Lee Young has looked into the disaster planning on record for New Orleans. Here is what he writes:

With the scope of the disaster becoming more evident with each passing hour, the critique of this event will undoubtedly focus on whether there has been a failure in planning or execution ..... or both ..... or that the cost of preparing for a natural disaster of this type is financially prohibitive or exceeds a pre—disaster cost /benefit ratio. The attached excerpts from the City of New Orleans Emergency Plan clearly identifies significant responsibility for local officials. Did city officials educate the residents of New Orleans about the provisions of the plan? Does this plan take into account the socio—economic/special needs of the residents? Did the city open special needs shelters provided for in the plan? Was the mandatory evacuation ordered soon enough?

This disaster has been forecast for decades so there will be plenty of blame for all levels of government ..... much like the 9/11 Commission Reported following that catastrophe ..... the devastation was predictable. 

Excerpts City of New Orleans Emergency Plan [With emphasis added]

Message from Mayor C. Ray Nagin

Dear Parish Residents,

The safety and well—being of the citizens of New Orleans is my greatest priority. For this reason, our Office of Emergency Preparedness has prepared this Guide to help individuals during times of natural or man—made disaster ...... Our City, due to its central gulf location, is one of the most vulnerable in America to the furies of a hurricane. Heavy rains, because of our topography, can and do cause severe flooding ..... This, our second annual update, serves that purpose. But, like any good tool, it is useless unless read and acted upon. Its place is not on a shelf gathering dust, but in an easily accessible family emergency kit where it can be used ......
Sincerely,

C. Ray Nagin
Mayor

EMERGENCY PLAN.....
..... The Office of Emergency Preparedness is responsible for the response and coordination of those actions needed to protect the lives and property of its citizens from natural or man—made disasters as well as emergency planning for the City of New Orleans. Our primary responsibility is to advise the Mayor, the City Council and Chief Administrative Officer regarding emergency preparedness activities and operations. We coordinate all city departments and allied state and federal agencies which respond to city—wide disasters and emergencies through the development and constant updating of an integrated multi—hazard plan. All requests for federal disaster assistance and federal funding subsequent to disaster declarations are also made through this office.....

Hurricane protection levees have been built in many coastal communities, especially the New Orleans area, to protect life and property from storm surge. While these levees do a very good job in protecting communities during minimal hurricanes, sophisticated computer modeling of storm surge effects indicate most levees in southeast Louisiana would be overtopped from the storm surge generated by a direct strike by a major hurricane. The result would be widespread flooding......

Even if you live behind hurricane protection levees, you may be asked to evacuate, as most levees can be overtopped by the storm surge generated from a powerful hurricane's direct strike....

..... CATEGORY 4. EXTREME DAMAGE
More extensive curtain wall failures with some complete roof failure on homes occur. Major damage is caused to lower floors of homes and businesses from storm surge flooding. Terrain continuously lower than 15 feet above mean sea level is flooded.

CATEGORY 5. CATASTROPHIC DAMAGE
There is complete roof failure of many homes and businesses as well as complete building failure of many small structures. Major storm surge flooding to lower floors of buildings located less than 20 feet above mean sea level occurs.

..... MANDATORY EVACUATION
This is the final, most serious phase of evacuation. Authorities will put maximum emphasis on encouraging evacuation and limiting entry into the risk area. The State Office of Emergency Preparedness, State Police, State Department of Transportation and The Louisiana National Guard will assume coordination and responsibility for traffic control on all major evacuation routes .....

Additional Guideline for Persons with Disabilities .....

Before the Disaster
There are several important things that can be done in order to reduce the effects of a disaster:

1. Make sure you have a support system in place.
2.Complete your individual personal assessment and prepare your individual disaster plan.
3. Gather the supplies you will need before, during and after a disaster. Make sure the supplies are specific to your disability.
4. Make sure your residence is as safe as possible in the event of an emergency.
Remember, preparedness must begin with you.

Support System
A support system, sometimes called the 'buddy system,' can help you prepare for a disaster as well as during and after a disaster. Members of your support system, or 'buddies', can be roommates, relatives, neighbors, friends, and co—workers. They should be people you trust to determine if you need assistance. Your support system members should know your capabilities and needs, and be able to help in a matter of minutes.

1. Have your 'buddies' assist you in preparing a written personal assessment.
2. Give your support system copies of your emergency information list, medical information list, disability related supplies and special equipment list, evacuation plans, any emergency documents and your personal disaster plan.
3. Arrange for your support system to check on you immediately if local officials give an evacuation order or if a disaster occurs.
4. Agree on the methods of communication to be used during a disaster.
5. Give your 'buddies' any keys they need for your place of residence or vehicle.
6. Make sure your support system knows how to operate and transport any equipment specific to your disability. Make sure it is labeled and laminated instruction cards are attached.
7. If you have a service animal, insure that the animal is familiar with your support system members and have written instructions on any care the animal may require.
8. Review and update your personal assessment and disaster plan with your support system on a regular basis. 'Practice your plan'.

Special Needs Shelter Plan

City of New Orleans Comprehensive Emergency Management Plan

I. PURPOSE

The shelter is intended for individuals who have no other resources and who need assistance that cannot be guaranteed in a regular shelter, i.e. medication that requires refrigeration, oxygen equipment, etc.The Special Needs Shelter (SNS) will only be activated by the Mayor of New Orleans or his designee.Entrance into the SNS does not relieve any individual of the responsibility for their own care.Admission into the Shelter is NOT TO BE INTERPRETED AS A GUARANTEE OF SAFETY, and the City of New Orleans is not assuring anyone protection from harm within the facilities that are being offered or opened for this purpose.

It is critical that everyone understands that this shelter will not be able to substitute for the comforts of the individuals' homes, and that all equipment and special furniture, which are normally used, may not be able to accompany them.It is recommended that all persons with special medical needs and/or their responsible family members develop a viable plan for transportation out of the community to a community that will be able to give long term assistance.The potential exists that New Orleans could be without sufficient supplies to meet the needs of persons with special considerations, and there is significant risk being taken by those individuals who decide to remain in these refuges of last resort.The plan is intended to identify the mechanics of establishing a SNS and when it shall be activated.

There's much more at the link.