Biblatex --- how to add colon after volume?

Question

How does one place a colon after the volume and before the page range for articles?

\documentclass{memoir}

\usepackage{biblatex}

\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}
@Article{Reference:1994,
  author =   {First I. Last, and Second Y. Author},
  title =    {This is the article title},
  journal =  {T Journal T},
  journallongtitle =     {The Journal Title},
  year =     1994,
  volume =   50,
  pages =    {30--40}
}
}
\end{filecontents}

\addbibresource{\jobname.bib}

\nocite{*}

\begin{document}

\printbibliography

\end{document}

Answer 1

The following works with either the default numeric or with the authoryear style but really only makes sense with the authoryear style since in the numeric style, the year comes after the volume. The punctuation before the pages is controlled by the macro \bibpagespunct.

\begin{filecontents}{\jobname.bib}
@Article{Reference:1994,
  author =   {First I. Last, and Second Y. Author},
  title =    {This is the article title},
  journal =  {T Journal T},
  journallongtitle =     {The Journal Title},
  year =     1994,
  volume =   50,
  number = 6,
  pages =    {30--40}
}
\end{filecontents}

\documentclass{article}
\usepackage[style=authoryear]{biblatex}
\addbibresource{\jobname.bib}
\renewcommand*{\bibpagespunct}{\addcolon\space}
\begin{document}
\autocite{Reference:1994}
\printbibliography
\end{document}

Answer 2

This solution will add the colon only for journal articles (which is the only place you would want this, I believe). I've also removed the "In:" and "pp.", which I think are unusual solutions.

\documentclass{article}
\usepackage[style=authoryear]{biblatex}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@article{myarticle,
    AUTHOR = "John Doe",
    TITLE = "My article",
    JOURNALTITLE = "A Cool Journal",
    VOLUME = "16",
    PAGES = "18--56",
    YEAR = "2005"}
@incollection{mycontrib,
    AUTHOR = "Peter Smith",
    TITLE = "My contribution",
    BOOKTITLE = "A collection of articles",
    EDITOR = "John Carpenter",
    YEAR = "2010",
    LOCATION = "London",
    PAGES = "685--764"}
\end{filecontents}
\addbibresource{\jobname.bib}
\renewcommand{\bibpagespunct}{\ifentrytype{article}{\addcolon\addspace}{\addcomma\addspace}}
\DeclareFieldFormat[article,incollection]{pages}{#1}
\renewbibmacro{in:}{\ifentrytype{article}{}{\printtext{\bibstring{in}\intitlepunct}}}
\begin{document}
\nocite{myarticle,mycontrib}
\printbibliography
\end{document}