A wall form $12\text{'}$ high is filled with $150$lb per cu ft concrete at a temperature of $70$ degrees F$.$ the concrete is type $1$ without retarder. concrete will be placed with normal internal vibration to a depth of less than $4\text{'}.$ the rate of placement is $5$ ft per hour. calculate the lateral pressure per sqft on the forms and diagram at what depth below the top that the lateral pressure will occur.