of information and future employment.