Hi John,
I'm just a rookie at this but I will tell you what worked for me. Maybe it will work for you also.
I created an anchor just above my captcha area using your example: <a id="valid"></a>
Then double click on the WA Server Validations in the Server Behaviors panel to reopen the Server Validations: Insert window, at the bottom for Failed redirect: I entered: mypagename.php#valid this is the name of the page with the validations.
You also have to make the modifications suggested by Jason above. For me this code was at line 83
Dennis