I ended up using a GET method and got rid of add_query_arg() function
$homezip = $_GET["search"];
<form action="local-concert-listings/" method="get">
<input id="address" size="6" type="text" placeholder="Zipcode" name="zipcode"/>
<div style="display:none;">
<input id="volume" size="1" name="miles" value="70" placeholder="70"></input>
</div>
<input type="submit" value="go" name="SubmitButton" onclick="codeAddress()" />
</form>