Halloween for the Dead by Timothy - Horror -  A night of trick or treating in a small Kansas town is interrupted by mutated dead soldiers who stagger the streets in search of human blood.  A nerd, fast food clerk, stripper, business-woman and cop join with a crazed army veteran to plan an escape.  114 pages - pdf, format

I like that you jump right into things, but already I'm a bit confused.  A news report says there's a chemical spill.  The next scene, there are hundreds of zombies.  So either those hundreds of zombies existed before the spill, or they are the result of the spill in which case you jumped WAY ahead in too short a time span.  Of course I'll find out as I read on -- and I will, because I'm a sucker for zombie scripts.

I do have an actual issue, though; namely in your choice of verb tense and some of the action/description being wordy.  To wit:

The grate is removed by a pair of gloved hands.
Four bags of blood plasma are placed in the shaft
and shoved forward by a broom.  A small live goat
is placed into the shaft and pushed forward by the
broom.

You want to use present tense verbs, and keep your actions concise and to the point, telling it as it happens/as we see it.:

A pair of GLOVED HANDS remove the grate.  They
place several bags of BLOOD PLASMA and an infant GOAT
into the shaft and push them forward with a broom.

This is exactly what you wrote, only less wordy and using the correct verb tense.  Of course the shortening of your action/descriptions and changing the verb tense take up less page space, which in turn will lower your page count.  114 pages/1hr 54 mins, unless you're George Romero, feels too long for a zombie script anyway.  Maybe aim for 100 pages/1hr 40 minutes.  The way you jump right into the story, that should be plenty.

I'll keep reading and provide more notes once I'm finished.

Best of luck.  Keep writing. -- Lon