the present invention is a collection assembly comprising a container , a cap assembly removably and sealably secured to the container whereby access to the interior of the container can be made with a piercing element without removing the cap assembly from the container . the cap assembly includes a cap body and a membrane like septum supported by the cap body . the septum provides for a pierceable element to have access to the interior of the container . the membrane is a thermoplastic elastomer and is self - sealing upon removal of the piercing element .