WordPress sharing root namespace

I desire a wordpress installation to sit side-by-side a codeigniter application. I wish for them to have no interaction with each other. The problem is as follows.

My Server

assets
wordpress
codeigniter
index.php
.htaccess

I want wordpress to control the following

https://site.com/blog
https://site.com/blog/2011/09/hello-world/
https://site.com/blog/category/uncategorized/
https://site.com/blog/tag/untagged/

As well as my custom post type

https://site.com/portfolio
https://site.com/portfolio/2011/09/hello-world/
https://site.com/portfolio/category/uncategorized/
https://site.com/portfolio/tag/untagged/

I have got this working with custom post types as well as nesting wordpress within its folder and permalink delegation, all is good on wordpresses end. My problem is that I also want codeigniter to occupy the same root namespace and control some basic pages.

https://site.com/about
https://site.com/resume

What I initially set up was the index.php file to contain a series of conditionals that can delegate to load which application like this

if (0 === strpos($cache, '/blog') ||
    0 === strpos($cache, '/portfolio') ||
    0 === strpos($cache, '/feed')
){
    // include wordpress
}else{
    //include codeigniter
}

I originally had /blog and /portfolio and when I found out about /feed I panicked are there any other wordpress pages that can be compromised?
Is there a better way that this could be handled?